Protein In Hepatopancreas Research Articles

Utilization of Cottonseed Meal Protein Hydrolysate by Crustaceans: Insights on Growth Performance, Protein Turnover, and Metabolism in Chinese Mitten Crab Eriocheir sinensis

Plant protein hydrolysates could enhance the growth performance and diet utilization of aquaculture species. The mechanisms underlying their beneficial effects, however, remain unclear. The purpose of this study was to appraise the effects of cottonseed meal protein hydrolysate (CPH) supplementation on the growth performance, amino acid profiles, and protein turnover and metabolism of Eriocheir sinensis. A total of 240 crabs (initial weight: 37.32 ± 0.38 g) were randomly assigned to six groups, and fed six iso-protein feeds supplemented with varying levels of 0% (the control group), 0.2%, 0.4%, 0.8%, 1.6% and 3.2% of CPH. These diets were continuously fed to the crabs for 12 weeks. The findings demonstrated that, compared with the control group, adding 0.4–0.8% CPH to the diet significantly increased the specific growth rate, nitrogen retention efficiency, hepatopancreas index, body crude protein content, hepatopancreas alanine aminotransferase and glutamine synthetase activities, hemolymph total protein content, the hepatopancreas transcription of S6 kinase-poly-peptide 1, and the hepatopancreas protein levels of insulin-like growth factor-1 (IGF-1), protein kinase B (Akt), and target of rapamycin (TOR) of crabs. In contrast, when the dose of dietary CPH reached 3.2%, the forkhead box O1 (FoxO1) protein expression showed a significant decrease compared with the control group. In addition, CPH supplementation also increased the amount of amino acids and free amino acids in hepatopancreas and hemolymph, respectively. Together, these findings demonstrated that dietary supplementation of 0.4–0.8% CPH could activate the IGF-1/Akt/TOR pathway of E. sinensis, thereby improving growth performance, protein synthesis, and utilization. For cost considerations, the recommended dietary dose of CPH for E. sinensis is 0.8%. Due to the above benefits, CPH has the potential to be used as a growth promoter for other aquatic animals, especially crustaceans.

Characterization of a Lipopolysaccharide- and Beta-1,3-Glucan Binding Protein (LGBP) from the Hepatopancreas of Freshwater Prawn, Macrobrachium rosenbergii, Possessing Lectin-Like Activity.

The study focuses on the isolation, characterization, and expression analysis of a lectin from the hepatopancreas of Macrobrachium rosenbergii. The protein was isolated by affinity chromatography on a melibiose-agarose column. The molecular weight of the native protein was found to be ~120kDa which consists of a single polypeptide of ~39.5kDa. On mass spectrometric analysis, the protein was identified as lipopolysaccharide- and beta-1,3-glucan binding protein (LGBP). LGBP showed hemagglutination with rabbit RBC like a lectin and its carbohydrate-binding specificity was determined by the hemagglutination inhibition test. The protein also showed antibacterial activity against two Gram-negative bacteria Vibrio harveyi and Aeromonas sobria, and one Gram positive bacteria Bacillus cereus in the disc diffusion test. Rabbit antiserum was raised against the purified LGBP and used to develop a sandwich ELISA system for quantitation of the protein in hepatopancreas and serum samples of M. rosenbergii. The expression of the LGBP transcripts in muscle, hepatopancreas, and gill tissues from M. rosenbergii juveniles at 72h post-challenge of V. harveyi was not modulated as noticed in qPCR analysis. However, significant increases in the concentrations of LGBP protein in hepatopancreas (5.23 ± 0.45 against 3.43 ± 0.43mg/g tissue in control) and serum (1.08 ± 0.14 against 0.61 ± 0.08µg/ml in control) were observed in the challenged group of prawns in ELISA suggesting its putative role against bacterial infections. The study for the first time characterized the native LGBP of M. rosenbergii showing a multifunctional role in immunity.

