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YANG He-Shu, SUN Jun-Xiao, YANG Hui-Jun, FAN Qi-Xue, YUAN Yong-Chao
 Available online   , doi: 10.7541/2021.2020.197
[Abstract](0) [FullText HTML](0) [PDF 892KB](0)
High protein content in feed easily leads to nutrient imbalance in feed, reduces the efficiency of digestion and utilization of nutrients in fish, and increases the discharge of pollutants in aquaculture. This not only increases feed cost, but also easily causes water environment pollution. Reducing feed protein level can effectively reduce ammonia nitrogen emission in animal feces, but it may lead to the degradation of animal production performance. Supplementation of restricted amino acids can improve the protein utilization rate of animals and also reduce the nitrogen emission in the breeding process. Yellow catfish (Pelteobagrus fulvidraco) is a benthic small economic fish with a large aquaculture yield. This experiment with yellow catfish hybrid larvae as the research object, explore the supplemental methionine and lysine of low protein feed for yellow catfish hybrid larvae growth performance, body composition, transaminase activity and the influence of antioxidant capacity, to cross the yellow catfish hybrid nutrition requirements and related research, and health breeding to provide theoretical basis and reference. In this study, five experimental diets were formulated and have three protein levels as 42% (control), 37% (LP1) and 32% (LP2). Use the control diet as standard, formulate other two low-protein diets (37% and 32%) and supplementation with lysine and methionine (LP1+AA and LP2+AA). Each diet was fed to triplicate groups of fish for 8 weeks, and the initial weight of fish is (0.96±0.01) g. At the end of the experiment, the growth performance, body composition, transaminase activity and antioxidant capacity of yellow catfish hybrid were measured. The results showed that: Compared with the control group, (1) the weight gain rate and specific growth rate of yellow catfish hybrid in LP1 group and LP2 group were significantly reduced (P<0.05). There was no significant difference in weight gain rate and specific growth rate between LP1+AA and LP2+AA yellow catfish hybrid (P>0.05). (2) The relative expression levels of GH, IGF-1 in pituitary and GH in hypothalamus of hybrid yellow catfish in LP2 group and LP2+AA group were significantly decreased (P<0.05), and there was no significant difference between the other groups with control group (P>0.05). (3) There was no significant difference in water content, crude protein, crude fat and crude ash content between muscle and whole fish in each experimental group (P>0.05). (4) There was no significant difference in AST activity in liver and serum between the all groups (P>0.05), and serum ALT activity in LP2 group was significantly higher than that in the control group and LP1+AA group (P<0.05). (5) CAT activity in serum, T-AOC and Cu/Zn-SOD、Mn-SOD、CAT mRNA relative expression in liver of both LP2 and LP2+AA groups decreased, and ROS content in liver and serum increased. There were no significant differences in SOD, CAT, T-AOC, MDA and ROS in liver and serum and Cu/Zn-SOD、Mn-SOD、CAT mRNA relative expression in liver of LP1+AA groups (P>0.05). These results showed that reducing the protein content of both 5% and 10% in the feed will negatively affect the growth performance and antioxidant capacity of yellow catfish hybrid. Reducing the protein content of the feed by 5% and adding lysine and methionine would not significantly affect the growth performance and antioxidant capacity of yellow catfish hybrid. Therefore, we suggest that the protein content in feed can be reduced by supplementing amino acid in feed production.
WANG Cai-Xia, JIA Yang, QIN Wen-Li, CHEN Bin-Bin, WANG Min, MA Zeng-Ling
 Available online   , doi: 10.7541/2021.2020.257
[Abstract](0) [FullText HTML](0) [PDF 2641KB](0)
Dinoflagellate Prorocentrum donghaiense is the most dominate harmful algal bloom (HAB) forming species in the coastal zones of East China Sea, according to the China Marine Environmental Quality Bulletin over the years, which has caused a huge damage to local aquatic systems and brought disaster to the aquaculture industry. In addition, blooms formed by P. donghaiense occur frequently in May every year, coincide with the sexual reproduction period of S. fusiformis. Small- to medium-sized HABs have been occasionally observed to invade into the aquaculture area S. fusiformis. To evaluate the effects of HABs formed by dinoflagellate P. donghaiense on Sargassum fusiformis and explore its mechanism, zygotes of S. fusiformis were cultivated with living cell suspension (LC), ruptured cell suspension (RC) and cell-free supernatant (FC) of 1.00×105 cell/mL P. donghaiense to measure growth rate and photosynthetic activities according to changes in sizes and chlorophyll (Chl.) a fluorescence transient (i.e., OJIP) of the zygotes. The results showed that LC, RC and FC of P. donghaiense at 1.00×105 cell/mL all significantly inhibited the development, growth, Chl. a contents, apparent photosynthetic efficiency (α), and the maximal electron transport rate (rETRmax) of the zygotes with greater inhibition by FC and LC. For other important photosynthetic parameters of the zygotes obtained through JIP-test analysis, FC and LC also greater reduced the maximum quantum yield (ϕpo), the performance index (PI), and the active reaction center density than RC. It indicated that the decrease in photosynthetic activities of the zygotes was caused by the allelocamicals released by P. donghaiense, and some reaction centers (RCs) in the zygotes exposed to the allelocamicals were inactivated, which led to higher dissipation of excitation energy. RC of P. donghaiense contained more allelochemicals than LC and FC because they were released into the media during cells lysis. Therefore, some other compounds that can stimulate the growth and photosynthetic activities of the zygotes were synchronously released, which partly offset the inhibitory effects of the allelopathic substances. These results indicate that the inhibitory effects of P. donghaiense on S. fusiformis zygotes were mainly caused by allelochemicals, and the blooms formed by P. donghaiense can restrain the development and photosynthetic activities of S. fusiformis zygotes, reduce the seedlings stock, and eventually hinder the development of S. fusiformis production industry.
JIANG Yu, YANG Ming-Yang, YE Qin, TAO Yi-Xi, XU Hao, LI Yun
 Available online   , doi: 10.7541/2021.
[Abstract](95) [FullText HTML](73) [PDF 24968KB](2)
In this study, we used transgenic zebrafish (Danio rerio) with green fluorescence protein labeling in the heart and vasculature as study models. Two dissolved oxygen conditions, hypoxia and normoxia, were set. The morphological structure of the embryo, heart and vascular shape, heart rate, and formation of the main vessel in the embryonic trunk were measured and analyzed by fluorescence microscopy. We found that the survival rate of embryos under hypoxia was reduced. Hypoxia not only delayed embryonic development but also caused abnormal morphology. Heart malformations in zebrafish embryos exposed to hypoxia mainly manifested as pericardial effusion and developmental arrest in the linear heart tube stage. Although the heart tube could differentiate into the atrium and ventricle, the right cyclization process could not be completed. Vascular development in zebrafish embryos was also affected by hypoxia. Hypoxia narrowed the diameter of the embryonic dorsal aorta and posterior cardinal vein, shortened the distance between the posterior cardinal vein and the dorsal longitudinal anastomotic vessel, caused abnormal blood vessel growth in the interstitial cells of the embryo, and led to the specific disappearance of the parachordal vessels and a lack of subintestinal venous vessels. The study aimed to elucidate the mechanism by which hypoxia impacts cardiovascular development. In situ hybridization and qPCR were performed to test the changes in cardiovascular development-related genes localization and quantity and explore the mechanism of cardiovascular development under different conditions of dissolved oxygen. Based on the functions of these genes in cardiovascular development, we speculated that hypoxia likely impacts cardiac looping via the Tbx5 gene. In addition, abnormal cardiac development under hypoxia might be attributed to impair cardiac looping. Hypoxia could impact vessel development through the VEGF/VEGFR and Notch signaling pathways. In conclusion, hypoxia caused embryo development arrest, heart and vascular abnormalities, and expression changes in cardiovascular development-related genes. Whether hypoxic stress in the early embryo development stage would affect the morphological structures and physiological functions of adult zebrafish remains to be further studied.
DANG Jiang-Yu, GAO Bo-Wei, XU Zhen, YANG Hang, LI Xiao-Qin, LENG Xiang-Jun
 Available online   , doi: 10.7541/2021.2020.202
[Abstract](0) [FullText HTML](0) [PDF 862KB](0)
To investigate the effects of starch on the growth, feed utilization, digestive enzyme activity, liver biochemical indexes and liver histology of brown trout juveniles, six isonitrogenous and isolipidic diets were formulated with corn starch and cassava starch at three levels of 5%, 10% and 15%, respectively, to feed brown trout juveniles with an initial body weight of (0.50±0.03) g for 84 days. The results indicated that the weight gain rate (WGR) first increased and then decreased, while the feed coefficient ratio (FCR) showed an opposite trend with the increasing dietary starch level (P<0.05). The 10% cassava starch group had the highest WGR (518.8%) and the lowest FCR (1.32). There were no significant differences in the survival, viscera-body ratio, condition factor, and body composition among the groups (P>0.05). The crude protein retention decreased with the increasing starch level, and the 15% starch group had significantly lower values than that of the other groups (P<0.05). While the lipid retention first increased and then decreased with the increasing dietary starch level, and the 10% cassava starch group showed significantly higher lipid retention than that of the 10% corn starch group (P<0.05). The starch types and levels did not significantly affect the activities of pepsin, gastric amylase, liver alanine aminotransferase, liver aspartate aminotransferase, and the contents of total cholesterol and triglycerides in liver (P>0.05), while the activities of intestinal amylase and protease in 15% starch group were significantly higher than those in other groups (P<0.05). The 15% starch groups showed significantly higher liver glycogen content and more nucleus shift and cell vacuolation than the other groups. In conclusion, the suitable diet for brown trout juveniles was suggested to be 10% cassava starch under the experimental conditions.
XIA Ping, TANG Fa-Hui, ZHAO Yuan-Jun
 Available online   , doi: 10.7541/2021.2020.289
[Abstract](212) [FullText HTML](171) [PDF 1217KB](7)
Trichodinids are tiny parasitic ciliated protozoans with high diversity, and mainly parasitic in the fishes, shellfishes and rarely in coelenterates. The serious infections caused by trichodinids may induce damage to the hosts, or even death in severe cases. Many previous studies focused on morphology and taxonomy of trichodinids have been carried out worldwide. Because it is difficult to differentiate similar species based solely on morphological characters, molecular examination has been accepted for identification of species. In recent years, some studies have begun to apply molecular approaches to shed light on the past confusion of identification of taxa. It has been a long time since Trichodinella myakkae (Mueller, 1937) Šrámek-HuŠek, 1953 was confused with its relative species, Trichodinella epizootica (Raabe, 1950) Šrámek-HuŠek, 1953 and Trichodinella subtili (Lom, 1959) Lom & Haldar, 1977. It’s also difficult to distinguish T. myakkae from other Trichodinella species by the only morphological characters, for T. myakkae shares similar shape and size to the related Trichodinella species and is often mixed infection with these trichodinids which are difficult to be isolated individually. Moreover, T. myakkae was reported from different regions around the world and mainly isolated from freshwater fish hosts, such as Ctenopharyngodon idellus, Aplites salmoides and other fishes. Therefore, it is of great significance to study phylogeny and the influencing factors of intra—species differentiation. This study collected three host fishes of Hypophthalmichthys molitrix, Aristichthys nobilis and Pseudorasbora parva for the examination of trichodinids. Under a binocular dissecting microscope, individual trichodinid was isolated from living host fishes by glass micropipettes. Three strains of T. myakkae were obtained, and their photomicrographs of silver impregnated specimen were provided. The PCA results showed that the morphological characteristics of the three strains were highly overlapping on the scatter plot. Besides, five 18S rDNA and ITS-5.8S rDNA sequences were obtained, all of which are highly similar to T. myakkae (AY102176) (sequence similarity ≥ 99.0%), and the GC content ranged from 50.8% to 51.2%. Taking T. myakkae (AY102176) as the reference sequence, based on 18S rDNA sequence, there were 7 variation sites in T. myakkae (AN) and T. myakkae (PP) respectively, and 8 variation sites in T. myakkae (HM). All strains appeared to have the same secondary structure, and the difference was only found in the primary sequence of V4 and V5 regions. The ML and BI trees constructed based on 18S rDNA indicated a highly similar topology. The results showed that there was no significant phenotypic difference among the three strains of T. myakkae, while T. myakkae showed the obvious difference from T. epizootica and T. subtili; meanwhile, T. myakkae (PP) showed the molecular difference from T. myakkae (HM) and T. myakkae (AN) at the intraspecies level. Based on the phylogenetic analysis, T. myakkae and T. epizootica were obviously independent, and all the strains of T. myakkae showed a significant coevolutionary relationship with their host fishes. In summary, our research clarified the confusions between T. myakkae and those similar or related species and provided the basic data for taxonomic and phylogenetic studies of Trichodinella species.
WANG Qing-Hua, SONG Hui-Yin, LIU Xu-Dong, HU Zheng-Yu, LIU Guo-Xiang
 Available online   , doi: 10.7541/2021.2021.030
[Abstract](169) [FullText HTML](121) [PDF 1969KB](6)
The genus Coelastrella was taxonomically positioned in the family Scenedesmaceae (Sphaeropleales, Chlorophyceae), and was characterized as unicellular or few-celled aggregations. Species within the genus are mostly found in aerial and sub-aerial habitats, which are different from other freshwater-living members of Scenedesmaceae. They have good tolerance to some stress conditions, such as high temperature, high salt, and ultraviolet. The most notable feature of the genus Coelastrella is that the cells tend to accumulate carotenoids and oils in the late growth stage, or under some stress conditions such as nitrogen deficiency and high salt. This group has been proved to have broad application prospects in the fields of natural antioxidants and food pigment production. In this study, two strains of the genus Coelastrella were collected from Chongqing and Xinyang, and they were identified as a new species of the genus Coelastrella by morphology and three molecular markers of 18S rDNA, ITS, and tufA gene. The remarkable morphological feature of Coelastrella chongqingensis is that the cell wall is approximately smooth or only slightly wrinkled, without the meridianal ribs of the typical Coelastrella species. The young cells are mostly ellipsoidal or oval with obtuse ends with a size of (0—9) μm×(5—7) μm. The mature cells are mostly spherical or ellipsoidal with a size of 8—14—(18) μm. The results of the phylogenetic analysis showed that Coelastrella chongqingensis was closely related to Coelastrella vacuolata and Coelastrella tenuitheca. They all have similar morphotype, and formed independent monophyletic group in the phylogeny of tufA gene. This branch represents the third morphotype of Coelastrella, that is, the cell wall is approximately smooth or with a network of fine ribs without the typical meridional ribs of Coelastrella.
MA Yue, BIAN Yao, WEN Xin, ZHANG Xin-Tao, WANG Hong-Wei
 Available online   , doi: 10.7541/2021.2020.231
[Abstract](172) [FullText HTML](136) [PDF 1301KB](1)
Grateloupia corymbcladia Li et Ding and G. subpectinata Holmes distributed in Nanji Island, Wenzhou City, Zhejiang Province (specimen of origin) were studied in detail using molecular-assisted alpha taxonomy (MAAT). The results showed that: (1)G. corymbcladia were upright, purple-red, cartilage and 15—30 cm height. The main branch was flat, and the end was elongated to a sub-flat shape with 2—5 mm wide. Branchlets and 1—2 pinnate branches were distributed on both sides of the main branch. The reproductive structure of the female gametophyte included carpogonial branch ampullae and auxiliary cell ampullae, which were composed of five cells and four cells (Grateloupia type), respectively. Mature tetrasporangia originated from inner cortex cells and split into cross. The above characteristics were consistent with G. subpectinata. (2)Under laboratory conditions, the female gametophytes of G. corymbcladia and G. subpectinata both produced and divided to form discoids. The spore development types were all “mediate discal type”. (3)Based on the results of rbcL and COⅠ gene sequence analysis, there were no pairwise divergence between the six samples of G. corymbcladia and the G. subpectinata. They all formed a single monophyletic subclade. These results indicate that G. corymbcladia and G. subpectinata were the same species, and G. corymbcladia was regarded as the synonym of G. subpectinata.
LONG Yong, GE Guo-Dong, LI Xi-Xi, CUI Zong-Bin
 Available online   , doi: 10.7541/2021.2020.191
[Abstract](261) [FullText HTML](172) [PDF 1040KB](4)
Exposure of fish to hypothermia stress may lead to damage to biological molecules, cells and tissues, and even death. When fish cells sense the cold stress, the cold signals are transduced into the nuclear by a variety of routes to trigger the cold stress responses. A new homeostasis will be established and the resistance of the cells to cold stress will be enhanced through these finely regulated stress responses. The endocrinology system of fish can be activated by cold stress to release hormones such as cortisol and thyroid. These hormones regulate metabolism, osmolarity and immune responses of the body and ultimately lead to alterations in physiology and behavior. Cold stress responses of fish are complexly regulated at multiple levels, including epigenetics, transcription, translation, alternative splicing of pre-mRNAs and post-translational modification of proteins. Recent omics studies have identified many cold responsive genes and metabolism pathways. Energy generation and anti-oxidation responses are critical for the establishment of fish cold resistance. Environmental factors including hypoxia and salinity, and the physiology of the fish such as fasting and nutritious status also can affect the responses and resistance of fish to cold stress. The identification of cold resistance-associated biomarkers and the discovery of functional mechanisms of the linked genes have paramount significance for the breeding of cold-resistant fish strains.
LI Yan, Wang Hong-Zhu, MA Shuo-Nan, LIANG Xiao-Min, WANG Hai-Jun
 Available online   , doi: 10.7541/2021.2019.225
[Abstract](987) [FullText HTML](374) [PDF 945KB](7)
To test the effects of different external nutrient loading on characteristics of phytoplankton community structure, a whole-ecosystem nutrient addition experiment was conducted in 4 ponds located at the Yangtze River Basin from December 2010 to June 2012. Four treatments were set to represent various nutrient loads, namely both nitrogen (N) and phosphorus (P) addition (+N+P), P addition (−N+P), N addition (+N−P), and no nutrient addition (−N−P) (Control). In terms of species number, all treatments showed similar characteristic with the species number of 75, 79, 75 and 75 in −N+P, +N+P, +N−P and Control respectively, and Chlorophyta were the dominant taxonomic group followed by Cyanophyta. In terms of functional group, the percentage of meso-eutrophic species in −N+P was similar to that in +N+P, both were higher than the two treatments without adding P. The percentage of oligotrophic species in +N−P was higher than that in +N+P treatment, and even higher than the Control. The above results suggest that the reduction of nitrogen cannot control the percentage of moso-eutrophic species of phytoplankton, while the reduction of P can induce the succession of phytoplankton community from a meso-eutrophic type to an oligotrophic type. These results provide theoretical foundation for N management strategy in mitigating eutrophication to a certain extent.
