To evaluate effects of decontamination time on the nutrient composition, texture and water holding capacity, flavor components and volatile odor substances in bighead carp muscle, the micro-water purification aquaculture system was established in natural lakes for a 2-month trial. The contents of protein and fat in bighead carp muscle were decreased significantly, and the ash showed no significant difference. The content of volatile basic nitrogen and carbonyl in the muscle of bighead carp decreased significantly by prolonging purification time. The hardness of bighead carp muscle texture increased significantly with the extension of purification; the adhesion and chewing of bighead carp muscle were higher than that of the early purification, while the elasticity and recovery in bighead carp muscle were similar to the early experiment. The contents of water-soluble proteins and free amino acids in bighead carp muscle increased at day 20, and then began to decline. We inferred that micro-water purification treatment can significantly enhance the quality of bighead carp and improve the taste and flavor of fish.
Lake Dongting is the second largest floodplain lake along the Yangtze River basin. However, the study on fish communities in the Dongting Lake is limited, lacking systematic research on the spatio-temporal variations of fish assemblages in this area. Fish were sampled seasonally from December 2012 to October 2014 in the Dongting Lake. 80 fish species belonging to54 genera, 17 families, and 7 orders with dominant Cyprinidae accounting for 58.8% of the total species were collected. The species richness reduced by 36 in contrast with the historic records. The number and percentage of riverine and river-sea migratory species decreased by 13 (2.2%) and 4 (3.0%) respectively in comparison with historic records. We detected significant seasonal and regional differences in species composition and biodiversity. The diversity and evenness of fishes were significantly higher in summer and autumn than those in other seasons. Meanwhile, significantly lower diversity was observed in the east Dongting Lake than other regions. Our results indicated that seasonal flood pulses and, assisting by river-lake connectivity may play a fundamental role for the fish resources supplement in floodplain lakes. This study demonstrated significant spatio-temporal variations of fish assemblages in the Dongting Lake, which provided scientific foundations for fish conservation in this area.
In order to explore the formation process, water purification effect, microbial structure and function of three types of biofloc in the water with Litopenaeus vannamei during hatchery period, the content of flocs and water quality index were measured, and Illumina MiSeq high-throughput sequencing technique was applied to compare the characte-ristics of biofloc in three groups with glucose, starch and sucrose, respectively. The results indicated that the biofloc formed in each group could effectively regulate water quality and reduce the levels of ammonia and nitrite. The concentrations of ammonia, nitrite and nitrate in the water samples from three experimental groups were significantly lower than those in the control group (P<0.05). The concentrations of ammonia, nitrite and nitrate in starch group were significantly higher than those in the glucose group and sucrose group (P<0.05). Moreover, the BFV in starch group was significantly lower than that in the glucose group (P<0.05), and the sucrose group possessed the highest BFV. The particle size of three groups was: sucrose group > glucose group > starch group. The quantity of 553, 515 and 542 OTUs was measured in the three groups respectively. Tthe microbial abundance index Chao1 and Shannon value implied the relationship in the three groups was: glucose group > sucrose group > starch group. Furthermore, regarding the phylum level, Proteobacteriae, Bacteroidetes and Planctomycetes were the dominant phylum in each group, and the proportion of three phylums in each group was 91.7%, 97.6% and 88.7%, respectively. However, in the genus level, Oceanicella was the dominant genus in glucose group, with the highest proportion of 18.4%, and the Muricauda and Cyclobacterium had the highest proportion in starch group, which were 9.8% and 5.9% respectively, and higher than those in glucose group and sucrose group. Rhodopirellula in sucrose group was 1.8% and 4.1% higher than that in the glucose group and starch group, respectively. Cell metabolism, genetic information processing and environmental information processing were detected in the three groups by Tax4Fun method. The gene function abundance in glucose group was higher than that in the sucrose and starch group. All of the results implied that biofloc in the breeding water with Litopenaeus vannamei could not only purify water quality, but also improve the microbial diversity, among which the glucose was the most effective carbon source. Nevertheless, biofloc technology is of essential to maintain the balance between water quality and water ecosystem.
This study analyzed the characteristics of algal blooms based on the spring algal blooms data collected from the tributaries of Three Gorges Reservoir from 2004 to 2015. Results showed that the algal blooms had occurred in 26 tributaries of Three Gorges Reservoir (TGR) with the highest rate in Xiangxi River. The dominant species of the algal blooms were Bacillariophyta and Dinophyta. The probability of Dinoflagellate blooms increased correspondently with the increased impounded level, but the occurrence rate of Diatom blooms increased after several years while reserving water level was up to 175 m. The concentrations of algae density, chlorophyll a and trophic state were low when the reservoir water level was below 175 meters, and then increased sharply when the reservoir water level raised to 175 meters with a trend of gradual decrease after years of reservoir impounding to 175 meters. The principal components analysis (PCA) showed that the algae density, chlorophyll a concentration, total phosphorus (TP), total nitrogen (TN) and permanganate index were classified into the same cluster. Algal density and chlorophyll a concentration were significantly positively correlated with TP, dissolved oxygen, permanganate index and pH. With the impounded level of Three Gorges Reservoir, the mean flow velocity of the tributaries decreased, which might result in the algal blooms at the tributaries of Three Gorges Reservoir under proper temperatures.
To assess tissues distribution and elimination of robenidine hydrochloride in Ictalurus punctatus, single and 5-day continuous oral administration (20 mg/kg) of robenidine hydrochloride has been conducted in healthy Ictalurus punctatus at (28±1)℃. The concentration-time curve of robenidine hydrochloride in plasma was a two-compartment model for the single oral administration with the kinetic equation: C= 7.69e–0.02t + 0.13e–0.01t–7.82e–0.27t. The T(peak) and Cmax in the plasma, muscle, skin, gill, liver and kidney of channel catfish were 10.03, 15.79, 11.10, 2.61, 12.89, 7.87 and 5.76 μg/mL, 2.91, 2.90, 3.05, 3.04 and 0.42 mg/kg, respectively. The elimination half-life and drug-time curve AUC were 58.63, 23.57, 35.37, 19.74, 29.34, 43.30h and 326.74 (μg/mL)/h, 157.58, 183.72, 95.09, 174.82, 29.85 (mg/kg)/h, respectively. For the 5-day continuous oral administration at 20 mg/kg, the highest and lowest concentration of robenidine hydrochloride was the intestines and the muscle, respectively. The elimination rate of robenidine hydrochloride in each tissue from fast to slow was plasma, gill, brain, muscle, skin, liver, kidney and intestines. If the maxi-mum residue limit (MRL) of robenidine hydrochloride in edible tissue is 10 μg/kg, the withdraw period should not be less than 23 days under this experimental condition.
A 66-day feeding trial was conducted to investigate the effects of different protein sources on growth, body composition and PEPT1 gene expression in the foreintestine and TOR gene expression in the liver of juvenile darkbarbel catfish [initial weight (2.90 ± 0.01)g]. Four isoproteic (39.0% crude protein) and isolipidic (9.0% crude lipid) diets were formulated with fish meal (FM), soy protein concentrate (SPC), fish hydrolysate (FH) and crystal amino acids (CAA) as the main protein source. No significant difference was observed in the survival rate among dietary treatments (P>0.05). Dietary protein had a significant effect on SGR. SPC group had lower SGR than that of the FM groups, while SPC group had higher SGR than FH and CAA group (P<0.05). The crude protein of SPC group was only lower than the FM group, while the crude lipid of SPC group was higher than the FM group (P<0.05). Dietary protein had a significant effect on PEPT1 mRNA expression. The PEPT1 mRNA expression in SPC group was significantly lower than the FM group, but significantly higher than the FH and CAA group at day 35. However, the PEPT1 mRNA expression of SPC group was significantly higher than the FM group at day 66 (P<0.05). Dietary protein source had no effect on TOR gene expression. These results suggest that juvenile darkbarbel catfish of SPC group had better growth performance than FH and CAA group, which might be attributed to the higher foregut PEPT1 mRNA expression.
Potamogeton crispus plays an important role in maintaining the balance of lake ecosystem in winter-early spring. Maternal environment can influence life-history and offspring performance traits of aquatic plant. Understanding maternal environmental effects could predict the response mechanism of aquatic plant life-history traits to climate warming. In this study, P. crispus was used to explore the response to warming with three heated modes by investigating morphology, stoichiometry and early germination strategy of turions. We found that warming had no effect on tu-rion wet weight, but extreme warming significantly increased turion length and width. The results of stoichiometry indicate that maternal extreme warming significantly increased N concentrations in turions, but significantly decreased C 鲶N ratio. And maternal warming accelerated the germination of turions and seedling growth. In summary, maternal warming significantly affected turion morphology, stoichiometry and germination.