The role of energy reserves in common carp performance inferred from phenotypic and genetic parameters

In temperate zones, energy reserves of fish are closely related to survival during the first winter of their life. In this study, the genetic and phenotypic background of the accumulation, mobilization and utilization of energy reserves was investigated in Amur mirror carp. To achieve this, the role of traits related to energy reserves on fish performance during the first winter and further periods of rearing was investigated. The experimental stock was established by four full-factorial matings of 5 dams and 10 sires to generate up to 200 full-sibling families. The offspring were sampled before and after the first winter rearing period. Seasonal variation in direct and indirect measures of energy status was examined using Fulton's condition factor (FC), hepato-somatic index (HSI), visceral index (VSI_NO), glycogen, fat and protein in hepatopancreas (HP) and muscle fat content. Other performance traits were also recorded (weight, resistance to koi herpesvirus disease). All traits related to energy reserves, except HP protein, were significantly lower after the first winter. Overall, HP glycogen and fat from muscle, HP and viscera were mobilized during winter. However, genetic correlations between same traits recorded in autumn and spring were lower than 0.8 for most of the traits, implying that not all families responded to overwintering in a similar manner. Heritability also differed before and after the first winter. Before the first winter, all traits had low to medium heritability (0.05–0.35), but after the winter the same traits were moderately or highly heritable (0.22–0.58). Interestingly, HP glycogen traits, unlike HP fat and HP protein, and HSI recorded in yearlings were positively genetically correlated with survival during the third growing season (rg = 0.49–0.72). This study provides the first evidence of a genetically based strategy for energy mobilization related to overwintering of common carp. Measuring of FC and HSI could be used to monitor the energy status of common carp and to provide a supplementary tool for management of carp stocks.

Large lipid transfer proteins in hepatopancreas of the mud crab Scylla paramamosain

Large lipid transfer proteins (LLTPs) are extensively involved in various physiological processes. In the present study, five LLTP sequences encoding apolipocrustacein 1 (apoCr 1), apoCr 2, precursor of the large discoidal lipoprotein (dLp) and high density lipoprotein/β-glucan binding protein (HDL-BGBP) (dLp-BGBP), microsomal triglyceride transfer protein (MTP) and clotting protein (CP) were identified in the hepatopancreas of Scylla paramamosain. Of these, apoCr 2, dLp-BGBP, and MTP were newly identified in this species, and the former two proteins were classified into the APO family while the later into the MTP family in phylogenetic trees. The apoCr 1 expression level was dramatically increased in the hepatopancreas towards ovarian maturation, which was extremely greater than that in the ovaries concurrently, likely to meet the considerable requirements of yolk protein and lipids for embryo development. The dLp-BGBP expression level in male crabs was comparable to that in female crabs, supporting HDL-BGBP acts as a major circulatory lipid carrier. The close phylogenetic relationship between dLp-BGBP and the scaffolding protein of lipid transfer particle implied dLp might facilitate lipid transfer between the hepatopancreas and HDL-BGBP-containing lipoproteins. The MTP expression level was positively related to ovarian development in both the hepatopancreas and ovaries, indicating MTP may be involved in lipoprotein assembly in the hepatopancreas and lipid droplet maturation in the ovaries. CP may play a crucial role in embryo development based on high expression level observed in the testes of mature crabs. Our findings provide novel insights into LLTP superfamily members and their functions in decapods.

Proteomic response of Macrobrachium rosenbergii hepatopancreas exposed to chlordecone: Identification of endocrine disruption biomarkers?

The present work is the first study investigating the impacts of chlordecone, an organochlorine insecticide, on the proteome of the decapod crustacean Macrobrachium rosenbergii, by gel-free proteomic analysis. The hepatopancreas protein expression variations were analysed in organisms exposed to three environmental relevant concentrations of chlordecone (i.e. 0.2, 2 and 20µg/L). Results revealed that 62 proteins were significantly up- or down-regulated in exposed prawns compared to controls. Most of these proteins are involved in important physiological processes such as ion transport, defense mechanisms and immune system, cytoskeleton dynamics, or protein synthesis and degradation. Moreover, it appears that 6% of the deregulated protein are involved in the endocrine system and in the hormonal control of reproduction or development processes of M. rosenbergii (e.g. vitellogenin, farnesoic acid o-methyltransferase). These results indicate that chlordecone is potentially an endocrine disruptor compound for decapods, as already observed in vertebrates. These protein modifications could lead to disruptions of M. rosenbergii growth and reproduction, and therefore of the fitness population on the long-term. Besides, these disrupted proteins could be suggested as biomarkers of exposure for endocrine disruptions in invertebrates. However, further investigations are needed to complete understanding of action mechanisms of chlordecone on proteome and endocrine system of crustaceans.

