Abstract:Changes in hepatic and ovarian superoxide dismutase (SOD) and catalase (CAT) activities, total antioxidant capacity (T-AOC) and malonyldialdehyde (MDA) contents in silver pomfret () during vitellogenesis and the responses of their levels to dietary n-3 long-chain polyunsaturated fatty acids (LC-PUFA) were investigated. Four iso-nitrogenous, iso-energetic and iso-lipidic experimental diets were formulated:(1) 100% fish oil (FO); (2) 70% fish oil and 30% soybean oil (FSO); (3) 30% fish oil and 70% soybean oil (SFO); and (4) 100% soybean oil (SO). Female silver pomfrets (1 year old) were assigned to one of the four diets (with three replicates each) for 185 d. The results showed that there was an increase in SOD and CAT activities, T-AOC levels and MDA contents in the liver and ovary during vitellogenesis, and that the levels of all the indices in the post-vitellogenesis stage were significantly higher than those in thepre-vitellogenesis stage (<0.05). No significant differences in hepatic SOD (except in the SO diet group) and CAT activities, T-AOC levels and MDA contents were found between the vitellogenesis and pre-vitellogenesis stages (>0.05). However, ovarian SOD and CAT activities, and T-AOC levels in the FO and FSO diet groups at the vitellogenesis stage, were significantly higher than those at thepre-vitellogenesis stage (<0.05). The highest levels of hepatic and ovarian SOD and CAT activities during vitellogenesis were found in the FSO diet group. At the post-vitellogenesis stage, hepatic and ovarian SOD and CAT activities in the FSO group were significantly higher than those in the SO group, respectively (<0.05); however, there was no significant difference between the FSO and FO groups (>0.05). No significant difference was found in hepatic and ovarian T-AOC levels among the diet groups at the pre-vitellogenesis stage (>0.05); however, at the post-vitellogenesis stage, the hepatic and ovarian T-AOC levels in the FO and FSO groups were significantly higher than those in the SO group (<0.05), while there was no significant difference between the FO and FSO groups (>0.05). The MDA contents in the liver and ovary increased with increasing dietary n-3 LC-PUFA, and this trend was more apparent in the liver tissue. There was no significant difference in ovarian MDA contents among the diet groups during vitellogenesis (>0.05), except for the FO group, which showed a significant increase at the vitellogenesis and post-vitellogenesis stages (<0.05). Statistical analysis showed that tissue antioxidant levels increased gradually during vitellogenesis, and the optimum dietary n-3 LC-PUFA content (4.01%, FSO group) could promote the tissue antioxidant levels in silver pomfret at the vitellogenesis and post-vitellogenesis stages. The results of two-way ANOVA indicated that statistically significant effects of both diets and stages were observed for the tissue antioxidant levels (<0.01). Meanwhile, the significant effects of interactions of diets and stages on the hepatic T-AOC levels and MDA content were also recorded (<0.05).

Abstract:To understand fish osmotic adjustment mechanisms in saline and alkaline water, the partial cDNA sequence was obtained from gills of . Physiological changes in serum osmolality, ion concentration (Na⁺, K⁺, Cl^- and Ca²⁺), and gill carbonic anhydrase (CA) activities were determined, and mRNA gene expressions under saline (10 g/L, 15 g/L NaCl), alkaline (1.5 g/L and 3 g/L NaHCO₃), and saline-alkaline (salinity 10, 15 g/L NaCl; salinity 1.5, 3 g/L NaHCO₃) conditions at different times (0 h, 6 h, 12 h, 24 h, 48 h, 72 h and 96 h) were compared. The results showed that serum osmolality, ion concentration, gill CA activity, mRNA gene expression correlated positively with the strength of saline, alkaline and saline-alkaline stress. Over time, serum osmolality and ion concentration trends increased and then decreased. Osmotic pressure insaline and saline-alkaline water was higher than that in alkaline water. Gill CA activity in alkaline and saline-alkaline water was higher than that in saline water. Under low concentrations of stressors, CA activity reached its highest level at a later time. Slightly higher gene mRNA expression was detected in gills under high concentrations of stressors ( mRNA expression in saline, alkaline and saline-alkaline water was increased, but the increase was more evident in alkaline and saline-alkaline water (<0.05). The results showed that CA and NBCe1 in Nile tilapia are involved in salinity and alkalinity regulation under osmotic stress. The results provide a basic understanding of the physiological regulation during salinity-alkalinity adaptation.

