Abstract:Due to its rapid growth rate and excellent adaptability to saline environments, the red tilapia () could be a suitable subject for studies on saline tolerance. In this study, to provide a theoretical basis for saline tolerance mechanisms, we aimed to screen and identify differentially expressed proteins in the gill of Red tilapia using protein chips and mass spectrometry, which were subsequently verified by using immunohistochemistry and western blot techniques. There were 181 differentially expressed protein spots detected (change multiple ≥ 1.5), which included 142 up-regulated proteins and 39 down-regulated proteins. Among these, three proteins were identified by mass spectrometry from five differentially expressed proteins:intermediate filament protein (IF), translocation protein 63 (SEC63), and disulfide-isomerase A3 (PDIA3). The immunohistochemistry results showed that IF and PDIA3 are expressed in the gill base of red tilapia under both freshwater and saline water conditions, and showed a trend of initial decrease and then increase with an increase of saline concentration. However, no positive reaction was detected for SEC63. The western blot results showed IF and PDIA3 expression level changes in different saline waters similar to those observed using immunohistochemistry. In the 30 g/L salinity group, the expression of IF protein decreased during the early stage of stress, reached the lowest value at 48 h, and thereafter began to rise significantly at 72 h, The expression of PDIA3 protein was significantly increased after 96 h ( < 0.05). These results suggest that IF and PDIA3 are positively responsive proteins in the gill tissues of red tilapia under salinity stress, and play important roles in the regulation of cytoskeleton and endoplasmic reticulum function.

Abstract:Aging and death are very complex biological phenomena. In recent years, aging has become an important research topic. Researchers have explored the mechanisms of aging at the cellular and molecular levels. is widely distributed in China's coastal areas, with high food, medicinal, and economic value; it is an important cephalopod of economic value in China. It usually dies after spawning, which is a common characteristic of cephalopods. However, the lifecycle and aging-related mechanisms in this squid are still unknown. In this study, we used to examine prohibitin, which is a highly conserved protein that is widely present in eukaryotes from yeasts to mammals and plays an important role in cell cycle management, differentiation, aging, and anti-proliferative activity. gene using rapid amplification of the cDNA end (RACE) technique. The full length of the sequence was 1283 bp, containing a 5'-untranslated region (5'-UTR) of 150 bp, a 3'-untranslated region (3'-UTR) of 236 bp, and an open reading frame (ORF) of 897 bp that was predicted to encode 298 amino acids. Sequence analysis showed that the protein encoded by the gene did not contain a signal peptide, but contained a domain of the PHB family, and the fragment including 20aa to 42aa was a transmembrane structure. The sequence was 87% similar to is clustered with mollusks and arthropods, and the chordate is another, which is in accordance with traditional taxonomy. The expression of S. japonica at different growth stages (larvae, spawning, spawning-and-postpartum). The results showed that the gene was expressed in all four developmental stages. The expressions were lower in the larvae and spawning-and-postpartum stages and relatively high during spawning and spawning. Expressions in brain and liver tissues were high at all stages. The optic gland, an endocrine organ, was associated with reproductive regulation, and its Phb2 gene was significantly decreased after spawning, which indicated that had pleiotropic functions of cycle regulation, controlling cell senescence, and apoptosis. The results of this study provide a basis for further study on the anti-aging effects of Prohibitin2 in and its expression in cephalopods, and also provides some theoretical basis and information for the causes of senility and senescence mechanisms in marine cephalopods.

Abstract:The objective of this study was to estimate genetic parameters and breeding values for growth traits in grass carp , an important economic freshwater fish in China. A factorial mating design was carried out to construct 21 full-sib families by artificial fertilization, and their parents were from a nucleus breeding population. Animal models and REML procedures were used to estimate genetic, phenotypic, and environmental parameters for body weight (BW), standard length (SL), body height (BH), and condition factor (. The results showed large variations for growth traits in the breeding population. Moreover, BW, SL, and BH traits displayed moderate to high levels of genetic variation (0.21 to 0.47) and relatively low heritability for condition factor (0.11). In addition, common environmental effects were relatively low for the four growth traits (0.07-0.17). Genetic and phenotypic correlations among BW, SL, and BH traits were all positive and ranged from 0.88 to 0.97. In contrast, the genetic correlations between =0.43). Overall, the results suggested that BW could be a single target trait for the genetic improvement of growth performance in grass carp. The individual breeding values were predicted using the best linear unbiased prediction (BLUP) method with the software ASREML. Selection was practiced on individual phenotype or breeding values for each trait. The results showed that, although Pearson's correlations between breeding values and phenotypic values for each trait were 0.77-0.93, the same selected individual rates for each trait ranged from 68.75% to 81.82%, and Spearman's correlation coefficients ranged from 0.19 to 0.81 at a 10% selection intensity. Both methods of selection presented significant differences, particularly for the trait with low heritability. This study provides a theoretical basis and technical support for selective breeding of growth traits in grass carp.

Abstract:The Pacific oyster () is the most widely cultured shellfish in the world. There is considerable focus on improving selective breeding procedures for economic traits. We used specimens of the white-shell strain of after four generations of family selection as parents to construct 30 full-sib families in a nested design. A mixed family approach combined with parentage analysis using highly polymorphic microsatellite makers and REML based on the animal model was used to estimate genetic parameters of white-shell at the age of 24 months. The results showed that heritabilities of shell height, shell length, total weight, shell weight, were 0.35±0.13, 0.18±0.09, 0.20±0.09, 0.16±0.08, 0.16±0.08, 0.27±0.11, and 0.19±0.08, respectively. Shell width, meat weight, meat ratio, and indexes of shell shape showed lower heritabilities of 0.07±0.02, 0.11±0.06, 0.02±0.03, 0.08±0.06, and 0.11±0.06, respectively. All phenotypic and genetic correlations among shell height, shell length, shell width, total weight, shell weight, and meat weight were positive. Genetic correlations were higher between shell height, shell length, total weight, and the other growth traits, ranging from 0.40±0.65 to 0.90±0.14, 0.39±0.55 to 0.97±0.24, and 0.50±0.66 to 0.99±0.02, respectively. Genetic correlation between index A of shell shape and shell height was -0.94±0.16, and -0.77±0.19 between index B of shell shape and shell height, suggesting that shell shape would not change if just shell height were selected in breeding programs. Genetic correlations were significantly different between shell color traits and growth traits, varying from -0.09±0.42 to 0.91±0.74. Higher genetic correlations between ^* (the same as shell height, shell length, and total weight) could improve other growth traits. There was a negative genetic correlation between of -0.96±0.04. Conversely, genetic correlations were lower between and could also decrease . This information will benefit genetic improvement of the white-shell strain of .

