This study was conducted to investigate the effects of 4 kinds [24L﹕0D (D1), 16L﹕8D (D2), 8L﹕16D (D3), 0L﹕24D (D4)] of photoperiods on feed consumption, digestive enzyme activities and blood hormone of turbotScophthalmus maximus L. juveniles with initial body weight of (30.5±2.0) g in 20 hours (8:00am—4:00am). The results showed that the feed rate decreased with the shorten of illumination time, and feeding peak in D1 group appeared every 8h, meanwhile others appeared at 8:00am and 4:00pm. Activities of protease and amylase of former 3 groups were appeared spike at 12:00am and 8:00pm, and lipase was significantly higher than that of the D4 group. There were no difference of GH contents from 8:00am to 8:00pm among all groups, and D1 group at 4:00am was significantly higher than others, but D4 group was significantly lower than others from 0:00am to 4:00am. COS contents of D1, D2 and D3 groups were not significant difference in 8h after first feeding, and then increased firstly and decreased afterwards; D4 group reached the maximum level at 8:00pm. NE content of D1 and D2 groups were significantly higher than that of the others at 0:00am, meanwhile D4 group was significantly lower than others at 8:00pm. T3 content of D2 group was significantly higher than that of the other groups at 8:00am and 12:00am; D4 group was lower at 8:00pm, and higher at 0:00am than others; D2 and D3 group were lower than those of D1 and D4 group at 4:00am; The highest values of T3 of all groups were appeared at 8:00pm. These results demonstrated that feed intake, digestive enzyme activities and serum hormone contents of turbot juvenile were affected by photoperiod under current experimental conditions. 8—16 lighting period and feed twice daily would be recommended for turbot culture under this intensity of illumination.
We discovered for the first time that Grateloupia turuturu filaments, which developed from discoid crusts, had the ability to form spores under laboratory condition. We hereby defined this category of spores as" disc-filamentospore”. The formation of disc-filamentospores were observed and the effect of various temperatures (6, 12, 16, 20, 24, 30℃) and light intensities (10, 30, 45, 60, 90, 120 μmol/(m2.s)) on the release of disc-filamentospores were analysed. The results indicated that: (1) Carpospores, which formed and released from cystocarps of female gametophyte of G. turuturu, first developed into discoid crusts. Then the discoid crusts were induced to form filaments of monolayer cells, which formed massive plurilocular sporangiums and released large amounts of disc-filamentospores. (2) The formation and release were significantly affected by temperature and light intensity. Our study revealed that the releasing efficiency of disc-filamentospores could get the maximum at 16℃ and 6 0 μmol/(m2·s). (3) The releasing number of disc-filamentospores was evidently reduced when the temperature was lower than 12℃ or higher than 24℃. (4) When the light intensity was less than 30 μmol/(m2·s) or more than 90 μmol/(m2·s), the releasing efficiency of disc-filamentospores was inhibited significantly. Our results improved the asexual reproduction process of Grateloupia turuturu and provided more abundant theoretical basis for its germplasm preservation, artificial breeding and aquaculture. Finally, we suggest a plausible solution to investigate the origin and evolution of Grateloupia turuturu.
Growth rate, feeding, development of organs, disease resistance, adaptability, and self-regulation to the change of environment are all associated with fish health assessment. With the rapid development of aquaculture, the assessment of fish health condition is increasingly important. The present manuscript reviewed the evaluation procedures and indices related to fish health condition and available shortcomings, and also discussed the possibility of developing new methods to assess fish health condition using computer technology and biotechnology, which are expected to provide new insights for fish health assessment.
Microcystis bloom has caused many environmental problems, and its mechanism of bloom-formation and adaptation has been noticed wildly. To examine the possible information transfer by chemicals between both algae, the effect of Ochromonas and its culture media filtrate on the growth and physiological traits of Microcystis aeruginosa was investigated in this study. The results indicated that the cell density in Microcystis decreased significantly, while the cell density in Ochromonas increased markedly when Microcystis and Ochromonas were co-cultured at three initial cell density (1﹕4, 1﹕1 and 4﹕1). Moreover, the culture media filtrate ofOchromonas sp. could inhibit the growth, and resulted in an increase of malondialdehyde (MDA) content and catalase (CAT) activity. Additionally, the content of extracellular polysaccharides (EPS) increased markedly in Microcystis when it was inoculated into the culture media filtrate of Ochromonas sp. These results indicated that Ochromonas not only could prey on Microcystis, but also might release some of the chemicals to inhibit the growth and physiological parameters of Microcystis. This suggested that Ochromonas might be used to inhibit the early proliferation of algae as a potential control of algae blooms.