Abstract:Transposable elements are major constituents of eukaryote genomes and have a significant effect on genome structure and stability. They also contribute to the genetic diversity and evolution of organisms. Knowledge of their distribution among several genomes is an essential condition to study their dynamics and to better understand their role in species evolution. Long terminal repeat (LTR)-retrotransposons have been reported in diverse eukaryote species, indicating a ubiquitous distribution. Among retrotransposons, the transposable element (TE) class, which are specific to eukaryotes, transpose via an RNA intermediate. Based on their structure, LTR-retrotransposons have been divided into two classes:ty3-gypsy and ty1-copia. In previous research, we found a ty3-gypsy-like retrotransposon, named JRE, in the genome of Jian carp, . To investigate the function of JRE in the genome of Jian carp, PCR amplification, fluorescence quantitative PCR and fluorescent in situ hybridization were used to explore the structure and characteristics of JRE retrotransposon. Multiple alignments of DNA and protein sequences were constructed using MEGA 5.0 software and were manually curated using BioEdit. Pairwise distances were estimated using the option pairwise deletion of gaps in MEGA5.0. The full-length JRE retrotransposon is 5126 bp, which includes two LTRs of 470 bp at the 5' end and 453 bp at the 3' end, and two open reading frames (ORFs) between them. One ORF of 4203 bp encodes the group-specific antigen (). The pol gene has a typical Ty3/gypsy retrotransposon structure, and the gene order is protease, reverse transcriptase, RNase H, and integrase (PR-RT-RH-IN). A phylogenetic analysis of the pol gene showed that it has similarities of 40.7%, 40%, 32.8%, and 30.1% to retrotransposons of the Yesso scallop, Farrer's scallop, a Great Barrier Reef sponge, and the spot swordtail fish, respectively. Therefore, JRE might belong to the JULE retrotransposon family. The copy number of the JRE retrotransposon in the genome of the Jian carp is 124, as determined by real-time quantitative PCR. The mRNA of the JRE retrotransposon is expressed in five Jian carp tissues:the liver, kidney, blood, muscle, and gonad, and is slightly higher in the kidney and liver than in the other tissues. Fluorescent in situ hybridization shown that JRE is randomly distributed in Jian carp chromosomes and no regular patterns were found. In conclusion, the complete structure of a retrotransposon found in a previous study was determined. Detailed analyses indicated that it has the typical structure of an LTR retrotransposon. Phylogenetic analysis showed that it is highly similar to JULE transposons. Its copy number in the Jian carp is not high, suggesting that its transcriptional activity is low. These findings extend our knowledge of the structure and features of the Jian carp genome, and might provide a new method of transgenic fish production.

Abstract:The growth hormone receptor (Andrias davidianus), based on a partial sequence from the transcriptome database. The full-length cDNA was 2992 bp, containing an open reading frame of 1812bpthat encoded a deduced protein of 604 amino acids with one conserved FGEFS domain and two BOX domains. System evolution analysis showed that Chinese salamander GHR had the highest similarity with the GHR proteins from amphibians ), and the lowest with mammals (). The expression pattern of in different tissues was evaluated. Its expression level was the highest in the liver, followed by the muscle, pituitary gland, kidney and gonads; its expression was very low in other tissues. The expression level of in the testis was higher at the early stage, and then decreased as the testes developed. However, the expression level increased as the ovary developed. Furthermore, transient treatment with 17α-Methyltestosterone (MT) and letrozole (LE) had different effects on the expression of in the brain and ovary was increased by MT treatment but decreased by LE treatment. Our results indicated that GHR may play an important role in gonadal development, and was affected differently by MT and LE treatment.

Abstract:The nuclear receptor superfamily contains a large number of transcription factors that mediate many physiological process, such as cell differentiation, growth and development. Family members have a conserved functional domain that includes a DNA-binding domain and a ligand-binding domain. HR38, a member of the nuclear receptor superfamily, is an orphan receptor for which no ligand is known. HR38 is involved in an unusual ecdysteroid signaling pathway in Drosophila. is a major Chinese aquaculture species and is also an important Chinese export. The crustacean molting cycle is a physiologically important growth process. To investigate its function in the molting cycle of Portunus trituberculatus was cloned by rapid amplification of cDNA ends (RACE) and named cDNA is 2950 bp, including a 101-bp 5' untranslated region (UTR) and a 551-bp 3' UTR. The 2298-bp open reading frame (ORF) encodes a 765-amino acid polypeptide. Bioinformatic analysis revealed that PTHR38 is anunstable protein and has no transmembrane domains. Homology analysis showed that has the highest homology to the HR38 gene of . Six crabs ateach main molting stage (inter-, pre-and post-molting) were selected by morphological feature observation. Eyestalks were excised, the crabs were depigmented, their exoskeletons were removed, and different tissues were sampled before being stored in Trizol Reagent for RNA extraction. Quantitative real-time PCR showed different expression patterns of PTHR38 functions in the molting cycle of . It also showed a similar expression tendency to ecdysone in hemocytes and thus might be associated with ecdysone. In muscle and the hepatopancreas, was upregulated in the post-molting stage. Previous studies showed that HR38 participates in the metabolism of carbohydrates, which suggested that might function in energy metabolism processes. After eyestalk ablation, the expression of PTHR38 and ecdysone.

Abstract:The hedgehog (HH) signaling pathway plays an important role in embryonic development and adult tissue balance. To understand the function of the (sonic hedgehog) gene in gonadal differentiation and development, we cloned cDNA was 1922 bp, including a 1296-bp open reading frame (ORF), a 266-bp 5'-untranslated region (UTR) and a 360-bp 3'-UTR. The cDNA encoded a predicted protein of 431 amino acid residues. Phylogenetic analysis showed that the putative protein belonged to the HH family, with typical HH-N and HH-C domains. Amino acid sequence analysis revealed that proteins in other fish and 60%-70% with Shh were significantly lower in females than in males and neo-males. Real-time quantitative PCR showed that the relative expression of the gene was significantly higher in the blastula stage than in other embryonic developmental stages ( was expressed in eight organs in males and females, and at the critical period of female gonad differentiation (50 d), the relative expression of the gene sharply increased compared with earlier stages and was significantly higher than at the same period in the male gonads (<0.05). In male gonads, during the critical period of differentiation (80 to 95 d), the relative expression of the gene was significantly higher than in the female gonads. In 5-month, 8-month and 1-year-old gonads, the relative expression of the gene was significantly higher in females than in males and pseudo males. These results suggest that the gene is highly conserved in evolution and plays an important role in embryonic differentiation, tissue and organ formation, gonadal differentiation and the development of .