Abstract:To analyze the morphometric differentiation of wild between the population from the Yangtze River Basin and that from the Pearl River Basin, the variation in morphological characteristics of among three populations from three different sampling sections (Yanhe section of the Wujiang River, Tongren section of the Jinjiang River in the Yangtze River Basin, and Guanling section of the Beipanjiang River in the Pearl River Basin) were assessed using multivariate analysis methods based on the measured morphological data and the truss network. The results showed that among the three populations, the eyes of the individuals from the Tongren section were the smallest, the body width from the Yanhe section was the thinnest, and the population from the Guanling section had the thickest body width, the shortest snout length, but the longest caudal peduncle length. After standardization and parameter selection for original data, the data for 12 selected characters were used to conduct principal component analysis. Two principal components were constructed, which resulted in a cumulative contributory ratio of 64.255%. Principal component 1 was mainly affected by characters, including body width, caudal peduncle shape, and distance between the eyes, whereas principal component 2 was mainly affected by the length of the snout and size of the eyes. A stepwise discriminant method was used to establish the characteristic discriminant functions of the three stocks, which revealed that the total accuracy rate of discrimination by the cross-validated method was 91.85%. The coefficients of differences for the 12 characters among the three stocks did not reach the threshold value of 1.28, although the subspecies could be clearly discriminated. In short, the morphometric differentiation between the two populations from the Yanhe section and Tongren section in the Yangtze River Basin were low, whereas the morphological differences were higher between these two populations and the population from the Guanling section sampled from the Pearl River Basin. Nevertheless, the morphological variation of the three populations shown in this study represented morphological variation from different geographic populations of the same species, which had not reached the level of subspecies variation.

Abstract:Egg quality is essential for fish breeding and the healthy development of aquaculture. In the artificial breeding of , in which ovulation cannot occur spontaneously, it is difficult to determine a suitable time for collecting eggs artificially from mature broodstocks, and artificial egg collection is frequently delayed in the breeding of . Aging of ovulated eggs in the ovary or in the coelomic cavity is defined as over-ripening of eggs and is always associated with a decrease in egg viability. It would thus be useful to investigate variations in physiological and biochemical parameters and their effects on the quality of eggs during egg over-ripening, and to define those parameters that are correlated with egg vitality and could be used as quality markers. In this study, we examined the effects of delaying artificial spawning of mature broodstocks for 1 and 2 weeks. In group A, artificial spawning was not delayed, whereas in groups B and C, artificial spawning was delayed for 1 and 2 weeks, respectively. Variations in the phosphatases, malate dehydrogenase (MDH), sialic acid, total amino acids (AAs), and fatty acids of eggs were analyzed by means of biochemical analysis and GC-MS. We also examined the correlations between these biochemical parameters and fertilization rates. The results showed that after delaying spawning for 1 week, the fertilization rates in group B decreased significantly (<0.05), and that after a delay of 2 weeks, the fertilization rates of group C decreased to 31.89%. With the delay in spawning, the activities of acid phosphatase (ACP) decreased significantly (P<0.05, =0.705). In group A, the activity of MDH was significantly higher than that in group B and group C (=0.630). AA contents showed the same variation tendency, with the AA contents in group A and group B being higher than those in group C (=0.706). The contents of myristic acid (C_14:0), pentadecanoic acid (C_15:0), palmitic acid (C_16:0), palmitoleic acid (C_16:1n-7), α-linolenic acid (C_18:3n-3), and eicosapentaenoic acid (EPA) in 100 g fat were highest in group A and were significantly positively correlated with fertilization rates () and the ratio of docosahexaenoic acid (DHA) to EPA were significantly negatively correlated with fertilization rates. These results demonstrate that the egg vitality of was significantly reduced during over-ripening in the coelomic cavity. The changes in egg vitality were associated with several alterations in egg physiology and biochemical compositions. Some of the parameters of the eggs that changed during over-ripening were also suitable for the determination of egg quality. These phenomena suggest that during the over-ripening of eggs, the egg membrane becomes damaged, and that there is a mixing of the contents of eggs and ovarian fluid, which leads to a decrease in the compositions of AAs, types of fatty acids, and other biochemical substances. C_14:0, C_15:0, and C_16:0 are important energy storage materials, whereas C_20:5n-3 is the precursor of EPA, which confers anti-inflammatory properties to eggs. AA content is an important index of AA metabolism. Clearly, as indicated by the results of this study, decreases in these biomolecules could lead to decreases in the fertilization rates of eggs. ACP is an enzyme that is indicative of lytic processes and is involved in the degeneration of phospholipids, whereas MDH is a key-enzyme in the tricarboxylic acid cycle, which is consistent with our results showing that decreases in the activities of ACP and MDH can impair egg viability. In conclusion, changes in phosphatase, malate dehydrogenase, total amino acids and fatty acids are correlated with egg viability, and it is thus essential to collect eggs artificially within 1 week when the ovaria of broodstocks are maturing.

Abstract:Crucian carp () vitellogenin (Vtg) is a commonly used biomarker for the detection of estrogenic activity in aquatic environments. In this study, gel filtration combined with ion-exchange chromatography and selective precipitation combined with ion-exchange chromatography were used to purify lipovitellin (Lv) from ovarian homogenates of crucian carp. Lv was identified as a phospholipogly coprotein with an apparent molecular weight of~521 kD and separated into two major polypeptides corresponding to~117 and~103 kD by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The results of the western blot showed that both anti-goldfish () Lv antibodies had good cross-reaction with crucian carp Lv. Using anti-goldfish Lv antibody, anti-zebrafish Lv antibody, and purified crucian carp Lv, two sandwich enzyme-linked immunosorbent assays (ELISAs) were established. The results showed that the binding curves of goldfish Lv and crucian carp Lv basically overlapped. The sandwich ELISA developed using anti-goldfish Lv antibodies and purified crucian carp Lv had a working range form 15.6 to 1000 ng/mL and a detection limit of 6.8 ng/mL, which was significantly lower than that of the anti-zebrafish Lv antibody-based ELISA and other ELISAs previously reported for crucian carp Vtg. Therefore, we suggest that it is a reliable tool for the quantification of crucian carp Vtg.