Dali Nor lake, one of the four lakes in Inner Mongolia Autonomous Region, China, is a typical saline-alkaline lake with high concentrations of carbonate salts (alkalinity up to 60 mmol/L, pH 9.6 and salinity 6‰). Amur ide (Leuciscus waleckii) is one of the only two existing economic fish in the Dali Nor Lake with the character of spawning migration. To investigate the osmotic and ionic regulation mechanism of the L. waleckii during spawning migration form Dali Nor lake to Gongger river, we analyzed serum ionic (Na+, K+, Cl−, Ca2+ and Mg2+) and hormone (PRL, GH and IGF-1) levels, Na+/K+-ATPase activities in gills, intestinal and kidney, Ca2+/Mg2+-ATPase activities in gills and structure of gills in L. waleckii collected form Dali Nor lake and Gongger river. In addition, above parameters were studied in L. waleckii during 24-h transfer from lake to river water. Compared to lake fish, river fish had decreased Na+, significantly increased Cl− in serum as well as significantly increased Na+/K+-ATPase activities in kidney and intestinal while no significant change in gills. There were no significant differences of K+, Ca2+, Mg2+ and hormone (GH, IGF-1 and PRL) levels in serum between lake and river fishes. During 24-h lake-to-river water transfer, Cl− increased and K+ decreased significantly in serum, Na+/K+-ATPase activities in gills, intestinal and kidney and Ca2+/Mg2+-ATPase activi-ties in gills, as well as PRL and IGF-1 levels all increased significantly (P<0.05). Histology of gills showed that mucous cell counts were significantly higher in lake fish compared to that of river fish, while branchial chloride cells (CCs) counts have no obvious difference between lake and river fish, but the size of branchial CCs on filaments slightly increased in river fish. It is concluded that L. waleckii could maintain high serum ionic levels though endocrine control of Na+, K+-ATPase in osmotic regulatory tissues during spawning migration form Dali Nor lake to Gongger river.
Coregonus ussuriensis, one coldwater fish, is an important economic fishery species in the Heilong River basin. The resources of Coregonus ussuriensis have been seriously impacted by anthropogenic influences such as pollution, habitat degradation and overfishing. Knowing the characteristics of life history at the important stage helps to better protect the Coregonus ussuriensis. Otolith element fingerprint could objectively and specifically reflect the character of the water which fish experienced. The element Sr and Ca microchemistry patterns have been used to reflect the water type which the fish lived in. To study the characteristics of life history for Coregonus ussuriensis, an electron probe microanalyzer (EMPA) was used to analyze the element Sr and Ca microchemistry patterns in otoliths for Coregonus ussuriensis collected from Suibin and Jiejinkou section of the Heilong River main stream and Tangyuan section of the Songhua River main stream from December 2013 to January 2014. Results of line transect analysis indicated the value of Sr/Ca significantly fluctuated including a low ration (<5) responded to freshwater life and some high rations (>10) responded to seawater life, revealing they had experienced an anadromous migration. The results of X-ray mapping analysis of EMPA reflected the same feature of anadromous migration. The annual ring of otolith characters analysis showed the bright and dark belt in the otolith match with the low and high Sr/Ca ratio areas well. It revealed that Coregonus ussuriensis migrate seasonally. Some species migrate to seawater in summer and return back to freshwater in winter regularly, and other species may not have significant regularity. The time of in fresh water and sea water is inconsistent. This study first reported the migratory characteristics of Coregonus ussuriensis, which can provide an important basis for further study on the life history.
The interplay between intestinal microorganism and their host has received extensive scientific attention, however, there is no study about the response of intestinal microorganism of the Chinese mitten crab in the hunger state. In the present study, 16S rRNA sequencing was used to investigate intestinal microorganism in Chinese mitten crab during the period of starvation and refeeding. The results showed that the Alpha diversity index of the intestinal microorganisms decreased by starvation, and re-feeding did not change the descending trend of the intestinal microbial diversity index. Besides, there was no significant difference comparing to the control group (P>0.05). In terms of the bacterial phyla composition, starvation gradually increased the proportions of the Proteobacteria, Firmicutes and Bacteroidetes and reduced the proportion of Tenericutes. Re-feeding restored Proteobacteria, Firmicutes, Bacteroidetes and Tenericutes to the level of control group. By comparing different strains under different conditions, 8 strains with significant differences (P<0.05) were sifted at the family and genus level. Among them, Candidatus bacilloplasma was characterized by high abundance of bacteria and significant response to starvation and refeeding, and its specific function of the flora needs further investigation. This study first reported the changes of intestinal flora of the crabs after starvation and refeeding, which could provide basic knowledge for the further exploration of the specific functions of the flora.
Resveratrol (Res) is an important active ingredient in Chinese herbal medicines such as rhubarb and polygonum cuspidatum with antibacterial, anti-inflammatory and antioxidant properties. To explore its application value in the prevention and treatment of bacterial diseases in aquatic animals, we explored the antibacterial activity of resveratrol against Aeromonas hydrophila, an important bacterial pathogen in freshwater aquaculture. The growth, biofilm formation, hemolysis inhibition, and virulence related gene expression of A. hydrophila under different resveratrol concentrations were detected. The in-vivo protection of resveratrol was confirmed by artificially infecting crucian carp with A. hydrophila. The results showed that the minimal inhibitory concentration (MIC) of resveratrol against A. hydrophila was above 1024 μg/mL, and the concentration less than 64 μg/mL did not affect the growth ratio of A. hydrophila. Resveratrol with more than 32 μg/mL significantly inhibited the biofilm formation and hemolytic activity of A. hydrophila (P<0.05) in a dose-dependent pattern. Resveratrol mediated heavy moisture of bacterium group sense of regulation and of QS system by inducing luxR and reucing luxS gene expression. The expression of omp was significantly down-regulated by resveratrol. Artificial infections showed that the mortality rate of allogynogenetic crucian carp infection in the 25－100 mg/kg resveratrol-treated group was significantly lower than that of the control group, and the expression of TNF-α and IFN-γ mRNA was significantly decreased. This study showed that resveratrol can effectively inhibit the viru-lence of A. hydrophila and reduce the inflammatory response at 2500 mg/kg on fish infected with A. hydrophila.
This study cloned the full-length of complement C7 cDNA by RACE (rapid-amplification of cDNA ends) from Russian sturgeon (Acipenser gueldenstaedti). It contained 3103 bp, including a 2502 bp open reading frame (ORF) encoding 833 dedueced amino acids, a 44 bp 5′-UTR and a 554 bp 3′-UTR. Multiple sequence alignment revealed that AgC7 proteins were well conserved with the typical structural motifs such as TSP1, LDLa, FIMAC, MACPF and had the sequence identity with Lepisosteus oculatus (56%), Ictalurus punctatus (46%), Danio rerio (49%), Salmo salar (49%) and Oreochromis niloticus (47%), respectively. AgC7 gene is constitutively expressed in all evaluated tissues with the highest expression in intestine and the weakest level in muscle. Chitosan oligosaccharide induced the expression of AgC7 gene to a certain degrees in all tissues with the highest increase in intestine (1.51 times). After infection with Aeromonas hydrophila, AgC7 gene exhibited distinct time-dependent response patterns in tested tissues with most obvious induction in gills and the maximum expression at 6h after infection (41.30 times). The expression of AgC7 gene decreased rapidly and returned to normal level after 12h. These results suggest that C7 of Russian sturgeon might play an important role in the immune defenses against bacterial infection.
This study analyzed the resources status and spatial distribution of Anguilla japonica and Anguilla marmo-rata in the Pearl River based on the data collected from 2015 to 2017. A total of 41 Anguilla japonica individuals with the average age of (4.2 ± 1.3) years were collected in these three years, and 93% individuals were sexually immature. A total of 12 Anguilla marmorata individuals with the average age of (4.3 ± 1.0) years were collected and 83% individuals were sexually immature. Anguilla japonica could migrate to the Heshan section of the Hongshuihe River with the percentages in individuals and in weight both less than one percent. Anguilla marmorata could migrate to the Shilong section of the Xijiang River with an occurrence rate less than one in 200. This indicated that the wild Anguilla spp. resources in the Pearl River are extremely rare and need to be protected. Redundancy analysis shown that river fractals and river width play important roles in spatial distribution for Anguilla japonica, while river width and river depth play important roles for Anguilla marmorata. This study is a part of a long-term investigation for the wild Anguilla resources of the Pearl River, and the results could be instructive to the conservation and management of Anguilla resources.