Abstract:Cyprinid herpesvirus II (CyHV-2) is the main pathogen causing haematopoietic necrosis disease in . Although many nucleic acid-based diagnostic methods have been applied, no stable and sensitive immunological diagnostic methods have been reported. In this study, to detect CyHV-2 in clinical samples by immunological methods, recombinant protein 72, encoded by the CyHV-2 ORF72 gene, was used as a capture antigen to identify specific antibodiesagainst CyHV-2 in the serum of infected fish. First, ORF72 was amplified from the purified CyHV-2 genome, and cloned into expression vector PGEX-4t-3 to produce recombinant GST-ORF72 in . The recombinant protein was detected by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The purified recombinant protein 72 was used to immunize mice and polyclonal antibodies were obtained. Western blotting showed that the polyclonal antibody could not only identify the recombinant protein, but could also recognize protein 72 in virus particles. A Western blotting protocol was established for the specific detection of antibodies against protein 72 protein of CyHV-2 and then applied to detect CyHV-2 infection in clinical fish sera samples. In conclusion, the Western blotting technique established in this study could be used for specific serodiagnosis of CyHV-2 infection.

Abstract:Acute outbreaks of gill hemorrhages of crucian carp () can cause high mortality rates, and the viral disease in China has had a devastating effect on some fish farms in recent years. To better understand the progression of the viral disease, we combined polymerase chain reaction (PCR) technology and light microscopy with electron microscopy to observe the pathological changes and virus distribution in the gill and head-kidney of diseased fish. Normal crucian carps were infected by injection with tissue filtrate (viral suspension) from naturally infected fish, which caused similar symptoms to those observed in naturally infected fish, and high mortality. The pathogen has the morphological characteristics of a typical herpesvirus (referred to as herpesvirus, CaHV). CaHV can be determined in infected fish tissues, liver, spleen, kidney and head-kidney, using a PCR assay for the major capsid protein (MCP) gene of the known cyprinid herpesvirus. The pathological changes in different tissues, such as the gill and head-kidney, were compared at different times after infection with CaHV. The results showed that CaHV caused varying degrees of pathological change among the various tissues. The pathological changes in the gills and head-kidney increased with time after CaHV infection. There were a large number of virus particles in the head-kidney cells, suggesting that the head-kidney might be the primary target organ for CaHV invasion and replication.

Abstract:Temperature has a significant effect on the growth, reproduction, distribution and abundance of sea cucumbers (). The suitable temperature range for this species is 5-20℃, and the optimum growth range is 10-16℃, which fluctuates depending on size. When the water temperature exceeds the optimal range, stops feeding and goes into aestivation. In recent years, as global warming has intensified, slow growth, malformation and high mortality of marine animals have been observed frequently because of high temperatures. High seawater temperatures during summer 2013 resulted in significant economic losses in the A. japonicus resistant to high temperatures is required urgently. In this study, we used 1-year-old juveniles (13.6 g±1.8 g) from a directed breeding population (F3 group) and a wild population (C group) as the experimental animals. High temperatures as in ponds in summer were imitated (25℃, 27℃, 29℃, 31℃, 32℃ and 33℃, increasing by 0.5℃ every 12 h). The activities of superoxide dismutase (SOD), catalase (CAT), acid phosphatase (ACP), alkaline phosphatase (AKP), lysozyme (LSZ) and total antioxidant capacity (T-AOC) of in F3 and C groups were determined and compared after 12 h thermal stimulus at different temperatures. The results showed that temperature had a significant influence on the SOD, CAT, ACP, AKP and LSZ activities, and T-AOC. The SOD activities ofthe F3 and C groups initially showed an upward trend, but declined as the temperature increased from 25℃ to 33℃. The activity of SOD in the F3 group was significantly higher than in group C (<0.05) at 31℃ and 32℃.The CAT activity and T-AOC declined in both groups as temperature increased from 25℃ to 33℃. The CAT activity in the F3 group was higher than in group C at every temperature level, and the difference was significant when the temperature was 27℃, 29℃, 31℃ and 33℃ (<0.05). The T-AOC in group F3 was significantly higher than in group C (<0.05) at temperature ranges from 25℃ to 33℃. The ACP and AKP activities in both groups declined as temperature increased; the ACP activity in group F3 was significantly higher than in group C (<0.05), except at 31℃; and the AKP activity in group F3 was significantly higher than in group C (<0.05) when the temperature was 25℃, 27℃ and 31℃. The LSZ activity showed an initial upward trend and then declined as the temperature increased in both groups; the activity in the F3 group was significantly higher than in group C at 27℃, 29℃ and 31℃. The results indicated that the immune capacity of thermotolerant to high-temperature stress has improved after three generations of directed breeding. This study provides useful information for further research on selective breeding of . The rate of global warming is increasing, and the average temperature of the earth's surface is predicted to rise by 1.5-6.0℃ by the end of the present century, according to the 2007 report by the Intergovernmental Panel on Climate Change (IPCC). Therefore, biological studies of organisms, including , under high-temperature stress are urgently required.

