Abstract:A weight-related QTL was found in the 15 linkage group (LG) during mapping the growth traits of grass carp (Ctenopharyngodon idella). And we tried to screen insert/deletion mutations on three scaffolds in the 15 LG, according to the previous consensus linkage map and draft genome of C. idella. At the meantime, the STR genotyping method was uesed in genotyping of insert/deletion mutations. Moreover, the association analysis of selected mutations and growth traits of 323 individuals was conducted. Results found that 17 of the 44 selected insert/deletion mutations were SSRs, and 2 loci failed to design primers; therefore, 25 pairs of primer were successfully designed. PCR amplifications showed that only 22 of the 25 primer pairs were effective. Then STR genotyping method was used for genotyping of those 22 insert/deletion mutations, and 7 polymorphic mutations were found in four parents. Afterwards, PCR products were sequenced to confirm the STR genotyping results. Sequencing results showed that STR genotyping method could not only classify insertion/deletion mutants accurately, but also reduce the genotyping costs. Finally, the general linear model was used to analyze the relevance between those 7 insert/deletion mutations and growth traits of 323 juvenile C. idella. Correlation results found that 2 loci (ID-10H and ID-41F) were not related with growth traits, while the other 5 loci were significantly related with one or more growth traits of juvenile C. idella. According to the 5 loci, locus ID-6H was significantly correlated with fatness traits of juvenile C. idella, while locus ID-11F, ID-15F, ID-32F and ID-39F were significantly correlated with body weight or length or width or height. In summary, the inexpensive STR genotyping method could be used in the development of insert/deletion mutations, and the 5 growth related mutations could be used in QTL density-increasing and molecular marker assisted breeding of C. idella.

Abstract:An 8-week feeding trial was conducted to assess the correlation of the dietary protein with growth of juvenile pearl gentian grouper (Epinephelus lanceolatus♂×E. fuscoguttatus♀), serum hormone and digestive enzyme activities, to explore the effects of dietary protein levels on healthy growth. Grouper[average body weight (6.50±0.00) g] were randomly divided into 6 groups with 4 replicates in each group. The fish were fed isoenergetic and isolipidic experimental diets with protein levels 35%, 40%, 45%, 50%, 55% and 60%, respectively. The results showed that weight gain rate and specific growth rate of the fish fed with 50% protein diet were significantly higher than those of fish fed other protein level diets. The concentrations of total protein (TP) in 50% group and 60% group were significantly higher than 35% group. The concentrations of growth hormone (GH) and insulin (INS) in 50% group were significantly lower than those in other groups. The highest insulin-like growth factors-Ⅰ (IGF-Ⅰ) concentration was found in 45% group and significantly higher than those in other groups. Pepsin and intestinal trypsin activities in 50% group were significantly higher than those in other groups. With increasing dietary protein levels, intestinal amylase activity was decreased, the lowest value was found in 55% group and 60% group and significantly lower than those in other groups. There was extremely significantly negative correlation between WGR and GH. According to these results, based on broken-line regression analysis of WGR, a diet containing 51.57% protein is recommended for efficient growth of juvenile pearl gentian grouper.

Abstract:In order to identify candidate genes involved in ovary development, Illumina Hiseq technology was used to define the transcriptome of spotted steed brain, ovary and liver. A total of 49 484 132, 47 540 538 and 50 622 304 clean reads were generated from brain, ovary and liver, and then assembled into 99 878 Unigenes with an average length of 1 430 bp. DEseq analysis revealed that 2 305 were found only in the expression of brain vs. ovary group, 839 were found only in the expression of brain vs. liver group, 1 474 were found only in the expression of ovary vs. liver group, and 860 genes were found to be co-expressed in the three comparison groups. Gene ontology analysis indicated that many of these genes encoded proteins involved in primary metabolic process, single-organism process, organic substance metabolic process. Based on KEGG pathway analysis, putative genes are novel candidate regulators of oocyte development and meiosis, such as GnRH signaling pathway, Steroid hormone biosynthesis, TGF-beta signaling pathway and Oocyte meiosis. The spotted steed transcriptome data reported here will provide valuable new data to increase genomic resources of this species. The data will also provide a valuable basis for further reproductive molecular biology studies of this commercial species.