This study investigated the isolation and purification of spermatogonial stem cells (SSCs) by single cell suspensions after enzyme digestion using testes of various months old tiger puffer. SSCs were enriched by Percoll discontinuous gradient. The SSCs were identified by optical observation and immunolocalization of Vasa protein. The majo-rity of SSCs at 14-month-old fish was type A spermatagonial cells that were significantly higher than those of the 22-month-old males (P< 0.05). SSCs were mainly enriched in 10% — 30% Percoll gradient belt, where the germ cells were mainly distributed at 14-month-old fish. These results indicate that 14-month-old male fish is a great source for SSCs using the current isolation method.
To investigate the effect of low salinity stress on Glucose-6-Phosphate Isomerase (GPI) in Takifugu rubripes, we cloned GPI and analyzed its expressions in tissues with and without acute low-salinity stress using RT-PCR and real-time quantitative PCR (qPCR) techniques. The results showed that the GPI cDNA of the T. rubripes was 1736 bp in length containing an Open Reading Frame of 1662 nucleotides that encodes 553 amino acids. The predicted amino acid sequence contains two Sugar Isomerase Domains without signal peptide and transmembrane domains. Results of multiple sequence alignment showed that GPI was highly conserved among species. qPCR results showed that GPI mRNA was expressed in all the tested tissues, with the highest expression level in muscle. Under low-salinity stress, the relative mRNA expression of GPI in gill increased firstly, then decreased and increased again in all low-salinity groups, and the relative mRNA expression of GPI in kidney differed among low-salinity groups. Therefore, it was speculated that GPI play a role in the response of T. rubripes to acute low-salinity stress.
The oligotrich ciliates are important components of the marine microplankton. Many studies have been carried out on the taxonomy of these taxa in the past one and a half centuries. However, ambiguities concerning their identification have been accumulated due to lacking key morphological characters. Ten poorly known oligotrichs, Strombi-dium apolatum Wilbert & Song, 2005, Strombidium capitatum (Leegaard, 1995) Kahl, 1932, Strombidium guangdongense Liu, et al., 2016, Strombidium paracalkinsi (Lei, et al., 1999) Agatha, 2004, Strombidium parastylifer Song, et al., 2009, Strombidium suzukii Song, et al., 2009, Spirostrombidium cinctum (Kahl, 1932) Petz, et al., 1995, Paralle-lostrombidium jankowski (Song, et al., 2009) Song, et al., 2018, Parallelostrombidium kahli (Song, et al., 2009) Song, et al., 2018, Strombidinopsis minima (Gruber, 1884) Song & Bradbury, 1998 were investigated using live observation and protargol impregnation methods. Based on the present populations, much more information particularly with respect to their morphological features in vivo as well as original morphometric data were provided. Compared with previous population, some variable characters of these species were recorded.
5 genera 13 taxa of Staurosiraceae (Bacillariophyta) were collected from Mugecuo Scenic Area, Sichuan province, China. Among them, 2 genera of Pseudostaurosiropsis Morales and Stauroforma Flower, Jones & Round were newly recorded in China, and there are 7 newly recorded species of China: Staurosirella frigida Van de Vijver & Morales, S. martyi (Héribaud-Joseph) Morales, Pseudostaurosira cataractarum (Hustedt) Wetzel, Morales & Ector, P. pseudoconstruens (Marciniak) Williams and Round, P. trainorii Morales, Pseudostaurosiropsis connecticutensis Morales and Stauroforma exiguiformis (Lange-Bertalot) Flower Jones & Round. The detailed morphology, habitat characteristics and geographical distribution of each taxon were given. Moreover, according to new classification system, Staurosiraceae species were revised in Algarum Sinicarum Aquae Dulcis (Tomus X).
sCAP could stimulate heart movement and contraction of muscle and fallopian tube, enhance posterior bowel contraction and participate in biological molting. This study identified the sCAP gene (GenBank accession No. MG779491) from Sepiella japonica as SjsCAP. We cloned a 696 bp full-length cDNA sequence of SjsCAP gene by RT-PCR and RACE techniques including 111 bp 5′ untranslated region (UTR), 324 bp 3′UTR, and 261 bp open reading frame (ORF) encoding a protein with 86 amino acids. The molecular weight of the protein was 9.331 kD and its pI was 8.52. The prediction of signal peptides and transmembrane domain indicated that SjsCAP might play an important role in extracellular. The protein is hydrophilic. Phylogenetics analysis based on SjsCAP amino acid sequences demonstrated that S. japonica has the closest relationship with Sepia officinalis with a 90% similarity. Expression analysis of SjsCAP gene in male and female individuals showed that it mainly expressed in optic lobe and also has the high expression in the brain. The expression level in male was obviously higher than that of female cuttlefish. The results of in situ hybridization assay showed that significant positive hybridization signals were detected in the optic lobe of the brain tissue of S. japonica, the vertical lobe, subvertical lobe, peduncle lobe, dorsolateral lobe of the esophageal nerve mass, and optic gland. These results provide some theoretical basis for genetic resource conservation and development of S. japonica.
To elucidate the role of intestinal fatty acid binding protein (Ifabp) in the regulation of lipids metabolism, unigenes were obtained from transcriptome of liver in spotted scat, Scatophagus argus. Two subtypes of ifabp genes (ssifabp2a and ssifabp2b) were isolated and analyzed in the female and male S. argus, respectively. Tissue distributions and changes of ssifabp2a and ssifabp2b in fast feeding and re-feeding were also observed. Phylogenetic tree results showed that ssIfabp2a was clustered with other Ifabp2a, Ifabp or IfabpX1, while ssIifabp2b was clustered with Ifabp2b or Ifabp-like in Osteichthyes. Homology analysis revealed that the sequence identity of ssifabp2a was 78.8%—87.9% with other Osteichthyes Ifabp2a, Ifabp or IfabpX1. The sequence identity of ssifabp2b was 79.5%—87.9% with other Osteichthyes Ifabp2b or Ifabp-like. The sequence identity was 73.5% between ssifabp2a and ssifabp2b. RT-PCR showed that ssifabp2a was the highest in intestine, and had a moderate level in kidney and liver. And ssifabp2b was also the highest in intestine, but had a moderate level in liver, stomach and hypothalamus in male. However, the expression of ssifabp2a was the highest in stomach, and moderate in kidney, liver and hypothalamus, with a weak expression level in other tissues and no expression in pituitary. The ssifabp2b was expressed strongly in hypothalamus, ovary, heart and intestine, and weakly in other tissues, but had no expression in gill of females. In the intestine, the expression of ssifabp2a decreased significantly, but there was no significant change of ssifabp2b after 2d of food deprivation. The expression of ssifabp2a decreased significantly compared with the control group, but there was no significant difference on the expression of ssifabp2b within the 7 day fasting group. The expressions of ssifabp2a and ssifabp2b increased significantly with refeeding 3-h after the scheduled feeding time. In liver, the expression of ssifabp2a was not changed, but the expression of ssifabp2b increased significantly after 2-day of food deprivation. However, the ssifabp2a and ssifabp2b were all increased during the 7-day fasting, and decreased significantly with refeeding 3-h after the scheduled feeding time. In summary, ssIfabp2a and ssIfabp2b are involved in the regulation of lipids metabolism at liver and intestine in Scatophagus argus.
Lamprey is of considerable model organism to subject of vertebrate evolution and developmental biology. The current study investigated the morphological characteristics and the growth pattern of embryos, yolk-sac larva and ammocoate of Lampetra morii. The results indicated that the cleavage of lamprey zygote was holoblastic cleavage and the embryology had been subdivided into cleavage, blastula, gastrula, neural plate and groove, head protrusion, prehatching and hatching. The newly-hatched larva breaks through the fertilization membrane at 11—12 day-post-fertilization at water temperature of (18±1)℃. The newly-hatched larva had body weight with (0.00032±0.00002) g and total length with (0.29±0.02) cm. During yolk-sac stage, the body weight and total length of larva generally increased over time. The snout length, eye length, postocular length, disc length, prebranchial length, branchial length, head length, trunk length, tail length and cloacal slit length exhibited allometric growth. The ammocoete stage reached when yolk extruded from the anus and the digestive tract completed at 15 day-post-hatch. In 5 months after hatching, the body weight and total length of ammocoete generally increased over time. The melanophores were extensively distributed and increased in ammocoete. The 5-momth old ammocoete had body weight of (0.07±0.01) g and total length of (3.87±0.32) cm. The early development of L. morii is the basic data for artificial culture and developmental biology, which is the basis for the model organism.