Abstract:An experimental ecological method was used to determinate the effects of hypoxia on the median lethal time (LT₅₀) and physiological function of two sizes of sea cucumber (large-size:with a body weight ranging from 28.00 g to 36.00 g; small-size:with a body weight ranging from 9.00 g to 13.00 g) at high temperature (25℃). The LT₅₀ in the two sizes of sea cucumber at a dissolved oxygen (DO) concentration of 1 mg/L were investigated. The diurnal metabolism in the two sizes of sea cucumber at DO concentrations of 1, 3, and 6.5 mg/L (normoxia) were estimated. The glutathione (GSH) content and activities of superoxide dismutase (SOD), catalase (CAT), and total antioxidant capability (T-AOC) in the coelomic fluid and respiratory tree, as well as the cortisol level in the coelomic fluid at 24 h hypoxia stress (the DO concentrations of 1 mg/L and 3 mg/L) and 72 h reoxygenation of the two sizes of sea cucumber were also measured. The results showed that, at first, at the DO concentration of 1 mg/L, the LT₅₀ for the large and small-size sea cucumber was 33.37 h and 28.84 h, respectively. The metabolism in the two sizes of sea cucumber was significantly lower than that in the normoxia condition (hereafter control), the overnight metabolic intensity was higher than during the daytime, and metabolic intensity in the small-size sea cucumber was higher than in the large-size one. Secondly, during the 1 mg/L hypoxia stress, the variations of the four antioxidant indices in the coelomic fluid in the large-size sea cucumber and those in the respiratory tree in both sizes of sea cucumber were similar:compared with the control group, the hypoxia exposure decreased the content of GSH and the activity of SOD and T-AOC, but increased the activity of CAT. However, at the end of the hypoxia stress, the content of GSH and the activity of SOD, CAT, and T-AOC showed no significant difference from the control group. After 72 h of reoxygenation, the above four antioxidant indexes of the coelomic fluid in the two size groups of sea cucumber recovered to the level of the control group but the four antioxidant indexes of the respiratory tree did not. During the 3 mg/L hypoxia, the variation trend of the four antioxidant indexes in the coelomic fluid and respiratory tree of sea cucumber was consistent with those in the 1 mg/L group. After 72 h of reoxygenation, the above four antioxidant indexes of the coelomic fluid in sea cucumber recovered to the level of the control group. Except for T-AOC, the other three indices of the respiratory tree also recovered. The recovery ability of the small-size sea cucumber was higher than that of the large one after hypoxia stress. Thirdly, at the DO concentrations of 1 mg/L and 3 mg/L, the content of cortisol in the coelomic fluid of both sizes of sea cucumber was significantly higher than the control group at the end of the stress (<0.05). The level of cortisol in the coelomic fluid of the large-size sea cucumber was higher than in the small one but both recovered to the control level after reoxygenation. The results showed that if the hypoxia duration is less than the LT₅₀(24 h, for example, in this paper), sea cucumber can alleviate the oxidative damage. However, if the time under hypoxia exceeds the threshold value, sea cucumbers will suffer irreversible damage and die.

Abstract:This experiment was conducted to determine the effects of starvation and refeeding on the growth performance, biochemical indices in the plasma, liver/muscle glycogen content, glucose metabolic enzymes, and gene expression of glucose transporter 1 () and then clarify the characteristics of glucose metabolism of grass carp under starvation and refeeding. The combined experiment consisted of a starvation group (S), refeeding group (R, starvation 4 weeks + refeeding 4 weeks), and continuous feeding group (C). Fish with an average initial weight of (125.35±0.54) g were randomly selected in each treatment and injected with 300 mg glucose per 100 g body weight for a glucose tolerance test (GTT) at the end of experiment. The results showed that starvation resulted in a low liver glycogen content, plasma glucose, and triglyceride concentration. However, starvation treatment had a significant effect on glucose tolerance, and the plasma glucose concentration of the S group was significantly lower (<0.05) than that of the other groups during the entire sampling period, whereas liver glycogen content peaked at 6 h. Starvation treatment had a significant effect on activities of carbohydrate metabolic enzymes. Starvation induced the liver PEPCK enzyme activity but depressed PK and PFK enzyme activities. However, PEPCK, PK, and PFK enzyme activities returned to their previous levels after refeeding. After glucose injection, a significant increase (<0.05) in GK and PK activities was observed in the S group, but PK activities of the R group significantly increased (<0.05) and then decreased. Starvation treatment had a significant effect on the expression of in hepatic and muscle tissues. After the glucose load, starvation and refeeding significantly induced the expression of GLUT1 expression in the muscle tissue of the R group decreased, whereas its expression in the muscle tissue of the S group was significantly higher than that of the other groups during the entire sampling period (<0.05). It could be concluded that during the stages of starvation, to deal with the challenges of food deprivation, grass carp depleted glycogen and triglyceride, suppressed hepatic glycolysis enzymes, such as PK and PFK, and activated hepatic glycogenolytic enzymes, such as PEPCK. The results of starvation treatment in grass carp favored the improvement of glucose tolerance through inducing GK and PK enzyme activities, increasing the synthesis of liver glycogen, and activating the expression of in hepatic and muscle tissues.