HUANG Wei, ZHOU Hua-Shu, Liu Lan-Ying, LUO Tu-Yan, SONG Yong-Kang
 Available online   , doi: 10.7541/2021.2020.072
[Abstract](160) [FullText HTML](133) [PDF 1260KB](0)
Sturgeon is rare ancient and diadromous fish. The microbial status of aquaculture environment is closely related to the health of fishes, which has drawn extensive attention. Here, high-throughput sequencing technology was used to determine the community composition and complexity of the microbiota in A. sinensis, A. schrenckii, H. dauricus, and hybrid sturgeon (A. schrenckii×H. dauricus ♀) breeding environment farmed in Chinese sturgeon conservation center. The potential pathogens of their microbial communities were assessed by Real-time fluorescence quantitative PCR technology (RT-PCR). The results demonstrated that the microbiota in cage culture water were dominated by bacteria in the phyla Proteobacteria, Actinobacteria, Bacteroidetes, Verrucomicrobia and Planctomycetes, which accounted for 88.81%—93.94% of the sequenced reads in all samples. At the genus level, unclassified genera represented a considerable proportion in all of the experimental samples. Statistical analyses revealed that the diversity of microbial community among the groups did not reach the significant level, and the similarity of the microbial communities was high. The potential pathogenic genera in the culture water were Aeromonas, Acinetobacter, Chryseobacterium, Edwardsiella, Flavobacterium, Pseudomonas and Vibrio. The RT-PCR analyses indicated that A. hydrophila [(7406±1892) copies/mL] was the most abundant pathogen in sturgeon cage culture water, followed by F. columnar [(4889±1649) copies/mL] and P. fluorescens [(3259±1117) copies/mL]. Our results will be the basis for guiding healthy aquaculture of sturgeon and the early warning of pathogenic diseases in the breeding processes.
LI Hai-Jie, GUO Guo-Jun, GUO Chao-Hui, WANG Lin-Feng, WANG Chun-Xiu, LI Ming, LI Guo-Xi, LIU Bian-Zhi
 Available online   , doi: 10.7541/2021.2020.295
[Abstract](216) [FullText HTML](126) [PDF 781KB](5)
To study the effects of Eucommia ulmoides leaf powder on body composition, muscle amino acid composition, physiological indicators of yellow river carp, the Eucommia ulmoides leaf powder were added into the diet at the concentrations of 0, 2%, 4%, 6% and 8%. 225 individuals with an average weight of (505.13±1.37) g were selected and fed for 55 days. The experimental data showed that: (1) Fresh drosal muscle lipid content and fresh body moisture content decreased significant while fresh drosal muscle protein and fresh body contents of crud protein, crud lipid and crud ash were significant improved with the increasing of Eucommia ulmoides leaf powder (P<0.05). (2) 16 kinds of amino acids were detected in the muscle of yellow river carp. The fresh content of Thr, Ser, His were significantly affected by the adding of Eucommia ulmoides leaf powder. The ratio of total acidic amino acids to total amino acids was significantly higher while the ratio of total pharmacodynamic amino acids to total amino acids was significantly lower in the 2% treatment compared with others (P<0.05). (3) The activities of GSH-PX, ACP, AKP and MDA content in plasma and liver significantly increased to the highest level and then decreased with the increased addition of Eucommia ulmoides leaf powder. SOD activity of Plasma and liver were significant increased according with the increasing Eucommia ulmoides leaf powder (P<0.05). In plasma, the activities of GSH-PX and content of MDA were all showed significantly higher in 6% treatment. AKP activity showed the highest in 4% treatment while ACP activity showed the highest in 8% treatment, respectively. SOD activity increased significantly to the control level at 8% treatment. In liver, GSH-PX activity and MDA content were the highest in 4% treatment (P<0.05). AKP activity and ACP activity were the highest in 6% treatment and 4% treatment respectively (P<0.05). SOD activity showed the highest at 8% treatment (P<0.05). In conclusion, according to the fish drosal muscle and body composition, muscle amino acid, antioxidant and non-specific immune indexes in plasma and liver, the recommended level of diet Eucommia ulmoides in yellow river carp should be at 4%—6%.
HE Yong-Feng, GONG Jin-Ling, WU Xing-Bing, ZHU Ting-Bing, ZHU Yong-Jiu, LI Xue-Mei, MENG Zi-Hao, YANG De-Guo
 Available online   , doi: 10.7541/2021.2020.255
[Abstract](114) [FullText HTML](60) [PDF 1408KB](3)
Genetic diversity and population demography of Coreius guichenoti from the middle and lower reaches of the Jinsha River were investigated using mitochondrial DNA Cyt b gene and COI gene sequences. The results showed that 91 haplotypes were identified from 393 individuals based on concatenated sequences, with relatively high haplotype diversity of (0.936±0.006) and low nucleotide diversity of (0.00489±0.00009). Phylogenetic trees and median-joining Network based on haplotypes indicate that all haplotypes from the middle and lower reaches of the Jinsha River were mixed with each other according to their geographical distribution, but exhibited three distinct haplotype lineages (Clade 1, Clade 2 and Clade 3). Clade 1 diverged at about 3.66 Ma, while Clade 2 and Clade 3 diverged at about 2.93 Ma. Analysis of molecular variance (AMOVA) showed that the larger genetic variances were within different geographical locations (96.62%) and between different haplotype lineages (81.29%), while the lesser genetic variance were between different geographical locations (3.38%) and within different haplotype lineages (18.71%). Pairwise comparisons of genetic differentiation index (Fst) among different populations ranged from –0.008 to 0.045. Except for the insignificant Fst value between PS and other locations, significant but low Fst were investigated between other two locations (Fst<0.05, P<0.05). In contrary, significant maximum genetic differentiation level was revealed between three haplotype lineages (Fst>0.25, P<0.001). Neutrality test, mismatch distribution and Bayesian Skyline Plot (BSP) all revealed that wild populations of C. guichenoti from the middle and lower reaches of the Jinsha River may have experienced the population expansion event. It may happen at 0.0007—0.0004 Ma during the Holocene small glaciers period. It suggests that the uplift of Qinghai-Tibet Plateau and the evolution of glaciers during Holocene small glaciers period may play important effect on the population demography of C. guichenoti in the Jinsha River. In order to better protect the wild resources of C. guichenoti, it was suggested to pay special attention to the three haplotype lineages of C. guichenoti in the middle and lower reaches of the Jinsha River for guiding its culture production.
YI Si-Yi, LI Qian-Zheng, WU Jun-Mei, XU Dong, WU Zhen-Bin, ZHOU Qiao-Hong
 Available online   , doi: 10.7541/2021.2020.168
[Abstract](210) [FullText HTML](168) [PDF 966KB](3)
To understand the utilization status of shoreline resources and provide scientific basis for ensuring the development of shoreline resources and ecological environment protection, this study analyzed the land use type area and landscape pattern index in different periods in the 1 km area along the shoreline of Yichang-Wuhan section of the Yangtze River using Taking land use in 2000, 2005, 2010, 2015 and 2019 as data sources. The results showed that the land use types were mainly farmland and building land from 2000 to 2019. The obvious features of the change included 9.39% decrease in farmland area in 2019 compared to 2000, expanded building land and forestland, and the more intense transformation between farmland and building land. The study area was rich in wetland resources, with the total wetland area accounting for over 70%, and the constructed wetland accounting for over 92% of the total wetland area. In the class level, the patch number in each land type increased obviously, and landscape fragmentation occurred in different degrees. The forest land area increased by 35.63 km2, but the patches number increased from 0.114 million to 0.618 million, the landscape shape index increased from 34.92 to 95.19, and the landscape aggregation index decreased by 10.82%. The patches tend to be fragmented and irregular in shape, which will hinder gene exchange among populations, change the biogeographic environment for species survival, and reduce the diversity of biological species. The compact structure will weaken the inhibition of some disturbances such as insect disasters and fires. In the landscape level, the patches number increased from 1.24 million to 2.34 million, Shannon diversity index increased by 0.14, and contag index decreased by 8.48%. The fragmentation of landscape in the whole study area has intensified. The original dominant patch types in the region were broken, the dominance gap has gradually narrowed, the spatial connectivity has decreased, and the spatial advantage has weakened. This study provides a basis for optimizing the landscape pattern and protecting the ecological environment of the Yangtze River.
ZHOU Yang, YU Dao-De, HU Xin, ZHENG Yong-Hua, TANG Hong-Yu
 Available online   , doi: 10.7541/2021.2020.270
[Abstract](182) [FullText HTML](165) [PDF 1393KB](1)
To investigate the adsorption and physiological response of Hydrilla verticillate under lead-zinc stress, H. verticillata were stressed by lead (Pb2+: 0, 0.01 mg/L, 0.05 mg/L, 0.10 mg/L and 0.20 mg/L) and zinc (Zn2+: 0, 0.05 mg/L, 1.00 mg/L, 2.00 mg/L and 4.00 mg/L) with single and composite process for 28 days to measure the adsorption of Pb2+, Zn2+, chlorophyll a, chlorophyll b, malondialdehyde (MDA), total antioxidant capacity (T-AOC), superoxide dismutase (SOD) and peroxidase (POD) activity. The result showed that the Zn2+ absorption was Zn2+ concentration-dependent, and the high concentration of Zn2+ (≥1.00 mg/L) promoted the Pb2+ absorption by H. verticillata; The low concentration of Zn2+ and Pb2+ promoted the synthesis of chlorophyll, while high concentration (≥1.00 mg/L) inhibited the synthesis of chlorophyll. Pb2+ and Zn2+ significantly mediated antioxidant indexes of H. verticillata to damage the organism. The results of this study will provide a theoretical basis for application of H. Verticillata in heavy metal remediation.
XIE Meng-Qi, ZHANG Shi-Yu, XU Li-Li, JIANG Fei, YUAN Jun-Fa, WU Zhi-Xin, CHEN Xiao-Xuan
 Available online   , doi: 10.7541/2021.2020.130
[Abstract](1103) [FullText HTML](379) [PDF 1880KB](8)
As one of the most important economic animals in China, red swamp crayfish (Procambarus clarkii) has been in short supply in recent years, and the market has put forward higher requirements for the production and quality of red swamp crayfish. To study the intestinal microbiota in red swamp crayfish at different sexes and stages of growth, we collected male and female adult crayfish of (27.00±1.50) cm in length from the natural environment and larval crayfish of (2.00±0.20) cm in length from lab, respectively, 16S rRNA high-throughput sequencing. The results showed that there were no significant difference in the diversity or function of the intestinal microbiota between different sexes, and the composition was relatively consistent (Independent sample t-test, P>0.05). The dominant bacterial phyla included Firmicutes, Proteobacteria and Bacteroidetes, and bacterial genera included Bacteroidia, Shewanella, Clostridium and Citrobacter. The abundances of dominant bacterial groups varied greatly among individuals. These dominant bacterial groups tended to be conservative in adult crayfish intestine as resident microorganisms. The analysis of Beta diversity showed that male and female crayfish samples were not clustered separately, which indicated no significant difference between male and female crayfish. Among the intestinal microbiota at different growth stages, the Alpha diversity indexes of intestinal microbiota in larval crayfish were significantly higher than those in adult crayfish (Independent sample t-test, P<0.05). In terms of the composition and structure at the phylum level, the dominant bacterial groups in two stages were relatively consistent, including Proteobacteria, Bacteroides, Firmicutes, and Actinobacteria. The ratio of Firmicutes to Bacteroides in adult crayfish was higher than that in larval crayfish, indicating that the adult crayfish has a greater potential to digest foods and absorb nutrients. At the genus level, the composition of the dominant genera in the two stages of growth were quite different. The dominant genera of larval crayfish included Unclassified_Burkholderiales (21.1%), Hydrogenophaga (7.6%), Flavobacterium (7.4%), Unclassified_Comamonadaceae (5.4%) and Alkaliphilus (5.2%). The dominant genera of adult crayfish included Bacteroidia (12.5%), Flavobacterium (10.8%), Paracoccus (9.1%) and Unclassified_ Lachnospiraceae (5.5%). The top 20 most diverse genera of adult and larval crayfish included Mycoplana, Asticcacaulis, Sphingomonas, Alkaliphilus, Novosphingobium, Methylopila, Sphingobium, Dyadobacter, Rhodococcus, Hydrogenophaga, Mycobacterium, Tepidibacter, Demequina, Kaistobacter, Ancylobacter, Delftia, Ochrobactrum, Rheinheimera, Methyloversatilis and Sediminibacterium. A large number of Flavobacterium, Bacteroidetes and Hydrogenophaga in the intestines of adult and larval crayfish help the body to carry out a variety of nutrient metabolisms and there were more bacteria related to carbohydrate metabolism in adult crayfish. The Beta diversity of intestinal microbiota showed that adult and larval crayfish samples were clustered separately in PCA analysis, PCoA analysis, NMDS analysis, UPGMA cluster analysis and PLS-DA analysis, indicating great difference between adult and larval crayfish. In addition, the analysis of Adonis/PERMANOVA showed significant difference in the intestinal microbiota between adult and larval crayfish. PICRUSt function prediction showed that the relative abundance of nutrient metabolism function was the highest in the functions of intestinal microbiota in crayfish. The dominant functions of intestinal microbiota in adult crayfish included membrane transport and carbohydrate metabolism, the dominant functions of larval crayfish included cell movement, biodegradation and metabolism of xenobiotics and lipid metabolism. The abundance of metabolizing carbohydrates in adult crayfish was significantly higher than that of larval crayfish. During the breeding cycle of red swamp crayfish, the diet habits will change from plankton to granular feed as the development of crayfish. The capacity of secreting various digestive enzymes in the intestine is enhanced, accompanied by the changes of intestinal microbiota in composition and function to adapt to the shift in diet habits. Our results provide reliable data support and theoretical guidance for the subsequent improvement of the production and quality of red swamp crayfish, the selection of intestinal probiotics and the study of probiotic preparations.
LI Jing, YANG Yi-Ling, ZHANG Cheng-Cai
 Available online   , doi: 10.7541/2021.2020.161
[Abstract](927) [FullText HTML](407) [PDF 1007KB](1)
This study investigated the role of DnaA in the relationship between cell cycle and heterocyst differentiation using Anabaena PCC 7120 as the model organism. When providing combined nitrogen, deletion or overexpression of DnaA did not affect cyanobacterial proliferation and heterocyst differentiation. Upon deprivation of combined nitrogen, DnaA deletion (Malr2009) showed no difference in heterocyst frequency (8.57%) compared with the wild type(8.64%) at 24h, and the proliferation rate of Malr2009 was similar to the wild type, DnaA deletion did not affect cyanobacterial frequency of heterocysts or proliferation rate, but the overexpression of DnaA protein (Oalr2009) reduced the frequency of heterocysts by 20% compared with wild type, and increased the cell proliferation rate by 30% with about 1.2 at the 12th day, higher than that of the wild type (about 0.9 at the 12th day). In conclusion, although DnaA is not necessary for the growth of Anabaena sp. PCC 7120 cells, but under deprivation of combined nitrogen, the increased free DnaA inhibited the frequency of heterocysts.
ZHU Jun-Xian, LI Wei, CHEN Chen, LIU Xiao-Li, WANG Ya-Kun, LEI Luo, HONG Xiao-You, YU Ling-Yun, XU Hong-Yan, ZHU Xin-Ping
 Available online   , doi: 10.7541/2021.2020.167
[Abstract](270) [FullText HTML](195) [PDF 1108KB](1)
Histone H2A and its variants play an important role in many cellular processes. However, their role in the germ cells differentiation of turtle has not been well characterized yet. Here, we cloned the Chinese soft-shell turtle (Pelodiscus sinensis) PsH2A and analyzed its expression pattern and cellular location during oogenesis. The 575 bp PsH2A cDNA was isolated from P. sinensis, which contains an open reading frame (ORF) of 399 bp encoding a protein of 133 amino acid residues, a partial 5′ untranslated region (5′-UTR) of 68 bp and a partial 3′ untranslated region (3′-UTR) of 108 bp. Real-time quantitative PCR (RT-qPCR) result showed that PsH2A mRNA expression level was higher in ovary than other tissues (P<0.01), such as heart, liver, spleen, kidney, brain, muscle, and testis. Reverse transcription PCR (RT-PCR) result showed that PsH2A mRNA only detected in ovary. Moreover, in the male and female gonads of 1-year, 2-year and 3-year-old P. sinensis, the PsH2A mRNA was only significantly expressed in ovary (P<0.01). The results of chemical in situ hybridization (CISH) showed that PsH2A mRNA was specifically expressed in oocytes. When primary oocytes developed to stage Ⅲ, strong signal could be detected and evenly distributed in the cytoplasm. From growing follicular stage (stage Ⅶ oocytes) to mature follicular stage (stage Ⅸ oocytes), the PsH2A mRNA signal gradually weakened and spread in the cytoplasm around the nucleus. The signal was distributed in the perinuclear cytoplasm, but was undetected in the peripheral cytoplasm. Furthermore, the relative expression level of PsH2A mRNA also responded to seasonal change in ovarian development in P. sinensis. In 1-year-old and 3-year-old ovaries, the relative level of PsH2A mRNA increased as ovary developing. However, in 2-year-old ovary, the relative level of PsH2A mRNA increased first and then decreased, reaching a peak level in April. In addition, in different season, the relative expression of PsH2A mRNA showed a downward trend with age increasing. In summary, these findings suggest that PsH2A may play an important role in oogenesis of P. sinensis.
CHEN Jie, LIU Zi-Ming, JIANG Wei, LÜ Yao-Ping
 Available online   , doi: 10.7541/2021.2020.294
[Abstract](168) [FullText HTML](132) [PDF 913KB](3)
Previous studies have demonstrated that sclerostin (SOST) binds to and antagonizes the activity of bone morphogenetic proteins (BMPs). Because of the potential role of BMPs in intermuscular bone (IB) development, we explored the relationship between SOST and IB development. In this study, we identified a cDNA sequence encoding a SOST homologue in barbel steed (Hemibarbus labeo). Sequence analysis revealed that the SOST protein is composed of a signal peptide and a mature peptide which contained a C-terminal cystine knot-like domain. Phylogenetic tree analysis indicated that barbel steed SOST was closely related to goldfish (Carassius auratus) SOST. Expression of SOST transcripts were detected in all the tested tissues, with the highest transcript levels being found in the gill. in situ RNA hybridization results showed that SOST mRNA was obviously distributed in the myosepta. RT-qPCR showed that the transcript levels of the SOST gene significantly changed during the four developmental stages of IBs. This timing overlapped with IB formation, providing support for a role of SOST in IB development.
ZHU Jing-Lin, LI Da-Yu, ZOU Zhi-Ying, XIAO Wei, YU Jie, YANG Hong, XUE Liang-Yi
 Available online   , doi: 10.7541/2021.2020.155
[Abstract](1011) [FullText HTML](477) [PDF 1254KB](2)
Streptococcosis, caused by Streptococcus agalactiae, seriously harms the Chinese tilapia aquaculture industry. Improving the internal disease resistance of tilapia is a preferred method to control this disease. We observed the physiological responses of hybrid tilapia (Oreochromis niloticus♀×O. aureus♂) and their parents after challenged with pathogenic S. agalactiae. The cumulative mortality was recorded at different time points. Blood and spleen samples were collected at 0, 7h, 24h, 48h, 72h, 120h and 168h after infection, respectively. Blood physiological and biochemical indexes were measured between hybrid tilapia and its parents. The expression of pro-inflammatory cytokines in spleen were compared to gain an in-depth understanding of the physiological and molecular basis of the disease resistance heterosis. The result showed that the cumulative mortality of hybrid tilapia was significantly lower than its parents. The white blood cell count, red blood cell count and hematocrit of hybrid tilapia were the highest of three tilapias before infection. The white blood cell count increased significantly after infection, whereas hematocrit and hemoglobin decreased significantly. The infection of fish resulted in a strong inhibition of the respiratory burst, and the blood physiological indexes of hybrid tilapia were closer to those of O. aureus. The result showed that the cumulative mortality of hybrid tilapia was significantly lower than their parents. The white blood cell count, red blood cell count and hematocrit of hybrid tilapia were the highest of three tilapias before infection. The white blood cell count increased significantly after infection, whereas hematocrit and hemoglobin decreased significantly. The infection resulted in a strong inhibition of the respiratory burst, and the blood physiological indexes of hybrid tilapia were closer to those of O. aureus. Hybrid tilapia had higher glucose, lysozyme activity and the respiratory burst compared with their parents. The pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) mRNA levels in the spleen were significantly up-regulated after infection (P<0.05), which peaked at 7h, 48h and 7h, respectively. The TNF-α and IL-6 mRNA levels of hybrid tilapia was the highest of three tilapias before and after infection, and the IL-1β mRNA levels of hybrid tilapia was significantly higher than their parents before infection and at 7−48h after infection. The results showed that hybrid tilapia had stronger defense ability against S. agalactiae infection than their parents with significantly increased pro-inflammatory cytokines after infection. Taken together, this study indicated that the pro-inflammatory cytokines might be involved in host defense against bacterial infection, and the immune response of hybrid tilapia is more active than their parents to support disease resistance.