Effects of dietary curcumin supplementation on growth performance, intestinal digestive enzyme activities and antioxidant capacity of crucian carp Carassius auratus

A 105-day feeding trial was carried out to investigate the effects of dietary curcumin (CM) supplementation on growth performance, digestive enzyme activities, and intestinal antioxidant capacity of crucian carp (Carassius auratus). A total of 585 crucian carp with average initial weight of 76.3±0.10g were fed three diets supplemented with 0 (basal group), 1, or 5gkg−1 CM. Fish fed the diet supplemented with 5gkg−1 CM showed significantly higher final body weight (FW), percent weight gain (PWG), and feed efficiency (FE) compares to those fed the basal or 1gkg−1 CM diet (P<0.05). Feed intake and body composition were not significantly different among dietary groups (P>0.05). The hepatopancreas weight, hepatopancreas protein content, intestinal weight, intestinal somatic index, intestine protein content, trypsin and lipase activities in hepatopancreas and intestine, amylase activity in hepatopancreas, Na+, K+-ATPase (NKA), alkaline phosphatase (AKP), gamma-glutamyl transpeptidase (γ-GT), and creatine kinase (CK) activities in intestine were significantly increased with dietary CM supplementation at 5gkg−1 (P<0.05). Fish fed the 5gkg−1 CM diet showed significantly lower malondialdehyde and protein carbonyl contents in the intestine (P<0.05). Superoxide anion and hydroxy radical scavenging ability, glutathione reducase (GR), catalase (CAT), total superoxide dismutase (T-SOD), glutathione peroxidase (GPx), and glutathione-S-transferase (GST) activities, and glutathione (GSH) content in the intestine were significantly increased with increased CM. The relative mRNA expressions of trypsin, lipase, NKA, AKP, γ-GT, CK, SOD1, CAT, GPx, GST, and GR in intestine were significantly up-regulated by dietary CM supplementation at 5gkg−1. These results suggested that dietary CM supplementation increased intestinal antioxidant capacity, digestive and absorptive ability, and promoted fish growth.

Live holding of Nephrops norvegicus (Linnaeus, 1758) in land-based facilities: Health and condition effects

Recent advances in the knowledge of the basic requirements to sustain captured lobsters, combined with improved transport links, has seen a dramatic expansion in the sale of live Nephrops norvegicus. In this paper, we describe the effects of storage system type on the health of lobsters held for periods up to three weeks in order to develop an optimal protocol for Icelandic producers for whom logistical challenges have thus far hindered access to the live market. Nephrops were caught by creel and transported to a holding facility in tanks supplied by either a flow-through from a harbour bore or recirculating water via a filtration system, where they were maintained without being fed for a period of three weeks. During this time, lobsters were assessed for haemolymph biochemistry and hepatopancreas composition and health. It was found that lobsters from both systems used storage reserves from the hepatopancreas, showing a progressive decline in hepatopancreatic index, hepatopancreas protein and glycogen. Nephrops from the flow-through system also presented indications of considerable health impacts with chronically elevated levels of circulating haemocytes during storage and granuloma plus melanized hepatopancreas tubules after three weeks.

Comparison of Protein Expression Profiles of the Hepatopancreas in Fenneropenaeus chinensis Challenged with Heat-inactivated Vibrio anguillarum and White Spot Syndrome Virus

Fenneropenaeus chinensis (Chinese shrimp) culture industry, like other Penaeidae culture, has been seriously affected by the shrimp diseases caused by bacteria and virus. To better understand the mechanism of immune response of shrimp to different pathogens, proteome research approach was utilized in this study. Firstly, the soluble hepatopancreas protein samples in adult Chinese shrimp among control, heat-inactivated Vibrio-challenged and white spot syndrome virus-infected groups were separated by 2-DE (pH range, 4-7; sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and pH range, 3-10; tricine-SDS-PAGE). Then the differentially expressed protein spots (≥1.5-fold or ≤0.67-fold averagely of controls) were analyzed by LC-ESI-MS/MS. Using Mascot online database searching algorithm and SEQUEST searching program, 48 and 49 differentially expressed protein spots were successfully identified in response to Vibrio and white spot syndrome virus infection, respectively. Based on these results, we discussed the mechanism of immune response of the shrimp and shed light on the differences between immune response of shrimp toward Vibrio and white spot syndrome virus. This study also set a basis for further analyses of some key genes in immune response of Chinese shrimp.