Abstract:Blunt snout bream (Cyprinidae family. It has been widely cultured in China due to its excellent value. Research on the feed ingredients should be conducted to optimize feed formula under various circumstances. This study investigated the apparent digestibility of dry matter (DM), crude protein (CP), gross energy (GE), total amino acid (TAA), and essential amino acid (EAA) in fish meal (FM), meat and bone meal (MBM), soybean meal (SBM), rapeseed meal (RSM), cottonseed meal (CSM), yeast extract fermentation (YEF), and peanut meal (PNM) at different temperatures (25℃ and 30℃) indicated by 0.05% Y₂O₃ for blunt snout bream (34.38±2.16 g). The diets consisted of a 70% basal diet and 30% test ingredients. Fish were fed twice daily in recirculation water system aquaria for 4 weeks. During the feeding trial, excrement was collected 30 minutes after feeding, then dried and stored for analysis. At 30℃, the apparent digestibility of DM, CP, GE, TAA, and EAA was approximately 24.88%-90.63%, 52.32%-94.88%, 47.77%-102.68%, 51.18%-95.15%, 42.97%-95.5%, and 50.49%-94.9%, respectively. YEF had the highest apparent digestibility of DM, CP, GE, and EAA. SBM had the highest apparent digestibility of TAA. MBM showed the lowest apparent digestibility of DM, CP, TAA, and EAA. CSM had the lowest apparent digestibility of GE. At 25℃, the apparent digestibility of DM, CP, GE, TAA, and EAA was approximately 33.65%-79.79%, 64.23%-96.53%, 58.17%-89.79%, 57.13%-97.4%, 49.03%-97.3%, and 56.85%-97.09%. SBM had the highest apparent digestibility of CP, TAA, and EAA, FM had the highest apparent digestibility of all other nutritional compositions. The same result was found at 30℃. In addition, the apparent digestibility of DM, CP, TAA, EAA, and MBM was the lowest, while CSM had the lowest apparent digestibility of GE. Therefore, the apparent digestibility of the seven feed protein ingredients were all different at different temperatures in blunt snout bream. In other words, temperature affected the apparent digestibility of feed protein ingredients. In conclusion, the apparent digestibility of animal protein feedstuff was better than nonanimal protein feedstuff for blunt snout bream, perhaps because this is an herbivorous fish that can use plant proteins more efficiently. YEF showed the highest apparent digestibility of all ingredients at 30℃; therefore, it can be used as a high quality fish feed ingredient. However, the amino acid balance of YEF was worse than FM, and should have methionine (Met) added to the feed, to enable the fish to use it better. Conversely, MBM had the lowest apparent digestibility, which may have been due to the numerous bones, which cannot be digested by fish, with the result that the nutriment of bone could not be used by blunt snout bream. Therefore, it should be used rarely in fish feed. At 25℃, the highest apparent digestibilities of all ingredients were in the FM and SBM, which can be used as high quality alternative protein sources for blunt snout bream. At 25℃, MBM was not a good feed ingredient. CSM showed the lowest apparent digestibility of GE under both temperatures, which may have been because CSM had a high level of cellulose, and the fish cannot process cellulose, so that this feed moved faster through the intestinal canal. The apparent digestibility of amino acids varied among different test ingredients, the same was found for single test ingredients. Overall, the apparent digestibility of DM, CP, GE, TAA, and EAA in FM, MBM, SBM, RSM, CSM, YEF, and PNM were different at different temperatures.

Abstract:The American shad, , is an economically and ecologically valuable anadromous herring native to the Atlantic coast of North America, which was introduced into China as an alternative species to the Chinese shad (because of the latter's near extinction), and is considered as an emerging aquaculture species in China. However, the high mortality rate in the early stage of development, particularly after ingestion of exogenous food, has seriously restricted the development of the industry. Therefore, food selection during seed rearing has important significance. In the present study, the effect of different diets on growth performance, survival, digestive enzyme activity, immune response, and body fatty acid composition in larval American shad were assessed. Larvae of American shad, 10 d after hatching, were reared with different diets ( and micro diet), in triplicate, for 30 d cultivation. The survival and growth performance (survival rate, total length, body weight, and specific growth rate) in the mixed feeding group were significantly better than those in the other two groups during the studied period (<0.05). This may be attributable to the difficulty in digesting micro diets during the early experiment stage and the deficiency of essential fatty acids in , particularly the deficiency of n-3 highly unsaturated fatty acids (n-3HUFA) and docosahexaenoic acid (DHA). There were no obvious differences between the micro diet group and group; however, the survival and growth performance of the micro diet group during the 20 d-30 d period were better than those in the <0.05). This may be because larval fish can digest and absorb micro diets efficiently during this period; moreover, micro diets have a better nutrient content. There were no significant differences in the pepsin and amylase activities among all groups, whereas the activities of trypsin, chymotrypsin, and lipase in the group were significantly lower than those in the other two groups (<0.05). Furthermore, chymotrypsin and lipase activities in the micro diet group were significantly higher than those in the mixed feeding group (<0.05). This indicates that fish larvae could digest micro diets efficiently at the end of experiment, and the addition of micro diets can improve digestive enzyme activities and digestion ability to a certain extent. There was no significant difference in the alkaline phosphatase and superoxide dismutase activities among all groups. The highest activities of catalase (CAT) and lysozyme (LZM) were recorded in the micro diet group, and the activities in this group were significantly higher than those in the <0.05). There was a certain correlation between the survival performance during the 20-30 d period and the activities of CAT and LZM. The mortality in the micro diet group and mixed feeding group remained stable, whereas that in the group continued to decline during this period. This indicates that the addition of micro diets may enhance the non-specific immune response of larval fish. The fatty acid composition of fish larvae was affected considerably by the fatty acid composition of diets. Due to the higher content of essential fatty acids in micro diets, the contents of n-3 HUFA and DHA in the mixed feeding group and micro diet group were significantly higher than those in the <0.05). The experimental results indicate that different diets have an obvious influence on the growth performance, survival, digestive enzyme activity, immune response, and body fatty acid composition of larval American shad. This preliminary analysis showed that mixed feeding with and micro diets before 20 d and full conversion to feeding with micro diets after 20 d can reduce costs and improve production efficiency.