Through regulating the post-transcriptional maturation of UsnRNAs (U-rich small nuclear RNAs), integrator complex has an effect on the intron splicing of pre-mRNA. Therefore, integrator complex plays an important role in the production of mature mRNA. However, the regulation and developmental functions of integrator complex are poorly understood in vertebrates. In this study, zebrafish (Danio rerio) was used to generate the ints12 knockout model by CRISPR/Cas9, and two homozygous lines were generated with different frame-shifts. Observation on the misprocessing of UsnRNA 3′ ends in zygotic mutant of ints12 (Zints12) was conducted through real-time quantitative PCR analysis. When compared with the control fish, the overall growth of Zints12 was largely retarded, and the Zints12 population was all-male. Further studies showed that cell proliferation was significantly interfered, and the level of introns retention of ints12 transcripts was significantly increased in Zints12, suggesting an " auto-regulation loop” in the splicing regulation by ints12. Overall, we obtained homozygous mutants of zebrafish ints12 by gene knockout technology and revealed that zebrafish ints12 regulates UsnRNA 3′-box processing to exert various effects on early embryonic development and body growth.
In order to investigate the role of TRAF6 in Lethenteron morii with signal pathway of TLR, the full-length cDNA of LmTRAF6 was cloned. The distribution of tissues (supraneural body, gill, intestine, kidney) and related gene expression in both juvenile and adult were studied with real-time quantitative PCR. Additionally, the change of gene expression in those tissues from adult L. morii was also examined after challenged by Pseudomonas aeruginosa. A recombinant plasmid pEGFP-TRAF6 was constructed by the double digestion method, and transformed into the HEK293T cells. Fluorescence observation was conducted after 48 hours, and the results were photographed. The results showed that the length of LmTRAF6 cDNA was 2751 bp, including 1785 bp open reading frame (ORF) and 594 amino acids. The structure of LmTRAF6 was highly similar to that in other mammal and fish species, containing one RING domain, one coiled-coil region, one MATH domain and two zinc fingers. Phylogenetic tree showed that LmTRAF6 was evolutionarily closer to that in mammals and fishes, but not to that in Drosophila melanogaster and Penaeus chinensis. LmTRAF6 was expressed in all tested tissues and their developmental stages. However, higher expression was detected in heart, skin, gill, liver of juvenile, as well as in kidney, gill, and muscle of adult. When adult L. morii was challenged by Pseudomonas aeruginosa, the expression of LmTRAF6 in gill, intestine and kidney reached to the peak after 24h. Subcellular localization showed that LmTRAF6 was expressed in both cytoplasm and nucleus.
The grass carp (Ctenopharyngodon idellus) infected with the hemorrhage virus was used to analyze the intestinal microbiota by using high-throughput sequencing. The results showed that microbiota significantly differed between grass carp reovirus (GCRV)-infected and control grass carp (multiple response permutation procedure (MRPP), analysis of similarity (ANOSIM), and Adonis; P<0.01). When we compared alpha diversity, we found that Shannon-Wiener index, inverse of Simpson's original index and Pielou’s evenness index of intestinal microbiota were all significantly decreased after infecting with GCRV (independent samplest-test, P<0.05). Besides, we found that the individual difference within GCRV-infected group was significantly greater than that in the controls (Wilcoxon signed-rank test,P<0.05), suggesting that the intestinal microbiota in GCRV-infected grass carps became disorganized and lost their original balance. Proteobacteria, Firmicutes, Fusobacteriaceae, and Bacteroidetes were dominant phylum in both GCRV-infected group and controls. However, the relative abundance of operational taxonomic units (OTUs) between the two groups was different. For example, OTU_69 (Pasteurellaceae), OTU_504 (Comamonadaceae), and OTU_1898 (Cetobacterium) were all significantly lower than that of controls (t-test, P<0.05), confirming that GCRV could make intestinal microbiota of grass carps became disorganized. The stability of intestinal microbiota is important for health of host. By detecting changes in the intestinal microbiota of GCRV-infected grass carp, we will be able to provide theoretical basis and data reference for the prevention and treatment of common disease of farmed fish, as well as providing a reference for healthy breeding.
In this study, the method of irradiation breeding was applied to wetland plants in order to improve its cold resistance. Herein, 25, 45, 60 and 80 Gy doses of gamma ray were used to irradiate Canna indica Linn (CIL) seeds, and the dose rate was 6 Gy/min. After CIL seeds were grown up, they were exposed to a low temperature stage, and their cold hardiness was accordingly evaluated. The results showed that the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in irradiated CIL seeds were higher than that of the control group. Malondialdehyde (MDA) in control group accumulated in large quantities under low temperature, which was higher than that of the irradiation treatment group. Besides, at low temperature, the content of proline, the total soluble sugar, and protein of irradiated seedlings were totally higher than that of the control group. The score of cold resistance in irradiated group was also higher than that of the control group, and the 45 Gy dose of gamma ray group showed the highest score. Moreover, CIL with the strongest cold resistance was planted in the constructed wetland to evaluate its purification effect in winter, and evaluation indexes were total phosphorus (TP), total nitrogen (TN), and chemical oxygen demand (COD). Results revealed that the removal rate of TP in the group of CIL in constructed wetland by using 45 Gy dose of gamma ray was significantly higher than that of the control group (P<0.05). It can be concluded that irradiation treatment can effectively improve the cold resistance ofCIL and enhance the effect of artificial wetland purification in winter.