Expression profiles and localization of vitellogenin mRNA and protein during ovarian development of the giant tiger shrimp Penaeus monodon

Ovarian maturation of the giant tiger shrimp (Penaeus monodon) results from rapid synthesis and accumulation of a major yolk protein, vitellin which is derived from its precursor, vitellogenin. The expression profiles and localization of P. monodon vitellogenin 1 (PmVtg1) were examined. PmVtg1 mRNA was expressed only in ovaries and hepatopancreas but not in other tissues of female and testes of male broodstock. In wild intact broodstock, PmVtg1 mRNA was expressed at a low level in stage I ovaries and up-regulated in stages II and III being significantly reduced in stage IV ovaries (P<0.05). In eyestalk-ablated broodstock, the expression level of PmVtg1 mRNA was increased to nearly a peak level in vitellogenic (stage II) ovaries and peaked in cortical rod (stage III) ovaries (P<0.05). The level of PmVtg1 mRNA in hepatopancreas of intact shrimp with stages II and III ovaries was significantly greater than those with stages IV and V (post-spawning) ovaries. Interestingly, PmVtg1 mRNA in hepatopancreas was 25–40 times higher than that in ovaries of intact shrimp with stages I–III of ovarian development. In situ hybridization revealed that PmVtg1 mRNA was clearly localized in the cytoplasm of follicular cells surrounding late previtellogenic, vitellogenic and cortical rod oocytes. Quantitative real-time PCR against different periods of spawned eggs suggested that PmVtg1 mRNA was also synthesized in oocytes. Western blot analysis revealed a similar profile of ovarian P. monodon vitellin and PmVtg1 mRNA during ovarian development and also suggested that the Vtg protein in hepatopancreas and Pm-vitellin in ovaries should have encoded from different Vtg genes. Immunohistochemistry confirmed that Pm-vitellin was localized in developing, vitellogenic and mature oocytes but not in the follicular cells.

Affinity of Heavy Metal Cations to a Protein in Hepatopancreas of Scallop

In this work, we obtained a protein that passed through an ultrafiltration membrane of 100 kDa and was retained on that of 30 kDa from the hepatopancreas of scallop. We measured the molecular weight of the protein by MALDI-TOF-MS, and evaluated the affinity of metal cations to it. The molecular weight of the protein was found to be around 20 kDa, despite the fact that the proteins were retained on a 30-kDa ultrafiltration membrane. Consequently, we poured a portion of EDTA solution onto the ultrafiltration membrane holding the protein. As a result, it passed through the 30-kDa ultrafiltration membrane. This implies that the protein may be dissociated by removing metal cations. Next, we studied the affinity of Cd2+, Cu2+, Ni2+, and Pb2+ to the protein immobilized on Sepharose (p-Sepharose). Adsorption isotherms were prepared to obtain the adsorption capacity and the adsorption constant by employing the Langmuir model. The order of the adsorption capacity was Cu2+ > Ni2+ > Cd2+ ≒ Pb2+. The mole ratios of metal cations to protein were 0.24 for Cd2+, 2.00 for Cu2+, 0.37 for Ni2+, and 0.24 for Pb2+. Mole ratios less than 1 support a hypothesis derived from MS measurements, that the proteins may associate with each other via metal cations. The order of the adsorption constant was Cu2+ > Cd2+ > Ni2+ > Pb2+. The Cd2+, which has a large ionic radius, has a low adsorption capacity, but does have the second largest adsorption constant. We confirmed a strong affinity of heavy metal cations to the protein in hepatopancreas of scallop.

Effects of formulated dietary replacement of trash fish on growth performance,body composition and fatty acid composition of Eriocheir sinensis