A 65-day trial was conducted to investigate effects of CLA on cytological morphology, activity of antioxi-dant enzymes, and gene expressions of lipid metabolism in the liver and muscle of grass carp. Seven isonitrogenous (crude protein: 36 g/100 g) and isolipidic (crude lipid: 4.5 g/100 g) diets were formulated: 0 CLA (control); 0.5% (CLA0.5); 1% (CLA1); 1.5 (CLA1.5); 2 (CLA2); 2.5 (CLA2.5); and 3% CLA (CLA3). Three biological replicates of fish were assigned to each diet with the initial body weight at (5.08±0.08) g. Endoplasmic reticulum in the liver, and loose sarcolemma of myocyte and degradation of myofibril in the muscle when compared with the control fish. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx), and the total antioxidant capacity (T-AOC) both in the liver and muscle of CLA1.5-CLA2.5 groups significantly (P<0.05) increased compared with control group. The activities of catalase (CAT) in the liver of CLA1.5-CLA3 groups were significantly (P<0.05) higher than that of control group, however, there was no significant (P>0.05) change in the glutathione reductase (GR) activity in the liver. The MDA contents in the liver of fish fed with CLA1.5-CLA2 diets were significantly (P<0.05) lower than that of control group, however, the MDA contents in the liver of fish fed with CLA2.5-CLA3 diets significantly (P<0.05) increased compared with control group. In contrast, fish fed with CLA3 had significantly higher MDA contents in the muscle (P<0.05) compared with control group. Compared with the control fish, the mRNA level of acetyl-CoA carboxylase (ACC) both in the liver and muscle of fish fed with CLA1.5-CLA2.5 diets were significantly (P<0.05) down-regulated; the mRNA levels of lipoprotein lipase (LPL), hormone-sensitive lipase (HSL), and peroxisome proliferator-activated receptor alpha (PPARα) of fish fed with CLA1.5-CLA2.5 diets were significantly (P<0.05) up-regulated; the mRNA levels of fatty acid desaturase 2 (FAD2) in the liver of fish fed with CLA2-CLA3 diets and in the muscle of fish fed with CLA1.5-CLA2 and CLA3 diets were significantly (P<0.05) up-regulated; the mRNA level of peroxisome proliferator-activated receptor gamma (PPARγ) in the liver of fish fed with CLA1-CLA3 diets was significantly (P<0.05) down-regulated. Conversely, there was no significant (P>0.05) difference for the PPARγ mRNA level in the muscle of fish fed with CLA0.5-CLA3 diets. In conclusion, supplementation of 2% CLA could significantly decrease the lipid contents in the liver and muscle without affecting cytological morphology of liver and muscle, the growth and feed utilization of grass carp by improving the antioxidant capacities in the liver and muscle.
A 84-day feeding trial was conducted to evaluate the effects of dietary aflatoxin B1 (AFB1) on growth, physiological responses, histological changes, and accumulation in juvenile grass carp (Ctenopharyngodon idellus). Triplicate groups of grass carp [(2.90±0.16) g] were fed with six semipurified diets formulated with isonitrogenous (crude protein: 32.96%), isocaloric (gross energy: 14.55 kJ/g) containing 0, 10, 20, 100, 1000 and 5000 μg/kg AFB1. AFB1 did not significantly impact behavior, the survival rate, final body weight (FBW), feeding rate (FR), specific growth rate (SGR) or feed efficiency (FE). No significant differences were found in hepatosomatic index (HSI) and viscera index (VSI) among all groups. AFB1 had no significant effect in activities of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). No significant histological lesions in hepatopancreas and kidney were identified between the control and increasing AFB1 treatments. No AFB1 residue was detected in muscles when fish fed with AFB1 up to 1000 μg/kg, however, tiny dose [(1.21±0.18)μg/kg] of AFB1 were detected in muscles in the group with 5000 μg/kg AFB1, which was below the safety limitation of FDA. The results indicated that juvenile grass carp is a little susceptible species to AFB1 exposure up to approximately 5000 μg/kg diet (determined level was 4979.2 μg/kg diet), at least for 84 days.
In order to study the molecular regulation mechanism of the soft intermuscular bones in Rice flower carp, the intermuscular bones of Rice flower carp and Jian carp were collected for high-throughput sequencing of microRNAs (miRNAs) and bioinformatics analysis. 25474895 and 24625715 high quality sequences of 18—32 nt, as well as 595 and 570 known mature miRNAs were obtained from the small RNA library of Rice flower carp and Jian carp intermuscular bone, respectively. Compared with Jian carp, 84 miRNAs were up-regulated and 267 were down-regulated in the intermuscular bone of Rice flower carp. Seven of the down-regulated miRNAs in Rice flower carp were reported as promoting human osteogenesis. Six of the up-regulated miRNAs were reported as inhibit human osteogenesis. These results indicated that Rice flower carp may inhibit the process of osteogenesis by down-regulating the expression of osteogenic miRNAs and up-regulating the expression of osteogenesis inhibiting miRNAs. Therefore it can maintain its intermuscular bone small and soft characteristics. This study laid the groundwork for the study of molecular regulation mechanism of intermuscular bone development.
This study evaluated the effects of dietary copper sulfate (CuSO4), glycine chelated copper (Cu-Gly), copper hydroxymethionine (Cu-MHA) on growth, antioxidant enzymes and intestinal morphology of juvenile pearl gentian grouper (Epinephelus lanceolatus ♂ × Epinephelus fuscoguttatus ♀). Juvenile pearl gentian grouper with the average body weight of (9.00±0.00) g were randomly divided into 3 groups with 3 replicates in each group and 30 fish in each replicate to feed isonitrogenous and isolipidic experimental diets with 3 different copper sources for 8 weeks. (1) The weight gain ratio (WGR), survival ratio (SR) in Cu-Gly and Cu-HMA groups were significantly higher than those in CuSO4 group (P<0.05). (2). The hepatosomatic index (HSI) and viscerosomatic index (VSI) in Cu-HMA group was significantly higher than those in CuSO4 and Cu-Gly groups (P<0.05). There was no significant difference in condition factor (CF) among all groups (P>0.05). (3) Cu contents of vertebrae in Cu-Gly and Cu-HMA groups were significantly higher than that in CuSO4 group (P<0.05). (4) The serum concentrations of triglyceride (TG) and low-density lipoprotein cholesterot (LDLC) in CuSO4 group was significantly higher than those in Cu-Gly and Cu-HMA groups (P<0.05). The serum concentration of high-density lipoproteot cholesterin (HDLC) in CuSO4 group was significantly lower than that in Cu-Gly and Cu-HMA groups (P<0.05). (5) The activity of serum ceruloplasmin (CP) in CuSO4 group was significantly higher than that in Cu-Gly and Cu-HMA groups (P<0.05). (6) The plica height (PH) of midgut and hindgut in Cu-HMA group were significantly higher than those in CuSO4 and Cu-Gly groups (P<0.05). These results revealed that dietary adding Cu-Gly and Cu-HMA could improve intestinal morphology and serum lipid metabolism to ameliorate growth of juvenile pearl gentian grouper.
To explore effects of stickwater (SW) on bile acid metabolism, 4 isonitrogenous and isoenergetic diets including the control diet containing 30% fish meal (FM) and three experimental diets without fish meal but with 8% (SW8), 17% (SW17), 25% (SW25) stickwater (dry matter) were fromulated to feed the yellow catfish with the initial body weight of (15.67±0.11) g for 60 days in pond cage farming. Compared with FM group, fat content of whole fish of SW25 group decreased observably (P<0.05), and liver fat content of SW17 and SW25 group reduced significantly (P<0.05); Cholesterol in serum of SW17 and SW25 groups decreased from 11.9% to 16.6%, and triglyceride decreased from 32.5% to 47.9% (P<0.05). Liver bile acid of SW25 group decreased by 76.3% (P<0.05) compared with FM group, but serum and intestine bile acid increased by 125.7% and 123.3% (P<0.05). The liver CYP7A1 at mRNA level had no significant difference among five groups, but the expression of BSEP, ABCC4, and NTCP increased by stickwater with 16.9%, 68.2% and 222.8%, respectively, in SW25 group. The mRNA level of ABCC4 and NTCP varied significantly (P<0.05). The results indicated that addition of 25% stickwater (dry matter) in diets without fish meal had no effect in liver bile acid synthesis, but it promoted transferring bile acid to serum and intestine to improve fat metabolism and reduce fat deposition in yellow catfish.