A newly isolated spontaneously flocculating microalgae Parachlorella kessleri F01 was used as the material, and the algae sample in autotrophic cultivation of one-step culture method was used as the control group. A two-step culture method was designed in which glucose was supplemented for mixotrophic cultivation at stage Ⅰ, and nutritional limitation treatments were done at stage Ⅱ, and we studied their effects on the lipid accumulation and flocculation performance of the algae. The algae cell number was determined by a hemocytometer. Biomass was measured via dry weight, and the total lipid was quantified with staining method. The extracellular polymeric substances (EPS) components of algae were analyzed by three-dimensional fluorescence spectroscopy. The results showed that: (1) The optimum glucose concentration was 10 g/L at stage Ⅰ. The alga lipid productivity reached to 204.25 mg/L/d on the 10th harvesting day, which was 16.20 times of that in the control group, and the self-flocculation rate of alga cell was 96.1% after sitting for 12h, which has no significant difference with that in the control group. (2) On the basis of stage Ⅰ, alga cells were cultured for 1 day in stage Ⅱ with different elemental treatments. The alga lipid productivity were 242.64 mg/L/d and 227.61 mg/L/d in the low-glucose group and the low-glucose coupled with low-nitrogen group, respectively, increasing by 18.8% and 11.4% of those at stage Ⅰ. After 4 days cultivation, the alga lipid productions of the four treatment groups including low-glucose, no-glucose, low-nitrogen and the low-glucose coupled with low-nitrogen significantly increased compared with those in the control group and stage Ⅰ. The highest production reached to 3.08 g/L in the low-glucose and low-nitrogen co-treatment group, which was 23.69 times of that in the control group, and increased by 51.0% compared with that in stage Ⅰ. The self-flocculation rates in four treatment groups at stage Ⅱ were nearly above 85.0%, which could satisfy the harvesting requirements. (3) The content of protein tryptophan in alga EPS was positively related to the self-flocculation rate. Different culture treatments could change the protein tryptophan content in EPS of algae cells, and thus affect their flocculation performance. Self-flocculation Parachlorella kessleri F01 is an excellent potential alga for biodiesel production. The two-step culture method can greatly enhance its lipid production. The advantage of self-flocculation combined with two-step culture method is expected to be the key breakthrough to solve the bottleneck of biodiesel production technology of microalgae.
This study was conducted to investigate the effect of transportation stress on the plasma biochemical indices, body color, fish quality of gibel carp [Carassis auratus gibelio var. CAS III, body weight of (116.46±2.09) g] and also water quality. Transportation was simulated on an automobile vibration bench for 4h. After 4h simulative transportation, the ammonia concentration of water in bags increased significantly (P<0.01), and the dissolved oxygen of water in bags was increased (P<0.05), while the pH value decreased significantly (P<0.05). Fish plasma cortisol, glucose and MDA concentration increased significantly (P<0.01), while plasma lactic acid concentration decreased (P<0.01). Plasma GSH-PX significantly decreased after 4h simulative transportation (P<0.05), and plasma SOD and CAT had a low value after simulative transportation (P>0.05). Dorsal skin showed significantly decreasing L* values after 4h simulative transportation (P<0.01), and the abdomen and lateral line L* values also decreased with no significance (P>0.05). While a* (P>0.05) and b*(P<0.05) values declined in these three parts after 4h transportation. Cohesiveness, chewiness and resilience decreased significantly in fillet (P<0.05). The fillet gumminess, springiness and adhesiveness were slightly decreased (P>0.05), while its hardness increased (P>0.05). The results indicated that transportation could induce stress response of gibel carp and reduce fish quality.
There is increasing evidence that different light intensities strongly modulate the effects of ocean acidification (OA) on marine phytoplankton, and elevated atmospheric CO2 concentration can affect the photosynthetic capacity of marine diatom to different degrees, however, little attention had been paid to their interaction on diatom. In this study, the growth rate, net photosynthetic (Pn) rate, biochemical composition, extracellular carbonic anhydrase (eCA) activity, and Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) activity were investigated when Phaeodactylum tricornutum was grown under different light intensities and CO2 concentrations. The results showed that the specific growth and Pn rates in P. tricornutum were not significantly affected by CO2 concentration under low light intensity, whereas in presence of the high light intensity (HLI), elevated CO2 concentration was beneficial to promote the increase of the rate of Pn. The eCA activity, chlorophyll content, and soluble protein content decreased with increase of CO2 concentration, regardless of the high or low light. It was revealed that no significant difference (P=0.6) was found in the net photosynthetic (oxygen evolution) rate between the high-CO2 (HC)- and low-CO2 (LC)-grown plants. Under LLI, RuBisCO activity of HC-grown algae was 2.42 and 1.39 times higher than that of LC- or MC-grown ones. However, RuBisCO activity of HC-grown algae was 6.72 and 3.45 times greater than that of LC- or MC-grown ones under high light. These results indicate that the algae can adapt changes of light intensity and CO2 concentrations in the environment by adjusting the allocation of energy during the operation of the CO2-concentrating mechanism and photosynthesis.