Effects of replacement of trash fish with formulated diets on growth performance,body composition and fatty acid composition of Chinese mitten crab(Eriocheir sinensis)were investigated in this study.The culture tests were carried out at Chongming County,Shanghai,which lasted 240 days,from March to November.The survival and weight gain of each treatment were counted after breeding.Random sampling and then the hepatopancreas index(HSI),gonad index(GSI),meat percentage,body composition and fatty acid composition of each tissue of both male and female crab were determined.The result indicated that the formulated diets treatment had no significant influence on trash fish treatment in survival,weight gain,HSI,GSI and meat percentage(P0.05).The moisture content in hepatopancreas of female and male crab of trash fish treatment were significantly higher than the formulated diets treatment(P0.01),and the moisture content in meat of male crab of trash fish treatment was significantly higher than that of formulated diets treatment(P0.01).Total lipid in hepatopancreas and gonad of female and male crab of trash fish group were significantly lower than that of formulated diets(P0.05),and total lipid in meat of female crab of trash fish was significantly lower than that of formulated diets(P0.05).Crude protein in hepatopancreas of female and male crab of trash fish was significantly higher than that of formulated diets(P0.05),while crude protein in ovary of female crab of trash fish was significantly lower than that of formulated diets(P0.05).Free fatty acid(FAA)in hepatopancreas of female of formulated diets treatment was significantly higher than trash fish treatment(P0.05),and phospholipids(PL)content in hepatopancreas of female of trash fish treatment was significantly higher than formulated diets treatment(P0.05).Triglycerides(TG)in both ovary and muscle of female of formulated diets treatment were significantly higher than trash fish treatment(P0.05 or P0.01),while FAA and PL contents of female of trash fish treatment were significantly higher than formulated diets treatment in ovary and muscle(P0.05 or P0.01).Cholesterol(CHO)in muscle of female of trash fish treatment was significantly higher than formulated diets treatment(P0.01).There were no significantly differences in hepatopancreas of two treatments(P0.05).FAA and TG in testis of trash fish treatment were significantly higher than formulated diets treatment(P0.01),while PL in testis of trash fish treatment was significantly lower than formulated diets treatment(P0.05).CHO in muscle of male of formulated diets treatment was significantly lower than trash fish treatment(P0.01).Linolic acid(C18∶ 2n-6)in hepatopancreas and meat of male crab of trash fish were significantly lower than that of compound feed(P0.01 or P0.05),while ARA(C20∶ 4n-6)in meat of trash fish was significantly higher than that of compound feed(P0.05).Linolenic acid(C18∶ 3n-3),DHA(C22∶ 6n-3)and ARA in ovary of female crab of trash fish were significantly lower than those of compound feed(P0.01 or P0.05).The results obtained from the present study indicated that suitable compound feed replacement of trash fish had no significant influence on growth and development of crab,while body composition and fatty acid composition of crab changed with different feeds.

Effect of dietary arginine on growth, intestinal enzyme activities and gene expression in muscle, hepatopancreas and intestine of juvenile Jian carp (Cyprinus carpiovar. Jian)

The present study was conducted to test the hypothesis that dietary arginine promotes digestion and absorption capacity, and, thus, enhances fish growth. This improvement might be related to the target of rapamycin (TOR) and eIF4E-binding protein (4E-BP). A total of 1200 juvenile Jian carp, Cyprinus carpio var. Jian, with an average initial weight of 6.33 (SE 0.03) g, were fed with diets containing graded concentrations of arginine, namely, 9.8 (control), 12.7, 16.1, 18.5, 21.9 and 24.5 g arginine/kg diet for 9 weeks. An real-time quantitative PCR analysis was performed to determine the relative expression of TOR and 4E-BP in fish muscle, hepatopancreas and intestine. Dietary arginine increased (P < 0.05): (1) glutamate-oxaloacetate transaminase and glutamate-pyruvate transaminase activities in muscle and hepatopancreas; (2) intestine and hepatopancreas protein content, folds height, and trypsin, chymotrypsin, lipase, Na⁺/K⁺-ATPase, alkaline phosphatase, γ-glutamyl transpeptidase and creatine kinase activities in intestine; (3) Lactobacillus counts; (4) relative expression of TOR in the muscle, hepatopancreas and distal intestine (DI); (5) relative expression of 4E-BP in proximal intestine (PI) and mid-intestine (MI), as compared with the control group. In contrast, dietary arginine reduced (P < 0.05): (1) plasma ammonia content; (2) Aeromonas hydrophila and Escherichia coli counts; (3) relative expression of TOR in PI and MI; (4) relative expression of 4E-BP in the muscle, hepatopancreas and DI. The arginine requirement estimated by specific growth rate using quadratic regression analysis was found to be 18.0 g/kg diet. These results indicate that arginine improved fish growth, digestive and absorptive ability and regulated the expression of TOR and 4E-BP genes.

Protein synthesis in wild-caught Norway lobster ( Nephrops norvegicus L.)