Abstract:Dicentrarchus labrax is an important economic fish in aquaculture in China. In the process of industrialized recirculating aquaculture, different spectral environments have important implications for the effects of feeding and growth. In this study, five different LED spectral processing groups of white light (λ_{400-780 nm}), red light (λ_{630 nm}), yellow light (λ_{595 nm}), green light (λ_{530 nm}) and blue light (λ_{455 nm}) were set in the seawater circulating aquaculture experimental system. The effects of five different LED spectra on feeding, growth and energy distribution of juveniles[(29.91±0.39) g, (13.78±0.35 cm)) were studied. The results showed that the effects of different LED spectra on the feeding, growth and energy distribution of juveniles were significantly different. The red light group had the best growth of the juveniles (41.09±5.70) g, and the blue group had the poorest growth of the juveniles (36.02±4.18) g; the DGC (daily growth coefficient) of the blue group was significantly lower than the other groups, and the difference between the other groups was not significant; there were significant differences in the feeding rate of the three groups of LED spectrum treatment groups, and the red light group had the highest feeding rate. The results of insulin-like growth factor IGF-1 and IGF-2 showed that the expression of IGF-1 mRNA was highest in the white light group; the mRNA expression level of IGF-2 was highest in the yellow light group. In terms of energy distribution, the red light group has lower fecal energy and metabolizable energy, and has the highest feeding energy and growth energy; the blue light group has the highest fecal energy, lower feeding energy and metabolic energy, and the lowest growth energy. The ratio of RNA/DNA in the muscle and liver of juvenile fish showed that the RNA/DNA ratio of the liver in the blue light group was significantly higher than that in the other groups; the RNA/DNA ratio in the muscles of the blue light group and the white light group displayed significant difference and no significant differences existed among the other groups. The results showed that the red light Eurasian larvae had better feeding and growth performance, and the blue-spectrum larvae had poor feeding and growth performance, and the red-spectrum larvae had higher feeding energy and growth energy. Therefore, the red spectrum has a better promoting effect on the growth of juveniles, and the blue spectrum has an adverse effect on the feeding growth of juveniles. This study provides a reference for the ground-based industrialized recirculating aquaculture of the D. labrax, creating a suitable spectral environment for growth.

Abstract:In this study, a static toxicology experiment was conducted to analyze the survival rate, Na ⁺/K⁺-ATPase (NKA) activity and phagocytic ability of the hemolymph of Sinonovacula constricta of two different sizes (small-size SSc and large-size LSc) under the acute stress of high pH and carbonate alkalinity (C_A). The results showed that when the C_A concentration was 2.5 mmol/L and the pH was 7.5-9.5, the survival rates of the two sizes were close to 100%.When the pH value was greater than 9.5, the survival rates of the two sizes were significantly decreased.When the concentration of C_A was 0-44.58 mmol/L and the pH value was 9.0-10.0, the survival rate of clams decreased with the increase of C_A concentration. Under the condition of pH 9.5, the NKA activity of LSc gill tissue increased with the increase of C_A concentration, and the phagocytic capacity of LSc haemolymph decreased with the increase of C_A concentration. It can be seen that S. constricta showed strong tolerance to high pH or C_A, but high pH and C_A had a great effect on the survival rate of S. constricta. The research results provide a theoretical reference for further exploration of breeding of S. constricta in saline-alkali soil.

Abstract:The aim of this study was to study the effect of infectious hematopoietic necrosis virus (IHNV) nucleic acid vaccine on the immune protection of Oncorhynchus mykiss and serum biochemical indices of Oncorhynchus mykiss. Cloning the glycoprotein gene (G) into pMD19-T vector, we transformed the linked product in DH5α, obtaining recombinant plasmid pMD19-T-G, and recovering the G gene fragment. The identified correct G gene fragment was cloned on eukaryotic expression vector pVAX1 using BamH I and Xho I cleavage sites to construct nucleic acid vaccine pVAX1-G. The recombinant plasmid pVAX1-G was injected into O. mykiss at a dose of 8 μg/ind. as pVAX1-G group, while 8 μg/ind. empty group, PBS control group and blank group were set up. Twenty-one days after immunization, an anti-virus experiment was carried out. After anti-virus, serum was collected and blood indexes were tested. The results showed that there were significant changes in 16 indexes in O. mykiss serum after the attack:glutamic-pyruvic transaminase (ALT), glutamate transaminase (AST), alkaline phosphatase (ALP), total bilirubin (TBIL), total bile acid (TBA), glucose (GLU), the urea (Urea), creatinine (CREA), total protein (TP), albumin (ALB) and globulin (GLO) were compared with normal O. mykiss, and the changes of 11 indexes in no-load group were more significant than those in pVAX1-G group. The cumulative death rate of pVAX1-G group was 19%(19/100)14 days after the attack, while that of no-load group and PBS control group was 62%(62/100) and 85%(85/100), respectively. The protective rate of pVAX1-G nucleic acid vaccine for O. mykiss was 78%. The results showed that pVAX1-G as a nucleic acid vaccine was helpful to reduce IHNV's injury to O. mykiss and had better immune protection effect against IHNV.