We investigated larval and eggs resource of Botia robusta at Laibin section in the Hongshuihe River from mid of April 2017 to August, and found that Botia robusta was the dominant species of collected eggs. We studied the ontogeny of Botia robusta from the Tail bud to Juvenile phase and described the features of 14 developmental stages respectively. The egg membrane was non-adhesive, averaging 6.8 mm. One chamber air bladder was 7.1 mm in total length and the muscle nodes were about 33 pairs. It took 20d to finish the Yolk-sac larva phase stage, spawning mainly from May to June. The total number of the eggs laid at Laibin section in 2017 was about 2.23×108. The correlation analysis between oviposition and major environmental factors found significant correlation between the water temperature with the spawning dynamics (P<0.05).
The target strength (TS) of fish and its relationship with body length is one of the core contents of research and application in fishery acoustic technology. The current study measured target strengths of two widespread commercial cyprinid fish species, Cyprinus carpio and Aristichthys nobilis with hydroacoustics experiment with tethering method and Simrad EY60 echosounder (120 kHz) under swimming status (26 individuals of C. carpio and 26 of A. nobilis) in an undisturbed cage in the Geheyan Reservoir (Yichang City, Hubei Province) from 1 May — 20 May, 2017. The total length of C. carpio and A. nobilis were from 19.9 to 29.6 cm and 49.2 to 74.2 cm, respectively. The body weight of them were from 175 to 461 g and 1200 to 4700 g, and their TS were from –59.35 to –45.20 dB and –34.22 to –17.49 dB, respectively. The regression relationship between target strength (TS, dB) and total length (TL, cm) for the two species were TS = 29.84×lgTL – 95.23 (R2 = 0.74, P < 0.01) for C. carpio, and TS = 35.88×lgTL – 90.33 (R2 = 0.83, P < 0.01) for A. nobilis. The TS-TL equation of A. nobilis was used to assess the total fish biomass of a small enclosed water body (Lake Yanlong) to 89.36 ton (i.e. 40.1 g/m2), which is close to the real total catch (73.61 tons) of this area, supporting the rationality of in method to evaluate fish target strengths and their relationship with body length. Exploring target strength for the two most common fish should benefit the development of hydroacoustics techniques in China’s inland waters.
The microscopic structure and cytochemical characteristics of peripheral blood cells in Megalobrama amblycephala were observed by routine Wright staining and cytochemical staining. Six types of cells were distinguished in the peripheral blood cells in Megalobrama amblycephala: erythrocytes, lymphocytes, monocytes, neutrophils, eosinophils and thrombocytes. The lymphocytes are the most abundant blood cells except erythrocytes, followed by thrombocytes, monocytes, neutrophils and eosinophils. The mature erythrocytes are mostly oval with smooth surface, oval or round nuclei whose chromatin is denser. The lymphocytes are usually round, with less cytoplasm, and the nucleus is usually eccentrically located. The monocytes are mostly round, the nucleus is round or oval, and vacuoles can be observed in the cytoplasm. Neutrophils are nearly round, and their nuclei are usually eccentrically located, lobed, kidney or oval shaped, with clear nucleoplasm boundaries. Eeosinophils are usually round, with reniform or oval nuclei, and the cytoplasm is filled with purple granules. Thrombocytes have various forms, most of which are oval, spindle, long-rod shaped or teardrop shaped, and their nucleo-cytoplasmic ratio is large. The lymphocytes were positive for periodic acid-Schiff reaction (PAS), weakly positive for naphythol AS-D chloroacetate esterase (AS-DCE) and α-naphthol ace-tate esterase (ANAE), and negative for Sudan black B (SBB), acid phosphatase (ACP), alkaline phosphatase (AKP) and peroxidase (POX). The monocytes were strongly positive for POX and ACP, while PAS, positive for SBB, AS-DCE and ANAE were and negative for AKP. Except weakly positive for PAS and ANAE, the cytochemical staining pattern of neutrophils were the same as those of monocytes. Eosinophils showed strong positive for POX and ANAE, positive for SBB and ACP, weak positive for PAS and AS-DCE, and negative for AKP. The thrombocytes were weakly posi-tive for PAS, AS-DCE and ANAE and negative for SBB, ACP, AKP and POX. The microstructural and cytochemical characteristics of peripheral blood cells in Megalobrama amblycephala were similar to those of other fishes, but also had obvious species specificity. The results of this investigation can be used as a basis for monitoring the health status of Megalobrama amblycephala and provide basic data for its farming and pathological diagnosis.
Excessive ammonia nitrogen in the aquaculture waters can impact immunity, growth, and morbidity and mortality of the cultured animals. The ammonia nitrogen in aquaculture waters is mainly removed by microbial degrada-tion. In this study, two ammonium removal strains were screened from a mixture of water and sediment in variety aquaculture ponds and identified as Bacillus coagulans. The degradation rate of the two strains were 97.8% and 97.8%, respectively. Two strains could adapt high pH value and C/N range, and have high resistance to high temperature and high salt. The oral administration trials verified that the two strains were safe for cultured aquatic animals. The two screened strains and the previously obtained mutagenic strain B38 in our lab were mixed with 1 鲶1 鲶1 ratio to make a probiotics complex, and its effects on the amount of ammonia nitrogen, nitrite and algae were evaluated by 18 days farming trials. Compared with the four commercial probiotics (Photosynthetic Bacteria, Yeast, EM and Bacillus), ammonia nitrogen decreased greatly in the ponds using probiotics complex. The number of algae in the ponds using probiotics complex and Bacillus from the 9th day was higher than other groups, and the amount of algae were about twice as much as the other groups on the 14th day. The probiotics complex can reduce ammonia nitrogen and increase the number of algae. This study provides a foundation for the development of complex probiotics.
This study explored the nitrogen-fixing microbial community structure, diversity and nitrogen fixation activity in urban landscape water column, and the nitrogen-fixing contribution of nitrogen-fixing cyanobacteria in water from Muye Lake and People’s Park in Xinxiang city. Physical and chemical indicators are eutrophic in these two lakes. This study measured 16S rDNA and Nitrogenase nifH gene of microorganism by High-throughput sequencing, and determined Nitrogen Fixation Rate of Nitrogen Fixing Microorganisms in two lakes by the acetylene reduction assay. A total of 32 phyla and 275 genera were detected in the prokaryote groups, and a total of 9 phyla and 66 genera were detected in the nitrogen-fixing microorganisms in Muye Lake. A total of 31 phyla and 238 genera were detected in the prokaryote groups; a total of 4 phyla and 13 genera were detected in the nitrogen-fixing microorganisms in the water column of the People’s Park. Nitrogen-fixing cyanobacteria accounted for 3% in the Muye Lake and 9.3% in People’s Park. The richness of Nitrogen-fixing microorganisms in Muye Lake is significantly higher than that of People’s Park. The nitrogen fixation activity in the two lakes was similar. It is speculated that nitrogen fixation activity may be inhibited in eutrophic water.
In this study, open reading frame (ORF) of glycoprotein (1530 bp) was amplified by using RNA extracted from Spring Virernia of Carp Virus (SVCV). The SVCV G ORF was cloned into pYD1 vector to construct a recombinant plasmid pYD1-G and then transformed into competent yeast cells EBY100, and positive colonies were screened by colony PCR. The expression of G gene was induced by 2% glucose and detected by cell immunofluorescence and flow cytometry. The immunofluorescence staining observed increased EBY100-pYD1-G signal of induced yeast cells with increased induction time. Flow cytometry analysis observed significantly increased fluorescence intensities in prolonged induced EBY100-pYD1-G cells (P<0.05). These results indicated the SVCV G protein has been successfully expressed and localized on the surface of yeast cell. This study laid a foundation for the novel oral vaccine development against SVCV infection in carps in future.