Although protein metabolism has been studied in fish and other crustaceans, this is the first study to measure protein synthesis rates for Norway lobster Nephrops norvegicus. This research aimed to assess the nutritional status of wild caught Nephrops by measuring tissue rates of protein synthesis and comparing these with rates from fed and starved Nephrops maintained in aquaria. Rates of protein synthesis were measured in the hepatopancreas, gill and tail muscle tissue. A time-course validated the use of a flooding-dose of 3H phenylalanine to measure protein synthesis in Nephrops and showed that the flooding-dose method is suitable for the study of protein turnover in Nephrops. The relationship between the measured rate of protein synthesis and capacity for protein synthesis (Cs) showed differences between tissues and between nutritional history. Measures of protein metabolism were generally higher in hepatopancreas, then gill and then tail muscle and generally lower in starved animals. Although individual variation meant there were few significant differences in tail muscle values between treatments, RNA concentration was higher in wild-caught than starved and suggested they were not starving. This was supported by hepatopancreas protein synthesis in wild-caught being intermediate between fed and starved, indicating relatively recent feeding had increased hepatopancreas protein synthesis due to increased RNA activity at constant RNA capacity. This study will add to our current but limited understanding of the effects of environmental variations on nutritional status and on protein metabolism and deposition in Nephrops species. Knowledge of the mechanisms enabling their survival is required to understand their ability to adapt to environmental variables.

Effect of dietary choline on growth, intestinal enzyme activities and relative expressions of target of rapamycin and eIF4E-binding protein2 gene in muscle, hepatopancreas and intestine of juvenile Jian carp ( Cyprinus carpio var. Jian)

The effects of dietary choline on growth, digestive and absorptive capacities, and target of rapamycin (TOR) and eIF4E-binding protein2 (4E-BP2) gene expression in muscle, hepatopancreas and intestine of juvenile Jian carp ( Cyprinus carpio var. Jian) were assessed. A total of 1200 juvenile Jian carp with an average initial weight of 7.94 ± 0.03 g were fed six semi-purified diets containing 165 (unsupplemented control group), 310, 607, 896, 1167 and 1820 mg choline kg − 1 diet for 65 days. Specific growth rate (SGR), feed intake, feed efficiency, protein retention value, protein content and lipid content of fish carcasses were significantly improved by dietary choline supplementation; whereas, protein efficiency ratio and body ash content were not significantly different among dietary groups. Patterns of differences in intestine length, relative gut length, intestine weight, hepatopancreas protein content, intestinal folds height in three intestinal segments, trypsin and chymotrypsin activities in intestine and hepatopancreas, α-amylase and creatine kinase activities in intestine, Na +/K +-ATPase activity in distal intestine and relative expression of TOR gene in distal intestine and 4E-BP2 gene in muscle responded similar to SGR; whereas, the trends of hepatosomatic index, lipase activity in intestine and hepatopancreas, Na +/K +-ATPase activity in proximal intestine and mid intestine, TOR gene expression in muscle and hepatopancreas, and 4E-BP2 gene expression in proximal intestine, mid intestine and distal intestine were opposite. Alkaline phosphatase and γ-glutamyl transpeptidase activities in intestinal segments were not significantly different among dietary groups. These results indicated that dietary choline could improve fish growth, enhance digestive and absorptive ability and regulate TOR and 4E-BP2 gene expression in tissues. The dietary choline requirement of Jian carp estimated by the broken-line model based on SGR was 566 mg choline kg − 1 diet in the form of choline chloride.

Effects of dietary zinc on gene expression of antioxidant enzymes and heat shock proteins in hepatopancreas of abalone Haliotis discus hannai

The expression patterns of different genes encoding antioxidant enzymes and heat shock proteins were investigated, in present study, by real-time quantitative PCR in the hepatopancreas of abalone Haliotis discus hannai fed with different levels of dietary zinc (6.69, 33.8, 710.6 and 3462.5 mg/kg) for 20 weeks. The antioxidant enzymes include Cu/Zn-superoxide dismutase (Cu/Zn-SOD), Mn-superoxide dismutase (Mn-SOD), catalase (CAT), mu-glutathione-s-transferase (mu-GST) and thioredoxin peroxidase (TPx). The results showed that the mRNA expression of these antioxidant enzymes increased and reached the maximum at the dietary zinc level of 33.8 mg/kg, and then dropped progressively. Expression levels of the heat shock proteins (HSP26, HSP70 and HSP90) firstly increased at 33.8 mg/kg dietary Zn level, and reached to the maximum at 710.6 mg/kg, then dropped at 3462.5 mg/kg ( p < 0.05). Excessive dietary Zn (710.6 and 3462.5 mg/kg) significantly increases the Zn content and significantly decreases the total antioxidant capacity (T-AOC) in hepatopancreas (p < 0.05). These findings showed that dietary Zn (33.8 mg/kg) could highly trigger the expression levels of antioxidant enzymes and heat shock proteins, but excessive dietary Zn (710.6 and 3462.5 mg/kg) induces a high oxidative stress in abalone.