XIANG Yao, ZHANG Jin-Ye, ZHAO Yuan-Jun
 Available online   , doi: 10.7541/2021.2020.186
[Abstract](193) [FullText HTML](204) [PDF 1792KB](2)
Myxosporeans are microscopic and simple in morphology, mainly parasitize in fish. Some species can cause host disease even lead to death. Among them, the species of the family Myxidiidae Thélohan, 1892 exhibit the broadest range of hosts among all myxosporeans. They are typically coelozoic (rarely histozoic) parasites of marine and freshwater fishes (poikilothermal animals), and a few species are found in another poikilothermal animals (amphibians and reptiles) and homothermal animals (birds and mammals). The genus Myxidium Bütschli, 1882 with 230 described species, currently includes the most known species in the family Myxidiidae. The members of the genus Myxidium exhibit the following characteristics: their myxospores are spindle-shaped, straight, crescent, or even sigmoid with somewhat pointed ends; two pyriform polar capsules are located at both ends of the myxospores; the shell valves are smooth or striated; and the suture line bisects the myxospores. Myxidium spinibarba Chen et al., 2020 was first collected and described from the gall bladder of Spinibarbus sinensis Bleeker, 1871. Present study reported M. spinibarba again from Myxocyprinus asiaticus Bleeker, 1864. Myxocyprinus asiaticus belongs to the family Catostomidaeis, in which only one species has been reported from China. Myxocyprinus asiaticus is a kind of omnivorous benthic fish with important ornamental and edible value. To improve higher economic benefits, M. asiaticus and other fishes with different diets and habitat preferences are often mixed feeding. However, polyculture creates conditions for material exchanges between M. asiaticus and other fishes, and, it also enhances the transmission of parasites or pathogens.  To study the host diversity for M. spinibarba and the species composition of myxosporean from M. asiaticus, we analyzed the morphometry characteristics and phylogenetic relationships of M. spinibarba from different hosts based on the morphological and molecular data. Myxosporeans were isolated and photographed from the gallbladder of different M. asiaticus in the same batch. Genomic DNA were extracted and 18S rDNA was amplified and sequenced. Myxospores were fusiform in frontal view, (12.6±0.6) μm (11.6—13.4 μm) long, (5.9±0.4) μm (5.1—6.9 μm) wide, and possessed distinctly longitudinal ridges. The two polar capsules were pear-shaped at the ends of the spore, with a length in (3.48±0.36) μm (2.63—4.22 μm) and a width of (2.83±0.26) μm (2.29—3.21 μm) with 4—5 turns polar filaments. The distance between two polar capsules was (3.66±0.29) μm (3.12—4.20 μm), and their openings were inclined towards the spore ends. These two sequences have the highest similarity with M. spinibarba (MH766654) parasitizing in S. sinensis (99.9%—100.0%). They shared 97.4%—97.7% identity with Zschokkella sp. (KM401441) from Labeo rohita Hamilton, 1822 and Myxidium sp. (MK913426) from Cranoglanis bouderius Richardson, 1846, respectively. Phylogenetic trees of the selected sequences were divided into branch A and B. Clade A was composed Myxidium and Zschokkella species from marine and freshwater fishes or amphibians. All species in clade B were collected from marine fish. Two strains in this study were located in branch A, where the strain (MT775466) and M. spinibarba (MH766654) were first clustered and then grouped with the strain (MT775467). The results of PCA showed that the two strains of this study (MT775466 and MT775467) and M. spinibarba (MH766654) overlapped on the scatter plot. The similarities and genetic distances of 18S rDNA sequences for three strains were 99.9%—100.0% and 0.000—0.001, respectively. Therefore, we conclude that these three strains from different hosts are the same species as M. spinibarba, with diverged molecular level, and that this is the first report of myxosporean in M. asiaticus.
NAN Fang-Ru, LI Juan, LIU Xu-Dong, FENG Jia, LIU Qi, LÜ Jun-Ping, XIE Shu-Lian
 Available online   , doi: 10.7541/2021.2020.200
[Abstract](188) [FullText HTML](200) [PDF 1158KB](10)
This study explored morphological observation and molecular phylogenetic analysis of two freshwater Hildenbrandia specimens from Yuxi, Yunnan Province (encoded as YZYUNNAN) and Jiaozuo, Henan Province (encoded as YZHENAN) in China. Morphological observation and molecular phylogenetic analysis were conducted on these specimens. Phylogenetic relationship of genus Hildenbrandia was constructed based on the obtained gene sequence and related molecular data previously reported in China. Ancestral geographical origin of freshwater Hildenbrandia was inferred based on reliable phylogenetic relationship and modern distribution pattern of each sample. The results are consistent using Bayesian Inference, Maximum Likelihood and Neighbor-joining based on rbcL, psbA and UPA sequences. The genetic distances of three molecular sequences between specimens collected and H. jigongshanensis were smaller compared with another freshwater species. The uncorrected p-distances of rbcL sequences between specimens and H. jigongshanensis were within intraspecific divergence of freshwater Hildenbrandia species. Phylogenetic trees showed that specimens YZYUNNAN and YZHENAN formed an independent branch with H. jigongshanensis, and obtained high supporting values. Specimens YZYUNNAN and YZHENAN shared close relationship with H. jigongshanensis based on molecular phylogeny. The morphological measurements of collected specimens were in consistent with another freshwater Hildenbrandia species H. rivularis. It has been acknowledged that the widely reported freshwater species H. angolensis and H. rivularis are distinguished by morphometric measurements, with H. angolensis characterized by smaller mean cell and filament dimensions (cells 4.0×4.4 µm, filaments 46.5 µm) and H. rivularis by larger parameters (cells 5.8×6.6 µm, filaments 55.3 µm). H. jigongshanensis is separated from other freshwater members by significantly larger cell dimensions (9.8—19.6)×(9.9—10.4) µm and filament height (364—409 µm). The morphological measurements of H. japananense, the cell size (8.4×10.5 μm) and filament height (308—491 μm) were overlapping with H. jigongshanensis whereas identified as a new species based on molecular sequences. with (5.0—8.0)×(4.0—6.7) μm and (4.8—8.0)×(4.8—6.4) μm in cellular diameter and 42—50 μm in thallus height, respectively. There exits contradiction in species identification based on traditional morphological taxonomy and modern molecular methods. By referring the criteria of species identification in other freshwater red algal taxa, the specimens YZYUNNAN and YZHENAN were determined to be H. jigongshanensis based on molecular evidences. The molecular phylogenetic study indicated H. jigongshanensis was firstly described from specimens collected from Jigongshan Mountain, Henan Province, China and follow reported in Niangziguan, Shanxi Province, China. It was found from Jiaozuo, Henan Province and Yunnan Province for the first time. This study expands the geographical distribution and genetic diversity of genus Hildenbrandia in China. Additionally, the traditional morphological characters including thallus height and cellular diameter were found variable under different environments and thus not reliable taxonomic criteria. Molecular-assisted species identification and phylogenetic analysis were necessary for genus Hildenbrandia due to its simple morphological structures. There are 4 widely accepted freshwater Hildenbrandia species up to now and H. rivularis proved monophyletic whereas H. angolensis was paraphyletic. Molecular phylogenetics in this study showed the monophyly of H. jigongshanensis and its close relationship with another freshwater species H. japananense. All freshwater Hildenbrandia species formed an independent clade from the marine species, suggesting that the freshwater Hildenbrandia was derived from the marine populations. The 4 freshwater species of Hildenbrandia were special in geographical distribution, with populations distributed in Europe were mainly H. rivularis, populations distributed in North America were mainly H. angolensis, and H. jigongshanensis and H. japananense were only reported from China and Japan respectively. Ancestral geographical origin reconstruction showed the freshwater Hildenbrandia was derived in North America and dispersed to Eastern Caribbean, Latin America and Eurasia. Sexual reproduction has not been documented for freshwater forms of Hildenbrandia and they reproduced only by asexual modes including fragmentation or gemmae, resulting in rare genetic exchange among species. It was speculated that the special species-related geographical pattern of genus Hildenbrandia was formed after dispersal events and independent evolution in each geographical area. The freshwater Hildenbrandia in North America derived ancestrally and had a long evolutionary history and rich genetic diversity, consistent with the paraphyly of the species H. angolensis distributed in this area.
DONG Xiao-Qi, LIU Guo-Xiang, ZHU Huan
 Available online   , doi: 10.7541/2021.2020.303
[Abstract](127) [FullText HTML](157) [PDF 1012KB](3)
Mesostigma is the most closely related unicellular flagellate algae to land plants, and is one of the key groups for studying the origin of land plants. However, there is no report of Mesostigma in China. Studies have shown that Mesostigma is mainly distributed in static fresh water bodies, such as ponds, reservoirs and small lakes. This study collected several strains of green algae using plankton net in ponds from Hechuan, Chongqing and in reservoirs from Jiulong River, Fujian. In order to identify the species and figure out the phylogenetic position of the green algae, morphological observations under the microscope and phylogenetic analysis by a variety of applications and softwares were accomplished in this study. Both the morphological observation results and the analysis of the phylogenetic tree based on 18S rDNA sequence showed that the green algae collected in this study were Mesostigma viride. In addition, this study also identified the existence of Mesostigma from the environmental DNA of the Three Gorges Reservoir, and the results showed that it mainly appeared in autumn, indicating that autumn may be the best season for collecting Mesostigma in China. This is the first report of Mesostigma in China, laying the foundation for future research on Mesostigma.
WEN Xin, BIAN Yao, ZHANG Xin-Tao, MA Yue, WANG Chen, WANG Hong-Wei
 Available online   , doi: 10.7541/2021.2020.157
[Abstract](897) [FullText HTML](424) [PDF 1303KB](3)
Grateloupia sorocarpus Li et Ding collected from Qingdao, Shandong Province was re-examined through morphological and early development observation followed by molecular analysis. The results showed that: (1) The thalli were upright, purplish red, single or clustered, up to 5—15 cm high, main branch width 1.5—2 mm, 1 mm thick. The texture was smooth and cartilaginous. The first branch was flat with pinnately branched 1—2 orders. Small plumes with flat or stick shapes. The branches were opposite, alternate or partial and usually constricted or tapered at the base. (2) Male gametophyte were not seen. The reproductive structure of the female gametophyte included carpogonial branch ampullae and auxiliary cell ampullae. The reproductive structure of female gametophyte showed representative Grateloupia-type; Carpogonial branch ampullae and auxiliary cell ampullae were composed of 6 cells and 5 cells (6cpb-5auxb type). Gametophytes dioecious, mature tetrasporangia originated from inner cortex cells and splited into cross. These characteristics were similar with those of G. asiatica Kawaguchi et Wang. (3) The early developmental type of G. sorocarpus Li et Ding were ‘mediate discal type’, consistent with that of G. asiatica. (4) Based on the phylogenetic tree constructed by gene (rbcL) sequences, there was no sequence divergence between the eight samples of G. sorocarpus and G. asiatica from Qingdao and Dalian, which formed an independent monophyletic subclade within the large Grateloupia clade of Halymeniaceae. The rbcL sequences differences between G. sorocarpus and G. asiatica from South Korea were 2 bp (0.124%) and the rbcL sequences differences between G. sorocarpus and G. asiatica from Japan were 3 bp (0.248%), belonging to intraspecific difference. Based on the phylogenetic tree constructed by COⅠ gene, there was no sequence divergence between the eight samples of G. sorocarpus and G. asiatica from Korea and Japan, which formed a single monophyletic subclade. Considering the morphological observations and molecular analysis, G. sorocarpus Li et Ding and G. asiatica Kawaguchi et Wang were proved to be the same species. According to the priority rule, G. sorocarpus Li et Ding was the synonym of G. asiatica.
ZHU Hao-Jun, QIANG Jun, XU Gang-Chun, TAO Yi-Fan, BAO Jing-Wen, XU Pao
 Available online   , doi: 10.7541/2021.2020.179
[Abstract](183) [FullText HTML](202) [PDF 1859KB](4)
Yellow catfish is a high-quality and popular fish that is widely grown in freshwater farms. The rice-fish co-culture systems in Hani Terrace is a new agricultural model. To explore the differences of intestinal microbiota of hybrid yellow catfish (Tachysurus fulvidraco♀×Pseudobagrus vachellii♂) between rice-fish co-culture system (DY group) and traditional pond system (CT group), we conducted feeding experiment in terraces and ponds at an altitude of 634 meters in Honghe Hani Autonomous Prefecture of Yunnan Province. The 16S rRNA gene profiling analysis showed that the dominant flora of yellow catfish were Proteobacteria, Firmicutes, Bacteroidetes and Fusobacteria. Different culture patterns did not change the dominant microflora of yellow catfish, but affected the relative abundance of dominant flora. Compared with the CT group, the DY group had more abundance of Firmicutes and Bacteroidetes and less Proteobacteria at phylum level. At genus level, compared with DY group, the CT group had significantly increased abundance of Plesiomonas and significantly decreased abundance of genera Clostridium_sensu_stricto_1, Romboutsia, Paludibacter, Epulopiscium, and Bacteroides. Different culture patterns did not significantly affect the intestinal microbial richness of yellow catfish, but DY group had higher microbial evenness. Moreover, gram_negative and facultatively anaerobic microorganisms were enriched in CT group, and gram_positive and anaerobic microorganisms were enriched in DY group. In addition, gene related to biofilm forming and potential_pathogenicity were depleted in the DY group. These results indicate that DY group had higher intestinal microbial diversity, better stability and stronger resistance to diseases. The rice-fish co-culture system can provide a better living environment for yellow catfish.
XU Wen-Xin, ZHU Qin, ZHU Mei, JI Chun-Li, ZHANG Chun-Hui, QIN Song, LI Run-Zhi, CUI Hong-Li
 Available online   , doi: 10.7541/2021.2021.106
[Abstract](112) [FullText HTML](113) [PDF 1249KB](3)
Haematococcus pluvialis is recognized as the ideal astaxanthin producer since high levels of astaxanthin can be accumulated in its cells under stress conditions. Although appropriate amount of ultraviolet-B (UV-B) can effectively induce astaxanthin biosynthesis, it remains to be elucidated whether the specific light signal perception and transduction mechanisms regulate astaxanthin accumulation in this alga. The present study was conducted to investigate the effects of different intensity of UV-B on the growth, photosynthesis and production of astaxanthin of H. pluvialis under six cultivation conditions (100-500 lux of UV-B was supplemented under LED light culture conditions). A series of physiological and biochemical parameters were examined under these six UV-B treatments designed as CK, U100, U200, U300, U400 and U500, respectively. The results revealed that UV-B radiation decreased the cell density, maximal quantum yield of PSⅡ (Fv/Fm), non-photochemical quenching parameter (NPQ) and chlorophyll (Chl. a and Chl. b) content in H. pluvialis. On the contrary, the astaxanthin content were enhanced with the increase of UV-B radiation intensity (100-400 lx). Compared with the control algal cells without UV-B treatment, astaxanthin content increased by 35.68% and 56.23% in the algal cells treated by 36h and 72h of high-intensity UV-B radiation (U400), with the level up to 5.82 and 7.06 mg/L. Expression analysis by qRT-PCR demonstrated that both 200 and 400 lx UV-B treatments significantly upregulated transcriptional expression of the four carotenoid biosynthesis -related genes (IPI, PSY, BCH and BKT) in H. pluvialis despite their expression profiles were different. UV-B radiation also upregulated the expression of UVR8 and the downstream genes COP1, SPA1, HYH and HY5 which are the core elements in UV-B signal transduction pathway. These findings indicated that the UV-B light signal transduction pathway may function importantly in the regulation of astaxanthin biosynthesis pathway, providing a scientific basis for optimizing culture system to increase astaxanthin accumulation in H. pluvialis by UV-B auxiliary light source. The present data also lay the foundation for further understanding the transcriptional regulation mechanisms of astaxanthin accumulation in this special agal under stress conditions, particularly in response to UV-B radiation.
DU Yan-Yan, LIAO Chuan-Song, YANG Zhuo-Yu, LOU Zhong-Yu, ZHANG Yan-Ping, WANG Hong, WANG Tai
 Available online   , doi: 10.7541/2021.2021.026
[Abstract](116) [FullText HTML](125) [PDF 1079KB](4)
Liujiaxia Reservoir is an important conservancy and hydroelectric project in the Yellow River which is the second largest river in China. With Liujiaxia Reservoir as the second water source of Lanzhou, water qualityhave drawn more and more attention from the government and researchers. Phytoplankton as the main primary producer, plays an important role in aquatic food, web ecosystem, and is a sensitive environmental indicator of water quality in lakes and reservoir. In this study, to understand the phytoplankton status and the nutritional conditions of Liujiaxia Reservoir, eleven sampling sites were established across the reservoir. We conducted 8 times qualitative and quantitative phytoplankton acquisitions from 11 sampling sites in Liujiaxia Reservoir. To analyzed the phytoplankton community structure during March to October in 2020 and discussed the impact of water level and other possible influencing factors on the phytoplankton community structure, a total of 63 species of phytoplankton were identified, which belonged to 35 genera and 7 phyla. Among which, the most abundant group was Bacillariophyta, with 40 species in 17 genera, followed by Chlorophyta (12 species in 8 genera), Cyanophyta (4 species in 4 genera), Pyrrophyta (2 species in 2 genera), Xanthophyta (2 species in 2 genera), Euglenophyta (2 species in 1 genera), Chrysophyta (1 species in 1 genera). The dominant species of year were Asterionella formosa, Fragilaria crotonensis and Synedra acus, they all belong to Bacillariophyta. The density of phytoplankton varied from 3.17×104 ind./L to 59.09×104 ind./L, with an average density of 13.54×104 ind./L. The biomass of phytoplankton varied from 0.0370 mg/L to 0.5004 mg/L, and the average biomass was 0.2137 mg/L. The indices of Shannon-Wiener H′, Margalefrichness index D and Pielouuniformity index J were 1.16—2.43 (averaging 1.84), 1.22—1.57 (averaging 1.42), and 0.23—0.51 (averaging 0.38), respectively. Due to release flood waters during flood season, phytoplankton community structure of Liujiaxia Reservoir did not change regularly, the results indicated that artificial regulation and storage had obvious effects on phytoplankton community structure. The phytoplankton in Liujiaxia reservoir are mainly diatoms and Chrysophyta, indicating that it is a poor nutritive water body. RDA indicated that the most influential environmental factors on phytoplankton were total nitrogen and transparency, followed by dissolved oxygen and water temperature. Water quality results show except for the total nitrogen, the other water quality indexes of Liujiaxia Reservoir meet the water quality standards of class Ⅰ or class Ⅱ of the National Surface Water Quality Standards (GB3838-2002). This study provides background data for water environment protection, rational utilization of fishery resources and sustainable development of Liujiaxia Reservoir.