To explore the species diversity of the marine diatom genus Thalassiosira Cleve, several monoclonal strains were established from Daya Bay, north coast of the South China Sea. The morphology of the cells was examined by light and scanning electron microscopy. The hypervariable D1-D3 region of the nuclear large-subunit ribosomal DNA and the relatively conserved region of the nuclear small-subunit ribosomal DNA were sequenced and used for phylogenetic relationship analysis. Combined the morphology and molecular data, a new species, T. flabellata sp. nov. X H Guo, Y Q Guo & Y Li was described. The cells normally form short chains or solitary. A central fultoportula, one ring of marginal fultoportulae and one marginal rimoportula are present on the valve face. This species is characterized by fasciculate areolae on the valve.
This study analyzed the external morphology, vegetative and reproductive structure, growth process, biomass variation, mature individual proportion, R/T index, as well as the large subunit of ribulose-1, 5-bisphosphate carboxylase/oxygenase (rbcL) gene and the partial cytochrome coxidase I (COI) gene sequences of Gloiosiphonia capillaris (Hudson) Carmichael populations collected in the coast of Heishijiao, Fujiazhuang, Shicao, Jinshitan, Zhangzidao and Haiyangdao in Dalian. The results indicated that the gametophytes of G. capillaris were androgynous, solitary or caespitose habit, and that the main axes were erect, disciformi affixus, gelatinous in texture, red or purplish red. The length and width of thallus collected in Zhangzidao and Haiyangdao were significantly higher than those in other sites. Thallus was composed of cortex that had 6—10 cell layers and medulla that was consisted of many rhizoidal filaments. The size of mature cystocarp was small and protruded from the thallus. Cystocarps were spherical or hemispherical, and often became a group with 2—4 members. The maximum biomass of gametophyte appeared in June with an average value of 3.628 g/m2. The proportions of mature individuals increased gradually from March to June and got 100% in June. The gametophyte growth cycle was from March to July, and the temperature property was temperate. According to the phylogenetic tree of rbcL gene sequences, there was no sequence divergence among the 6 sites and clustered in a single monophyletic subclade with the sample from Canada. There was also no sequence divergence among the 6 sites based on the phylogenetic tree of COI gene sequences. The samples were clustered in a single monophyletic subclade and identified as G. capillaris.
Microcystis strains isolated from bloom-forming ponds were analyzed based on gvpA-C intergenic sequence and 16S rDNA. Several gvpA-C intergenic sequences contain an 172-176 bp extra sequence. An alignment of different types of 0.27 kb sequences, exclusive of the extra sequence, showed over 50 sites of base substitutions. 8 sites of base substitutions were identified in a 0.69 kb region of 16S rDNA, where most substitutions between Microcystis strains are located. Compared to 16S rDNA, the gvpA-C intergenic sequence that can be generated by one-step PCR without contamination from co-existing bacteria showed much higher variability, which is useful in typing of Microcystis. Due to horizontal gene transfer, the two sets of types showed a cross relationship. Based on the presence of extra sequence, the Microcystis gvpA-C intergenic sequences formed two distinct clusters in a phylogenetic tree.
Sinogastromyzon sichangensis is a small-size fish endemic to the upper Yangtze River mainly distributed in main stream and tributaries. Twenty-nine polymorphic microsatellite loci of the S. sichangensis were isolated by next-generation sequencing techniques. Four wild populations in Chishui River were amplified by 20 loci with mean alleles 14.5. The mean observed (Ho) and expected (He) heterozygosity were 0.620 and 0.882, respectively and the mean polymorphic information content (PIC) was 0.859. The Ho ranged from 0.520 (Maotai Town) to 0.669 (Chishui Town) and PIC ranged from 0.841 (Maotai Town) to 0.868 (Xishui River). The Fst value and analysis of population structure revealed a genetic differentiation between populations from Xishui River and the main stream of Chishui River. AMOVA showed that the genetic variation was 3.33% among populations while it was 96.67% within populations. These novel loci could use to investigate the population genetics and biological resource conservation strategy in S. sichangensis.
To investigate the effects of ammonia exposure on amino acid metabolism, the Paramisgurnus dabryanus were exposed to 30 mmol/L NH4Cl solution to assess plasma, liver and muscle free amino acid contents. The free amino acid concentrations in plasma, liver and muscle of P. dabryanus were significantly affected by ammonia exposure (P<0.05). The plasma free alanine contents were significantly increased with increased exposure time (P<0.05). The liver free glutamate contents increased significantly at 12h of ammonia exposure and then obviously decreased at 72h (P<0.05). While the liver free alanine contents remained constant during the first 24h of ammonia exposure, these values remarkably increased at 72h (P<0.05). The muscle free glutamate increased significantly (P<0.05) at 12 hours and then rapidly decreased (P>0.05), and eventually significantly lower than that of the control group at both 72h and 96h (P<0.05). Two peak values of the muscle free alanine contents were found at the 12h and 48h, which were significantly higher than the control values (P<0.05). The remarkably decreased free glutamate values in plasma, liver and muscle of P. dabryanus and the significantly increased glutamine contents and glutamine synthetase activities during ammonia exposure suggest that the glutamate and
The Yarlung Zangbo River (the upper Brahmaputa River) is the largest river on the Tibetan Plateau. The present study investigated the genetic diversity and population demography of Schizothorax molesworthi from the Motuo area of lower reaches of the Yarlung Zangbo River and Lohit River using mitochondrial DNA Cyt b gene sequences. The results showed that 21 haplotypes were identified for 167 individuals with relatively high haplotype diversity (h= 0.768) and low nucleotide diversity (π=0.00167). Phylogenetic trees and Network diagram based on haplotypes indicated all haplotypes from the lower reaches of the Yarlung Zangbo River and Lohit River were not clustered separately but mixed with each other according to the geographical distribution. Pairwise comparisons of genetic differentiation index (FST) among different populations ranged from –0.014 to 0.771 with highly significant genetic differentiations between the JZZB population and other populations (FST: 0.372—0.771). The analysis of molecular variance (AMOVA) showed that the largest mean FCT index was found between JZZB population and the group of other six populations. Neutral test, mismatch analysis and BSP (Bayesian skyline plot) analysis showed that overall S. molesworthi population from the lower reaches of the Yarlung Zangbo River and Lohit River experienced population expansion during the last glaciations BP (0—0.137 Ma).
Gymnocypris potanini Herzenstein, an endemic freshwater species in China, distributes in the upper reaches of the Minjiang River and the Lancang River and some plateau areas with low water temperature even in the summer. The present study investigated the morphological characteristics, formation period of increment, and hatching date of G. potanini. Larvae were identified by coⅠ sequences, which were caught in the Mengtun River at 2015 and 2016. Homology analysis showed that the coⅠ sequence of captured larvae and juvenile were genetically similar to G. potanini and then identified as the G. potanini. The shape of lapilli finally changed into mussel shape, whereas sagittae became wedge-shaped, the long ellipse shape, and eventually changed into long pointed. Then one increment of lapilli by marked temperature was formed every day. The number of marked increments on lapilli were linearly related to the age, and the slopes of the equations were closed to 1.0 (P>0.05). These results demonstrated a daily formation of otoliths increments. By counting the number of daily increment and confirming daily pattern of the increment deposition, the back-calculated hatching dates of the larvae were from 29 June to 15 July in 2015 and from 13 July to 18 August in 2016, indicating that G. potanini has a long spawning period in late summer. These results provided important information on the spawn time of estimation and the basic data for resources conservation of G. potanini.
Aquaponics, a new type of sustainable, cyclic and zero-emission composite farming system, has become an effective method to solve the agricultural ecological crisis because of its good ecological environment effect and food safety guarantee. The 16S rRNA gene (V3-V5 region) of microorganisms in aquaculture environment and roots was sequenced by using Illumina high-throughput sequencing platform under the typical aquaculture pond mode in Northwest China. The comparison of microbial community structure and diversity showed that the total effective sequence of bacteria was 56444, and the average number of annotated OTU was 945. The dominant bacteria were phyla Proteobacteria, Bacteroidete, Firmicutes and Cyanobacteria. The dominant bacteria in MD.R and JH.R were phyla Bacteroidetes and Proteobacteria, respectively. There were 165 OTUs in the six samples with the highest OTU in JH.KX (137), the lowest one in JH.R (30), and the same OTU (85) in MD.R and JH.C. Rhizobia, fish pathogenic bacteria, cold-resistant bacteria and bacteria that decompose organism and reduce heavy metals and toxins were detected by annotating the OTUs. This study revealed the microbial community structure and its ecological regulation mechanism under the aquaponics model.