Abstract:This study compared the effects of four different tilapia cultivation systems (a tilapia-water spinach integrated system, a sewage discharging system, a sewage discharging and tilapia-water spinach integrated system, and a tilapia monoculture system as a control) on the variations in water quality, tilapia production, and off-flavor contents in water and tilapia in June, July, and August 2016. Using gas chromatography and mass spectrometry (GC-MS) based on microwave-assisted distillation followed by purge-and-trap, the off-flavor compounds geosmin (GSM) and 2-methylisoborneol (2-MIB) were determined in water and tilapia tissue. The results showed that production in the tilapia-water spinach integrated system was the highest among the systems examined (<0.05). The contents of ammonia nitrogen and nitrite in the sewage discharging and tilapia-water spinach integrated system were significantly lower compared with the control group[(0.67±0.02) μg/kg and (0.870±0.018) μg/kg]. In addition, the concentrations of 2-MIB and GSM in the muscle of tilapia in the sewage discharging and tilapia-water spinach integrated system[(0.31±0.02) μg/kg and (0.53±0.042) μg/kg] were significantly lower than those in the control group[(0.67±0.02) μg/kg and (0.870±0.018) μg/kg, respectively]. These results indicate that the sewage discharging and tilapia-water spinach integrated system reduced the accumulation of off-flavor compounds in water and tilapia muscle in an intensive tilapia farming system.

Abstract:The pearl oyster is noted for producing the largest and most valuable colored pearls in the world. In French Polynesia, is the most important aquaculture species, far ahead of any other main food species. Indeed, the pearl culture industry plays a major economic role and represents the largest export industry in the region. Traditionally, culture has been based on spat collected from the wild, which are then on-grown to a suitable size prior to seeding for pearl production. However, in a number of Pacific countries, the abundance of adult pearl oysters is low and there is limited natural spatfall. Hatchery production has been considered as an important alternative to wild spat collection for pearling industries. However, high mortality rates during spatfall and a few days after settlement have been limiting factors. This study was conducted using larvae at different stages to observe their swimming behavior, swimming speed, natural sedimentation, and the filtering of microalgae under an optical microscope, so as to provide information for optimizing larval breeding facilities and feeding strategies. The results showed that the larvae swim and filter microalgae by beating their cilia. When functional, the double shells on the top of the larvae open with the umbo toward the bottom, and the velum projecting from back of the shell is used to propel the body when swimming. Larvae swim around clockwise in circles of a certain radius, and in the vertical direction the larvae swim in a spiral either rising or falling. The 1~25-day-old post-hatch (dph) larvae have a horizontal swimming speed ranging from 246.88 μm/s to 3641.94 μm/s, and the relationship between shell length ² +37.2690 P<0.05) positive correlation between the swimming speed and the surrounding radius. With an increase in body weight and degeneration of the velum, the velum can no longer be used for larval swimming, which causes an increase in the natural sedimentation rate, and at 13 dph the shell length of larvae settled on the bottom substrate was significantly (<0.05) larger than that when in suspension. Excessive ingestion of baits would lead to indigestion, with bait being directly excreted from the body without being fully digested and exploited.

Abstract:Studies on the phytoplankton functional group (PFG) composition of intensive-culturing fishponds were carried out in the Pearl River Delta during the initial, mid-, and late stages of the culture period. The results showed that high phytoplankton density, algal biomass and species abundance were observed in the sampling ponds. The average phytoplankton cell density was 1.32×10⁸ cells/L, with a maximum of up to 3.00×10⁸ cells/L. The average phytoplankton biomass was 168.17 mg/L, with a maximum of up to 345.41 mg/L. A total of 196 algal species, including a few varieties and forma, were distributed among the following 8 major taxonomic categories:Chlorophyta (91), Euglenophyta (40), Bacillariophyta (27), Cyanophyta (23), Dinophyta (7), Cryptophyta (4), Xanthophyta (3), and Chrysophyta (1). The algae in the sampling ponds were identified to the following 28 PFGs:A, B, C, D, F, G, G₂, H1, J, K, L₁, LM, L₀, M, MP, N, P, S1, S2, T, T_D, W1, W2, W_S, X1, X2, X_Ph, and Y. Frequency distribution analysis showed that C, F, J, MP, N, P, W1, X2, Y, K, L₀, M, and W2 were the dominant PFGs. These PFGs showed high biomass and occurrence frequency in the sampling ponds, which indicated that the phytoplankton community structure in the culturing ponds was in a stable state with simple ecological functions. Redundancy analysis between the environmental factors and the dominant PFGs showed that organic content was the primary affecting factor, followed by nutritive materials and their proportions (including TP and N:P). Least influential were physical parameters, including transparency, pH, dissolved oxygen, total dissolvable solids, and water temperature. On the basis of the traditional biodiversity evaluation standard, the water quality of the sampling ponds was clear, but the habitats of the dominant PFGs indicated that the water was heavily polluted, which was consistent with the results of the measured parameters and water appearance. In this study, we observed that the number of PFGs in the mid-stage of culture was greater than that in the initial or late stage. This pattern was obvious in the pond, which underwent frequent water changes during the mid-stage. It was concluded that providing sufficient water changes could be an important measure for preventing water quality deterioration during the megathermal period. Furthermore, the results of the present study showed that compared with traditional biodiversity methods, the phytoplankton functional group concept could be successfully used to assess the real ecological status of phytoplankton in intensive-culturing fishponds, and also provides a method for analyzing pond ecosystems.