In order to understand the community characteristics of zooplankton and relationships with environmental factors, and aimed to use zooplankton community parameters monitoring the water quality of water source reservoirs, a seasonal investigation was conducted on the water quality parameters, abundance and biomass of zooplankton in water source reservoirs (K1— K10) from January, 2014 to October, 2016 in Zhejiang Province. The relationships and action mechanism between water environment factors and zooplankton abundance and biomass were studied by the method of multiple stepwise regression and path analysis. The results showed that the average abundance of zooplankton in the reservoirs was 97.5 ind./L from 2014 to 2016, mainly composed of copepods nauplii (36.3%), Rotifer (28.4%) and Cyclops (20.0%). The average biomass was 289.3 μg/L, which was mainly composed of Cladocera (39.3%), Cyclops (29.0%) and Cyclops (14.5%). Chl. a content was the decisive factor of zooplankton abundance in spring and summer, and TP content was the limiting factor for fluctuation of community abundance in autumn and winter, and the community abundance was affected by TN through N﹕P ratio in spring. DO content was a decisive factor in the development of zooplankton biomass in winter and summer, and the community biomass was promoted by DO through reducing N﹕P ratio in winter. The present zooplankton stock in the reservoirs was affected by the fluctuation of TP content, the change of N﹕P ratio and the Chl.a content of the water body ultimately reflected.
In order to provide basic information for protecting and rational utilizing resources of the Yangtze Estuary, feeding types, trophic level, energy flow, and food web, 43 aquatic animals were studied by using stomach content analysis. The species were classified into four groups according to their feeding habit: plankton feeding, benthic feeding, nekton feeding, and mixed feeding (benthic and nekton feeding). Among the samples collected in this study, the plankton predators were dominant accountings for 39.53%, and the nekton predators had the minimum dominancy, accounting for 11.63%. The results of trophic level showed that according to the dietary habits, these aquatic animals can be also divided into 3 different groups, which herbivorous consumers were dominant, and accounted for 76.75%, while intermediate carnivorous fish had the minimum dominancy, accounting for 4.65%. Through the overfishing and environmental degradation, the trophic levels of the 12 common fish in the Yangtze Estuar were generally lower than those of the 1990s, the average trophic level dropped from 3.80 to 2.87. According to each consumer’s stomach content, this study determined the benthic algae and phytoplankton, and organic detritus, including particulate organic matter (POM), as the main producers of the Yangtze Estuar aquatic food web, and drew their own energy flow. Eventually, based on the nutritional relationship among different aquatic animals, this study proposed a simplified model for the Yangtze Estuar aquatic animals’ food web.
To investigate the effects of acute cold stress on the mucosal histology in different sections of the juvenile Pelodiscus sinensis, the activity of serum diamine oxidase (DAO) and histological features of intestinal mucosa in Chinese soft-shelled turtle in culture temperature and acute cold stress were conducted. The first acute cold stress reduced the DAO activity with the lowest level at 48 h after cold stress. In the acute cold stress and rewarming experiment, the DAO activity decreased significantly after 3 days of cold stress and then restored to normal level with the recovery of temperature. Histopathological results showed no significant difference in the morphology of mucosal epithelium in the intestine (posterior segment of ileum and large intestine) between acute cold stress group and control group. There were no significant difference in the number of goblet cells, the length of villus and the ratio of villus length to crypt depth in the posterior segment of ileum between acute cold stress group and control group, while the mucosal thickness in the posterior segment of ileum significantly decreased in the acute cold stress group in comparison to control group. Acute cold stress significantly reduced the large intestine number of goblet cells. The structures of the intestinal mucosal mechanical barrier of Chinese soft-shelled turtle under acute cold stress are an intestinal segment dependent pattern. These results suggest that the various segments of the intestine of Chinese soft-shelled turtle have a special response style to acute cold stress.
In this study, the cDNA sequences of FcγRα and FcRγ subunits of FcγR rainbow trout were cloned for the first time by RACE technique. The sequences of FcγRα and FcRγ were analyzed by using bioinformatics software. The expressions of the genes in different cell subpopulations and tissues, as well as in the head kidney after Poly (I∶C) and lipopolysaccharide (LPS) stimulations were analyzed by real-time fluorescent quantitative polymerase chain reaction (PCR). The results showed that the full-length cDNA of FcγRα is 1677 bp with an open reading frame (ORF) of 954bp encoding 317 amino acids. The FcγRα is composed of a signal peptide and two Ig-like domains, however, without including transmembrane and intracellular regions. There are three kinds of FcγR subunit, involving FcRγ1, FcRγ2a, and FcRγ2b. FcRγ1 and FcRγ2 genes are located on different chromosomes, while FcRγ2a and FcRγ2b are two splicing isoforms of FcRγ2 gene. These subunits are composed of signal peptide, transmembrane domain, and immunoreceptor tyrosine-based activation motif (ITAM). Amino acid sequence similarity analysis showed that the highest identity (30%) of FcγRα is between rainbow trout and channel catfish (Ictalurus punctatus), and FcRγ1 and FcRγ2a/2b in rainbow trout have the maximum sequence identity (40%) with mammalian FcRγ. Tissue distribution analysis showed that the expression of FcγRα, FcRγ1, and FcRγ2a/2b was higher in head kidney, spleen, and blood cells, respectively. Analysis of cell subpopulations showed that the expression of FcγRα, FcRγ1, and FcRγ2a/2b was the highest in the myeloid cell population. In addition, the expression of FcγRα, FcRγ1, and FcRγ2a/2b in the head kidney was significantly up-regulated after LPS and Poly (I 鲶C) stimulations, indicating that FcγR plays an important role in the antibacterial and antiviral immunity.