CHEN Jin-Mei, CHU Yi-Fan, TAN Qi-Yang, LIU Wei, YANG Lin-Li, HUANG Tao, WU Zhen-Bin, HE Feng
 Available online   , doi: 10.7541/2021.2020.180
[Abstract](166) [FullText HTML](203) [PDF 1399KB](4)
Plants are an important part of constructed wetlands, but most wetland plants cannot survive in low temperature environments, and their microbial activity is inhibited, thus limiting the application of constructed wetlands at low temperature. This study explored the role of abscisic acid at 0, 5, 10, 15, 20 and 25 mg/L to improve wetland plants in cold resistance. The results showed that under low temperature conditions, exogenous abscisic acid significantly reduced malondialdehyde (MDA) and relative conductivity, increased the contents of proline, soluble sugar and protein in seedlings, and enhanced SOD, POD and CAT activities with the best effects at 15 mg/L abscisic acid group. Then 15 mg/L abscisic acid was applied to constructed wetlands to evaluate its winter purification effect. 15 mg/L abscisic acid significantly increased the removal rate of TP, TN and COD in constructed wetlands in winter (P<0.05). Thus, abscisic acid can effectively improve the cold resistance of Canna Indica and improve the purification effect of constructed wetland in winter. This research provides new ideas and solutions for breaking through the bottleneck of low-temperature operation of wetland systems.
HU Wei-Hua, XIONG Yang, GUO Wen-Jie, WANG Yu-Hong, ZHU Xiao-Ming, MEI Jie
 Available online   , doi: 10.7541/2021.2020.222
[Abstract](134) [FullText HTML](156) [PDF 1380KB](6)
One of the main problems with the farmed yellow catfish (Pelteobagrus fulvidraco) is that there is no appropriate mode for breeding parents. A large number of female parents of yellow catfish are selected from commercial fish, which have the problem of accumulation of mesenteric fat and visceral fat, resulting in uneven quality of fry and low survival rate. To evaluate the relationship between mesenteric fat deposition (MFD) and reproductive performance of yellow catfish, this study selected four populations of female parent including group 1, a wild population of yellow catfish with low mesenteric fat index [MFI, (0.56±0.17) %]; group 2, a cultured population with low MFI (1.97±0.40) %; group 3 and 4, two cultured populations with high MFI [(5.92±1.85)% and (9.62±1.01)%]. Our results showed that there was a grossly negative correlation between MFI and gonad somatic index (GSI). There were no significant differences in the spawning rate, fertilization rate and number of fry produced per female between group 1 and group 2, which were significantly higher than those in group 3 and group 4. In addition, the malformation rates of fries in group 1 and 2 were significantly lower than those of group 3 and 4. The serum Luteinizing hormone (LH) and Vitellogenin (VTG) levels decreased with the increase of MFD, while the contents of lipid and glycogen in livers and eggs increased with the increase of MFD. In conclusion, our results indicate that female yellow catfish with excessive MFD had reduced physiological indexes and reproductive performance and poor quality of the fries. Establishing proper parental breeding methods and reducing MFD can significantly improve the reproductive performance, which provide clues for improving the quality of fish fry.
XU Yi, XU Xu-Dong
 Available online   , doi: 10.7541/2021.2020.262
[Abstract](52) [FullText HTML](45) [PDF 1250KB](0)
Cyanobacteria are oxygen-evolving photosynthetic prokaryotes that synthesize organic substances from CO2 and other inorganic nutrients. As a unicellular cyanobacterium, Synechococcus elongatus PCC 7942 can be cultured in large scale photobioreactors and easily genetically manipulated. Through systematic deletions of non-essential genes or DNA regions, the genome of this cyanobacterium can be trimmed into a more suitable chassis for synthetic biological studies. The non-essential genes usually include those involved in responses to environmental changes or stresses. Even so, during the process of genome simplification, physiological effects of large fragment deletions should be monitored at each step. ∆Synpcc7942_0233-0253 and ∆Synpcc7942_2169-2187 are two mutants of S. elongatus with an 18-Kb or a 14-Kb deletion of non-essential genome region, named as ∆Synpcc7942_0233-0253 and ∆Synpcc7942_2169-2187, respectively. PCR examinations indicated that these mutants were completely segregated (no wild type genome copy was found). Comparisons of the two mutants and the wild type under different stressful conditions demonstrated that addition of 0.4 M NaCl significantly inhibited the growth of the two mutants; under normal conditions, however, these These 2 mutants showed no or very slight difference from the wild type under normal conditions, but the addition of 0.4 M NaCl significantly inhibited the growth of the two mutants. Under the salt stress condition, the photosynthetic activity of ∆Synpcc7942_0233-0253 and ∆Synpcc7942_2169-2187 reduced to 41% and 51 % of wild type at 96h, respectively. In contrast, two mutants of S. elongatus had higher respiratory activities under the salt stress. The salt stress reduced electron transfer reactions (ETR) of photosystems (PS) II at 96h in the wild type by 52%, in ∆Synpcc7942_0233-0253 by 77% and in ∆Synpcc7942_2169-2187 by 82%. At the same time, the salt stress decreased the ETR of PS I by 32% in the wild type, by 50% and 47% in the two mutants, respectively. We reported two examples of large genomic fragment deletion had stress intolerance and a problem for mass production of the cyanobacterium, which provide necessary information for the design of chassis genomes and the control of conditions for industrialization in the future.
WU Jun-Jie, LI Gaung-Hua, JIN Fang-Peng, ZHAO Jing-Xia, LEI Chun-yun, GAO Hai-Tao, FU Shi-Wei, ZHOU Rui, LUO Yong-Xin, XUE Shao-wei, ZHANG Wen-Kui, LENG Yun, LIANG Yong-Ben, MA Chun-ming, WANG Yan
 Available online   , doi: 10.7541/2021.2020.250
[Abstract](54) [FullText HTML](49) [PDF 1085KB](1)
Anabarilius graham is a kind of native fish in the Fuxian Lake, Yunnan Province, and its germplasm resources had been drastically reduced since the 1990s due to overfishing and invasive species. After many years of artificial propagation and releasing, in order to realize the present genetic diversity, we sampled a total of 133 Anabarilius graham from 7 geographic populations and conducted genetic diversity analysis based on sequences of D-loop control region. The results showed that A+T base composition (62.28%) was higher than the C+G combination (37.72%); A total of 40 polymorphic sites were identified and 36 haplotypes were defined. The overall haplotype diversity index (Hd) was 0.791±0.036 and the overall nucleic acid diversity index (π) was 0.00254±0.00027, which suggested a distribution of “high Hd and low π”. The average Hd and π of west group (Hd=0.826–0.846, π=0.00236–0.0031) was higher than that of east group (Hd=0.657–0.805, π=0.00204–0.00271). The highest and lowest index value of nucleic acid diversity and haplotype diversity were identified in MX and XB population, respectively. What’s more, the furthest genetic distance was found between LQ and HJ population, but insignificant genetic differentiations were identified in 7 populations. The results of the neutrality test (Tajima’s D=–1.73617, P=0.03729; Fu’s Fs=–1.64259, P=0.23943) and nucleotide mismatch distribution revealed that no population expansion happened in evolutionary history of Anabarilius graham. In conclusion, the distribution of “high Hd and low π” was identified in Anabarilius graham, which could be caused by faster evolutionary speed in mitochondrion. Meanwhile, insignificant genetic differentiations among each population may be caused by the dispersive life history of Anabarilius graham and artificial releasing. This study preliminarily revealed the current genetic diversity of Anabarilius graham in the Fuxian Lake, and provided necessary basis for the protection of germplasm resources and genetic breeding.
HAN Xue-Qing, GAO Feng-Ying, LIU Zhi-Gang, CAO Jian-Meng, KE Xiao-Li, WANG Miao, YI Meng-Meng, GAO Yan-Xia, LU Mai-Xin
 Available online  
[Abstract](66) [FullText HTML](60) [PDF 874KB](2)
Tumour necrosis factor receptor-associated factor 6 (TRAF6) is a key adaptor protein that plays important role in signalling pathways triggered by the Toll-like receptor/interleukin-1 receptor (TLR/IL-1R) superfamily, which is highly involved in innate immunity. In this study, we investigated expression patterns and preliminary functional analyses of Nile tilapia traf6. In healthy fish, traf6 transcripts were broadly expressed in all examined tissues with the highest expression level in the blood and the lowest in the liver. traf6 was also detected at various embryonic developmental stages. After challenge with S. agalactiae in vivo, upregulated mRNA expression of traf6 was observed in most examined tissues. Moreover, traf6 expression could be significantly induced in Nile tilapia macrophages by treatment with LPS, Poly I:C and S. agalactiae. In addition, overexpression in HEK293T cells showed that TRAF6 was distributed in the cytoplasm and could significantly increase NF-κB activation. Co-immunoprecipitation (Co-IP) assays showed that TRAF6 could interact with IRAK1 (interleukin-1 receptor associated kinase 1), which also plays a vital role in the TLR/IL-1R signalling pathway. In vivo, TLR2, TLR21 and TLR13b overexpression could upregulate traf6 expression levels, which indicates that TRAF6 is involved in the signal transduction of TLR2, TLR21 and TLR13b. These findings suggest that TRAF6 plays important roles in the immune response to pathogen invasion.
CHEN Fang, ZHONG Chong-Chao, CHEN Shu-Wei, ZHANG Dian-Guang, LÜ Wu-Hong, TAN Xiao-Ying
 Available online   , doi: 10.7541/2021.2020.195
[Abstract](67) [FullText HTML](58) [PDF 941KB](2)
Nowadays, fatty liver and visceral excessive lipid accumulation are common in cultured fish, which reduces survival rate, growth performance and disease resistance. Yellow catfish Pelteobagrus fulvidraco is widely distributed in rivers, lakes and other fresh waters in China, and cultured in China and several Asian countries. The fish has relatively high economic value because of delicious taste and abundant nutrition. However, due to intensive culture and improper feeding, excessive fat accumulation in abdominal cavity and liver commonly occurs, which seriously affects the taste and health of yellow catfish. Therefore, the research on fat metabolism of yellow catfish has always been the focus. Lysosomal acid lipase (LAL), encoded by LIPA, hydrolyzes cholesterylesters (CEs) and triglycerides (TGs) to cholesterol and free fatty acids (FFAs), which are then used for metabolic purposes in the cells. The present studies have been conducted to explore lal structure in mammals, but were scarce in fish. For this reason, it is important to study the molecular characteristics of lal in the regulation of lipid metabolism and physiological nutrition of yellow catfish. In this study, we analyzed molecular structure, tissue expression, promoter structure and function, and transcriptional regulation of lal. The lal gene was amplified from yellow catfish by RT-PCR and RACE approaches. The cDNAs of lal was 1802 bp, encoding a peptide of 398 amino acid residues, and 5’ upstream promoter was 2052 bp in length. The molecular weight of the theoretical protein was 45.42 kDa, the isoelectric point was 7.70, and it had a signal peptide with 23 residues, five glycosylation sites, three cysteines, a catalytic ternary and a “cap” domain and a “lid” region. The amino acid alignment and phylogenetic analysis revealed that lal of P. fulvidraco was closely related to that of Ictalurus punctatus. The lal mRNA expressed in all tested tissues (heart, liver, brain, spleen, kidney, muscle, fat, intestine, testis and ovary), with the highest expression levels in spleen, intestine and testis. Promoter sequence analysis revealed several transcription factor binding sites in lal promoter, such as Sp1, STAT3, PPARα, FOXO1, PPARγ, and HNF4α. Studies on promoter activity showed that -1507/-1016 region negatively regulated promoter activity, while -1016/+51 region positively regulated promoter activity. The present study indicated that lal mRNA was expressed in multiple high metabolism tissues. The transcription of lal was regulated by multiple transcription factors. This study help us to understand the structure and function of lal in fish, and lay a foundation for further research on the relationship between physiological nutrition and lipid metabolism in fish.
LAI Ting, NIE Zi-Ying, ZHANG Xiao-Yu, SUN Cun-Xin, XU Xiao-Di, JIANG Qing, LIU Ming-Yang, LIU Bo, WANG Ai-Min
 Available online   , doi: 10.7541/2022.2020.199
[Abstract](70) [FullText HTML](72) [PDF 1529KB](2)
Procambarus clarkii originated from the south-central United States and northern Mexico. In the 1930s, it was introduced to China as a freshwater economic crustacean via Japan because of its good economic benefits and a characteristic industrial chain. As the consumption hotspot of P. clarkii to grow, fundamental researches on the cultivation of P. clarkii were incredibly important. At present, researchers carried out a large number of analysis on the effects of starvation on the physiology, endocrine, and digestive systems of crustacea To explore the effects of starvation stress on hemolymph physiological biochemical indexes, intestinal histology and intestinal flora of P. clarkii through histopathology, high-throughput sequencing and bioinformatics analysis techniques. P. clarkii was subjected to a 28-day starvation. Hemolymph and intestinal tract were collected at 0, 7, 14 and 28 days of starvation, respectively. Hemolymph was collected to assess the physiological status of P. clarkii by measuring conventional physiological and biochemical indexes; the intestinal tract was collected in 4% paraformaldehyde fixative for intestinal HE staining and TUNEL cell apoptosis detection; and intestinal contents were taken for 16S rRNA sequencing. The results of hemolymph biochemical analysis showed that alanine aminotransferase (ALT) did not change significantly; glucose (GLU) levels gradually decreased with the prolongation starvation (P<0.05). The levels of urea (UREA) and triglyceride (TG) first increased and then decreased (P<0.05), total protein (TP) and aspartate aminotransferase (AST) first decreased and then increased (P<0.05). Starvation stress caused significant changes in the intestinal morphology of P. clarkia: the intestinal cavity became wider, the intestinal villi were atrophied, the thickness of the muscle layer became thinner, and the tissue cell apoptosis index increased. High-throughput sequencing was performed on the 16S rRNA V3-V4 region of intestinal microbes. The Alpha diversity analysis showed that the highest diversity of intestinal microbes was on the day 7 of starvation. At the phylum level, the 12 samples were mainly anaerobic microorganisms such as Proteobacteria, Bacteroidetes, Firmicutes, etc. However, on the 7th day of starvation stress, the population abundance of anaerobic microorganisms (Bacteroidetes, Firmicutes, and Proteobacteria) decreased significantly; at the genetic level, the abundance of Bacteroides, Citrobacter, Streptococcus, Neisseria and Haemophilus increased significantly. The results indicate that P. clarkii may adapt to the process of starvation metabolism by changing the energy material utilization pathways and the intestinal microbiological composition structure.
XING Ying-Chun, GAO Wan-Ru, BAI Jie, ZHAO Ya-Hui
 Available online   , doi: 10.7541/2021.2020.237
[Abstract](66) [FullText HTML](73) [PDF 951KB](3)
Lake is indispensable part of inland water ecosystem, and China harbors numerous lakes with rich biodiversity. In recent years, the degradation of lakes severely lead to the decreasing of level of biodiversity. Therefore, lake biodiversity has always been a research hot-spot in limnology. All efforts to research on lake biodiversity essentially depend on monitoring species composition, population size and distribution. Such studies traditionally rely on morphological identification through biological specimen surveys, until to Environmental DNA (eDNA) arose. eDNA exists in the environmental samples such as water, soil and sediments. This feature makes eDNA to be a good indicator to monitor past and modern biodiversity. Using molecular biology methods to monitor lake biodiversity is conducive to understanding the dynamic changes of lake ecosystems and is of great significance to the development of lake ecological protection. Compared to traditional investigation methods, eDNA is an non-invasive, efficient and easy to be standardized research approach. It especially doesn’t rely on experts’ experience and professional level of morphological classification. With the development of high-throughput sequencing (HTS) technology and emergence of eDNA metabarcoding, eDNA can be used as a supplement or alternative to traditional investigations. It is currently the most economical and effective method for lake biodiversity research. Lakes are easier to be enriched DNA owing to static water environment, therefore more suitable for applying eDNA methods to carry out their biodiversity research. This article reviewed the application of eDNA in studies of the lake biodiversity. We also summarized the related experimental design, and analyzed challenges and prospects of this method. The application of eDNA in the lake biodiversity indicated characters of research objects from low-level organisms to high-level organisms. The samples are mainly water and sediments. By extracting ancient DNA from lake sediments, the lake history and the evolution of biodiversity have been studied; eDNA extracted from water samples can be used to understand the current aquatic biodiversity in the lake. The experimental technology of eDNA includes sampling and preservation, DNA extraction and detection. The three main aspects to determine quality of eDNA samples include suitable amount of samples, sampling methods and storage ways. eDNA can be used to detect specific taxa or multi-taxa based on PCR/qPCR with specific primer or meta-barcoding technology. The application of eDNA in lake biodiversity faces challenges such as lack of optimal experimental protocols, contamination, errors and imperfect taxa DNA database. In the future, the application of eDNA method needs to improve relevant experimental techniques and develop DNA database to solve the corresponding dilemmas. We recommend that human contamination and cross-contamination between samples should be avoided as much as possible during sampling. For the lack of database, we suggest establishing a regional eDNA database, conducting targeted data management and strengthening data sharing among various laboratories.
KE Zhu Fang, XU Xu Dong, GAO Hong
 Available online   , doi: 10.7541/2021.2020.217
[Abstract](75) [FullText HTML](73) [PDF 1185KB](0)
In synthetic biology of cyanobacteria, unmarked deletions of large fragments accelerate the process of genome simplification. In this study, three genomic regions of more than 10 kb, namely Synpcc7942_0050-Synpcc7942_0064, Synpcc7942_0233- Synpcc7942_0253 and Synpcc7942_1391-Synpcc7942_1400, were successfully deleted in Synechococcus elongatus PCC 7942 via traditional homologous double crossovers. Non-replicative plasmids with the two flanking homologous fragments were constructed and introduced into cyanobacterial cells to produce single-crossover recombinants. At this step, single crossover recombination occurred in one or both homologous region(s). Next, colonies freed of sacB(a conditional lethal gene in the vector portion) were selected on sucrose plates. Such colonies could be either double-crossover recombinants or revertants, depending on where the second recombination occurred; however, those single crossover recombinants with the plasmid integrated at both homologous regions were inclined to produce mutants rather than revertants. Large fragment deletion mutants were then identified by PCR examinations. This study demonstrated that traditional homologous recombination techniques can be used to generate unmarked large fragment deletions in cyanobacterial genomes.