Abstract:To reveal the main immunogenic domain of the glycoprotein of spring viremia of carp virus (SVCV), the glycoprotein encoding gene was truncated and expressed, and the immunogenicity of the truncated glycoprotein was analyzed using a rabbit polyclonal antibody produced in response to the recombination protein. The transmembrane, antigenic and hydrophilic domains of SVCV were analyzed by SOSUI and DNAStar 6.0 software. The predicted main immunogenic domain was amplified by reverse transcription polymerase chain reaction and cloned into a prokaryotic expression plasmid. The truncated glycoprotein was expressed in BL21 cells. After purification and refolding, the protein was used to produce antiserum in rabbits. The antiserum titer was tested by an enzyme-linked immunosorbent assay and the immunogenicity of the protein was tested by immunoblotting and indirect immunofluorescence assay (IFA). The results showed that the truncated glycoprotein gene was 1339 bp encoding a 439 aa peptide (from 29 to 467aa of the full-length glycoprotein) with a predicted molecular weight of 49.6 kD. The antiserum titer against the recombinant glycoprotein was 1:64000. Immunoblotting and IFA results demonstrated that the antiserum reacted immunologically with the natural glycoprotein on the surface of SVCV-HN. There was no difference in immunogenicity between the truncated glycoprotein produced in this study and the natural glycoprotein of SVCV. Therefore, the truncated glycoprotein of SVCV had good immunogenicity and could be used in immunological diagnosis and genetic engineering vaccine development of SVCV.

Abstract:To determine the best change frequency of substrates in the sea cucumber seedling cultivation system in summer, the relationship between the substrate change frequency and growth of sea cucumbers, and the microflora structure on the substrate, was investigated using an experimental ecology method, a traditional bacterial culture method and 16S rDNA sequence analysis. Five different substrate change frequency groups (10 d, 20 d, 30 d, 40 d, 50 d) were set and termed CF₁₀, CF₂₀, CF₃₀, CF40 and CF₅₀. Judged by the weight gain of the whole cultivation tank and the main body weight, the group achieved the best growth rate, followed by the CF₃₀ group. The CF₅₀ group achieved the highest death rate, which caused a decrease in the weight of the whole tank. The specific growth rate and the survival rate of the CF₂₀ group were (5.986±0.135)%/d and (95.231±0.265)%, respectively, which were significantly higher than the other groups (+-N), nitrite (NO₂^--N) and chemical oxygen demand (COD) of the pond water increased along with the decrease in the change frequency of substrates, reaching 0.53 mg/L, 0.28 mg/L and 0.18 mg/L on the 50th day, respectively. In terms of the concentrations of heterotrophic bacteria and vibrios in the pond water and on the substrate, the concentrations of heterotrophic bacteria and vibrios in the pond water did not change significantly with the change frequency of substrates; however, the concentrations of heterotrophic bacteria and vibrios on the substrate increased with decreasing change frequency of substrates, reaching 1.38×10⁵ cfu/cm² and 1.5×10⁴ cfu/cm² on the 50th day in the CF₅₀ group, respectively. Bacterial identification showed that the dominant bacteria on the substrates were Staphylococcus equorum, Vibrio parahaemolyticus, of which is an etiological pathogen for ; therefore, it might have a close relationship with the occurrence of skin ulcerative syndrome in the CF₅₀ group. Harmful animals, such as , compete for living space and food, causing slow growth of sea cucumbers. These animals emerged when the substrates had not been changed for a long time. The above results indicated that the optimal substrate change was once every 20 d in summer (July to September). Taking the production cost in consideration, it was suggested that the substrate should normally be changed once between 20 d and 30 d. These results will help to optimize breeding processes and health management for sea cucumbers.

Abstract:Five diets, including complete formula diet (control), soaked broad bean (SBB, fed as crumbled pieces after immersionin water), broad bean, common vetch seed and bitter melon seed diets (BBD, CVD, BMD), which included 75% broad bean, 60% common vetch seed and 60% bitter melon seed in formula diet, respectively, were fed to juvenile grass carps with an initial body weight of (59.0±0.6) g. After 8 weeks of feeding, the control fish had the highest weight gain (WG) and lowest feed conversation ratio (FCR) among all groups (<0.05). Compared with the SBB group, the WG was 56.9% in the BBD group, and -30.6% and -21.2% in the CVD and BMD groups (<0.05), respectively. Muscle collagen contents of the SBB, BBD, CVD and BMD groups were significantly higher, while muscle lipid contents were significantly lower than those of the control (<0.05). The BMD group had higher total amino acids and delicious amino acids contents in muscle than those of the control and SBB groups (<0.05). The hepatopancreatic superoxide dismutase (SOD) activities of fish fed the BBD, CVD and SBB diets were significantly lower (<0.05), and hepatopancreatic malonaldehyde (MDA) content and muscle creatine kinase (CK) activity were higher than those of fish fed the control diet (<0.05). However, fish fed the BBD diet had lower hepatopancreatic MDA than fish fed the SBB diet. Fish fed the BBD, CVD, BMD and SBB diets had a lower lipidase activities and a higher amylase activities in their intestines compared with the control fish (<0.05). The fish fed the BBD, CVD and SBB diets also showed lower protease activities than the control (<0.05). In conclusion, soaked broad bean and high levels of dietary broad bean, common vetch seeds and bitter melon seed saltered the muscle composition of grass carp, and significantly decreased their growth performance. For growth and muscle composition, a broad bean diet has more advantages in the culture of crisped grass carp than common vetch seed, bitter melon seed and soaked broad bean diets.