In this study, we explored the ability to remove nitrate and phosphorus of two strains of Stigeoclonium spp. (SHY-370 and HB1617) by setting different initial concentrations of ammonia nitrogen and nitrogen/ phosphorus (N/P) ratios in synthetic wastewater. The results indicated that different initial concentrations of ammonia nitrogen in synthetic wastewater could affect the biomass concentration and the ability to remove N and P of SHY-370 and HB1617. The maximum ammonia nitrogen concentration in synthetic wastewater that SHY-370 can tolerate was 10mg/L, while that was 5mg/L for HB1617. The ammonia-nitrogen removal rate of SHY-370 and HB1617 was above 97% and the maximum daily ammonia-nitrogen removal rate was 3.98 mg/L/d, while the initial concentration of ammonia nitrogen in synthetic wastewater varied between 1-10mg/L. N/P ratios had a slight impact on the biomass concentration of the SHY-370, however, the biomass concentration of HB1617 was reduced when the corresponding rate was over 20 mg/L. The concentration of total phosphorus (TP) in synthetic wastewater was 10mg/L. When the N/P ratio was 2, the content of TP in synthetic wastewater was higher than 10mg/L, which led to a low TP removal rate. According to the results of our study, we can conclude that SHY-370 and HB1617 are appropriate for the treatment of urban sewage in which the concentration of ammonia nitrogen is relatively low, whereas the concentration of TP and NO3-N is relatively high.
To explore the cause of Potamogeton lucens’s decline, a dominant plant inhabiting the shallow water of Nansi Lake, the physiological and biochemical changes of P.lucens were examined under a group of constant temperatures at 25℃, 30℃, 35℃, and 40℃, respectively, for 3h. The results showed that the contents of protein, soluble sugar and chlorophyll decreased significantly, while the content of malondialdehyde (MDA) increased significantly at a high temperature above 35℃. The results indicated that high temperature above 35℃ had significant damage to P.lucens. The photosystem of P.lucens was more sensitive to heat stress. The characteristics of standardized chlorophyll fluorescence kinetics curves under heat stress were as follows. Peaks at J and K phases were observed, but no L-band was found on the normalized chlorophyll fluorescence kinetics curves. The chlorophyll fluorescence parameters were calculated from the OJIP curves of the heat-treated leaves. The results showed that the initial closing speed of the reaction center (dVG/dto, dV/dto) slowed down with the increase of temperature under heat stress, but it took a shorter time to reach the maximal fluorescence (Tfm). The maximum quantum yield of PSII (Photosystem II) photochemistry (Fv/Fm) decreased. However, the non-photochemical constants (Kn), relative variable fluorescence at the J-step (Vj), and dissipated energy flux (DIo/RC, DIo/CSo, Fo/Fm) increased under heat stress. Although the turn-over number of QA (N), average redox state of QA (Sm/Tfm), and relative variable fluorescence at the I-step (Vi) barely changed, the plastoquinone pool (Sm) decreased significantly at high temperature. Absorption and trapped energy flux per RC (ABS/RC, TRo/RC; reaction center, RC) increased, whereas the electron transport efficiency per RC (ETo/RC) decreased when temperature increased. Heat stress also decreased the trapped energy flux, electron transport flux and density of RCs per CS (TRo/CSo, ETo/CSo, RC/CSo; cross section, CS). These effects of heat stress on photosystem eventually led to a significant reduction in the structure and function index (SFIabs), performance index (PIabs), and drive force for photosynthesis (DF) of the P.lucens leaves. These results demonstrated that heat stress mainly caused inactivation of oxygen-evolving complex of PSII, reduction of the density of RCs, and decrease of photochemical efficiency of RC in P.lucens plants, and these led to the production of reactive oxygen species, and thus caused remarkable damage to cells. Therefore, P.lucens is a sensitive aquatic plant to high temperature in summer.
Hukou section, the connection between the Yangtze River and Poyang Lake for the migration route of many fish species, plays a vital role in the proliferation of fish. A systematic investigation on larval and juvenile fish resources were conducted during the fish breeding period in the Hukou section from May to August 2016. The community structure, dominant species, fish density, time-space distribution and their relationships with environmental factors in Hukou section were studied during the continuous 88-day investigation. A total of 39 larvae and juvenile taxonomic groups including 7 orders and 12 families were identified. Among them, 37 were identified to species level, one was identified to subfamily, and one was identified to family. Hemiculter bleekeri is the first dominant species and other dominant species are Gobiidae, Parabramis pekinensis, Pseudolaubuca sinensis. The larval and juvenile fish density reached its peak level on July 1 with 1230.77 ind./100 m3. The overall fish density showed a trend of decreasing volatility from July 1 to August 15. The cluster analysis divided 6 periods into 2 groups: Late May to early July in group Ⅰand late July to early August in group Ⅱ. Hemiculter bleekeri, Culter alburnus, Coilia nasus, etc. peaked in late June and Parabramis pekinensis, four famous domestic fishes, Siniperca chuatsi, etc. peaked in early July. The density of larval and juvenile fish on the south and north sides of the section were higher than that of the center section. Redundancy analysis (RDA) found that water temperature, transparency, and flow are the main environmental factors affecting the community structure of larval and juvenile fish. Correlation analysis showed highly significant correlation between water level and larval and juvenile fish density (P<0.01). This study indicates a large amount of fishes of early life history in Hukou section. The community structure of larval and juvenile fish is dominated by middle and small-sized fishes, and the proportion of river-lake migratory fishes are relatively high. Larval and juvenile fish have different adaptation characteristics to various environmental conditions. The species showed different degrees of positive and negative correlations with water temperature, transparency and flow. The results provide the scientific basis for the protection strategy of fisheries resource in the middle-lower reaches of the Yangtze River.