WANG Yuan-Zhu, ZHANG Chun-Mei, ZHU Yu-Xuan, SONG Gao-Fei, MI Wu-Juan, WANG Shu-Lei, LIANG Jiang-Kui, BI Yong-Hong
 Available online   , doi: 10.7541/2022.2020.206
[Abstract](90) [FullText HTML](89) [PDF 1980KB](3)
In order to recognize the spatiotemporal dynamics of odorous compounds in nine sampling sites along the main canal of the Middle Route of South-to-North Water Diversion Project, we monitored six odorous compounds, phytoplankton communities, physicochemical parameters every month, from September 2018 to August 2019. Results showed that the average concentration of 2-methylisoborneol was (7.431±9.631) ng/L, which exceeded the olfactory threshold in summer. The mean concentrations of β-cyclocitral and β-ionone were (12.371±12.800) ng/L and (11.973±20.643) ng/L, respectively, and β-ionone exceeded its olfactory threshold in autumn. The average concentration of dimethyl-trisulfide was (173.014±302.047) ng/L, which was not detected in winter and spring. Geosmin and dimethyl-sulfide did not surpass the olfactory threshold in the whole year along the MRP. The seasonal variance of six odorous compounds were greater than the spatial difference in MRP. Redundancy analysis showed that CODMn had a significant negative relationship with dimethyl-sulfide and dimethyl-trisulfide. β-Cyclocitral, β-ionone, dimethyl-sulfide and dimethyl-trisulfide were significantly correlated with nitrate, and chl. a had a remarkable positive relationship with β-cyclocitral and β-ionone. Nitrate, CODMn and chl. a were the influencing factors to predict the dynamic change of odorous compounds. There was a significant positive correlation between the concentration of 2-methylisoborneol and geosmin with Chrysophyta sp. and Anabaena pseudoanabaena. There was a time overlapping between the cell density of Microcystis sp. and the concentration of β-cyclocitral and β-ionone. Microcystis sp. had 13.8% explanatory weight to the concentration of β-ionone. There was a correlation between dimethyl-sulfide and dimethyl-trisulfide with Pyrrophyta sp. and total cells density. These findings reveal that the odourous problem in the main canal of MRP is generally not serious, but algae is an important contributor to the odorous compounds. In order to prevent the odorous problem, it is necessary to pay attention to the algae community composition and its dynamic variations in summer and autumn.
LIU Wei, JIANG Ming, WU Fan, TIAN Juan, LU Xing, YU Li-Juan, WEN Hua
 Available online   , doi: 10.7541/2022.2020.164
[Abstract](84) [FullText HTML](86) [PDF 836KB](13)
To investigate the effects of dietary energy density (DED) and dietary feed ration (DFR) on fish growth and health, a 2×2 factorial experiment was designed, including 2 DED (control diet and high carbohydrate and fat diet) and 2 DFR (1 and 1.2 times energy level of fish fed to control diet apparent satiation). To evaluate the effects of DED and DFR on growth performance, feed utilization, body composition, hematological indices and resistant to Streptococcus agalactiae infection of genetically improved farmed tilapia, Oreochromis niloticus (14.59±0.06 g), the study set 40d as a cycle for 2 cycles (period Ⅰ and Ⅱ). The results showed that DED and DFR did not affect the feed efficiency (P>0.05), and DED did not affect the fish growth performance (P>0.05). High DFR improved the final mean weight (P<0.05), but reduced protein retention during period Ⅱ (P<0.05). DED and DFR had no impact on the conditional factor (P>0.05); in period Ⅰ, high DED only induced the viscerasomatic index (P<0.05), but in period Ⅱ, DED and DFR had significant effects on intestinal-somatic index and viscerasomatic index (P<0.05). High DED increased crude lipid content in the eviscerated whole fish and visceral mass (P<0.05); in period Ⅰ, high DFR enhanced crude lipid content in the liver (P<0.05), and in period Ⅱ, high DED and DFR induced crude lipid content in the eviscerated whole fish, liver, and muscle (P<0.05). High DED and DFR increased in the serum triglycerides and malondialdehyde content (P<0.05), and hematocrit in period Ⅰ(P<0.05), but it decreased the white cell count in period Ⅱ (P<0.05); high DED increased the serum alkaline phosphatase activity, and serum cholesterol (period Ⅱ) (P<0.05), but decreased the catalase and glutathione peroxidase activity (period Ⅰ) (P<0.05); high DFR increased the serum glucose levels (P<0.05). After infection with S. Agalactiae, DED and DFR did not affect the survival rate in period Ⅰ (P>0.05); however, high DFR decreased the survival rate in period Ⅱ (P<0.05). In conclusion, these results suggest that high DFR could improve the growth rate of tilapia, increase the fat deposition and reduce the health level of fish; and that DED is more prone to fat deposition to impact fish health.
LIU Hua, DENG Tao-Qiu, SHI Yin-Kui, YU Hui, YANG Ying, SHI Yi-Ru, CAI Ming-Hui, DUAN Yu-Wan
 Available online  
[Abstract](137) [FullText HTML](170) [PDF 1068KB](2)
With the increasing influence of human activities on the climate, global warming and a variety of thermal pollution become more and more serious, which leads to the aggravation of fish disease outbreaks worldwide and thus causes serious production and economic losses to aquaculture and fishery industries. Moreover, with the rapid development of aquaculture industry, the abuse of antibiotics has caused a series of problems such as the deterioration of aquaculture environment, frequent occurrence of diseases and drug residues, which not only hinder the sustainable development of aquaculture industry, but also pose a serious threat to human health. Therefore, the research and application of antibiotic substitute additives have attracted great attention. Polysaccharide from Traditional Chinese medicine (TCM), having a variety of biological activities and no toxic and side-effect, is a green, safe and non-residual feed additive with great potential for development and is potential to be used as an antibiotic substitute product. Yu-Ping-Feng powder is a compound Chinese herb medicine composed of Atractyloids, Astragalus and Fangfeng and Yu-Ping-Feng Polysaccharide (YPF-P) has the strongest pharmacological activity among the polysaccharides in YPF-powder. It has the effect of enhancing aquatic animal immunity, improving intestinal morphology and structure and promoting growth and development. Probiotics refer to microorganisms that promote other biological health, such as Lactobacillus acidophilus, Streptococcus thermophilus and Bacillus subtilis, etc. They are relatively stable in an acidic environment of the intestinal tract of fish, which can not only improve the immunity of the organism but also promote the level of glucose metabolism in the fish. Grass carp is one of the four major fish, and is the largest economic fish in freshwater aquaculture production in China, which has the characteristics of rich nutrition and delicious taste. Hence, in this study, the effect of polysaccharide additive of Traditional Chinese medicine was improved by preparing the YPF-P compound synbiotics, and its effect on the immune function of grass carp under high temperature was studied, so as to lay a research foundation for the application of YPF-P compound synbiotics in grass carp as an antibiotic substitute additive. To investigate the effects of Yu-Ping-Feng polysaccharide Synbiotics on immune performance of grass carp under heat stress, 360 healthy grass cars weighed of (20±2) g were randomly divided into four groups with 3 replicates per group and 30 fish per replicate for 21 days. The 3 experimental groups (group Ⅰ, Ⅱ and Ⅲ) were supplemented with YPF-P at 0.08%, 0.12% or 0.20% in 0.1% Synbiotics (including Streptococcus thermophilus, Lactic acid bacteria and Bacillus subtilis). At the end of experiment, the grass carps were treated with heat stress various time points before collecting samples. The results showed that 1) in each group, under stress, the activity of the Alanine transaminase (ALT) increased at the beginning and dropped with time in the later period; the activity of Aspartate Transaminase (AST) displayed an upward trend and were different between different time points (P<0.05). 2) In each group, the activities of Superoxide dismutase (SOD), Glutathione peroxidase (GSH-Px) and Glutathione reductase (GR) and Total antioxidant capacity (T-AOC) showed an upward trend at the beginning and reduced in late period; the content of Malondialdehyde (MDA) increased by stress. At any time points, the activities of the antioxidant enzyme (SOD, GSH-Px and GR) in the group Ⅲ were lower than the other two groups (group Ⅱ and Ⅳ). 3) In each group, stress induced the expressions of Nrf2, Keapl, HSP70 and IL-8 reduced the expressions of Cu/Zn-SOD, GR and MHC Ⅱ in a time-dependent pattern; the expression of GSH-Px at three time points under stress was not different from that before stress (P>0.05), but it displayed downward trend over time. These results indicate that grass carp can produce a strong stress response after heat stress, and 0.12% Yu-Ping-Feng polysaccharide compound Synbiotics can improve the anti-oxidative stress ability, effectively relieve the oxidative damage of liver, and have a preferable immune regulation effect.
GAO Xue-Zheng, ZHANG Pei-Yu, SHI Xue-Ying, BEN Ling-Zhi, GUO Qing-Qing, LIU Hai-Yan
 Available online  
[Abstract](969) [FullText HTML](369) [PDF 843KB](16)
Turbot (Scophthalmus maximus L.) is an important industrial mariculture species in China. With the development of high-density and intensive culture, turbot always suffer from various kinds of environmental stresses, which led to the reduction of fish immunity and brought out many diseases. Therefore, it is urgent to find the green feed additives to improve the immunity of fish to avoid the disease. Chinese herbal medicine is rich in carbohydrate, lipid, vitamin and minerals, and other bioactive substances such as alkaloids, saponins, polyphenols, flavonoids, polysaccharides and terpenoids, which could stimulate the activities of complement, lysozyme and antibody reaction and promote the function of phagocytes to improve the bactericidal activity. And the herbal medicine has the advantages of non-toxic, no drug resistance, no residue and environmental friendly. “Sijunzi Decoction” is an ancient prescription in China, and mainly composed of Panax ginseng, Atractylodes macrocephala Koidz, Wolfiporia cocos and Glycyrrhiza uralensis. The main active chemical components analyzed in this Decoction are ginsenosides (from Panax ginseng), flavonoids and triterpenoids (from Glycyrrhiza uralensis). It has the pharmacological activities including improving the gastrointestinal function, invigorating spleen-reinforcing Qi and immunomodulatory activity for human. However, there is no report about the application of this Decoction in fish. Based on the components of the traditional prescription of “Sijunzi Decoction”, nine kinds of Chinese herbal medicines was chose to apply in the feed of fish in this study. To investigate the effects of different levels of a Chinese herbal medicines mixture (CHMM: decoction of Codonopsis pilosula, Atractylodes macrocephala Koidz, Wolfiporia cocos, Rehmannia glutinosa Libosc, Glycyrrhiza uralensis Fisch, Crataegus pinnatifida Bunge, Rhus chinensis Mill, Gardenia jasminoides Ellis, Zingiber officinale Roscoe) on growth performance, feed utilization, body composition and related immune indices of juvenile turbot, basal diets were supplemented with 0, 1%, 2% or 4% CHMM in the form of water decoction to feed juvenile turbot (initial mean body weight was 22.01±0.01 g) for 40d. The fish were fed two times every day (8: 00 and 18: 00), the light period was 14h light and 10h dark, the water dissolved oxygen was greater than 6.0 mg/L, salinity was 25—28‰, water temperature was 15—18℃, and ammonia nitrogen concentration was less than 0.05 mg/L. The results indicated that dietary supplementation of CHMM had no significant influence on feeding rate (P≥0.05). However, the dietary CHMM significantly influenced the growth performance and feed utilization efficiency of turbot (P<0.05), the specific growth rate (SGR)and weight gain rate (WGR) of turbot in 1% group were significantly higher than those in other groups (P<0.05, no significant difference was observed between 2% group and control group (P≥0.05). The feed coefficient (FCR) in 1% group was significantly lower than other groups (P<0.05), and there were no significant differences among other groups (P≥0.05). The supplementation of CHMM in diet significantly affected the condition factor (CF)and spleen index (SI) of turbot (P<0.05), and the highest CF and SI were observed in turbot fed 1% CHMM diet (P<0.05). Meanwhile, the supplementation of CHMM had no significant effect on the visceral index (VSI), hepatosomatic index (HSI) and body composition of turbot (P≥0.05). The contents of C3 and activities of lysozyme in plasma were significantly affected by the dietary supplementation of CHMM (P<0.05, while no significant difference was observed in the contents of plasma IgM among all treatments. The contents of plasma C3 in 1% group were significantly higher than that in control group (P<0.05), the activities of plasma LZM in 1% group were significantly higher than those in other groups (P<0.05), and no significant differences were observed among other groups (P≥0.05). In conclusion, the supplement of CHMM in diet significantly improved the growth performance, feed utilization and non-specific immunity of turbot. The optimum supplemental level of this compound Chinese herbal medicine in the feed of turbot was 1%.
TAN Long-Fei, XU Dong-Po, QI Hon-Fang, FANG Di-An, DING Long-Qiang, A Huai-Yun, LI Yuan-Dong, WU Yan-Hon, MAO Cheng-Cheng
 Available online  
[Abstract](924) [FullText HTML](328) [PDF 1355KB](4)
Gymnocypris przewalskii is a typical plateau cold-water fish with saline-alkali tolerance, and the only aquatic economic animal in Qinghai Lake. It is the core of the entire ecosystem of Qinghai Lake that was once endangered, which is gradually recovering. To investigate the spatiotemporal variation characteristics of eggs and larvae of G. przewalskii in the Shaliu River, the second largest tributary of Qinghai Lake, a total of 3, 386 eggs and 4, 690 larvae of G. przewalskii were collected from May 26 to September 2, 2019. The results indicated that the parents fish began to migrate at the end of May, and the eggs appeared in early June. The egg production peaked from late June to early July, then gradually decreased, and basically disappeared in mid-August. The number of eggs peaked in July, tapered off in mid-August, and then disappeared. The number of larvae increased from early July, peaked in August and gradually disappeared in early September. It was estimated that the eggs runoff of the Shaliu River was 25.58×106, and the larvae runoff was 62.00×106. The spatial distribution of eggs seedlings is that the abundance decreased successively from the estuary upwards, and the horizontal distribution of cross section was the center > on the right bank and > on the left bank. Kruskal-wallis test showed that there was a significant difference in eggs abundance between day and night (P<0.05); the abundance of larvae between day and night was significantly different (P<0.01); the floating peak of eggs seedlings were all concentrated at night. There was a significant positive correlation between eggs abundance and flow rate (P<0.05), and the abundance of larvae was significantly positively correlated with flow rate (P<0.01), which was significantly positively correlated with the daily increase rate of runoff (P<0.01). This first study filled in the gap of the abundance of eggs and larvae of G. przewalskii in this water area to provide basic data for estimating the amount of upstream parents and juvenile fish entering Qinghai Lake of G. przewalskii and scientific basis for protecting the resources management and protection of G. przewalskii.
ZHANG Wen-Xin, PAN Xia, SHEN Xi-Quan, XU Yong-Jian
 Available online  
[Abstract](995) [FullText HTML](430) [PDF 1245KB](9)
Salinity is an important environmental factor that affects the life cycle of aquatic organisms, including their growth, development and reproduction. In fish, acute salinity changes cause a series of physiological responses. Hippocampus kuda is an important economic resource and can adapt to a wide range of salinity levels, while the juveniles are highly sensitive to salinity stress, which may cause pathological signs or diseases by alleviating the immune roles and then lead to mass mortality. The survival rate of cultivated H. kuda is low in China because of the toxic effects of salinity stress on juvenile seahorse. To understand molecular mechanisms of its low survival rate, this study used high-throughput sequencing technology to analyze differentially expressed genes (DEGs) in juvenile seahorse hepatopancreatic tissues treated with normal-salinity water (CK, salinity=25‰), low-salinity water (LS-test, salinity=17‰), and high-salinity water (HS-test, salinity=31‰) respectively for 12h. According to the result of RNA-Seq, a total of 71794 unigenes were produced among control group, high-salinity stress group and low-salinity stress group, and the sequence N50 value was 1780bp, with an average length of 820.71 bp. Compared with the control group, there were 2740 differently expressed genes selected in high salinity group, of which 495 genes were up-regulated and 2245 were down-regulated. On the other hand, 3715 differently expressed genes were selected in low-salinity group, of which 1854 genes were up-regulated and 1861 genes were down-regulated. Ten dysregulated DEGs (Gst, Bcl-2, Fas, Vlcad, Pdha1, Mdh1, Idh3b, G6pd, Gadd45α and SOD) were confirmed by qRT-PCR. According to the result of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, the DEGs were mainly related to metabolism and immune responses. With respect to metabolism, the low-salinity group had enhanced energy and amino acid metabolism, while high-salinity group had reduced lipid metabolism related genes expression. Both high- and low-salinity group had enhanced immune metabolism pathways. Based on our results, we collected the lipid metabolism related genes (Fadsd6, Fas, Sqle, Cyp51, Elovl6 and Slc27a6), amino acid metabolism related genes (Gldc, Atp6v1e1, Sms, Fadh, Asl, Ass1 and Glud1), energy metabolism related genes (Vlcad, Pdha1, Mdh1, Idh3b, G6pd and Sdhd) and immune related genes (Gst, Hsp70, Hsp90, Sod, Bcl-2, Gadd45α, Tcrβ, Tap2 and Traf3) of H. kuda as genetic indicators to identify the stressor. This study will promote the discovery of the molecular mechanism of salt stress adaptation of aquatic organisms, and provides a reference for ambient salinity control in aquaculture.
JIAO Hou-Qi, HUO Shi-Tian, YAN Li-Ming, LI Yan-He, LIU Xue-Qin
 Available online   , doi: 10.7541/2021.2019.280
[Abstract](888) [FullText HTML](498) [PDF 0KB](1)
The crayfish (Procambarus clarkii) is one of the important economic shrimp species in China which is widely distributed in the southeastern and central regions of China. In recent years, with the continous rise of peoples’ demand and the continous development of aquaculture industry, various diseases in the aquaculture have frequently outbroken, including bacterial and viral diseases, causing huge economic losses to the crayfish culture industry. As an invertebrate Procambarus clarkii lacks an adaptive immune system, which mainly resists the invasion of pathogens through the innate immune system. Antimicrobial peptide (AMP), as an important effector in the invertebrate’s innate immune system, is one of the substitutes for traditional antibiotics due to its broad-spectrum antibacterial activity and resistance to drug resistance. Crustin is one of the omst widely studied antibacterial peptide in Procambarus clarikii. This study amplified and identified a new type of Crustin from Procambarus clarikii, named Pc-CruL.In order to reveal the function of Pc-CruL in Procambarus clarikii, its antibacterial activity was determined by means of recombinant expression in vitro. It was hoped to reveal its relationship with pathogens in the form of the prevention and control of the disease and the opening of medicines for Procambarus clarikii.Amplifying the Pc-CruL gene in Procambarus clarikii and ligating this gene to the PGEX-4T-1 vector to construct a prokaryotic expression plasmid. The recombinant plasmid was induced and purified in competent BL21 (DE3) for in vitro and in vivo antibacterial experiment. The CDS region of Pc-CruL contains 330bp and encodes 109 amino acids. Pc-CruL is expressed in all tissues of normal Procambarus clarikii, with higher expression levels in hemocytes and relatively lower expression levels in hepatopancreas. The results of liquid antibacterial assay showed assay showed that Pc-CruL protein significantly restricted the growth of Vibrio parahaemolyticus. Staphylococcus aureus, Aeromonas hydrophila, and Aeromonas veronii, and had broad-spectrum antibacterial activity. The injection of exogenous recombinant Pc-CruL protein could improve the survival rate of infection with Vibrio parahaemolyticus. In general, Pc-CruL is an important immune molecule in Procambarus clarikii and plays a vital role in defending against bacterial infections.