Abstract:In this paper, the microstructure and ultrastructure of zebrafish heart were observed by light microscopy and transmission electron microscopy. The results showed that the heart of zebrafish was composed of four parts:ventricle, atrium, bulbous arterious and venous sinus. The ventricle is brown-red and the stratification was obvious, it was divided into a compact layer of the epicardial region and a sponge layer of the endocardial region. The atrium is bright red and consists only of a loose sponge layer. An arterial trunk (abdominal aorta) was issued in front of the ventricle and the starting part of the arterial trunk expands into ellipsoidal shape, called the bulbous arterious. The bulbous arterious was pear-shaped, which can be divided into three layers from the inside to the outside, and they were the inner layer, the middle layer and the outer layer respectively. The venous sinus was difficult to isolate separately, therefore, the sinus was not isolated and observed separately. In this paper, the presence of telocyte interstitial cells was observed in the ventricles, atrium and arterial spheres. Their morphology was slender and long and could be divided into podomeres and podoms. The presence of multivesicular bodies was observed in the cardiomyocytes of the ventricles, which were often distributed on the outer edge of the cardiomyocytes, close to the sarcolemma or adjacent to the mitochondria of the outer edge of the cardiomyocytes.

Abstract:This study explored the effects of multiple freeze-thaw cycles on myofibrillar protein intermolecular force of Sepia esculenta and its protein properties. Fresh S. esculenta meat were defrosted by three different ways which are 0℃, running water and normal temperature for 9 freeze-thaw cycles. The results showed that the effects of defrosting ways were significant on intermolecular forces, and thaw at 0℃ is better than running water and normal temperature. With the increase of freeze-thaw times, the content of ionic bond and hydrogen bond showed a significant decline, the ionic bond decreased by 7.71%, 10.64% and 13.61%, respectively, and the hydrogen bond decreased from 31.91%, 31.97% and 31.87% to 26.76%, 25.53% and 23.94%. On the contrary the hydrophobic interaction force, disulfide bond and non-disulfide covalent bond tended to increase, the hydrophobic forces increased by 8.86%, 12.35%, and 14.72%, respectively, and the disulfide bonds increased by 1.43%, 1.96%, and 2.85%, respectively, the non-disulfide covalent bonds increased from 1.16%, 1.28%, and 1.55% to 3.75%, 4.05% and 5.50%. The surface hydrophobicity of myofibrillar protein increased from 30.47 μg, 31.31 μg and 32.26 μg to 46.10 μg, 53.51 μg and 58.91 μg, respectively, consistent with hydrophobic force results. Both sulfhydryl and reactive thiol content were decreased, the sulfhydryl groups were reduced by 13.07 nmol/mg, 38.99 nmol/mg and 40.32 nmol/mg, respectively, and the active sulfhydryl groups were decreased by 6.55 nmol/mg, 24.26 nmol/mg and 43.16 nmol/mg, consistent with disulfide bond generation trends. The changes of the secondary structure of myofibrillar protein were analyzed by Infrared spectroscopy (FTIR), indicated that during the freeze-thaw cycles the spatial conformation of myofibrin made a change. Three thawing ways were treatments after 9 freeze-thaw cycles, the spectral band shifted to different wavelength regularly, and the amide A band and the amide Ⅲ band moved slightly toward the high wave number direction, and the amide Ⅰ band and the amide Ⅱ band moved to the low wave number direction. The secondary structure of the protein changed, as the sum of the contents of both α-helix and β-sheet reduced, and the sum of the contents of β-turn and random curl increased. Repeated freezing and thawing is actually a process of slow oxidation of proteins.

Abstract:The present study analyzed the spatial distribution of Oratosquilla oratoria in the southern coastal waters of Shandong Peninsula based on bottom-trawl surveys in October 2016, January 2017, May 2017 and August 2017. We used center of gravity and Moran's I index to estimate the distribution center of this species, compared the seasonal differences of spatial autocorrelation, and explored the potential influential factors of the spatial patterns. This study found substantial seasonal variations in the relative biomass of O. oratoria, which showed the highest relative biomass of 3.02 kg/h in summer, followed by 0.75 kg/h in spring, 0.65 kg/h in autumn and 0.22 kg/h in winter. The center of gravity showed remarkable seasonal changes, with the corresponding water depth ranging from 20 m to 30 m in spring and summer and from 30 m to 50 m in autumn and winter. The distributional pattern of O. oratoria was relatively consistent, exhibiting significantly positive spatial autocorrelation in four seasons. Moran' I index was the highest in autumn (0.34), followed by spring (0.30) and summer (0.28), and was the lowest in winter (0.16). According to Moran' I scatterplots, we identified survey sites with strong influence on biomass concentration. The seasonal changes in spatial distribution of O. oratoria might attribute to its spawning activities, and the biomass concentration implied that muddy silt and sand-silt-clay were the preference of sediment types of O. oratoria. We discussed the implications of our results for the management of O. oratoria and put forward the priorities for future fisheries research on spatial analyses.