Different species of Rhodeinae have been wildly distributed across China. Different species have shown very similar morphological characteristics, making their distinguish to be indeed difficult. In order to compare the morphological differences among Rhodeus sinensis, Acheilongnathus tonkinensis, A. macropterus, A. chankaensis and A. taenianalis by the morphometric characteristics, and enrich the classification features, multivariate morphometrics were used to analyze the morphological variations of five Rhodeinae species in Huaihe River Basin (Henan province, China). The results showed that there were significant differences in the body’s width/body’s length, head’s length/body’s length, snout’s length/body’s length, caudal peduncle’s length/body’s length, dorsal fin base’s length/body’s length, pectoral fin’s length/body’s length, pelvic fin’s length/body’s length, and head’s length/snout’s length among the five species (P<0.01), and there were significant differences in the total length/body’s length and body’s height/body’s length (P<0.05). Therefore, these differences mainly focus on the head, tail, fin, and so on. Principal component analysis, discriminant analysis, and cluster analysis showed that the five species had obvious morphological differences, the most significant difference betweenA. taenianalis and A. tonkinensis was found, and the most insignificant difference was observed between A. taenianalis and A. macropterus. The discriminant accuracy rate of the five species varied from 82.35% to 100%, effectively realizing the distinguish of the five Rhodeinae species.
To establish a simple and reliable index for determining silvering stages of the Japanese eel, Anguilla japonica, we observed the colorations of various body parts and biological characteristics on the reproductive stock of theeels collected in the Yangtze River estuary before starting their oceanic migrations. The characteristics of body color, and the changes in age, total length, body weight, and silvering index were analyzed in the silvering process of the Japanese eel. The two silvering stages are characterized by the colorations of trunk skin as follows: (1) Pre-silver stage: pigments deposited completely on the upper edge of pectoral fin on the lateral sides of trunk, (2) Silver stage: pigments deposited completely on the lower edge of pectoral fin on the lateral sides of trunk.Our results indicated that body size, eye diameter, pectoral fins length and gonad-somatic indexincreased from pre-silver stage to silver stage during the ontogenic process of silvering, and digestive tract index decreased in contrast. The principal component analysis suggested thatthe silver stage eels had enlargement of the eye and pectoralfins, high sexual maturity and the degenerated disgestive tract compared to pre-silver stage eels. Because Japanese eel must swim three thousands kilometers from the growth habitats in northeast Asia to reach the West Mariana Ridge spawning area without feeding, these various modifications to the bodies and physiological changes had indicated that silver eels develop various adaptations that prepare them for their long oceanic migrations. The silver stage eels and pre-silver stage eels could be also distinguished by canonical discriminant function analysis using five characters, which showed up 95% reliability of their correct classification. Our results also suggested that an eye index of about 5.0 is a cut off point for distinguishing the silver stage from the pre-silver stage of the Japanese eels for a convenient use of field survey.
To investigate the structure characteristics of skeleton of Acipenser baeri, the conventional method was used to study the skeletal system of A. baeri Brandt mainly focusing on morphology and taxonomy. The results showed that the skeletal system ofA. baeri Brandt juvenile consists of two parts, axial skeleton and appendicular skeleton. The axial skeleton of A. baeri was composed of skull, vertebral column and ribs. The appendicular skeleton of A. baeri included fin-ray, pterygiophore and girdle. We found that the skeletal system ofA. baeri Brandt was more similar to Acipenser schrencki Brandt than other sturgeons, which probably explained by the long-term life adaptation to the high latitude and low temperature environment.
To investigate the effects of histamine and Lactobacillus reuteri on Pelteobagrus fulvidraco, three isonitrogenous diets, namely diet C (control, with a 147 mg/kg content of histamine), diet H (with a 479 mg/kg content of histamine) and diet H+B (histamine+ bacteria: a 496 mg/kg content of histamine and 1×105 CFU/g L. reuteri), were formulated for a 56-day trial of P. fulvidraco juveniles (14.23±0.65) g. Our data indicated that plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity were significantly lower in group H+B compared with those of group H (P<0.05), while there was no significant difference between group H+B and group C (P>0.05). Meanwhile, liver glutathione-s-transferase (GSH-ST) activity and malondialdehyde (MDA) content were dramatically reduced in group H+B compared with those of group H (P<0.05), while there was no significant difference between group H+B and group C (P>0.05). Furthermore, the HE staining showed that there were inflammatory cells infiltrating in the liver of fish fed with diet H, while no hepatocyte abnormality observed in group C and group H+B, and that the intestinal folds decreased significantly with shorter and edema in diet H group, while this is no marked difference in the length of intestinal folds between group C and H+B. Overall, our studies indicated the protective effect ofL. reuteri against histamine in cultured fish diet.