Abstract:The Chinese mitten crab, , is an important aquaculture species in China that is widely distributed in the east Pacific coast of China, from 24°N northwards to the Korean Peninsula, 42-43°N, from 112° to 114°E. Its high market demand, favorable taste and significant advances in hatchery and grow-out techniques have resulted in this crab being cultured widely in ponds, reservoirs and lakes throughout China since the 1990s. As a consequence, aquaculture yields have steadily increased over the past decades, from 8000 t in 1991 to approximately 729900 t in 2013. The main culture areas are located in the three principal drainage basins, i.e. the Liaohe, Yellow and Yangtze Rivers. The Yangtze delta is the largest culture area among the three drainage basins. Although pond-reared populations of originated from their native habitats, i.e. the Liaohe, Yellow and Yangtze Rivers, the Yangtze population generally had the largest body size of adult crabs, the best growth performance and the best taste among three populations. Therefore, pond-reared populations of , originating from the wild Yangtze population, have become the common and major culture population in Middle and East China. Inbreeding depression and adverse selection for smaller-sized crabs eventually resulted in the genetic degeneration of pond-reared . Moreover, the blind introduction and culture of different populations of in their native habitat has led to hybrid germplasms for pond-reared populations. Previous studies have shown that wild crab seeds of juvenile showed different culture performance in ponds, and the wild crab seeds from the Yangtze River system generally had the best perform ance and attracted the highest price among these wild populations. However, to date, there is no reliable discrimination method to identify the origins of wild crab seeds from different rivers. Therefore, the current study was designed to investigate the differences and similarities of wild juvenile crabs from the three river systems. Based on morphological measures and biochemical analyses, we determined and compared the morphological parameters, hepatosomatic index (HSI), proximate composition, lipid composition and fatty acid composition of wild juvenile crabs from the three river systems. The results showed that:(1) significant differences in morphological characteristics were observed for wild juvenile crabs from the three river systems, including 12 and 18 morphological indices for female and male crabs, respectively. However, their coefficient of variation did not reach the threshold value for the subspecies. Cluster analysis showed that the wild juveniles from the Yangtze and Yellow Rivers were pooled and separated into one group, while the wild crabs from Liaohe River were divided into another group. (2) Based on the 7-10 indices with high contribution to the discrimination of wild juveniles from the three populations, different discrimination equations were established for female and male crabs of each population, respectively. The overall accuracy of discrimination was 87.5%. (3) The wild juvenile female crabs from Yangtze River had the highest HIS, while the lowest was found in the males from Liaohe River; female crabs from the Liaohe population contained higher moisture and protein levels in their hepatopancreas, while females of the Yangtze population had the lowest moisture, crude protein and carbohydrate contents. The wild crabs from Liaohe River had the highest moisture content in their body muscle, while the crabs from Yangtze River contained the highest body crude protein and total lipid contents, but the lowest carbohydrate levels. (4) For the lipid composition, except for the hepatopancreas of male crabs, the triglyceride levels in the tissues of Yangtze crabs were significantly higher than those of the other two populations, while the tissue of the Yellow River crabs had lower free fatty acid and cholesterol contents, but the highest levels of phospholipids. (5) The Yellow River crabs had the lowest levels of 18:1n9 and 18:2n6 in the hepatopancreas and body muscle, but the highest contents of 20:5n3 and 22:6n3. Overall, the hepatopancreatic differences in fatty acid composition among crabs of the three river systems were higher than those in the body muscle. In conclusion, there were significant differences in morphological indices and biochemical composition in the wild juvenile from the three river systems, which might be related to their growth environment, natural diets and heredities. These results not only provide useful information for the discrimination of wild seeds from the Liaohe, Yellow and Yangtze Rivers, but also contribute to the evaluation of wild germplasm resources and the rational utilization of natural resources of wild .

Abstract:This feeding trial was conducted to evaluate the effects of replacing soybean meal with fermented brewer's grain levels on the growth performance, body composition and serum biochemical indices of juvenile hybrid tilapias (s). Five hundred and forty juveniles with an initial weight of (3.00±0.08) g were randomly divided into six groups, with three replicates of 30 fish. Six isonitrogenous and isoenergic experimental diets were formulated to contain different levels of fermented brewers' grains to replace soybean meal at 0, 20%, 40%, 60%, 80% and 100%, respectively. The experiment was performed for 60 days in anindoor recirculating culture system. The results showed that there were no significant differences in weight gain, specific growth ratio, feed efficiency and protein efficiency ratio when the replacement level was 0-60% (>0.05). When the replacement level was more than 60%, the growth performance of the fish was significantly lower compared with the control group (<0.05). Based on weight gain and feed efficiency by quadratic regression analysis, the best replacement ratios of soybean meal with fermented brewer's grain were 54.1% and 55.4%, respectively. The crude lipid contents in the whole body and muscle decreased as the replacement level increased, while the moisture and ash contents showed the opposite trend (>0.05). Meanwhile, the viscerosomatic index (VSI) and hepatosomatic index decreased with increasing dietary fermented brewer's grain level (>0.05). When the replacement level was 100%, the VSI was significantly lower than in the control group (<0.05). The activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and the glucose content significantly increased as the replacement level increased; when the replacement level was more than 40%, serum ALT and AST activities were significantly higher than in the control group (<0.05). When the replacement level was more than 20%, the glucose content was significantly higher than in the control group (<0.05). In addition, the triglyceride and cholesterol contents were reduced with increasing dietary replacement level; when the replacement level was more than 60%, serum cholesterol levels were significantly lower than in the control group (<0.05). Meanwhile, when the replacement level was more than 40%, serum triglyceride levels were significantly lower than in the control group (<0.05). Based on the results of growth performance, body composition and serum biochemical indices, the optimal replacement level was 54.1%-55.4% for juvenile hybrid tilapias.