Effects of dietary methionine hydroxy analogue supplement on growth, protein deposition and intestinal enzymes activities of juvenile Jian carp (Cyprinus carpio var. Jian)

A total of 900 juvenile Jian carp (Cyprinus carpio var. Jian) (8.24 ± 0.03 g) were fed practical diets containing graded levels of methionine hydroxy analogue (MHA) (0, 5.1, 7.6, 10.2, 12.7 and 15.3 g kg⁻¹ diet) for 60 days to investigate the effects of MHA on growth, protein deposition and intestinal enzymes activities. Per cent weight gain (PWG) significantly increased with increasing levels of MHA up to a point (P < 0.05), and thereafter declined. Feed efficiency was the highest when MHA level was at 5.1 g kg⁻¹ diet. Feed intake (FI) significantly enhanced with dietary MHA level up to a point (P < 0.05), beyond which it plateaued. Patterns of differences in protein production value, lipid production value, intestosomatic index, folds height, lipase, chymotrypsin, γ-glutamyl transpeptidase, Na⁺, K⁺-ATPase, creatinekinase, glutamate-oxaloacetate transaminase and glutamate-pyruvate transaminase activities were the same as that in PWG, whereas the trend of plasma ammonia content was opposite. Hepatopancreas protein content, trypsin and amylase activities followed the same trend as that of FI. The optimal supplemental level of MHA for fish meal and miscellaneous meals-based diet (6.9 g methionine kg⁻¹ diet) for PWG was 8.2 g kg⁻¹ diet by the quadratic regression analysis.

Growth, body composition and intestinal enzyme activities of juvenile Jian carp (Cyprinus carpio var. Jian) fed graded levels of dietary zinc

A 6-week trial was carried out with 900 juvenile Jian carp (Cyprinus carpio var. Jian) to investigate the effects of dietary zinc on growth, body composition and intestinal enzyme activities. Diets supplemented with increasing levels (15.3, 26.9, 40.8, 58.2, 68.9 and 92.5 mg Zn kg−1) of zinc lactate were fed to Jian carp (mean initial weight 15.7 ± 0.01 g). Results indicated that per cent weight gain (PWG), feed efficiency (FE), protein efficiency ratio (PER) and lipid productive value (LPV) enhanced with dietary zinc levels up to 40.8 mg kg−1 diet (P < 0.05), and plateaued thereafter (P > 0.05). Feed intake (FI) was similar to that observed for PWG. Intestosomatic index (ISI), relative gut length (RGL), hepatopancreas protein content (HPC), intestine protein content (IPC), trypsin, chymotrypsin, lipase, amylase, alkaline phosphatase (AKP), Na+, K+-ATPase and γ-glutamyl transpeptidase (γ-GT) activities were all higher by dietary zinc supplementation than zinc un-supplementation (P < 0.05). These results suggested that zinc could promote growth and increase nutrient deposition and intestinal enzyme activities. The dietary zinc requirements (use zinc lactate as zinc source) of juvenile Jian carp (15.7–42.2 g) based on PWG and serum zinc were 48.7 and 43.2 mg Zn kg−1 diet, respectively.

A thioredoxin response to the WSSV challenge on the Chinese white shrimp, Fenneropenaeus chinensis

Thioredoxin (TRX) is involved in cell redox homeostasis. In addition, it is responsible for maintaining proteins in their reduced state. In our study, a Fenneropenaeus chinensis thioredoxin ( FcTRX) gene was identified from the Chinese white shrimp. The full length of FcTRX was 777 bp, including a 60 bp 5′ untranslated region (UTR), a 318 bp open reading frame (ORF) encoding a 105 amino acids protein, and a 399 bp 3′ UTR. FcTRX contained a TRX domain with a conserved motif of Cys-Gly-Pro-Cys (CGPC). No signal peptide was predicted by SMART analysis. The molecular mass and pI of FcTRX were 12 kDa and 4.62, respectively. FcTRX is a widely distributed gene, and its mRNA is detected in hemocytes, hearts, hepatopancreas, gills, stomach, and intestine from an unchallenged shrimp. The expression level of FcTRX was the highest in hepatopancreas, where it was down-regulated to the lowest level at 12 h white spot syndrome virus (WSSV) challenge. In the gills, it went up to the highest level at 6 h. Western blot showed that FcTRX protein in hepatopancreas challenged with WSSV was down-regulated from 2 h to 12 h and then restored to the level similar to that of unchallenged shrimp at 24 h. In the gills challenged with WSSV, the FcTRX protein was up-regulated from 6 h to 24 h. Our research indicated its possible role in the anti-WSSV innate immunity of shrimps.