Abstract:Environmental changes have caused shifts in the population abundance, size structure, and habitat distribution of many marine fish species, and the impacts tend to aggravate with the future global climate changes. A better understanding of the relationship between the fish distribution and environment is helpful in coping with the further changes of climate and fisheries. Based on survey data of fishery resources and the habits collected from 99 stations in January, May, and August, 2017 and October, 2016 in Shandong offshore, we analyzed spatiotemporal distribution of Conger myriaster, and examined its relationship with environmental variables, including water depth, bottom salinity, bottom water temperature, bottom sediment types and prey density, using generalized additive model (GAM). The result showed significant seasonal variations in the distribution of C. myriaster. The stock density was 66.38 kg/h in spring, 87.31 kg/h in summer, 79.01 kg/h in autumn and 10.44 kg/h in winter. GAM identified depth and bottom water temperature as the major influencing environmental factors. In spring, both depth and sea bottom temperature had positive correlations with resource density of C. myriaster which was primarily distributed in the central part of Haizhou Bay, especially at latitudes 35°N. In summer, stock density of C. myriaster was influenced by water depth, and mainly distributed in the south coastal waters of Shandong Peninsula. Water depth, water temperature and prey density had positive relationships with resource density of C. myriaster in autumn. In winter, resource density of C. myriaster had a positive relationship with water depth, and north of Haizhou Bay and longitude 123.5°E-124.0°E were its main distribution area. The distribution of C. myriaster might be attributed to its migratory habits and the variation of the environment conditions caused by seasonal changes, such as water temperature, Qingdao cold water mass and Yellow Sea warm current.

Abstract:In order to investigate the effects of long-term salinity adaptation on growth, ovarian development, osmoregulation, metabolism and antioxidant capacity of adult female swimming crab (Portunus trituberculatus), adult female P. trituberculatus post puberty molt was subjected to four water salinities (10, 15, 20 and 25) for 60 days. The results showed as follows:The survival rate, weight gain rate, specific growth rate and gonadosomatic index of female crabs increased significantly with increasing water salinity. The serum osmolality and the contents of Na⁺, Cl^-, Ca²⁺, Mg²⁺ and major free amino acids, and total free amino acids in the serum, as well as the posterior gills Na⁺/K⁺-ATPase activity showed an overall increasing trend with increasing water salinity. The contents of serum glucose and hepatopancreas lactic acid decreased significantly with increasing water salinity, while the levels of serum urea nitrogen, uric acid, and hepatopancreas uric acid showed an increasing trend. The higher contents of triglyceride, total cholesterol and urea nitrogen in the hepatopancreas were detected in 20 and 25 salinity treatments. The activity of total superoxide dismutase in the serum and hepatopancreas of females from 10 salinity treatment was significantly lower than that of other salinity treatments, while the highest levels of total antioxidant capacity, glutathione peroxidase, γ-glutamyl transpeptidase and hemocyanin in the serum, as well as and hepatopancreas glutathione peroxidase and malondialdehyde were detected at 10 salinity treatment. In conclusion, elevating water salinity could promote the growth and ovarian development of adult female P. trituberculatus, and the females had lower levels of metabolism and oxidative stress under the conditions of 20 and 25 salinities.

Abstract:In order to explore the effect of ecological operation of Three Gorges Reservoir on breeding of the four major Chinese carps in Jianli section of the Yangtze River, and evaluate the quantitative range of ecological hydrology indexes that stimulate spawning behavior of four major Chinese carps, in this study, we investigated the early life resources of the Four Major Chinese Carps in Jianli section of the middle reaches of the Yangtze River, from May to July, 2013-2017. Correlation analysis was made between the Four Major Chinese carps' spawning and larvae collected and the ecological hydrology index. The results show that there is a significantly positive correlation between the daily flow increasing rate and the quantity of fish eggs. When the duration is 4 d and more, and the daily flow increasing rate is from 1 600 to 2 833[m³/(s·d)], ecological operation is more effective to stimulate the reproduction of the Four Major Chinese Carps in late June. Preliminary results indicated, water rising of ecological operation of Three Gorges Reservoir has improved the hydrological conditions for the breeding of four major Chinese carps in Jianli section. The implement of ecological operation not only reduced the negative impact on fish breeding in the midstream of the Yangtze River, but also maintained fish population resources after the operation of the Three Gorges Reservoir.