Abstract:This feeding trial was conducted to evaluate the effects of replacing soybean meal with brewer's dried grain levels on the growth performance, body composition, serum biochemical indices and antioxidant capacity of juvenile hybrid tilapias (s). Five hundred and forty juveniles with an initial weight of (3.00±0.08) g were randomly divided into six groups with three replicates of 30 fish. Six isonitrogenous and isoenergic experimental diets were formulated to contain different levels of brewers' dried grains to replace soybean meal at 0, 20%, 40%, 60%, 80% and 100%, respectively. The experiment was performed for 60 d in an indoor recirculating culture system. The results showed that there were no significant differences in weight gain, specific growth ratio, feed efficiency and protein efficiency ratio when the replacement level was 0-40% (>0.05). The growth performances of the fish were significantly poorer in 60%, 80% and 100% groups (<0.05). Based on weight gain and feed efficiency of broken-line analysis, the best replacement ratios of soybean meal with brewer's dried grain were 27.0% and 28.9%, respectively. The crude protein and lipid contents in the whole body and muscle decreased as the replacement level increased. When the replacement level was 100%, the crude protein and lipid contents in the whole body were significantly lower than those in the control group (<0.05). In addition, the viscerosomatic index (VSI) of the fish decreased with increasing dietary brewer's dried grain level, as did the condition factor (<0.05). The activity of alanine aminotransferase (ALT) significantly increased as the replacement level increased; when the replacement level was more than 60%, serum ALT activities were significantly higher than those in the control group (<0.05). Aspartate aminotransferase activities significantly increased as the replacement level increased (<0.05). The glucose contents were significantly reduced with increasing dietary replacement level (<0.05). The serum total antioxidant capacity (T-AOC) decreased with increasing dietary brewer's dried grain level; when the replacement level was more than 20%, the T-AOC was significantly lower than that in the control group (<0.05). Serum superoxide dismutase activities significantly decreased as the replacement level increased (<0.05). Based on the results of growth, serum biochemical indices and antioxidant capacity, the optimal replacement level was 27.0%-28.9% for juvenile hybrid tilapias.

Abstract:Half smooth tongue sole () is a large bottom-dwelling fish that lives in warm water, mainly distributed along the coast of the Bohai Sea and Yellow Sea in China. The half smooth tongue sole is large, grows fast, has a favorable flesh quality and high economic value, and is appreciated by consumers. EPA and DHA are ω-3 polyunsaturated fatty acids that are appreciated for their nutritional and human health values. Pregnant and breastfeeding woman require ω-3 polyunsaturated fatty acids in their diet to promote their baby's development. EPA and DHA lower the incidence of type II diabetes mellitus, hypertension, atherosclerosis and inflammation. Although alphalinolenic acid may be used as a raw material to synthesize EPA and DHA, increasing age and pathological factors mean that the amount of synthesized ω-3 polyunsaturated fatty acids may be insufficient for some tissues and organs, and must be obtained from food intake. Natural aquatic products are very important sources of EPA and DHA. Therefore, it is necessary to determine the EPA and DHA contents to improve farmed fish quality. To study the composition and content of fatty acids in muscles of different half smooth tongue sole families and bred strains, 164 samples from 15 different half smooth tongue sole families were cultivated in the same environment. The muscle fatty acid composition and content of the 164 samples were tested using a gas chromatograph and analyzed comparatively to identify families with high contents of EPA, DHA and EPA+DHA, and to study the relationship between gender and the contents of EPA, DHA and EPA+DHA. There were no significant differences in patterns and types of fatty acids among the different families, while there were significant differences in fatty acid contents. The fatty acid content characteristic of all families was the same:PUFA (polyunsaturated fatty acids)> SFA (saturated acids)> MUFA (monounsaturated fatty acids). The predominant PUFAs were ω-3 polyunsaturated fatty acids. The ratio of ω-3/ω-6 ranged from 4.16 to 5.03. The contents of EPA and DHA were all significantly correlated among families and three high-content families, F13012, F13023 and F13031, were identified. There were no significant correlations between EPA and the gender of the fish; however, there were significant correlations between the gender of the fish and the contents of DHA and EPA+DHA. The contents of DHA and EPA+DHA in males were significantly higher than in females, which will be important for selecting and improving cultivated varieties.

Abstract:Based on the wild base-populations sampled from Hunan and Jiangsu provinces, six breeding populations of , including four pedigree-bred and two population-bred populations, were cultured. The growth properties of four pedigree-bred populations were studied and the genetic characteristics of all six breeding populations were analyzed with seven microsatellite DNA markers. The growth speed of the pure-bred families were significantly higher than geographic hybrid families, but there was no direct relationship between the growth rates and heterozygosities. The number of private alleles of the pedigree-bred populations was about 29.33% more than that of the two population-bred populations. This means that the establishment of family with different geographic populations might raise the level of genetic diversity. The genetic differentiation within breeding populations was significant (=0.4388). The relative farther genetic distance between the pure-bred populations and the pedigree-bred populations revealed that the hybridization between them might obtain some offsprings which exhibited heterosis. Private allele G14₄₃₇ could be used as the specific molecular markers for JCJC population, while G5₅₃₀ used to distinguish the geographic hybrid populations (HCJC and JCHC) from other breeding populations.