Abstract:This study was conducted to evaluate the effects of chronic ammonia nitrogen (N) stress (concentration gradient:0 mg/L, 2 mg/L, 4 mg/L, 6 mg/L, 8 mg/L, 10 mg/L) on the feeding and activities of three types of digestive enzymes (protease, amylase, lipase) in sea cucumbers ( Selenka) of three different sizes (initial body weights:15.13±0.02 g, 28.42±0.32 g, and 60.14±0.88 g) over a 14-day period. The results obtained were as follows. (1) With an increase in ammonia-N level, the survival and growth of sea cucumbers were significantly different from those in the control group. When the ammonia-N level was higher than 2 mg/L, the final body weight and specific growth rate of sea cucumbers show a marked downward trend with an increase in ammonia concentration. As the ammonia-N level increased to 8 and 10 mg/L, all sea cucumbers of the three different sizes appeared evisceration, with skin ulceration until death. When the ammonia-N level was 10 mg/L, the survival rate of medium-sized sea cucumbers reached 81.3%, the lowest among the three sizes. (2) When the ammonia-N level was lower than 10 mg/L, the effect of ammonia-N stress on the feeding rate of sea cucumbers of all three weights was not significant (>0.05), whereas the food conversion efficiency of all the experimental groups was significantly lower than that of the control group (<0.05). (3) There were significant differences in the digestive enzyme activities of the three-sized sea cucumbers under the stress of ammonia-N. With an increase in ammonia concentration, protease activities decreased. When the ammonia-N level was 8 mg/L and 10 mg/L, the protease activities of all the experimental groups were significantly lower than those in the control group (<0.05). With an increase in ammonia concentration, the activities of lipase and amylase initially increased and then decreased, peaking at 2 mg/L. When the ammonia-N level was 6 mg/L, the amylase activity of the small-sized sea cucumbers decreased to 0.30 U/mg protein, which was significantly different from the control group (<0.05). When the ammonia-N level was from 6 mg/L to 8 mg/L, the activity of lipase in the three-sized sea cucumbers was markedly affected, being significantly lower than that in the control group (<0.05). Under the same ammonia concentration, the activities of digestive enzymes in the medium-sized sea cucumbers were significantly higher than those in the other sizes. These results indicate that ammonia-N stress can affect the feeding and digestive enzyme activities of sea cucumbers. Therefore, in the process of sea cucumber breeding, particularly in large-scale seed culture, it is preferable to control the concentration of ammonia-N in the water environment to within 4 mg/L.

Abstract:Surveys were conducted in the Yichang section in the middle reaches of the Yangtze River from May to June in 2014 and 2015 to reveal the current status of the spawning grounds of fishes with pelagic eggs. A total of 12209 eggs was collected in the Yichang section and the eggs were identified by molecular biological methods. The eggs belonged to 27 species in 4 families in 2 orders. Among them, most were Cyprinidae (77%), followed by Cobitidae, accounting for 15%, and Homalopteridae and Salangidae had the least frequent, each at 4%. Of the 27 identified species, 22 were middle drifting fish eggs or 81% of all species. The total of pelagic eggs in the middle reaches of the Yangtze River was estimated to be 79.1×10⁸ individuals and 70.9×10⁸ individuals, and that of the four major Chinese carp species was 5.65×10⁸ individuals and 6.13×10⁸ individuals during 2014 and 2015, respectively. During the surveys, fishes had a total of seven spawning peaks. Spawning peaks occurred in late May and early June. A series of strong tendencies were found for the four major Chinese carp species regarding the amount of daily fish spawning and the daily flow rate. In 2014, the spawning grounds of the four major Chinese carp species was located in the Gezhouba, Yichang, and Baiyang reaches. The four major Chinese carp species were located in the Gezhouba and Yichang reaches in 2015. Compared with historical data, the range of the spawning grounds of the four major Chinese carp species moved downstream and the number of eggs displayed a decreasing tendency in recent years in the Yichang section in the middle reaches of the Yangtze River, where they have gradually decreased. It is suggested that scientific and suitable ecological reservoir reoperation and enhancement is needed, and fish release should be conducted to meet the demand of fish breeding in the middle reaches of the Yangtze River.

Abstract:To evaluate the relationship between the dynamic changes in the macrobenthic community and environmental factors in Jiaozhou Bay, macrobenthic samples were collected at 12 stations in the winter of 2016. A total of 66 species were identified in the survey area, including 32 species of Annelida, 17 species of Arthropoda, 9 species of Mollusca, 3 species of Echinodermata, 2 species of Chordata, and 1 species each of Nemertinea, Cephalochordata, and Hemichordata. There were 3 dominant species:Branchiostoma belcheri tsingtauense, the dominance of which were 0.02, 0.147, and 0.024, respectively. The average abundance of macrobenthos was 176.7 ind/m²; annelid abundance accounted for 46.01% of the total abundance, arthropod abundance accounted for 17.84% of the total abundance, mollusk abundance accounted for 6.57% of the total abundance, and the abundances of the other phyla accounted for 28.58% of the total abundance. The average biomass was 159.5 g/m² in the investigated waters; annelid biomass accounted for 6.42% of the total biomass, arthropod biomass accounted for 3.74% of the total biomass, mollusk biomass accounted for 76.56% of the total biomass, and the biomass of the other phyla accounted for 13.27% of the total biomass. The horizontal distribution of abundances showed that the abundance in the nearshore area of Jiaozhou Bay was the highest, followed by those of the area outside the bay and the offshore area of Jiaozhou Bay. The horizontal distribution of biomass showed that the biomass inside Jiaozhou Bay was higher than that outside the bay, in general. The value range of Shannon-Wiener index (') of macrobenthos in the investigated area was 1.19-3.54, with an average value of 2.65; the value range of Margalef's richness index () was 0.91-2.29, with an average value of 1.47; the value range of Pielou's evenness index () was 0.46-1.00, with an average value of 0.87. According to the result of CLUSTER analysis, macrobenthos in the survey area could be divided into 4 groups (S7 and S10 for Group I; S1, S2, S3, S4, S6, S8, S11, and S12 for Group Ⅱ; S5 for Group Ⅲ; and S9 for Group IV). The abundance/biomass curves showed that Group I ('=2.84) and Group Ⅲ ('=3.54) was not disturbed, which was consistent with the evaluation based on the Shannon-Wiener index (') values. BIOENV correlation analysis showed that the best combination that most affected the community structure of macrobenthos was depth + DOC + median diameter + Zn content, with a correlation coefficient () of 0.524. The macrobenthic community is unstable in Jiaozhou Bay owing to human activities, and needs long-term monitoring and evaluation.