YU Jia, LIU Jia-Rui, WANG Li, WU Zhi-Xu, YU Zuo-Ming, LIU Ming-Liang, HAN Yi-Cai, XIE Ping
 Available online  
[Abstract](5393) [FullText HTML](1636) [PDF 804KB](32)
To explore the current status and historical changes of the Qiandao Lake ecosystem, the survey about fishery resources and water environment in Qiandao Lake in 2016 were used to establish an Ecopath model of its ecosystem and analyze the trophic level structure, energy flow and ecosystem characteristics. The Ecopath pedigree index (P index) was 0.544, with high data reliability. Ecopath model was consisted of 18 functional groups, and the fractional trophic levels ranged from 1 to 3.14. Energy flow of Qiandao Lake ecosystem was dominated by grazing food chain, accounting for 56% of the energy source. The parameters reflected the complexity of the ecosystem, for example, the system connectance index (CI), the omnivory index (SOI), the Finn cycling index and the Finn mean path length were 0.263, 0.132, 5.150% and 2.464, respectively. Compared with other reservoirs, it showed that the functional groups of Qiandao Lake ecosystem had higher polymerization, closer connection, higher rate of material recycling and the ecosystem was more mature. However, the total system throughput of Qiandao Lake in 2016 was low at 24698.27 t/(km2·a), and the total primary production was 6.509 times of the total respiration, indicating that the Qiandao Lake ecosystem was small and still in the developmental stage. According to the historical analyses of the Qiandao Lake ecosystem, the scale of the ecosystem has become larger, and its stability and complexity have enhanced, but the nutrient interaction relationship has weakened, and the ability of the ecosystem to resist external interference was still weak. At the same time, the conversion efficiency of primary producers of Qiandao Lake ecosystem was low, and the food web was simple. So appropriate management measures should be taken to ensure the healthy development of Qiandao Lake ecosystem.

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2021, 45(5): 0 -0  
[Abstract](204) [FullText HTML](103) [PDF 12954KB](24)
2021, 45(5): 1 -3  
[Abstract](186) [FullText HTML](90) [PDF 1142KB](20)
Fishery and Biotechnology
WU Shi-Pei, OU Mi, LI Kai-Bin, XU Qiao-Qing, XU Hong-Yan
2021, 45(5): 945 -950   doi: 10.7541/2021.2020.043
[Abstract](1423) [FullText HTML](415) [PDF 1241KB](80)
fbxo32, a muscle-specific E3 ubiquitin ligase, can enhance protein degradation to associate with atrophy. Here, we found that traf6 mutant zebrafish liver fbxo32 mRNA level increased dramatically. To find out the role of fbxo32 in liver disease, we performed histological analysis of mutant and wildtype zebrafish liver. The result showed that the mutant liver exhibited apparent characteristics of liver atrophy, such as loose liver tissue structure, irregular arrangement and rare lipid droplets of the hepatocytes. The qRT-PCR result showed that fbxo32 mRNA was widely expressed in most tested tissues with the highest level in ovary and low level in liver of wildtype zebrafish. Especially, compared with the wildtype, the liver fbxo32 mRNA was elevated about 100 folds in the traf6 mutant. Additionally, fbxo32 mRNA was mainly distributed in hepatocytes based on in situ hybridization, but cannot be detected in blood cells. The signal of fbxo32 mRNA was much stronger in traf6 mutant liver. These findings indicate that the knockout of traf6 might induce the expression of fbxo32 mRNA in liver and result in liver developmental abnormality and atrophy.
ZHA Huang-Yuan, YU Guang-Qing, CHEN Xiao-Yun, XIAO Wu-Han, LIU Xing
2021, 45(5): 951 -957   doi: 10.7541/2021.2020.106
[Abstract](1192) [FullText HTML](453) [PDF 1834KB](39)
As a group of the lower vertebrates, fishes live in water for almost their whole life and have evolved gill as a specific organ to absorb oxygen dissolved in water but not in air. Compared to land environment, oxygen in water is much lower. In addition to altitude, oxygen in water is also influenced by temperature, sun light, season, water mobility, aquatic life, etc. Thus, fish has evolved a variety of species with a high range of hypoxia adaptation. For aquaculture, due to the influence of oxygen dissolved in water on survive, growth, reproduction and disease-resistant, oxygen is one of the major limiting factors. With the development of aquaculture, in order to obtain high yields in a limited body of water, high density cultivation has become a pursuing tendency. So, oxygen is becoming more and more critical for improving aquaculture constantly and healthily. Similar to mammalians, during speciation, fishes have evolved sophisticated cellular sensors and systematic physiological systems responding to O2 gradients. It is well-known that the hypoxia-inducible factors 1α and 2α (HIF-1α and HIF-2α) are master regulators of the cellular response to O2. HIF-1α and HIF-2α orchestrate this cellular response to hypoxia by regulating the expression of a wide set of genes involved in multiple biological processes.  In order to study the function of fish methyltransferase set9 (SET domain containing (lysine methyltransferase) 9, also called set7 or setd7) in hypoxic tolerance, we used zebrafish as the model organism. We targeted the first exon of set9 gene, and obtained a mutant line with 8 base pairs deletion of set9 gene using CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR associated protein 9) technology. The putative transcript from this mutant line was predicted truncated peptide due to premature termination. The predicted protein encoded by set9−/− was 14aa residues starting from the amino terminus and semi-quantitative RT-PCR assays showed that set9 mRNA was reduced in the mutant line as compared with the WT, indicating that set9 had been successfully knocked out in the mutant line. Then, a Ruskinn Invivo2 I-400 work station was used for hypoxia treatment. For hypoxia treatment of zebrafish embryo and larvae at 3 days postfertilization (dpf), the oxygen concentration in the Ruskinn Invivo2 I-400 work station was set to 2%. During preliminary experiments, we noticed that zebrafish adults were less tolerant of hypoxic conditions than larvae (3 dpf) and the zebrafish body weight significantly affected hypoxia tolerance. Then, we selected adult zebrafish (3 mpf) with similar body weights to test their hypoxia tolerance and the oxygen concentration in the Ruskinn Invivo2 I-400 work station was set to 5% instead of 2%. The apoptotic cells in the brains of set9-null zebrafish and their WT siblings subjected to hypoxia (5% O2) were detected by TUNEL assay using the Apoptag Peroxidase In Situ Apoptosis Detection Kit (Millipore) following the manufacturer’s instructions. After 6h of hypoxia, there were significantly more apoptotic cells in the WT zebrafish brains than in the set9-null zebrafish brains. The results indicated that set9-deficient zebrafish showed significantly enhanced hypoxic tolerance and significantly reduced apoptosis in brain tissue. This study provides clues for further reveal the function and molecular mechanism of fish methyltransferase set9 in hypoxic tolerance, and provides a candidate target for breeding new fish species with enhanced hypoxia tolerance.
YE Huan, WU Meng-Bin, WEI Qi-Wei, YUE Hua-Mei, RUAN Rui, DU Hao, LENG Xiao-Qian, LI Chuang-Ju
2021, 45(5): 958 -965   doi: 10.7541/2021.2020.108
[Abstract](1303) [FullText HTML](412) [PDF 1392KB](57)
Yangtze sturgeon, Acipenser dabryanus, is a freshwater fish that mainly distributed in the upper reaches of Yangtze River and its tributaries. Male and female Yangtze sturgeons in the wild reach sexual maturity at 4—6 and 6—8 years, respectively. Currently, it is a critically endangered species due to overfishing, habitat degradation and pollution. In order to protect and restore this species, many efforts have been made, such as building nature reserves and fishery stock enhancement and releasing. However, the wild population of Yangtze sturgeon has sharply decreased, and it is hardly observed in the Yangtze River now. Previous studies, such as diet supplemented with exogenous hormone and juveniles injected with peptide, were performed to short its sexual maturation time, but no effect has been observed. The oogenesis-related gene, org, plays an important role in the growth and development of oocytes in teleost fish. In order to reveal its function during the oogenesis of Yangtze sturgeon, a full-length cDNA of an org homologue was isolated (designated as Adorg), which was 1031 bp, encoding 233 amino acids. Multiple sequence alignments showed that AdOrg shared the highest sequence identity (49.5%) with zebrafish. By quantitative real-time PCR analysis, Adorg mRNA was specifically transcribed in the gonad, abundant in the ovary and weak in the testis. Transcription of Adorg was not detected in other somatic tissues including liver, intestine, spleen, kidney, heart, muscle, gill, pituitary and hypothalamus. During embryogenesis, Adorg was proved to be maternally transcribed, maintaining a high level before the gastrula stage, and then declining dramatically in later developmental stages. The transcription of Adorg was very limited in undifferentiated gonads, but it sharply increased in the following process of oogenesis, with its highest expression in stage Ⅱ oocytes. In situ hybridization of gonad indicated that the signal of Adorg mRNA was specifically located in the germ cells. In the ovary, Adorg signal was weak in the oogonia, and it increased rapidly in the cytoplasm of primary oocytes, and became stronger with the development of oocytes. In the testes, the expression of Adorg was restricted to type A and B spermatogonia, and was barely detectable in spermatocytes. These findings suggested that Adorg gene might play vital roles not only in oogenesis, but also in development and differentiation of germ cells. Knock-down or knock-out of this gene is necessary for exploring its specific function. These results paved the way for understanding the function of Adorg gene in Yangtze sturgeon during oogenesis.
QI Mei, WU Jia-Wei, TAN Feng-Xia, LUO Ming-Zhong, CHENG Bao-Lin, ZHANG Yuan-Song, CHAI Yi
2021, 45(5): 966 -974   doi: 10.7541/2021.2020.134
[Abstract](1194) [FullText HTML](441) [PDF 1137KB](48)
Hemoglobin is one of the most important proteins for aerobic metabolism in vertebrate. The studies of Hb are more in Mammalia, but less in fishes with low-oxygen environment. This study cloned Hba1/2 and Hbb1/2 cDNA sequences of Culter alburnus (C. alburnus) hemoglobin, which encode 143, 143, 147 and 147 of amino acids, respectively. The second structure analysis of proteins indicated that Hba1/2 and Hbb1/2 included 7 and 8 helical regions, 14 and 13 α1β2 interfaces, 12 and 16 heme bindings, 16 and 16 α1β1 interfaces, respectively, and 6 Bohr effect residues only for Hba1/2. Compared with amphibians and mammalia, there were 10 and 5 amino acid substitutions in fishes of Hba and Hbb functional domains, which may be used to adapt to hypoxia. However, compared with tolerant and intolerant hypoxia fishes, we did not find any coherent substitution in the second structure of proteins, indicating that the tolerant hypoxia trait of fish may be regulated by upstream signal pathways. The phylogenetic relationship showed the duplication events of Hba1/2 and Hbb1/2 isoforms may occurre after vertebrate and before teleost of whole-genome duplications. Interestingly, in the phylogenetic trees, the genetic relationships of C. alburnus and Danio rerio of Hba1/2 and Hbb1 were closer than those of C. alburnus and other fishes, probably because both C. alburnus and Danio rerio belong to Cypriniformes and intolerant to hypoxia. This study cloned Hba1/2 and Hbb1/2 cDNA sequences of C. alburnus hemoglobin, analyzed molecular characteristics and phylogenetic relationships with others, and discussed the possible causes of fish tolerance to hypoxia. These findings provide a theoretical basis and potential direction for fish tolerant hypoxia biology.
XIONG Yang, WANG Shuai, DAN Cheng, ZHANG Yi-Bing, MEI Jie
2021, 45(5): 975 -985   doi: 10.7541/2021.2020.193
[Abstract](1282) [FullText HTML](454) [PDF 1382KB](42)
All-male yellow catfish (Pelteobagrus fulvidraco) and hybrid yellow catfish (P. fulvidraco♀×P. vachelli♂) are the main breeding varieties of yellow catfish. The “white spot disease” caused by Ichthyophthirius multifiliis (Ich) is one of the main diseases of yellow catfish in China. Ich resistance assay was performed on all-male and hybrid yellow catfish, as well as the darkarbel catfish (P. vachelli). By bioinformatics analysis, we identified an antimicrobial peptide HBβ-C from the skin mucus proteome of yellow catfish, a 33 amino acid peptide derived from the C terminal of hemoglobin β chain (HBβ). The anti-parasitic test indicated that HBβ-C effectively killed the trophont, tomont and theront, especially in trophont stage, and 15 µg/mL HBβ-C killed all trophont within 3min. Gene expression analysis showed that the expression of HBβ mRNA in gill and skin of hybrid yellow catfish was higher than that of all-male yellow catfish. Ich challenge significantly increased HBβ mRNA level in all-male yellow catfish, which was higher than that of hybrid yellow catfish. Interestingly, the HBβ protein level in gill of all-male yellow catfish was higher than that in hybrid yellow catfish. Immunofluorescence results showed that the antimicrobial peptide HBβ-C was specifically expressed in red blood cells. After Ich infection, HBβ-C was secreted and attached to the trophont in skin and gill. Thus, our results revealed that all-male yellow catfish was much more resistant to Ich than hybrid yellow catfish. The high HBβ protein in all-male yellow catfish and its ability to kill all stages of Ich might be closely associated with the resistance of all-male yellow catfish to Ich.
YAO Chao-Rui, MA Pin, LI Da-Peng, LI Li, TANG Rong
2021, 45(5): 986 -994   doi: 10.7541/2021.2019.199
[Abstract](1162) [FullText HTML](366) [PDF 1266KB](20)
The protective effects of sodium selenite (Na2SeO3) on oxidative damage and apoptosis of liver cells (L8824) induced by sodium nitrite (NaNO2) were investigated. Cells were pre-incubated by Na2SeO3 for 12h and then exposed to NaNO2 (5, 10 and 25 mg/L) for 24h. The results showed that the apoptotic rate was highly induced by NaNO2, and the activities of glutathione peroxidase (GPX), superoxide dismutase (SOD), catalase (CAT) as well as the expressions of glutathione peroxidase (gpx), superoxide dismutase (sod) and catalase (cat) genes were reduced (P<0.05). After the cells treated by Na2SeO3 for 24h, the expressions of gpx, sod, cat and the activities of GPX, SOD, CAT increased (P<0.05), the expression of anti-apoptosis gene bcl-2 and the marker gene of Nrf2 pathway Keap1 up-regulated significantly. When the cells were pre-incubated by Na2SeO3 for 12h and then exposed to NaNO2 for 24h, the antioxidant and apoptosis indicators could be maintained at normal levels, as well as the Nrf2 and Keap1. Na2SeO3 might prevent the decrease of GPX, SOD, CAT levels and the increase of apoptotic rate. The results showed that the supplement of selenium in the liver cells of grass carp could prevent the damage of antioxidant system and apoptosis-promoting caused by NaNO2 exposure, and the Nrf2 pathway might play an important role in this process.
ZHANG Wen-Xin, PAN Xia, SHEN Xi-Quan, XU Yong-Jian
2021, 45(5): 995 -1004   doi: 10.7541/2021.2020.152
[Abstract](1019) [FullText HTML](387) [PDF 1292KB](24)
Salinity is an important environmental factor that affects the life cycle of aquatic organisms, including their growth, development and reproduction. In fish, acute salinity changes cause a series of physiological responses. Hippocampus kuda is an important economic resource and can adapt to a wide range of salinity levels, while the juveniles are highly sensitive to salinity stress, which may cause pathological signs or diseases by alleviating the immune roles and then lead to mass mortality. The survival rate of cultivated H. kuda is low in China because of the toxic effects of salinity stress on juvenile seahorse. To understand molecular mechanisms of its low survival rate, this study used high-throughput sequencing technology to analyze differentially expressed genes (DEGs) in juvenile seahorse hepatopancreatic tissues treated with normal-salinity water (CK, salinity=25‰), low-salinity water (LS-test, salinity=17‰), and high-salinity water (HS-test, salinity=31‰) respectively for 12h. According to the result of RNA-Seq, a total of 71794 unigenes were produced among control group, high-salinity stress group and low-salinity stress group, and the sequence N50 value was 1780 bp, with an average length of 820.71 bp. Compared with the control group, there were 2740 differently expressed genes selected in high salinity group, of which 495 genes were up-regulated and 2245 were down-regulated. On the other hand, 3715 differently expressed genes were selected in low-salinity group, of which 1854 genes were up-regulated and 1861 genes were down-regulated. Ten dysregulated DEGs (Gst, Bcl-2, Fas, Vlcad, Pdha1, Mdh1, Idh3b, G6pd, Gadd45α and SOD) were confirmed by qRT-PCR. According to the result of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, the DEGs were mainly related to metabolism and immune responses. With respect to metabolism, the low-salinity group had enhanced energy and amino acid metabolism, while high-salinity group had reduced lipid metabolism related genes expression. Both high- and low-salinity group had enhanced immune metabolism pathways. Based on our results, we collected the lipid metabolism related genes (Fadsd6, Fas, Sqle, Cyp51, Elovl6 and Slc27a6), amino acid metabolism related genes (Gldc, Atp6v1e1, Sms, Fadh, Asl, Ass1 and Glud1), energy metabolism related genes (Vlcad, Pdha1, Mdh1, Idh3b, G6pd and Sdhd) and immune related genes (Gst, Hsp70, Hsp90, Sod, Bcl-2, Gadd45α, Tcrβ, Tap2 and Traf3) of H. kuda as genetic indicators to identify the stressor. This study will promote the discovery of the molecular mechanism of salt stress adaptation of aquatic organisms, and provides a reference for ambient salinity control in aquaculture.
WANG Ruan-Lin, XIAO Yu, LI Jia, LIANG Ai-Hua
2021, 45(5): 1005 -1013   doi: 10.7541/2021.2020.150
[Abstract](243) [FullText HTML](185) [PDF 1893KB](18)
Microtubules represent one of the major cytoskeletal filament systems of all eukaryotic cells. They play a key role in spatial arrangement of the organelles, intracellular transport, nuclear and cell division, and ciliar motility. Ciliates are ideal model organisms for studying the functional diversity of tubulins. Here, a total of 20 tubulin genes were identified in the macronuclear genome of the ciliate Euplotes octocarinatus. Based on ortholog comparisons and phylogenetic analysis, these genes were clustered into six groups: α-, β-, γ-, δ-, ε- and η-tubulins. Sequence analysis and western blots suggested that the η-tubulin gene of E. octocarinatus required a +1 programmed ribosomal frameshifting to produce complete protein product. The slippery sequence is AAATAAT. We further systematically identified tubulin genes from 9 other ciliates and compared them with E. octocarinatus. The α- and β-tubulins of all investigated free-living ciliates are encoded by multigene families, and each tubulin isotype may be used to form distinct tubulin structures. Phylogenetic analysis showed that α- and β-tubulin genes underwent multiple independent duplications and losses in ciliate. Our study lays a foundation for studying the biological function of tubulins and exploring the mechanisms of microtubule diversity.