Family selection has emerged as a crucial tool for selective breeding in aquaculture. The current artificial selection for Japanese scallop (Mizuhopecten yessoensis) predominantly focused on the apparent characters,e.g. growth,shell color and survival rate. Little studies of selective breeding were based on nutritional value of adductor muscle. The present study investigated the growth performance,the fatty acid composition,the content of carbon and nitrogen and C/N ratio of adductor muscle in distinct selective breeding families of M. yessoensis and explored the correlation between C/N ratio and fatty acid content. The results demonstrated that the growth features of the families 25#,54# and 19# were superior to those of 32#,87# and 93# (P<0.05). No significant difference of the total major fatty acids was observed between distinct families,but the relative abundance of the major fatty acids was obviously different between distinct families as PUFA>SFA>MUFA. The amounts of EPA and DHA based on dry weight of adductor muscle in M. yessoensis varied from 3.59 to 4.09 mg/g,and from 3.03 to 3.46 mg/g,respectively. The relative abundance of both EPA and DHA ranged between 47.19 and 49.32% of the total fatty acids. Moreover,the content of carbon and nitrogen of adductor muscle in distinct families of M. yessoensis remained constantly with (39.21±0.04)% and (10.62±0.16)%,respectively. The C/N ratio was (3.70±0.06). The further correlation analysis showed that the C/N ratio was positively related to the growth of adductor muscle in distinct families. On the contrary,a prominently negative correlation existed between the C/N ratio and the content of TFA,SFA,PUFA,EPA or DHA with the most evident one between C/N ration with DHA. Our results indicated that the fatty acid composition,the content of C and N and the C/N ratio of adductor muscle could be used for selective breeding of M. yessoensis. These findings provide important implications for the broad development of the selective breeding in scallops.
Black carp Mylopharyngodon piceus, the most important freshwater fish in China, is widely distributed in the Yangtze River and along the Yangtze River. This study developed 12 highly polymorphic loci from 25 polymorphic microsatellite markers to analyze genetic diversity and population structure of 4 wild and 1 aquaculture populations in the Yangtze River system. The results showed that the polymorphic information content (PIC) of these 12 loci was between 0.660－0.923, indicating that all 12 loci were highly polymorphic (PIC>0.5). The allele number (Na) of the 5 populations was between 7.917－11.667 and the effective allele number (Ne) ranged from 4.837 to 6.035. The observed heterozygosity was between 0.713-0.861 and the expected heterozygosity was between 0.749－0.819. The average polymorphism information content was between 0.711－0.788. These results indicated the high genetic diversity in all 5 populations. The genetic distance between the 4 wild populations was relatively closer. The genetic distance between the cultured population and the 4 wild populations was much larger than that of the 4 wild populations. In the UPGMA phylogenetic tree, the Xiangjiang population and the Shishou population were first gathered together, and then clustered with the Hanjiang and Jiaxing populations, and finally together with the Wujiang culture population. The 12 microsatellite loci can be used for the assessment of germplasm resources and genetic diversity of different populations in black carp.
To investigate the effect of temperature on transcripts and relative mRNA levels, high-throughput RNA sequencing were used for Yersinia ruckeri grown at 28℃ and 37℃. After the quality control, all differentially regulated genes were enriched and annotated by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and verified by Rockhopper software. The results showed that 173 differentially expressed genes were identified (P-value<0.05), including 58 up-regulated genes mainly enriched in several KEGG pathways: Phosphotransferase system, Starch and sucrose metabolism, Galactose metabolism and Other glycan degradation; and 115 down-regulated genes mainly enriched in several KEGG pathways: Two-component system, Thiamine metabolism and Flagellar assembly. In summary, the SC09 had lower motility and weaker glucose metabolism at temperature 37℃. The compensatory overexpression of some specific carbohydrate metabolism might play important roles for the survival of this bacterial under high temperature. This study provides an important basis for further research on the molecular mechanisms of SC09 in different temperature.
Growth traits are controlled by multiple genes to cause minor phenotypic effect. To understand the pyramiding effect of advantage genotypes of growth-related molecular markers in largemouth bass (Micropterus salmoides), thirteen molecular markers related to growth traits were selected obtained on previous studies, which were located in PCK1, HSBP1, FOXO3b, MYH, HSC70-1, CTSB, HBP, POU1F1, PACAP, IGF-I, ghrelin, ApoproteinA and MSTN. The genotype of each marker in forty largemouth bass parents was analyzed and 2 families were constructed basing on pyramiding advantage genotypes. 305 and 266 individuals were sampled randomly from second filial generation of two families at nine month old, respectively. The results showed that the number of advantage genotypes was various in all offspring of family 1 with the number of individuals of each group 8, 26, 75, 74, 76, 35 and 11, respectively. The average weight of advantage genotypes group was 185.03, 196.46, 198.73, 212.59, 222.66, 235.54 and 261.27 g, respectively. In the offspring of family 2, the number of advantage genotype ranged from one to six with the average weight 184.43, 213.17, 243.77, 249.98, 252.11 and 266.00 g, respectively. Correlation analysis showed that the pyramiding number of advantage genotype was correlated with growth traits. Our results present evidence to improve the growth trait of largemouth bass by utilizing the limited advantage genotypes. This study provided scientific basis for the application of molecular marker assisted breeding in largemouth bass.
To reveal the characteristics of external morphology and internal organ during the growth and development of larvae to juveniles of pearl oyster Pinctada fucata and the relationship between morphology, organs and motion, ingestion behavior, optical microscopy was used for observations and nonlinear regression parameters were used for descriptions. The results showed that during the normally larval rearing, the growth of shell length was accelerated positively, the growth of shell height was decelerated positively, the growth of hinge length was accelerated negatively, the growth of shell height was faster than shell length, and the growth of hinge length was slower than shell length. When the larvae grown to a shell length of (209.26±9.22) μm, the internal organs began to change, the velum gradually degenerated and developed into a gill, and the foot gradually formed. when the shell length reached (234.30±14.00) μm, the secondary shell appeared and the external morphology gradually changed to the juvenile. In the juvenile stage, the growth of gill filament length, gill filament distance and number of gill filament were slower than shell length. The larvae swim and filter microalgae by beating their cilia. When swimming, the double shells on the top of the larvae opened the umbo toward the bottom, and the velum projecting from back of the shell is used to propel the body. Larvae swim around clockwise with a certain radius in the vertical direction with a spiral either rising or falling. In the juvenile stage, the reciprocating expansion of the foot and the filtration of the sputum conducted the crawling and the feeding, respectively. During the metamorphosis of larvae stage, the velum is degraded, the motor function of the metamorphosis larvae is reduced, the feeding function has disappeared, larvae relied on reserved energy to complete growth and organ development, which is an important step in larval rearing.
We compiled the distribution and traits of 214 fish species and subspecies in the Jinsha River basin to investigate systematic and effective conservation planning in the basin. First, we modelled the distribution of widespread species throughout the basin with environmental factors such as climate, riverscape, land-use, and soil type; we used the occurrences as the distribution for other species. We planned the protected area (PA) network with the Marxan software to determine the species-specific conservation targets (grouped by mobility, distribution range, and conservation status) and evaluate the protection status of the current wetlands PAs. The best solution selected 486 planning units (47950 km2) that was 7.7% of the total planning units. The current wetlands PAs was not enough for fish conservation, which shelters 59.3% of all fishes (127 species) and 109 species require additional conservation area. The planning units’ area protected by the wetlands PA need to expand 55.9% to reach our conservation target.
Based on the Gini coefficient and Mann-Kendall test, the runoff variation in the Yichang reach of Yangtze River from 1982 to 2017 was evaluated, and its influence to the Chinese sturgeon spawning below the Gezhouba Dam was discussed under the cascaded hydropower operation. The results showed that the runoff and Gini coefficient decreased significantly after the construction of Gezhouba Dam, which synchronously decreased the flow and water levels in spawning days of the Chinese sturgeon. Water temperature had no significant change. The analysis of the abruption revealed great change of hydrological conditions in the spawning days and Gini coefficient in 2004 and 2009, which are coincided with time of the second and fourth phase impoundment of the Three Gorges Reservoir. The correlation analysis indicated that the higher runoff and Gini coefficient would induce Chinese sturgeon to spawn in days with high flow and water levels. These results suggest that the ecological operation of the Three Gorges-Gezhouba cascaded hydropower could enhance the runoff with large inequality and create long duration of high flow pulses during flood seasons.