Abstract:Fisheries-dependent or -independent data are often limited in fisheries stock assessment, particularly for cephalopod populations. Cephalopods are fast-growing and short-lived ecological opportunists, which contributes to the difficulty of swift data collection, as well as presenting the challenge of modeling fast and flexible population dynamics. Consequently, most cephalopod fisheries are currently managed using precautionary approaches without regular stock assessments, although multiple stock assessment models have been used to evaluate many of these stocks. Under these conditions, stock assessment with limited data becomes a problem that must be solved for the adaptive management and sustainable exploitation of cephalopods. is one of the most important economic cephalopods in the world and is mainly distributed in the southwest Atlantic Ocean. It is also one of the important species targeted by China's mainland and Taiwan squid jigging vessels. In this study, we applied a stochastic surplus production model in continuous time (SPiCT) to assess stocks of cephalopod species in data-limited situations, using stock in Argentina as a case study. SPiCT not only models the dynamics of the fisheries and biomass but also incorporates observation error of biomass indices and catches. The model was fitted to time series of catch and biomass index data during the years 2001 to 2010 under six different scenarios of parameterization. Parameter estimates and stock status from different scenarios were then compared to evaluate the impact of parameterization on fisheries stock assessment. Results showed that the optimal parameterization occurred in Scenario 3, which set the prior distributions of based on previous studies. Under this scenario, the stock was neither overfishing nor overfished in 2010, with lower fishing mortality than the fishing mortality under maximum surplus production and higher stock biomass than the stock biomass under maximum surplus production. The annual total catches were lower than the maximum surplus production. Compared with other continuous surplus production models (e.g., S, F-EDSP, and S-F-EDSP), SPiCT turns out to be more suitable for short-lived species in data-limited situations based on this study. In addition, the initialization of catchability coefficient ) estimation of SPiCT. Optimizing the parameterization of I. argentinus, which needs further investigation.

Abstract:In recent years, immunostimulants have become a new research field in aquaculture. -glucan is one of the most important immunostimulants, which can enhance the body's resistance to infection by improving the non-specific and cellular immunity of animals. The present study evaluated the effects of different dietary -glucan dosages (0, 0.05%, 0.1%, and 0.2%) on the anti-infection ability of rainbow trout () after 42 days of feeding. Thereafter, rainbow trout were infected with and sampled on the 2nd, 4th, and 6th days post-infection. Survival rates as well as the regulatory processes of serum stress-related factors were analyzed. Survival rates in the -glucan groups increased significantly compared with those in the control group after P<0.05). On the 4th day after infection, the serum total protein concentrations in all -glucan groups were significantly higher than those in the control group (<0.05). Serum malondialdehyde activity in the 0.1% and 0.2% groups reached a peak on the 2nd day post-infection, which was earlier than in the other infected groups. The activity of serum myeloperoxidase in the 0.1% and 0.2% groups increased significantly after infection, whereas in the 0.05% and control groups, it decreased significantly (-glucan groups after infection was significantly lower than that in the control group (-glucan groups increased more obviously than those in the control group (<0.05). On the 4th day after infection, the serum urea nitrogen concentration in all -glucan groups was markedly lower than that in the infected control group (<0.05). Total bilirubin (T-BIL) concentration decreased significantly after infection; however, T-BIL in the 0.2% group was clearly higher than that in the other groups. After infection, expression in the liver and spleen in all groups increased significantly. In the 0.1% and 0.2% groups, it reached a higher peak earlier than in the control group. Overall, the liver and head kidney in rainbow trout were damaged to a certain extent after infection with -glucan can effectively protect fish from damage caused by -glucan showing the best effect.

Abstract:Hemocyanin is an extracellular copper-containing protein present in the hemolymph of both mollusks and arthropods. Several studies have shown that hemocyanin could produce some fragments with antibacterial and antifungal activities. Interestingly, we recently found 12 chemically synthesized peptides, predicted by bioinformatics, derived from hemocyanin in the shrimp Vibrio parahaemolyticus and However, to date little is known about antifungal activities of these peptides. Here, by using the methods of chemical synthesis, antifungal experimentation, and microscopy, we attempted to determine the anti- activity of the 12 chemically synthesized peptides and the possible mechanism. Our results showed that six synthetic peptides (B2, B10, B13, B14, S7, and S9) exhibited obvious anti- activity at a concentration of 80 μg/mL, with the inhibition rate ranging from 30% to 100%. We selected B10 for further analysis, including the effect of concentration and shape of spores. Light microscopy and scanning electron microscopy analyses showed that the sporangium of grew more slowly under the action of B10 and the experimental groups treated for 30 h, 35 h, and 40 h had significantly reduced spore numbers (50%-90%); additionally, the sporangial morphology of the experimental groups was significantly smaller than that of the control group. Thus, it was preliminarily shown that six of the 12 chemically synthesized peptides from activities by inhibiting sporangium growth. This research is of significant value in explaining the immunological activity and functional mechanism of the fragments of shrimp hemocyanin.

Abstract:In order to study the immune responses and protective efficacy in Amur sturgeon (Aeromonas hydrophila to immunize healthy Amur sturgeon by peritoneal injection. We investigated the following immune parameters:peripheral blood cell count, differential leucocyte count, phagocytic activity and index, acid phosphatase activity, lysozyme activity, neutralizing antibody, and relative percentage survival. The numbers of erythrocytes and leucocytes in the peripheral blood of immunized fish increased rapidly and reached maximum values of (8.50 ±0.17)×10⁸/mL and (8.96 ±0.44)×10⁶/mL, respectively, at 4 d post-immunization. The percentages of monocytes and neutrophils reached maximum values of 10.50% and 15.53%, respectively, at 4 d post-immunization, and were very significantly higher than those of fish in the control groups ( < 0.01). However, lymphocyte percentage reached a maximum value of 73.51% at 21 d post-immunization. The phagocytic index and percentage of neutrophils were 4.53 and 30%, respectively, at 4 d post-immunization. The activities of lysozyme and acid phosphatase in serum reached peaks at 7 d and 14 d post-immunization, respectively. Neutralizing antibodies in the immunized fish reached 1:203 at 21 d post-immunization. When the immunized fish were challenged with live , the relative percentage survival of the immunized group was 76.84%. These results showed that the formalin-killed was able to elicit immune protection in Amur sturgeon, which lays the foundation for the further research on immunoprophylaxis against the diseases caused by infection in sturgeons.