HE Yan, YIN Jia-Qi, SHENG Xin
2021, 45(5): 1014 -1023   doi: 10.7541/2021.2020.212
[Abstract](1052) [FullText HTML](403) [PDF 1261KB](17)
To explore genome structure characteristics, gene function and expression regulation of Euplotes amieti, high-throughput sequencing technique was used to sequence the macronucleus genome and transcriptome of Euplotes amieti. A total of 10.92 Gb data and 50287 Contigs were obtained after filtration. The GC content was 31% and the average length of exons and introns were 311.69 bp and 150 bp, respectively. The number of microchromosomes with telomeres at both ends was 27542, accounting for 54.76%, and the number of genes containing only one telomere was 6118. 38588 Unigenes were split, and the average length was 1189 bp. There were 2%—3% PRF in the total Unigenes, and most of which were +1PRF. Besides, the stop codon of Euplotes amieti also has a reconfiguration phenomenon. The stop codons are UAA and UAG, while UGA codes cysteine and selenocysteine. This was consistent with the characteristics of programmed ribosomal frameshifting and stop codon reassignments in Euplotes. 27650 genomic contigs and 38588 transcriptome Unigenes were successfully annotated. Gene function analysis showed that transcripts were significantly enriched in multiple biological processes, mainly involved cell growth and death, membrane transport, transport, and cytology. Moreover, 50 genes were randomly selected from the genome and transcriptome for PCR verification, and 95% of them were successfully verified. The results indicated that in addition to the characteristic microchromosomes and programmed frameshift, the Euplotes amieti had a large number of “combined microchromosomes” and encoded a large number of special proteins related to the perception of changes in the external environment, cell cycle, and protein expression regulation. In addition,, the gene expression may be regulated by some miRNA and zinc finger transcription factors.
Water Ecology and Environment
LIU Cui, LIU Hao-Kun, ZHU Xiao-Ming, HAN Dong, JIN Jun-Yan, YANG Yun-Xia, XIE Shou-Qi
2021, 45(5): 1024 -1033   doi: 10.7541/2021.2020.139
[Abstract](2044) [FullText HTML](618) [PDF 969KB](36)
Arthrospira platensis is rich in protein, vitamins, minerals, essential amino acids, pigments carotenoids, essential fatty acids and antioxidant compounds. Carotenoids, including lutein, β-carotene, astaxanthin and so forth, which dissolve in fat and result in yellow, red, orange, and green pigmentation of the eggs, skin, and flesh of many fish species. Antioxidant compounds, such as phycocyanin, and tocopherols have significant effects on scavenging free radicals. Lutein is considered as an effective functional compound benefiting human health and widely used as a natural food colorant due to its antioxidant potential and the intense yellow color. However, high density in intensive aquaculture has let to outbreaks of bacterial infections that caused high mortality of yellow catfish, which impeded the further rapid development of the yellow catfish culture industry. Nutritional and environmental factors can cause abnormal body color, which also has a negative effect on the quality and value of fish. To evaluate the effects of Arthrospira platensis and lutein on the growth, pigmentation, antioxidant capacity and disease resistance in hybrid yellow catfish (Pelteobagrus fulvidraco♀×Pelteobaggrus vachelli♂), four isonitrogenous (400 g crude protein/kg diet) and isolipidic (85 g crude lipid/kg diet) diets containing 2% A. platensis (SP), 0.2% lutein (Lut), 2% A. platensis with 0.1% lysophospholipids (SPL) and without pigments (Control) were designed. A total of 720 fish [initial body weight of (4.79±0.01) g] were stocked into 12 tanks at a density of 60 fish per tank. Fish were fed a diet without pigments for 20 days, then fed four experimental diets for 35 days. A bacterial challenge test using Aeromonas hydrophila was subsequently conducted. The results indicated that there were no significant difference in final body weight (FBW), specific growth rate (SGR) and feeding rate (FR) among all groups (P>0.05). The feed efficiency (FE) of the 2% A. platensis and 2% A. platensis with 0.1% lysophospholipids groups were significantly higher than those of the 0.2% lutein and control groups (P<0.05), and supplementing 0.1% lysophospholipids significantly increased feed efficiency (P<0.05). The protein retention efficiency (PRE) of the control group was the lowest (P<0.05), and 2% A. platensis with 0.1% lysophospholipids had the highest PRE (P<0.05). The chemical composition results showed that there were no difference on moisture, crude protein and crude lipid of the whole body of each group (P>0.05), while the ash content in 0.2% lutein and 2% A. platensis groups were lower than the control group (P<0.05). There was no difference on the skin lightness between different groups, while the skin yellowness of the 2% A. platensis and 2% A. platensis with 0.1% lysophospholipids groups were significantly higher than those in the 0.2% lutein and control groups (P<0.05). The skin redness of the 2% A. platensis with 0.1% lysophospholipids group was significantly higher than the control group (P<0.05), and the redness of dorsal skin in the 2% A. platensis group had similar results. The skin chroma of the 2% A. platensis and 2% A. platensis with 0.1% lysophospholipids groups were significantly higher than those in the 0.2% lutein and control groups (P < 0.05). The lutein contents in abdominal skin of the 2% A. platensis and 2% A. platensis with 0.1% lysophospholipids groups were 18.65 and 18.10 µg/g, respectively, which significantly increased compared with the control group (13.16 µg/g) and the initial level (13.32 µg/g) (P<0.05). There was no significant difference in lutein content in dorsal skin among all groups (P>0.05). The experimental fish fed 2% A. platensis and 2% A. platensis with 0.1% lysophospholipids had better body color. Dietary A. platensis and lutein significantly increased the activities of plasma SOD (P<0.05). The activities of plasma GPX and the contents of plasma GSH in the 2% A. platensis with 0.1% lysophospholipids group were higher than those in the 0.2% lutein and control groups (P<0.05). The MDA contents decreased significantly in the 2% A. platensis and 2% A. platensis with 0.1% lysophospholipids groups (P<0.05). 96h post challenge with A. hydrophila, the cumulative survival rates of yellow catfish of 2% A. platensis, 2% A. platensis with 0.1% lysophospholipids, 0.2% lutein and control groups were 20.83%, 16.67%, 5.55% and 0, respectively. The cumulative survival rates of yellow catfish of 2% A. platensis, 2% A. platensis with 0.1% lysophospholipids were significantly higher compared to those of 0.2% lutein and control groups (P<0.05). In conclusion, supplemental A. platensis can increase pigmentation and enhance total antioxidant capacity and disease resistance of hybrid yellow catfish. Lutein can also effectively enhance pigmentation, and lysophospholipids can significantly improve feed utilization. However, dietary A. platensis is more effective than lutein in improving the body color and enhancing antioxidant capacity and disease resistance of hybrid yellow catfish.
PAN Ying-Zi
2021, 45(5): 1034 -1044   doi: 10.7541/2021.2020.176
[Abstract](951) [FullText HTML](406) [PDF 1217KB](20)
Glyptosternum maculatum is the only fish belong to Glyptosternum in China, and it is the fish that only lives in the Yarlung Zangbo River in Tibet Autonomous Region. In order to understand the community structure of gastrointestinal helminths and infection of G. maculatum, the endemic fish of Tibet Autonomous Region, 383 individuals of the species were dissected from May 2019 to August 2019. Seven species of gastrointestinal helminths were found of G. maculatum, including Bathybothrium sp., Proteocephalus sp., Allocreadium sp., Neoechinorhynchus sp., Echinorhynchus gymnocyprii, Contracaecum eudyptulae and Rhabdochona sp.. Most of them were widespread parasites. The population of G. maculatum were divided into whole group, different sex groups and different total-length groups. The gastrointestinal helminths’ community diversity, dominant species and infection of G. maculatum with different groups were respectively analyzed. The results were as follows: in the whole group of G. maculatum, the Shannon-Wiener index and the Berger-Parker index of the gastrointestinal helminths were 1.53 and 0.37 respectively, and the dominant species was C. eudyptulae, which had the highest infection quantity, infection rate, infection intensity and average abundance. In the different sex group, the Shannon-Wiener index was 0.2—1.57, the Berger-Parker index was 0.34—0.93, the dominant species was Contracaecum sp. in all sex groups, and the Neoechinorhynchus sp. was the dominant species in the female group. The infection rate and mean abundance of C. eudyptulae and Neoechinorhynchus sp. were high. In the different total-length group, the Shannon-Wiener index was 0.22—1.59, the Berger-Parker index was 0.34—0.94, the dominant species was C. eudyptulae or Neoechinorhynchus sp. The infection rate and mean abundances with both helminths were high. It can be concluded that the dominant species in the gastrointestinal helminths of native fishes in Tibet Autonomous Region were mainly nematodes, and most of them were heteroparasites. Fish were only their intermediate hosts, and birds play an important role in their transmission. This study was to understand the community structure and infection of gastrointestinal helminths of G. maculatums, to further clarify the species composition and parasitic characteristics of the parasites in Tibetan fishes, and to provide basic data for studying the environmental adaptability of endohelminths and the coevolution with the host.
LIU Mei, YUAN Ju-Lin, LIAN Qing-Ping, NI Meng, GUO Ai-Huan, ZHANG Lei-Min, GU Zhi-Min
2021, 45(5): 1045 -1056   doi: 10.7541/2021.2020.158
[Abstract](809) [FullText HTML](463) [PDF 1475KB](26)
To reveal the spatial and temporal distribution characteristics of different phosphorus forms in the overlying-sediment-interstitial water, the release flux of phosphorus at sediment-water interface as well as relevant main influence factors from the Inner-circulation Pond Aquaculture (IPA), 4 IPA tanks were sampled to measure the composition of phosphorus forms in sediment by the Standards Measurements and Testing Program of the European commission (SMT method). Each IPA tank has 6 sampling points at the front and rear ends, and the Usual Pond Aquaculture (UPA) has 5 sampling points. The results showed that: (1) different forms of phosphorus content from overlying and interstitial water of IPA were lower than those of UPA, and the spatial distribution of phosphorus in IPA water body was quite different. The P at the front of water tank diffused from the sediment to overlaying water, while the P at the rear end of water tank collected from overlaying water into sediment. (2) In the middle and later stage of aquaculture, different phosphorus forms in the sediment at the back of IPA tank gradually decreased with the increase of distance, which were lower than those in the UPA. TP, IP, OP and Fe/AL-P increased significantly with the proceeding of agriculture under both modes, while Ca-P showed a trend of first decreasing and then increasing. (3) In the UPA mode, phosphorus was basically absorbed by the sediment, while in the IPA mode, phosphorus release flux varied greatly with time and space. In the early stage of aquaculture, phosphorus was absorbed at the front end of water tank, and a small amount of phosphorus was released within 10 m from the back end of water tank. In the middle or late stages of aquaculture, a large amount of phosphorus were released from sediment within 10 m from the back end of water tank. At 20 m and 30 m from the rear end, the initial phosphorus flux was small, and phosphorus was absorbed in the middle stage of agriculture, and phosphorus was released at the end of aquaculture. (4) The relationship between phosphorus flux and environmental factors was generally consistent in both models. There was a significant positive correlation between TP/IP release flux and pH, while there was a significant negative correlation between release flux for forms of phosphorus and sediment Eh. The increase of T significantly promoted the release of various inorganic forms of phosphorus. IPA sediment was significantly different in time and space. Sediments were mainly distributed within 10 m from the rear end of water tank, and a large amount of P was released upward into the overlying water in the middle or late stage of aquaculture. This study provides a theoretical support for improving solid particle interception method, promoting efficiency for collection of residual bait and feces, and regulating aquaculture water environment under IPA mode.
GAO Qin, AN Yue-Qi, CHEN Zhou, XIONG Shan-Bai
2021, 45(5): 1057 -1066   doi: 10.7541/2021.2021.002
[Abstract](621) [FullText HTML](394) [PDF 945KB](20)
In order to explore the effect of short-term micro-flow water treatment on the muscle taste quality of bighead carp (Aristichthys nobilis) cultured in ponds, the micro-flow device was used to treat bighead carp in ponds. The treatment times were set as 0, 2d, 4d, 6d, 8d, and 10d. The contents of moisture, protein, lipid, ash, free amino acids, free fatty acids, nucleotides and betaine, and the sensory analysis of the treated bighead carp muscle were determined to get an appropriate treatment time. The results showed that with the extension of the micro-flow water treatment time, the total free amino acid content, adenosine monophosphate content, and betaine content in the bighead carp muscle increased first and then decreased, and the contents of them were the highest at the 6th day of the treatment. While the content of lipid, the total free fatty acid, hypoxanthine riboside (HxR), and hypoxanthine (Hx) gradually decreased. The content of protein showed no significant change during the treatment. Taste analyzer (electronic tongue) and sensory analysis showed that the micro-flow water treatment significantly improved the umami and sweet taste of bighead carp muscle, and reduced the saltiness, bitterness, and fishy taste. In addition, the sensory score of the taste of bighead carp muscle was the highest at the 6th day of treatment. Therefore, the short-term micro-flow water treatment could significantly improve the muscle taste quality of bighead carp without reducing the nutritional quality, and the appropriate treatment time was 6 days.
LU Cai-Ping, YANG Rui, LUO Qi-Jun, CHEN Juan-Juan, ZHANG Peng, WANG Tie-Gan, CHEN Hai-Min
2021, 45(5): 1067 -1073   doi: 10.7541/2021.2020.177
[Abstract](710) [FullText HTML](254) [PDF 1102KB](17)
In order to reflect the correlation between the biochemical parameters and traits of Neoporphyra haitanensis conchocelis and establish a biochemical evaluation system for the selection of new varieties, the photosynthetic pigments and growth indicators of the conchocelis of 5 varieties/strains were compared, and the contents of floridosides, mycosporine-like amino-acids (MAAs) and phytohormones were determined by liquid chromatography-mass spectrometry. The results showed that phycobiliprotein and chlorophyll a were positively correlated with the net photosynthetic oxygen release rate and the relative growth rate, and were related to the high-yield characteristics of N. haitanensis. The conchocelis of Zhedong 2 (ZD2), Shenfu 2 (SF2) and Minfeng 1 (MF1) had higher phycoerythrin content and relatively fast growth rate. Floridosides were related to the high-temperature resistance of N. haitanensis. MF1 and MF2 were dominated by isofloridosides, while other varieties/strains were dominated by floridosides. MAAs is related to resistance to ultraviolet radiation. MF1 and MF2 contained high Shinorine content, and the content of MAAs in MF2 was much higher than that of the other 4 varieties/strains, reflecting the high temperature tolerance and UV resistance of the characteristics of southern varieties of Minfeng. Four plant hormones were found in the conchocelis of N. haitanensis, including isoprene adenine, isoprene adenosine, trans-Zeatin nucleoside and brassinolide, but the relationship between the hormones and production traits was not clear. In summary, the parameters of phycobiliprotein, chlorophyll a, floridosides and MAAs are closely related to the different biological characteristics of N. haitanensis. This study constructed a set of feasible evaluation index system for the selection and cultivation of the conchocelis of new varieties of N. haitanensis.
ZHANG Shi-Wen, LIU Chang-Zi, MU Dan-Dan, WU Zhi-Gang, LI Tao
2021, 45(5): 1074 -1081   doi: 10.7541/2021.2019.260
[Abstract](1822) [FullText HTML](713) [PDF 1111KB](16)
An experiment of hydroponic culture was carried out to investigate the effects of copper and chromium on Lythrum salicaria Linnaeus aseptic seedlings. The plants were cultured in 1/10 sterile Hoagland nutrition liquid with Cu2+ at 0, 5, 10, 20, 40 mg/L and Cr6+ at 0, 5, 10, 20, 40 mg/L respectively for 4 days. We analyzed the toxic effects on chlorophyll content, malondialdehyde (MDA) content, the activity of antioxidant enzymes (SOD, POD, CAT), soluble sugar content and soluble protein content of the seedlings. The results suggested that the osmotic regulatory substances (soluble sugar and soluble protein) increased at low copper concentrations and then decreased at higher concentrations. With the increase of Cu2+ concentration, the degree of membrane peroxidation increased, while the chlorophyll content was not significantly affected. The activity of antioxidant enzymes (SOD, POD and CAT) was high under the copper treatment. With the increase of chromium concentration, the chlorophyll content was also not inhibited. The extent of membrane peroxidation was not significantly affected when the chromium concentration was 0—20 mg/L. The CAT activity was continuously inhibited, but SOD and POD were well activated. In conclusion, L. salicaria has a certain resistance to copper and chromium. Its chlorophyll content was rarely affected, the antioxidant enzyme system responded well, and could regulate the osmotic system for stress reaction. When the concentration of Cu2+ is lower than 5 mg/L and the concentration of Cr6+ is lower than 20 mg/L, its physiological and biochemical indicators are relatively less affected. Our findings provide theoretical basis for further research on the response of L. salicaria under the treatment of heavy metals, as well as its ecological application of water restoration.
SONG Gao-Fei, ZHU Yu-Xuan, Anila P. Ajayan, YANG Li-Hua, JIA Yun-Lu, JIANG Chuan-Qi, BI Yong-Hong
2021, 45(5): 1082 -1092   doi: 10.7541/2021.2020.138
[Abstract](1320) [FullText HTML](496) [PDF 1830KB](21)
To study the community structure of phytoplankton in different aquatic bodies polluted by heavy metals and its relationships with environmental factors, field surveys were conducted in Youxian County and Wanshan District in November 2019. A total of 67 phytoplankton species were identified, belonging to 7 phyla and 52 genera. The community structure of phytoplankton has no remarkable difference between different water types (R=–0.022, P=0.549), but the two study areas were different (R=0.152, P=0.083). The communities were dominated by Chlorophyta, Bacillariophyta, and Cyanophyta. The phytoplankton abundance ranged from 1.11×104 to 1.17×107. The species richness of the phytoplankton community was 10—31 in Youxian County and 6—18 in Wanshan District, the Shannon-Wiener index of the phytoplankton community was 2.28—3.29 in Youxian County and 0.482—2.401 in Wanshan District, the evenness index of the phytoplankton community was 0.979—0.996 in Youxian County and 0.244—0.742 in Wanshan District. These three indices showed significant differences in different districts (P<0.05). Pearson correlation analysis indicated that CODMn, TOC and ORP were significantly positively correlated with phytoplankton abundance, and Cr, Se, Ba and V were significantly negatively correlated with phytoplankton abundance. Mantel test analysis indicated that CODMn, WT, pH, TC, IC, \begin{document}${\rm{PO}}_4^{3 - }$\end{document}-P and Co, Ni, Zn, Cd, and Pb were the key factors that explain the phytoplankton community structure. The canonical correlation analysis indicated that the changes in the phytoplankton community were more related to routine physics and chemistry index than to heavy metals. There were significant differences in phytoplankton community structure in heavy metal polluted areas, and heavy metal ion content and routine physics and chemistry index had significant influences on the community structure. These results provide a research basis for isolating heavy metal tolerant algal strains and carrying out subsequent transformation. Meanwhile, the research is of great significance to the management and protection of water ecosystem.