To investigate the effects of exhaustive chasing training on parameters of respiratory and circulatory system and excess post-exercise oxygen consumption (EPOC) in juvenile qingbo (Spinibarbus sinensis) and rock carp (Procypris rabaudi), sixty samples of S. sinensis (28.36±0.08) g and sixty samples of P. rabaudi (19.53±0.13) g were randomly divided (equally 30 fish in each group) into control group and training group, respectively. Then, these fish in the training group were analyzed under exhaustive chasing training once per day for 3 weeks at 25℃ to measure the heart index, gill index, hematological parameters, and EPOC. The results showed that there were no significant differences in the heart index, gill index, hemoglobin content, and number of red cells between the control group and training group of S. sinensis and Procypris rabaudi(P<0.05). The gill index in the control group ofP. rabaudi was significantly lower than that in the control group of S. sinensis(P>0.05), whereas the heart index, hemoglobin content, and number of red cells in the control group ofP. rabaudi were not significantly different than that in the control group of S. sinensis(P<0.05). No significant differences were found in pre-exercise metabolic rate, peak post-exercise metabolic rate, factorial metabolic scope, and recovery rate between the control group and training group (P>0.05), whereas duration of EPOC in the training group was significantly higher than that in the control group ofS. sinensis (P<0.05). The pre-exercise metabolic rate in the control group was significantly lower than that in the training group (P<0.05), whereas peak post-exercise metabolic rate and factorial metabolic scope, duration of EPOC, and recovery rate in the control group were not significantly different than that in the training group ofP. rabaudi(P>0.05). The pre-exercise metabolic rate, peak post-exercise metabolic rate, EPOC magnitude, and recovery rate in the control group ofP. rabaudi were significantly lower than that in the control group of S. sinensis(P<0.05), whereas factorial metabolic scope and duration of EPOC in the control group ofP. rabaudi were not significantly different than that in the control group of S. sinensis(P>0.05). Our results suggested that (1) exhaustive chasing training had no significant effects on the parameters of respiratory and circulatory system ofS. sinensisandP. rabaudi(P>0.05); (2) exhaustive chasing training significantly increased anaerobic capacity ofS. sinensis(P<0.05); and (3) the pre-exercise metabolic rate and peak post-exercise metabolic rate ofS. sinensis were significantly higher than those of P. rabaudi(P<0.05), which may be related to active habits ofS. sinensis.
The next-generation sequencing technology was used to obtain the whole mitochondrial genome sequences of Gadus macrocephalus. The mitochondrial gene was annotated and its structure was analyzed. The results showed that the circular genome was 16569 bp in length with typical mtDNA components. The mitochondrial genome encodes 13 proteins and 22 tRNAs, 2 rRNAs and a D-Loop region. The base composition showed a tendency of high AT and AT weak negative skewness. There were five kinds of termination codon in the protein coding gene of G. macrocephalus mitochondria, including AGG and AGA which were commonly found in mammalian mitochondria. It was shown that most of the tRNA structures share the classical clover shape, but the tRNA-Ser(GCT) is unique because of a shortage of DHU. Two sequences with the functions of TAS and CSB, as well as 17 bp pyrimidine-rich sequences were found in D-Loop region. The non-coding region contains a conserved sequence controlling the initiation of light chain replication (OL) and a gene spacer with 74 bp. Based on the whole mitochondrial genome sequence and the Cytb gene, the phylogenetic trees were constructed separately with several cod fish that belong to Gadiformes. The results provide an important evidence to reveal the evolutionary status of the pacific cod.
Oils are widely used in aquatic feed to supply essential fatty acids and energy for the fish. However, the abundance of unsaturated fatty acids makes oils susceptible to be oxidized, resulting in harmful effect on the health of fish. To investigate the effect of dietary oxidized oils on the growth performance, body color and antioxidant capacity in liver of channel catfish, Ictalurus punctatus, six isonitrogenous and isolipidic diets were prepared to feed channel catfish (150.5±4.2) g. The six diets were designed with 6% supplementation level of fish oil (FO-6), soybean oil (SO-6), mixed oil (3% fish oil + 3% soybean oil, MO-6), oxidized fish oil (OFO-6), oxidized soybean oil (OSO-6), oxidized mixed oil (3% oxidized fish oil + 3% oxidized soybean oil, OMO-6), respectively. After 8 weeks feeding, the fish fed FO-6, SO-6 or MO-6 diet showed no differences in weight gain (WG), feed conversion ratio (FCR), muscle composition, body color and antioxidant indicators in liver (P>0.05), which indicated that soybean oil could completely substitute the inclusion of fish oil in the diet of channel catfish. The WG and muscle lipid level of the three oxidized oil groups were significantly lower, andFCR, skin yellowness, liver malondialdehyde content, and total bilirubin, direct bilirubin, alanine aminotransferase, aspartate aminotransferase in serum were significantly higher (P<0.05) than that of the normal oil groups. The activities of catalase and superoxide dismutase, and the glutathione contents in liver were reduced by dietary oxidized oils (P<0.05), but the dorsal muscle color and moisture, crude protein, ash content in flesh were not affected (P>0.05). The above results showed that 6% oxidized oils (fish oil, soybean oil, or mixed oil) reduced the growth performance, increased the yellowness of skin and damaged the antioxidant capacity of liver of channel catfish. Soybean oil could completely replace the fish oil inclusion in the diet of channel catfish.