The Yangtze River basin harbors a high degree of fish diversity, with 378 fish species distributing in the mainstream and its attached waters, and 149 of these species are endemic to this river. Meanwhile, the Yangtze River is an important fishery ground in China, contributing more than 60% of the total catch of freshwater fishery. Therefore, the Yangtze River plays important roles in both biodiversity conservation and capture fisheries. However, due to the increasing human activities in the past decades, fish resources in the Yangtze River have declined sharply. Firstly, more and more species have been assessed as threatened and the endangerment categories of many species have been upgraded. Secondly, the population size of many iconic species, such as Acipenser sinensis, the four famous Chinese carps and Coreius guichenoti, have declined continuously. Thirdly, the miniaturization tendencies of major fishing targets have become more and more obvious. Last but not the least, the total fishery catch reduced significantly. Overfishing, water projects construction, enclosing-lake cultivation, water pollution and alien invasion were the main reasons contributing to these changes. In most situations, these factors interacted together, which imposed more damage to the fish resources and increased the difficulty of conservation. In order to protect the fish resources in the Yangtze River effectively, following conservation strategies are suggested: establishing specialized nature reserve, banning commercial fishing completely, implementing river ecological restoration, strengthening scientific research and establishing comprehensive regulation mechanism.
To better understand zooplankton distribution and its relationship with the physical-chemical factors in middle Yangtze River, we collected 20 zooplankton samples from segments at Yichang, Jingzhou, Yueyang, Wuhan and Hukou in October, 2016. A total of 23 species that belong to 13 families and 14 genera were identified, among which 16 species belong to Rotifera, 4 to Copepoda and 3 to Cladocera. Among the five segments, the highest number of zooplankton species was detected at Hukou (9 species), while the lowest was at Yueyang (5 species). The average density at Wuhan (10.94±5.81) ind./L was higher than that at Hukou and the other segments. Rotifers (3.41±0.21) ind./L were dominant in the zooplanktonic community, and Keratella valga, Synchacta atylata and Keratella cochlearis were the dominant species. The average density of copepods (mainly nauplius) was (0.75±0.07) ind./L. Cladocera had the lowest average density. Similarly, the zooplankton biomass at Wuhan was also higher than that at Hukou and the other three segments. Comparing with studies at other segments of Yangtze River, we detected lower zooplankton diversity in our investigation. Spearman correlations indicated that the biomass and diversity of zooplankton were significantly and positively correlated (P<0.05) to chlorophyll a.
PAEs have been proved to be one of the major organic pollutants. The present study determined the level of PAEs using surface water samples from the upper reaches of the Yangtze River. The results showed that DEHP contributed the most to PAEs pollution, followed by DBP. Risk Quotients of PAEs were used for preliminary screening, and DEHP and BBP were identified as potential risk factors with RQ of 310 and 70.7. The MOS10 of DEHP and BBP were 1.40 and 1.32×105, respectively, indicating that BBP may pose little risk to aquatic organisms. The potential risk of DEHP was further analyzed with joint probabilistic curves. Among different biological groups, fish and zoobenthos were two major groups sensitive to DEHP-induced damage under current concentrations with 99.4% and 98.3% for 5% species of each group. While among the toxicity endpoints, reproduction may be more sensitive than others. The 5% and 10% aquatic species were suffered from reproductive damages by 100% and 97.8%, respectively. Overall, our results indicated that DEHP in the surface water of the upper Yangtze River may pose potential risk to aquatic organisms, especially on their reproduction. Therefore, more concerns should be paid in species protection and environmental management.
Three Gorges Reservoir (TGR) is the key project for the governance and development of the Yangtze River. TGR is an important region for the ecological and environmental protection in the Yangtze River economic belt. The hydrology and water environment have taken fundamental changes since the impoundment of TGR with some negative ecological and environmental problems. To address whether the aquatic ecosystem of TGR is healthy or not, the phytoplankton community index (PhyCoI) was used to assess the ecosystem health of TGR. Field survey was carried out on April 2015 in the whole region of TGR, including 23 tributary bays and 18 sections in the main channel of TGR with 174 sampling sites. A total of 61 phytoplankton taxa were identified, belonging to Cyanophyta, Chlorophyta, Bacillariophyta, Cryptophyta, Pyrrophyta, Euglenophyta, and Chrysophyta. Based on the scores of PhyCoI, the overall health status of TGR is good, with 68% sites in the status of very healthy (4≤PhyCoI<5) or healthy (3≤PhyCoI<4), 26% sites in sub-healthy (2≤PhyCoI<3), and 6% sites in general sick condition (1≤PhyCoI<2). Specifically, 96% sites in the main channel of TGR are healthy, and other 4% sites are in the status of sub-healthy. In the tributary bays, the ratios for the status of very healthy, healthy, sub-healthy, and general sick are 2%, 53%, 35%, and 9%, respectively. From the view of spatial distribution, overall health status of the main channel of TGR is good, and the health status of the main channel in Hubei Province is better than that in the Chongqing Province. In addition, the health status of sites in the Xiangxi Bay, Meixi Bay, and Xiaojiang Bay were highly variable. And in general, the health status of the bays near the dam of TGR is better than the bays far away from the dam. These results provide science and technology support for ecological and environmental protection of TGR.
The Yangtze River is the largest river in China. It is a priority conservation area for biodiversity of the world, with its main river, branches and wetlands. As an essential part of freshwater ecosystem, aquatic vegetation has been well studied by Chinese researchers since 1950s, but large-scaled analysis on the biodiversity pattern is lacked. Based on published studies, we analyzed spatial and temporal pattern of aquatic plant diversity in the Yangtze River Basin, and calculated the suitable habitat area and underlying influence of environmental factors using MaxEnt software. A total of 298 species are recognized, belonging to 121 genera in 52 families, which is 57.6% of the total aquatic vascular plants in China. The Yangtze River Basin is the key area for aquatic plant diversity of China, especially the subregions of middle reaches. The elevation and land use are the key environmental variables to the spatial pattern of aquatic plants. The separation among water systems have weak influence on the spatial pattern of diversity in aquatic vascular plants, but potamo-lacustrine habitats facilitated the species homogenization of the flora in a sub-basin scale. The network consists of Poyang Lake, Dongting Lake, Tai Lake, and the middle and lower mainstream is the suitable area for the aquatic plants based on the MaxEnt model. In the past half century, the decline or loss of aquatic vegetation occurred in plenty of lakes in the Yangtze River Basin. We suggested that the protection of aquatic vegetation should be incorporated into the integrated conservation of the middle and lower Yangtze River.
The Yangtze floodplain is one of the most important wetlands in the world. For decades, many lakes in this region have suffered from multiple stressors, such as over-exploitation fishery resources and cultural eutrophication. To solve these problems, it is necessary to establish a quantitative lake ecosystem management platform at a regional scale. Recognizing the lack of regional scale zoobenthos models with high predictive power, we carried out 105 lake-time investigations on 46 small-to medium-sized lakes along the mid-lower Yangtze River in this study. The results showed that the density and biomass of zoobenthos of these lakes were (847±248) ind./m2 (mean±SE) and (29.41±3.97) g/m2, respectively. The density and biomass of oligochaetes, gastropods and chironomids were (403±225) ind./m2 and (1.12±0.39) g/m2, (82±20) ind./m2 and (26.38±3.99) g/m2, and (356±62) ind./m2 and (1.86±0.58) g/m2, respectively. Further analyses showed that water depth, Secchi depth, water temperature, total phosphorus, phytoplankton chlorophyll a, and submersed macrophyte biomass were the important factors affecting the standing crops of zoobenthos. A series of models were therefore established. The explanation of variations in zoobenthos density among lakes was generally better than that of biomass. The explantion percentage of simple regression models were between 18%—33% for density and 7%—18% for biomass. In the multiple regression models, the explanation percentage was 46%—49% for density and 16%—55% for biomass. Considering the large sampling size of this study, the explanation of these research models was significantly higher than that of previous studies. When comparing the percentage predictive errors (PPE), the simple models and multiple models showed similar results: PPE was 76%—171% for density and 115%—1034% for biomass in simple models, and 88%—114% for density and 141%—1015% for biomass in multiple models. Therefore, these simple regression model with relatively few variables and good predictive power are suggested in practical application.