Effect of dietary pantothenic acid supplement on growth, body composition and intestinal enzyme activities of juvenile Jian carp (Cyprinus carpiovar. Jian)

A 9-week feeding trial was carried out with juvenile Jian carp to study the effect of dietary pantothenic acid (PA) on growth, body composition and intestinal enzyme activities. Semi-purified diets with seven levels (4.0, 15.5, 25.6, 36.1, 45.9, 56.1 and 65.9 mg PA kg−1) of supplemental calcium d-pantothenate were fed to Jian carp (13.0 ± 0.0 g). PA improved specific growth rate (SGR), protein productive value (PPV), protein efficiency ratio (PER) and lipid production value (LPV) (P < 0.05). Fish fed the control diet had significantly lower feed efficiency (FE) than that in any other group (P < 0.05). Body protein content increased with increasing PA levels (P < 0.05), but moisture, lipid and ash of fish carcasses were negatively related to the graded PA levels (P < 0.05). Intestine protein content (IPC), hepatopancreas protein content (HPC) and activity of α-amylase, lipase, trypsin, Na+,K+-ATPase, alkaline phosphatase (AKP) and gamma-glutamyl transpeptidase (γ-GT) were all positively affected by the dietary PA levels (P < 0.05), while intestine index (ISI) and hepatopancreas index (HSI) decreased with the increment of supplemental levels of PA (P < 0.05). These results suggested that PA could enhance fish growth and intestinal enzyme activities. The dietary PA requirement of juvenile Jian carp, Cyprinus carpio var. Jian (13.0–73.0 g), for optimal growth estimated by the broken-line analysis was 23.0 mg PA kg−1 diet.

Effects of cadmium on cellular protein and glutathione synthesis and expression of stress proteins in eastern oysters, Crassostrea virginica Gmelin

Cadmium (Cd) is an important toxicant in estuarine and coastal environments that can strongly affect energy balance of aquatic organisms by increasing the organism's basal energy demand and reducing its aerobic capacity. Mechanisms of cadmium-induced increase in basal metabolic costs are not well understood and may involve elevated detoxification costs due to the synthesis of cellular protective proteins and glutathione. We studied the short-term effects of cadmium exposure (4 h) on protein and glutathione (GSH) synthesis and expression of stress proteins (heat shock proteins HSP60, HSP70 and HSP90) and metallothioneins in isolated gill and hepatopancreas cells of the eastern oyster, Crassostrea virginica. Our study showed that exposure to cadmium resulted in a dose-dependent increase in the rate of protein synthesis in oyster cells, which reached 150% of the control at the highest tested Cd level (2000 micromol l(-1)). GSH synthesis was significantly inhibited by the highest Cd concentrations, especially in hepatopancreas, which resulted in a slight but significant decrease in the total GSH concentrations. Elevated protein synthesis was associated with the increased expression of metallothioneins and heat shock proteins. Interestingly, stress protein response differed considerably between gill and hepatopancreas cells. In hepatopancreas, expression of metallothionein mRNA (measured by real-time PCR) increased 2-8-fold in response to Cd exposure, whereas no significant increase in metallothionein expression was found in Cd-exposed gill cells. By contrast, HSP60 and HSP70 protein levels increased significantly in Cd-exposed gill cells (by 1.5-2-fold) but not in hepatopancreas. No change in HSP90 expression was detected in response to Cd exposure in oyster cells. These data indicate that metallothionein expression may provide sufficient protection against Cd-induced damage to intracellular proteins in hepatopancreas, alleviating the need for overexpression of molecular chaperones. By contrast, Cd detoxification mechanisms such as inducible metallothioneins and GSH appear to be insufficient to fully prevent protein damage in gill cells, thus necessitating induction of HSPs as a secondary line of cellular defense. Therefore, gills are likely to be among the most Cd-sensitive tissues in oysters, which may have important implications for impaired oxygen uptake contributing to energy misbalance and reduced aerobic scope in Cd-exposed oysters.