A 80-day feeding trial was conducted to assess the interactive effects of β-glucan (BG) and Heat-killed Lactobacillus plantarum (HK-LP) on growth performance, intestinal fatty acid composition, and immune function of juvenile loach Misgurnus anguillicaudatus. Fish [average initial weight of (0.17±0.01) g] were fed with six experimental formulated diets containing two levels of BG (0% and 1%) with three levels of HK-LP (0.025%, 0.05%, and 0.1%) in triplicate. Results showed that supplementation of BG and HK-LP increased the body weight gain, specific growth rate, while significantly reduced the feed conversion ratio of fish. However, interaction between BG and HK-LP showed no significant effect on those parameters. Supplementation of BG remarkably decreased the percentage of C16 鲶1n-7 and C18 鲶2n-6 in intestinal fatty acid composition. Meanwhile, the percentage of C22 鲶1n-11 was decreased by dietary HK-LP. Dietary BG, HK-LP and two-factor interactions significantly influenced the activities of alkaline phosphatase (AKP) from skin mucus. Increase of dietary BG and HK-LP levels enhanced the activities of lysozyme. Supplementation of dietary 1% BG and 0.05% HK-LP significantly increased the expression levels of Hsp70 and Hsp90α. Therefore, the addition of BG and HK-LP in the diets could improve the growth performance of juvenile loach, and in the experiment, the optimum level of BG and HK-LP in the loach diet was 1% and 0.1%, respectively.
In order to provide biological information for research on sex-determination mechanism in Pelodiscus sinensis, we here first attempted to clone and analyze the partial-length of Foxl2 cDNA. In addition, to address the differential expression of Foxl2 at genetic and physiological levels, both male and female sexes of Pelodiscus sinensis were treated with 10 mg/kg E2 and 17α-methyltestosterone (MT), respectively; Foxl2 mRNA expression was quantitatively examined in the gonads after injection treatment at 6, 12, 24, and 48h, as well as 7 and 14d, respectively. Foxl2 (GenBank Accession No.KP734210) was achieved, belonging to Forkhead family of transcription factors that is involved in ovarian development and functional maintenance, as well as a 903 bp of open reading frame (ORF) encoding 300 amino acids. Multiple sequence alignment showed that Foxl2 contained typical FH-domain, and the most similar ortholog was Trachemys scripta, reaching up to 99%. Stability analysis of phylogenetic trees showed that Pelodiscus sinensis Foxl2 was clustered with reptile Foxl2 as a sub-branch, and was closely associated with Foxl2 from Chrysemys picta bellii. Results of quantitative reverse transcription PCR (RT-qPCR) indicated that, compared to the control group, E2 significantly up-regulated Foxl2 mRNA repression in ovary after 24h (P<0.001), which in testis was significantly increased after 7 and 14d (P<0.001). MT treatment strongly and equally up-regulated expression levels ofFoxl2 mRNA in ovary and testis at 24h (P<0.001). These results suggested that E2 and MT could up-regulate Foxl2 expression. Moreover, the sex differences in E2 promoting Foxl2 expression is more significant than MT. It can be concluded that the present research contributes to better understanding of the functional role of Foxl2 and provide basic data for further study on how exogenous hormone mediates Foxl2 in Pelodiscus sinensis.
Three variants of EcHcL1 and 2 based on Exopalaemon carinicauda transcriptome library were obtained by using RACE technique. The total length of EcHcL1 and 2 were 2248 bp and 2121 bp, which encoded protein of 685 and 676 amino acids, respectively. EcHcL1 and 2 are relatively conservative in evolution, and has typical domains of hemocyanin, including copper ion binding region, conserved His site and Ig-like region. EcHcL1 may relate to pigment metabolism and phenoloxidase activity because of more than a tyrosinase domain. The results of tissue expression distribution showed that EcHcL1, 2 were expressed in all the 10 tissues, and higher expressed in hepatopancreas and haemocytes. Different variants of E. carinicauda hemocyanin subunit may also have various immunological functions. The expression of the 2 variants of mRNA after pathogen stresses were investigated using the Real-time PCR strategy. The results showed that EcHcL1 had higher expression level during 12—48h after Staphylococcus aureus, Vibrio parahaemolyticus and WSSV challenges, and its among more 1.5—4 times higher than that in control group. The expression level of EcHcL2 reached the highest value among 24—48h after stress, which increased 2—9 times compared with the control group. Therefore, we speculated that the E. carinicauda hemocyanin subunit variants may related to immune defenses closely and might have antimicrobial resistance activity.
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.