Abstract:Jellyfish bloom has had numerous deleterious effects in the marine ecosystem worldwide in past decades. In particular, jellyfish bloom impedes the recovery of fish stocks by preying on fish eggs and larvae, and competing strongly for food with fish. Recently, studies have focused on the predatory relationship between fish and jellyfish. However, the species involved vary among different jellyfish-bloom areas. are, the three common jellyfish species along Chinese coastal seas, of which is a cosmopolitan jellyfish species, and the other two species were indigenous. To the best of our knowledge, the predatory ability of different jellyfish species has not been estimated, as well as the predation of jellyfish on larger fish larvae (more than 10 mm). In this study, the predation of three common jellyfish species (), as 4-cm medusae, in Chinese coastal seas on fish larvae of , was studied using the clearance method. All three jellyfish species could prey on fish larvae, and their predatory abilities decreased as the fish grew. The ranges of were not bigger than 15 mm and 20 mm, respectively; the ranges of were not bigger than 20 mm and 30 mm, respectively; and the ranges of were not bigger 30 mm (the experiment of was not done). Clearance rates were similar between the different prey concentrations, and metamorphosis of helped to avoid predation. The clearance rates of different jellyfish species mainly depended on their vitality, though body structure and toxicity of jellyfish were also important factors. Accordingly, had the highest vitality and predatory ability toward fish larvae, followed by . The results provide theoretical evidence of the relationship between fish and jellyfish, and will further the study of the recruitment mechanisms of natural fish resources in Chinese seas.

Abstract:The Pearl River Basin, as the largest river of southern China, comprises the Xijiang River, North River, East River and Pearl River Delta. With abundant water and fish resources, Xijiang River, which comprises the Nanpan River, Hongshui River, Qianjiang River, Youjiang River and Zuojiang River, has a wide basin that represents 77.8% of the Pearl River Basin. The big-eye mandarin fish (i Garman, 1912), belonging to the Perciformes, Serranidae, , is a special and precious freshwater fish distributed only in China, especially in the Pearl River. , which is a carnivorous freshwater fish with a favorable taste and abundant nutrients, has become one of the most important commercial freshwater fish in China, and has the potential to be a candidate aquaculture species because of its significant economic and ecological value. However, some negative factors, such as the constant severe water pollution, the building of water conservation engineering works, overfishing, and electrifying and bombing of fishes, have led to its miniaturization, low annualized phenomenon and rapid reduction of its wild population. Morphological differentiation among three wild populations (YJ:Youjiang River, ZJ:Zuojiang, HSH:Hong Shui He River) of in the Pearl River was studied based on traditional morphology and a truss network of distance measurements. We aimed to learn more about the germplasm resource of by determining the differences among the three populations and to provide reliable scientific evidence to underpin the protection and use of germplasm resources of . Three multivariate analysis methods were used (One-Way ANOVA, principal component analysis and cluster analysis) for 33 morphometric proportional parameters, using SPSS17.0 software. Based on the LSD results of one-way ANOVA for the measurable characters, there were significant differences between three populations, mainly in the head and tail traits. Specifically, there was a significant difference in the head traits[HW/BL, ED/BL, U (10-11)] and tail traits[CPL/BL, N (5-6)] between the HSH population and ZJ population, and between the HSH population and YJ population, respectively; however, there was no significant difference between the ZJ population and YJ population. For the morphological differences among populations, the contribution of the truss network of distance measurements C(1-11), E(2-11), F(2-10), G(3-4), I(3-9), M(4-10), K(4-9), J(4-5), T(9-10), O(5-8), N(5-6), P(5-7), R(7-8) and S(8-9) indicated that the truss network of the head and trunk of was the principal component, and the contribution of traditional characters was the second. Cluster analyses suggested consistently that the ZJ and YJ populations clustered first and then clustered with the HSH population, whether based on the traditional morphology or the truss network. All of the above indicated that morphological differentiation nexisted among the three populations and was closely associated their geographical distribution. The results, representing basic knowledge of in Pearl River, provide reliable scientific evidence for the protection and use of germplasm resources and for artificial selection breeding of .