YANG Xiao, MA Ji-Shun, ZHANG Huan, ZHOU Qiong
2021, 45(5): 1093 -1103   doi: 10.7541/2021.2020.148
[Abstract](1339) [FullText HTML](282) [PDF 1275KB](23)
Poyang Lake is a large Yangtze-connected lake in the middle and lower reaches of the Yangtze River and its water level fluctuates periodically with the hydrological rhythm. In order to clarify the characteristics and influencing factors of plankton community structure during different hydrological periods, the survey on plankton structure was conducted at five typical sampling sites of Poyang Lake in August (wet season) and December (dry season) of 2017. The results indicated that phytoplankton assemblage was composed of 186 species and 75 genera, belonging to 8 phylum. Bacillariophyta and Chlorophyta dominated in wet and dry seasons. Zooplankton was composed of 76 species, belonging to four taxonomic groups. Protozoa and Rotifers were dominant during wet and dry seasons. The density and biomass of phytoplankton were statistically significantly higher during wet season than those during dry season (P<0.01). The density of zooplankton in wet period was higher than that in dry water period, but there was no significant difference (P>0.05). The biomass of zooplankton (P<0.05) was significantly different in different hydrological periods. Redundancy analysis suggested that there was negative correlation between the plankton community structure and transparency. The conductivity showed a positive correlation with the plankton community structure. Transparency, conductivity and nutrient were key factors affecting the community structure of plankton during wet season, whereas water temperature and dissolved oxygen were key factors affecting the community structure of plankton during dry season. Based on the diversity indices of Shannon-wiener, Margalef and Pielou, the results showed that the water quality of Poyang Lake was at low-to-medium pollution level. Our findings revealed the impact of two hydrologic periods on the plankton of Yangtze-connected lakes. Seasonal change did not change the species composition and dominant species of plankton in Poyang Lake, but affected the abundance and diversity of plankton greatly.
XIAO Ling-Jun, WANG Pu-Ze, XIONG Man-Tang, YE Shao-Wen, ZHANG Tang-Lin, LIU Jia-Shou, LI Zhong-Jie
2021, 45(5): 1104 -1111   doi: 10.7541/2021.2020.109
[Abstract](193) [FullText HTML](125) [PDF 1131KB](20)
In order to evaluate the spatiotemporal dynamics of water quality during the transformation stage of lake fishery model, we selected Longgan Lake, a typical lake in the middle and lower reaches of the Yangtze River, as our research site. From 2017 to 2018, seasonal water quality monitoring were conducted on the Huangmei waters and Susong waters of the lake. Principle component analysis (PCA) and self-organizing mapping neural network (SOM) modelling were used to analyze the spatiotemporal changes of physical and chemical parameters of water body. The eutrophication status of water body was evaluated by the method of comprehensive trophic level index (TLI). PCA results indicated that the water quality of Susong and Huangmei waters in Longgan Lake had little difference, while the seasonal dynamic was obvious. The average concentration of ammonia nitrogen in the whole lake was the highest (0.64 mg/L) in summer. The average concentrations of total nitrogen in summer and in winter were 2.30 mg/L and 1.04 mg/L respectively. The average concentrations of chlorophyll a in summer and autumn were 95.28 μg/L and 28.30 μg/L respectively. The pH value was the highest (9.27) in summer, while the average concentration of total phosphorus was highest in winter with the value of 0.22 mg/L. The TLI index showed that Longgan Lake had a mild eutrophic level in autumn and a moderate eutrophic state in the other three seasons. The results of SOM model clearly and intuitively reflected the temporal and spatial distribution of water quality in Longgan Lake. Management measures such as eliminating purse seine and prohibiting fishing can help restore lake fishery environment and fishery resources. It is suggested that a long-term follow-up investigation and assessment should be carried out on the lake ecosystem after the transformation of fishery model.
Aquatic Animal Behavior
ZHOU Long-Yan, LI Xiu-Ming, FU Shi-Jian
2021, 45(5): 1112 -1119   doi: 10.7541/2021.2020.015
[Abstract](856) [FullText HTML](256) [PDF 985KB](26)
Whether fish species can adjust their physiological and behavioral traits well to the change of environmental condition of their habitats are key for the future fate of the local population. The aim of the present study was to investigate the physiological and behavioral responses of two endangered fish species, i.e. Chinese sucker (Myxocyprinus asiaticus) and Qingbo (Spinibarbus sinensis) subjected to short-term predation acclimation. We measured the maximum acceleration swimming speed (Ucat), spontaneous shoal behavior (percent time spent moving, median swimming speed and inter-individual distance), innate immune indicator (plasma lysosome activity), specific immune indicator (plasma IgM level), and antioxidant defense ability (plasma SOD activity) of either predation acclimated (reared with snakehead, Channa argus without direct contact) or non-acclimated (as control) juveniles of Chinese sucker and Qingbo for a period of 1 week. The plasma cortisol level and spontaneous activity were measured under both predator present and predator absent conditions. The main results of this study are as follows: (1) Qingbo showed stronger swimming capacity, more active spontaneous behavior, higher plasma cortisol and IgM levels as well as more profound response of both plasma cortisol and IgM level to predation acclimation, compared to those of Chinese sucker. (2) predation acclimation elicited higher plasma cortisol and IgM levels and higher plasma lysosome activity, especially in Qingbo. (3) acute predator exposure resulted in higher plasma cortisol and shorter inter-individual distance whereas the later only manifested in non-acclimated groups. In conclusion, both non-specific and specific immune function up-regulated after predation acclimation possible via the increased release of cortisol which might evolved with purpose to a fast recovery after possible non-lethal hunting. These adjustments indicated that predation training might act as a potential training process for fisheries releasing in the Yangtze River water system. The distinct difference in behavior, immune system and their response to predation acclimation or acute predator exposure suggested that these two fish species might have different fate in near future due to the unpredictable change in environmental factor such as predation.
ZHOU Yang-Hao, WU Yan-Hong, ZHANG Ping-Mei, ZHOU Wei-Guo, RONG Yi-Feng, XIAO Xin-Ping, LI Xin-Dan, QI Hong-Fang, SHI Jian-Quan, DU Hao
2021, 45(5): 1120 -1128   doi: 10.7541/2021.2020.031
[Abstract](1234) [FullText HTML](373) [PDF 10467KB](21)
This study investigated reproductive behaviors of Gymnocypris przewalskii in artificial mimic spawning environment by visible marker tracking and video monitoring. The typical reproductive behaviors of G. przewalskii can be divided into chasing, accompanying, diving tail, attracting and mating behaviors. Among them, the attracting behavior of the broodstocks described as surface slapping with the dorsal and pectoral fins of a single female or male fish was first confirmed, which is often mistaken for the mating behavior. The daily frequency of chasing, accompanying, diving tail and attracting behaviors were 5.7, 14.7, 9.3 and 3.5 times, respectively. 32 of 34 observed mating behaviors (94.1%) were confirmed as one female with one male. The results showed that female G. przewalskii are one-time oviposition. The frequencies of mating behaviors (spontaneously ovulating and inseminating) were 3—9 times per day and the mating durations were 4—9 seconds with an average 131 (range 15—376) eggs per time. Each female can lay eggs for 3—7 days. Among the 34 mating behaviors, 31 (91.1%) occurred at night (23:00—2:00 the next day) and 3 (8.9%) occurred during the day (6: 00—7: 00 in the morning). This study first clearly described the characteristics of reproductive behaviors of G. przewalskii ex situ, which can provide basic data for mimic-natural spawning ground construction, wild broodstock conservation and natural spawning habitat protection of G. przewalskii.
XI Jie, ZHENG Zong-Lin, MU Zhen-Bo, Liu Fei, LIU Xin-Yuan, SHEN Jian, LIU Hai-Ping, ZHOU Yan
2021, 45(5): 1129 -1137   doi: 10.7541/2021.2020.068
[Abstract](912) [FullText HTML](343) [PDF 1120KB](21)
In order to optimize the breeding model and improve the breeding conditions, the early behavior characteristics of Glyptosternum maculatum larvae and juveniles, such as gap, bottom color and bottom species selection, were studied. The results showed that the preference of the Glyptosternum maculatum larvae and juveniles for gaps was significantly higher during the day (7:00—20:00) than that in night (21:00—6:00) (P<0.05). There were no preference for gaps (P>0.05) in feeding days on the 22th, 23th and 25th—30th, and no preference for gaps (P>0.05) at night (except feeding days on the 6th, 11th—13th). On the 12th, 13th, 15th and 24th day of feeding, the larvae and juveniles showed preference for smaller gaps (0.9 cm) (P<0.05); On the 2nd and 3rd days of feeding, the larvae and juveniles showed preference for bottom gaps (P<0.05); On the 5th, 6th, 8th, 21st and 24th days of feeding, the larvae and juveniles showed a preference for surface gaps (P<0.05); Under the light compensation of (400±50) lx, the preference of larvae and juveniles for the different background colors was not obvious; under the light compensation of (10±2) lx (P<0.05), the larvae and juveniles have a strong hiding behavior during the day to the small gap and they like black substrate under the condition of low light compensation. The hiding characteristics of juveniles and juveniles provide an important scientific basis for optimizing seedling cultivation and improving the environment of seedling cultivation.
XU Meng, ZHU Bing-Tao, YANG Ye-Xin, SONG Hong-Mei, LIU Chao, MU Xi-Dong
2021, 45(5): 1138 -1144   doi: 10.7541/2021.2020.268
[Abstract](1287) [FullText HTML](498) [PDF 1049KB](22)
Exotic fish garpikes have caused some social panic due to their occurrence in the freshwater lake. As ferocious predators, they have high threats to native fish species and the aquatic ecosystem. However, we know very little about how strong garpikes feed on native fish species, and whether they are different from other native predators in feeding efficiency. Using a manipulative experiment, we studied the functional response of a common garpike, Lepisosteus oculatus on three prey, Cirrhinus molitorella, Megalobrama terminalis, and Ctenopharyngodon idellus. The functional response of L. oculatus was further compared with that of native similar predatory species, Channa maculata. Specifically, we studied the types of functional response, constructed the functional response curves, estimated the parameters representing feeding efficiency. By combining the functional responses and food conversion efficiency, we constructed a mechanistic model to simulate their population developments with time when considering the potential different mortality rates due to intraspecies density dependence. We found that both L. oculatus and C. maculata had Type-Ⅱ functional responses. It was not significantly different in the rate of unit resource consumption between the two species, that is, there was no significant difference neither in the attack rate (P=0.383) nor in the handling time (P=0.663). While the relative growth rate of L. oculatus was higher than that of C. maculata (P<0.05), there was no significant difference in food conversion efficiency between these two species (P=0.132). We also found that L. oculatus had faster population growth and higher stable population density than C. maculata. Collectively, our results indicate that L. oculatus have neither a higher resource consumption rate nor food conversion efficiency than native similar predators. However, we suggest that it is still very necessary to monitor and control this exotic fish in the natural aquatic ecosystem, given that it has no natural enemies, consumes many native fishes, and competes with native predatory fish. Our quantification of functional responses provides a basis for future systematic assessment on the ecological impacts of L. oculatus, and can serve as a reference for assessing resource consumption rate and potential ecological impacts of other exotic fishes.
CHEN Huan, HE Yan, LIU Xiao-Ling, ZENG Ling-Qing
2021, 45(5): 1145 -1153   doi: 10.7541/2021.2020.276
[Abstract](949) [FullText HTML](425) [PDF 1569KB](29)
The vulnerability to angling refers to the stable difference in the probability of being caught among individuals within a fish species, which is easy to be affected by various environmental factors. Fish in nature are affected by human angling activities, but the characteristics of the effects of different angling intensities on the vulnerability to angling and growth of the Cyprinidae fishes are not clear. In order to investigate the effects of different angling intensities on the vulnerability to angling and growth performance of the Cyprinidae fishes in the Yangtze River, the juvenile crucian carp (Carassius auratus) was used as the experimental object in this study under the condition of the laboratory (26.9±0.1)℃, angling with different intensities for three treatment groups that have similar size and physical fitness, three treatment groups [high frequency group (angling once a day), medium frequency group (angling once every two days) and low frequency group (angling once every four days)]; three parallel groups were set up in each angling treatment group, including 40 fishes in each parallel group. After 10 hours of angling in each repetition, the angling activities of the group were stopped. The angling time, angling serial number and electronic information of each fish successfully fished were recorded. The angling ratio, individual fish angling interval, average angling serial number and its coefficient variation as well as the specific growth rate of fish during the experimental period (9d) were all calculated. The results showed that the angling proportion of the three angling intensity groups decreased with the increase of angling times, and the individual angling interval showed an increasing trend with angling time increased, which results in a negative correlation between angling proportion and individual angling interval. Except for the low intensity treatment, the average angling serial number of both the high and medium angling intensity treatments showed a decreasing trend with the increase of the angling times, and the coefficient variation of the average angling serial number of the two intensity treatments increased with the increase of the angling times. The average angling serial number of the three treatment treatments was negatively correlated with its variation coefficient. The specific growth rates of the three angling intensity treatments were all negative during the experiment, but there was no significant difference among the three groups. Our results suggested that high intensity angling activities can reduce vulnerability to angling of the juvenile crucian carp, and it can lead to obvious negative angling effect of individual growth, which shows that high-intensity fishing activities may affect vulnerability to angling and evolutionary trajectory of other related phenotypes of the wild fish populations.
WANG Ya, FU Cheng, HU Yue, FU Shi-Jian
2021, 45(5): 1154 -1163   doi: 10.7541/2021.2020.285
[Abstract](1088) [FullText HTML](401) [PDF 1082KB](26)
In nature, fish often suffer from various of predation stress. Thus, prey fish often respond to their predators by adjusting their behavior, which is called anti-predator behavior. Investigating the correlations between behavioral characteristics of fishes and their physiological functions and habitat environment at the interspecific level is helpful to understand the internal mechanism of interspecific differentiation of behavioral strategies of fishes, therefore ecologically important. The previous predation stress experience and the presence of predators in the current environment may act different effects on the behavior of prey fish, because the prey fish need to maximize survival and minimize the cost of anti-predator behavior. The aims of this study were to compare the effects of previous predation stress experience and the presence of predators in the current environment on the behavior of prey fish, and to examine whether there are interspecific differences for these effects. In this study, the effects of both previous predation stress experience and present predation stress on exploration, activity and boldness in juvenile bream (Parabramis pekinensis), grass carp (Ctenopharyngodon idellus), crucian carp (Carassius auratus) and qingbo (Spinibarbus sinensis) were investigated. The results showed that, the effects of predation stress experienced early on the behavior of fish are quite different from those of predators in the current environment, and these effects are also quite different among the four species. The naïve bream, grass carp and qingbo performed anti-predator behavior to the strange predator snakehead fish (Channa argus), which suggested that these three fish could recognize the strange predator snakehead fish, but such a recognition is still different from the recognition obtained from real predation experience. The bream and qingbo with predation stress experience did not exhibited anti-predator behavior in blank environment, which may be a strategy for conserving energy. In general, grass carps were more sensitive to predation stress and environmental treatment, while the response of qingbo was more conservative. The differences in anti-predator responses among the four cyprinids may be closely related to the physiological phenotypes of the four cyprinids, such as morphology and swimming performance, and the predation pressure in the habitat environment. In terms of similarities, all the four species respond to predators by maintaining high levels of swimming in the presence of predators. Maintaining this stress state may be critical to keeping the prey fish stay away from the predator and staying alert at all times.
ZHOU Ke-Xin, WEN Xin, DENG Cheng, CHEN Shuai-Long, QI Xing-Zhu, LUO Jian
2021, 45(5): 1164 -1170   doi: 10.7541/2021.2020.291
[Abstract](1519) [FullText HTML](484) [PDF 1093KB](26)
Body color is an unique phenotypic trait of fish, which is of great significance to the survival of species, avoiding enemy damage and preventing ultraviolet erosion. Coral reef fishes have rich species diversity and body color variation. Plectropomus leopardus, a coral reef fish, shows significantly different body colors in different environments. Its body color is gorgeous and bright, with high ornamental value and high economic value. Plectropomus leopardus is a valuable material to study the development and variation of body color. In order to reveal the mechanism of fish body color variation, Plectropomus leopardus individuals with different colors were selected. The skin color, types of pigment cells and movement state of pigment cells in different parts were observed by means of paraffin section, frozen section and stereoscopic microscope to compare the red and black Plectropomus leopardus. Then, the skin sections of the individuals with different colors were observed to analyze the influence of the number and distribution of pigment cells on the change of body color. Meanwhile, the difference of pigment cells between stress and non-stress groups was also studied. The results showed that the morphology of melanocytes and erythrocytes was mainly dendritic, and some are punctate. The size of melanocytes was 20—35 μm, and that of erythrocytes was 20—25 μm. In the black individuals, the back epidermis were mainly melanocytes, and the cells were zonal distribution. In the abdomen epidermis of the black individuals, a large number of melanocytes were observed. While in the tail of the black individuals, a large number of melanocytes were mainly distributed, the cell density was the largest, some cells were stacked distribution, and the tissue color was the deepest. In the red individuals, the dorsal epidermis was mainly composed of red pigment cells. In the abdominal epidermis, only red pigment cells were observed, with a small number of cells scattered in the tissues and the lightest color. In the tail of the red individuals, red pigment cells were widely distributed, with a block distribution, and a small number of melanocytes were observed in the tail epidermis. In the stress group, body color changed quickly and the granular pigment cells were smaller and darker than those in non-stress group, which was mainly due to the rapid expansion and contraction of pigment cells. This research will lay the foundation for further discovery of the development mechanism of body color formation of Plectropomus leopardus, and also provide theoretical guidance for the breeding.
LI Wei, RONG Kuan, QIN Li-Rong, LI Wei-Wei, DUAN Ming, ZHANG Tang-Lin, LIU Jia-Shou
2021, 45(5): 1171 -1180   doi: 10.7541/2021.2020.305
[Abstract](1533) [FullText HTML](435) [PDF 898KB](73)
The behavioral study of aquatic animals is an important research direction in the field of fishery, which has important theoretical and application value for understanding the behavioral phenotypes and functions of aquatic animals, and for improving the effect of fishery production. At this stage, the research results of aquatic animal behavior have been widely applied in aquaculture, fishery resource protection and utilization, capture fishery and other fields. In the process of aquaculture production, understanding the behavior of aquatic animals can help farmers to continuously improve and optimize the culture environment and technology, and improve the efficiency of aquaculture. In fishery fishing production, the development of fishing activities should make use of the behavioral characteristics of fishing objects to a great extent. Fishermen can arrange fishing time scientifically and choose fishing methods and equipment reasonably according to the behavior characteristics of fishing objects, so as to increase the catch. In the protection of fishery resources, reasonable artificial measures should be taken to protect and restore fishery resources according to the behavioral characteristics of aquatic animals, such as habitat selection, breeding site selection, prey selection and so on, in order to realize the sustainable utilization of fishery resources. This article reviewed the current research status of aquatic animal behavior, the main types of aquatic animal behavior, the occurrence and mechanism of each behavior, the interaction between behaviors, and the application status of behaviors in fisheries. At the same time, in view of the existing problems in current aquatic animal behavior research, the future research direction and research focus of aquatic animal behavior are proposed. We suggested that the monitoring and quantification of the behavior of aquatic animals should be further strengthen. The simulation and construction of habitats in the artificial culture environment should be pay more attention in order to better study and understand the behavior of aquatic animals in the closest natural state. We encourage more systematic research on the combination of basic theory and practical application of aquatic animal behavior. This article aims to provide reference and inspiration for research in the field of aquatic animal behavior, and to provide a theoretical reference for the application of aquatic animal behavior research results in fishery.


Journal Introduction

  • Establishment Time:1955  Bimonthly
  • Competent unit:Chinese Academy of Sciences
  • Host unit:Institute of Hydrobiology, Chinese Academy of Sciences ; Chinese Society for Oceanology and Limnology
  • Editor-in-Chief:GUI Jian-Fang
  • ISSN 1000-3207
  • CN 42-1230/Q

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