Abstract:The Manila clam (Ruditapes philippinarum), with annual yield of 4 million tons in 2015, is a kind of important economic shellfish in China. The breeding technique in diked tidal flat which is the most productive technology, is not particularly reliable. In order to optimize it, a pond (A) was set up to induce phytoplanktonic blooms, which was regularly distributed to the nursery pond (B), and nursery pond (C) without algae superinduced as the control. The water, sediment quality and phytoplankton of A, B, C were compared with those of adjacent natural sea area (D). The growth of juveniles in B and C were also compared. The results showed that, there was no significant difference between A, B and C in water and sediment quality, but the water quality parameters(S, pH, DO, NH₃-N, NO₃-N, PO₄-P) and the sediment quality (organic carbon, sulfide) of the three ponds were significantly different from D; the phytoplankton density followed the order of A > B > C > D, but only A had significant difference with D; the shell length and density of juveniles in B were significantly higher than those in C. This indicated that there was a great difference in the environment between the diked tidal flat ponds and the natural sea area, and phytoplankton supplement can increase the growth and survival of the juveniles, thus ensuring the success rate of the breeding of R. philippinarum in diked tidal flat ponds.

Abstract:To elucidate the role of sox9 in sex determination and differentiation of the large yellow croaker (Larimichthys crocea), the full length of sox9a and sox9b were cloned using reverse transcription-polymerase chain reaction (qRT-PCR) and rapid amplification of cDNA ends (RACE). The difference of the gene expression in various tissues and development stages was analyzed through quantitative real-time PCR. Expression profiles of sox9a/b after 17β-estradiol or 17α-methyl testosterone treatments were also examined. The full-length cDNA of sox9a gene is 2 442 bp (NCBI:MH996431), including a 476 bp 5' UTR, a 466 bp 3' UTR and a 1 500 bp ORF coding a polypeptide of 499 amino acids. The full-length cDNA of sox9b gene is 2 199 bp (NCBI:MH996432), including a 335 bp 5' UTR, a 415 bp 3' UTR and a 1 449 bp ORF coding a polypeptide of 482 amino acids.Quantitative Real-time PCR results showed that sox9a was primarily expressed in gonad, eye, brain, liver, and the expression level in testis was significantly higher than that in ovaries. sox9b was widely expressed in multiple tissues in large yellow croaker; the expression level was the highest in testes, but can be barely detected in ovaries. At early developmental stages of fry, sox9a/b was expressed at a lower level. Sox9a/b peaked at 84 dph (day post hatch) and 123 dph, then their expression declined and gradually rose again at 10 mph. In addition, 17β-estradiol can significantly down-regulate the expression of sox9a and sox9b in testes. 17α-methyl testosterone can significantly elevate the expression of sox9a and sox9b in gonads. The study demonstrated that sox9a/b may play important roles in sex determination and differentiation in the large yellow croaker. However, the functions of the two genes may be different.

Abstract:A suspended growth reactor under continuous carbon resource feeding method (SGR-Con) and another under several steps carbon resource feeding method (SGR-Sev) were operated in a pilot-scale recirculating aquaculture system to compare their water treatment efficiency. It indicated that the concentrations of dissolved organic carbon in the reaction zone of SGR-Con was at a high and stable level, while that in SGR-Sev firstly increased to the same level of SGR-Con during the 0 h in cycle to the instantaneously carbon feeding time and it subsequently decreased to a lower and stable level after 4 h in cycle. Dissolved oxygen in the reaction zone of SGR-Sev, as well as the settling zone was significantly higher than that in SGR-Con. The pH in the reaction zone between different reactors had no significant difference, and it was same in settling zone. Several steps carbon resource feeding method significantly increased the nitrogen removal of reactor. Overall the experimental period, the removal rate of nitrate and total nitrogen in SGR-Sev could be 63.91%±14.31% and 64.07%±12.11%, respectively. Besides, alkalinity in the effluent of SGR-Sev was (278.18±80.33) mg/L. SGR-Sev was favorable to achieve good settling performance of bio-flocs. However, the concentrations of total ammonia nitrogen and nitrite in the effluent of SGR-Sev were higher than those of SGR-Con. In summary, it is better to adopt the several steps carbon resource feeding method for suspended growth reactors.