Abstract:Cyprinid herpesvirus 3 (CyHV-3), also known as koi herpesvirus (KHV), is the etiologic agent of koi herpesvirus disease (KHVD) causing morbidity and mortality in common carp and koi L. populations around the world. Recently, knowledge about diagnosis and detection based on nucleic acid has been reported, but validation of serological techniques for virus infection is limited due to lack of effective antibodies. Additionally, fundamental research on the function of structural proteins from CyHV-3 is necessary to understand the relationship between host and virus. ORF136 is one of the predicted envelope proteins incorporated into mature virions. To study the function of proteins encoded by the gene of CyHV-3 and to establish serological methods for detection of CyHV-3, the predicted antigenic determinant based on amino acid sequences of proteins encoded by was amplified using PCR. Then, the recombinant prokaryotic expression vector was constructed by connecting the cloned fragment to prokaryotic expression vector pET-32a (+), used for transformation of Rosetta (DE3) and protein expressions induced by IPTG. New Zealand white rabbits were immunized with the recombinant proteins of pET-32a-ORF136 four times. Furthermore, the antiserums were collected and affinity purification was used to obtain polyclonal antibody after 66 days. Characterization of the polyclonal antibody against the ORF136 protein was further analyzed using western blot and indirect immunofluorescence assays. The expected product size of 381 bp was obtained and the recombinant prokaryotic expression vector pET-32a-ORF136 was confirmed to be constructed as expected using enzyme digestion. As SDS-PAGE analysis indicated that the molecular weight of recombinant protein pET-32a-ORF136 was consistent with the expected size (about 35 kD) and was distributed in the inclusions. Western blot analysis further showed that the purified polyclonal antibody could specifically recognize purified CyHV-3 virions and KS cells infected with CyHV-3. Moreover, immunofluorescence staining showed that specifically green fluorescence was present in the cytoplasm of KS cells infected with CyHV-3, but not in the negative control, further suggesting that CyHV-3 was recognized by the polyclonal antibody. The purified recombinant proteins and effective antibodies are necessary to develop serological methods to detect antigens, except nucleic acid detection method. The purified recombinant proteins could be used as antigens to capture antibodies against CyHV-3 from common carp or koi exposed to KHVD. Similarly, development of a double antibody sandwich ELISA for detection of CyHV-3 also requires an effective polyclonal antibody to capture antigens released from the host. Antibodies produced by recombinant proteins from rabbit or mouse provides the foundation for functional research into structural and nonstructural proteins. In this study, the polyclonal antibody against the ORF136 protein was prepared and analyzed using immunoblotting and immunofluorescence techniques, which provides an essential and valid tool for further research into CyHV-3.

Abstract:The Chinese giant salamander , a member of the family Cryptobranchidae, is the largest extant amphibian species in the world, which is valued for food, medicine, and research on animal evolution and biodiversity because of its unique phylogenetic position and physiological features. Within the last decade, Chinese giant salamander farming has increased rapidly in China. However, with the rapid development of Chinese giant salamander aquaculture, a severe epizootic recently occurred in cultured Chinese giant salamanders in Hubei, Hunan, Sichuan, Shannxi, and Zhejiang Provinces of China, causing tremendous economic losses. The causative pathogen has been identified as the giant salamander iridovirus (GSIV). At present, no effective methods are available for the control of the disease. Immunoprophylaxis is considered the best measure in controlling viral diseases in aquatic animals, and the large-scale cultivation technology of giant salamander cells and GSIV are of significance for the immunoprophylaxis of the disease. In this study, by using Cytodex 3 microcarriers to culture giant salamander muscle cells (GSM) and GSIV at a large scale, the GSM cell morphology, proliferative characterization, and GSIV growth dynamics were investigated. The results showed that the attachment efficacy reached 95% after 10 h of cultivation with intermittent agitation of 30 r/min for 2 min followed by 40 min still culture during the cell attachment period in the Cytodex 3 microcarrier culture system. The optimal culture conditions are as follows:serum concentration 5%, microcarrier concentration 2 g/L, and initial inoculation cell density of 1.2×10⁵ cells/mL. During the cell growth period, the continuous stirring speed was 25 r/min. Under inverted microscopy and electron microscopy, the GSM cells on the Cytodex 3 microcarriers were long, spindle-shaped, and well adhered. After infection with GSIV at a multiplicity of infection of 0.5, the GSM cells on Cytodex 3 microcarriers showed the typical cytopathic effect at 48 h post infection, and the highest virus titer (TCID₅₀/mL) of 10^-8.50±0.20/mL was reached at 72 h post infection. This study established a solid foundation for further investigation on the large-scale technologies of GSIV vaccine production in the future.

Abstract:In this study, the glycoprotein (G) gene of the infectious hematopoietic necrosis virus (IHNV) isolate XJ-13 was cloned and inserted into a commercial vector pcDNA3.1 (+) to construct a nucleic acid vaccine (pIHNxj-G). Rainbow trout (5±0.5) g were immunized using this vaccine via the base of the dorsal fin at a dose of 2 μg vaccine per fish. At 4 and 30 days post-vaccination (d.p.v.), the rainbow trout were challenged by IHNV-XJ-13 at a dose of 100 TCID₅₀ by intraperitoneal injection. Expression of the gene in the head kidney and muscle from the vaccine delivery site was detected by real-time PCR at 4 and 7 d.p.v., respectively. During the following 65 days, fecal matter, water, and intestinal contents of the rainbow trout were collected at different time points to identify ampicillin-resistant bacteria. The results of the challenge test showed that the relative protection rate of the nucleic acid vaccine was higher than 90% at 4 and 30 d.p.v. The results of gene was significantly up-regulated in the head kidney and muscle from the vaccine delivery site. Neutralizing antibody titers showed that there was no neutralizing antibody (titer<20) in any of the sera at 4 d.p.v. At 30 d.p.v., neutralizing antibodies were detected from 8 of 10 serum samples, and the highest titer was 160. The ampicillin-resistant bacteria isolated in this study mainly belonged to sp., which are naturally resistant to ampicillin. However, no indicator bacteria like were isolated, and there were no significant differences in the number or the species of the isolated ampicillin-resistant bacteria between the vaccination group and the control. This study not only provided an effective IHNV DNA vaccine, but also provided supportive data for the safety evaluation of the IHNV DNA vaccine.