Abstract:The macrobenthos is an important part of the ecological system in biological communities, and plays an important role in energy transformation and material circulation. With the decline of marine fishery resources, the intertidal zones in six important islands of Zhejiang are seriously threatened by human activities, causing deep recession of some significant economic macrobenthos living resources. We investigated the taxonomic diversity of the macrobenthos of the intertidal zone, and protected the macrobenthos resources in several important islands of Zhejiang (East China Sea). We used the macrobenthos composition produced by the Checklist of Marine Biota of China Seas, which is based on the historical data of macrobenthos surveys in several important islands of Zhejiang since the 1980s. The species number, taxonomic diversity, index and composition of species similarity index in the order and family levels were calculated. The results showed that species number in the macrobenthos differed in several important islands of Zhejiang. The largest species number occurred in the Nanji Islands:a total of 330 macrobenthos species were recorded, belonging to 213 genera, 124 families, 42 orders, 18 classes and 10 phyla. The lowest species number was recorded in the Taizhou Islands, with a total of 133 macrobenthos species belonging to 105 genera, 73 families, 29 orders, 15 classes and nine phyla. We used the PRIMER 5.2 software to calculate the average taxonomic distinctness index and the variation in taxonomic distinctness index for several important islands of Zhejiang. The Shengsi islandshad the maximum average taxonomic distinctness index (84.76), while the minimum was the Taizhou Islands (70.89). Thus, the genetic relationship of the composition of the macrobenthos species in the Shengsi Islands was more distant than that of the other six islands. The maximum variation in taxonomic distinctness index was calculated for the Dongtou Islands (846.94) and the Shengsi Islands had the minimum (630.25). The islands showed the maximum -index on the premise of a constant -index. Compared with the composition of macrobenthos species similarity index analysis at the order level, the composition of macrobenthos species similarity between the Dongtou Islands and Taizhou Islands was the highest (0.651) and the lowest was between the Yushan Islands and Shengsi Islands (0.480). At the family level, the highest composition of macrobenthos species similarity index was between the Dongtou Islands and Taizhou Islands (0.781) and the lowest was between the Taizhou islands and Yushan Islands. Thus, the macrobenthos species compositions were not significantly different between the Dongtou Islands and Taizhou Islands at the order and family levels. The macrobenthos of the intertidal zone taxonomic diversity in six important islands of Zhejiang was analyzed, which provided references for conservation, development and management within the macrobenthos of the intertidal zoneof the Zhejiang Islands.

Abstract:The purpleback squid () is widely distributed in the South China Sea and northwestern Indian Ocean, with significant diurnal vertical movement. Therefore, it is very important to study the relationship between the catch of , the surface temperature and the vertical temperature structure. Based on catch data from a light-falling net fishing vessel and temperature data in the South China Sea from September to October 2012 and March to April 2013, the relationships among the catch per net of , surface temperature and vertical temperature structure were studied. The degree of gray incidence was used to confirm the greatest factors affecting the catch of . The results indicated that spring was the best fishing period for ; the total catch and the catch per net were obviously higher than that in autumn. Thus there was obvious seasonal variation in the fishing grounds of . The catch was mainly concentrated in the waters near 10°-15°N, 111°-117°E in spring, and in the waters near 13°-15°N, 117°-118°E in autumn. The suitable sea surface temperature (SST) in the fishing grounds was 25.6-29.6℃ in spring and 27.6-30.0℃ in autumn; however, the optimum SST of was the same at 28.5-29.5℃ in spring and autumn. The temperature gradient in the fishing grounds was different between spring and autumn when choosing the S15 and S22 sites as representative sites. A thermoclineboth in spring and autumn was formed in the water layer at 50-100 m, and the thermocline intensity in spring was higher than in autumn. The catch per net of decreased with the increase in the temperature gradient from 5 m to 50 m in spring, and the catch per net in the class interval of 0.00-0.05℃/m was higher than the others. By contrast, the catch per net of increased with the increase in the temperature gradient from 5 m to 50 m in autumn, and the catch per net in the class interval of 0.15-0.20℃/m was higher than the others. The degree of gray incidence (0.84) indicated that the temperature gradient from 5 m to 50 m was the greatest factor affecting the catch of , followed by the latitude, temperature gradient from 5 m to 100 m, SST and longitude.

Abstract:Based on the data taken from fishery resource surveying of the sea areas around Qinshan Nuclear Plant during spring (2010-05), summer (2010-09) and winter (2009-12) and the mathematical simulation results of thermal discharge diffusion in Qinshan Nuclear Plant, we studied the temporal and spatial distribution pattern of fish assemblies, the dominant species, and the contributions of dominant species to fish quantities in the water of Qinshan Nuclear Plant. The results showed that the density of fish in terms of individuals was highest in summer (22.10×10³ ind/km²), intermediate in winter (10.52×10³ ind/km²) and lowest in spring (5.55×10³ ind/km²). However, the seasonal variation in fish quantities in terms of weight was different from other waters. The fish density in terms of weight was highest in winter (66.46 kg/km²), intermediate in summer (59.06 kg/km²), and lowest in spring (33.80 kg/km²).The seasonal variation in fish resource quantities was different to other seas; the densities in terms of weight were higher in winter than those in spring and summer. This was probably related to thermal discharge from the plant making the proximal sea regions warmer than the surrounding sea waters, which could benefit the fish assemblies in winter because of a warm pool effect. Thus, fish assemblies aggregated in the thermal plume of the plant to overwinter. Horizontal distribution of thermal discharge has an important effect on fish distribution patterns. The fish density in the thermal discharge seas in summer was generally lower than other seas and was the opposite in winter:fish may have been stranded in the hot thermal discharge plume areas, thus showing a higher fish density. Thermal discharge has different effects on fishes with different adaptabilities to temperature; the warm temperature species that are adapted to relatively low temperature, such as Collichthys lucidus, which has high thermal tolerance, became the dominant species in the thermal discharge-impacted seas in summer. The adaptability to temperature of the dominant species of fish determines the distribution characteristics of fishes; the most important dominant species in winter was , whose contribution rate on the mantissa was up to 45.02. They aggregated densely in the hot thermal discharge plume area, which caused the fish density in the thermal discharge seas to be greater than the surrounding waters. The thermal discharge-inducedchange in the fishes' environment led to the formation of new wintering grounds, which would be likely to form a new fishing season, leading to changes in local fishery attributes.