Molecular cloning of fatty acid synthase from grass carp (Ctenopharyngodon idella) and the regulation of its expression by dietary fat level

The fatty acid synthase (FAS) gene was cloned from liver of grass carp (Ctenopharyngodon idella) by degenerate oligonucleotide primed PCR. The obtained cDNA fragment was 683 bp, which encoded 227 amino acids. Then, grass carps with initial body weight of (134.89 ± 12.12) g were fed diet supplemented with 0, 20, 40 g kg^?1 fat to investigate the impacts of dietary fat levels on growth, liver FAS enzyme activity and mRNA expression. After 8 weeks feeding, final body weights of the three groups were 344.11, 347.23 and 373.02 g. Compared with control group (0 g kg^?1), growth rate of 40 g kg^?1 fat group was increased by 14.03%, and feed conversion rate decreased by 11.32% (P < 0.05), liver FAS enzyme activity of 20, 40 g kg^?1 fat groups were reduced by 33%, 64% (P < 0.05), and FAS mRNA expression level reduced by 18%, 74% (P < 0.05), respectively. Results above showed that 40 g kg^?1 fat addition can significantly improve growth performance of grass carp. Liver FAS activity and mRNA expression tended to be inhibited by the increasing dietary fat level. Fat containing high levels of polyunsaturated fatty acids had strongly inhibitory effects on liver FAS activity and gene expression.     

Effect of dietary lipid level on growth, feed utilization and body composition by juvenile grass carp (Ctenopharyngodon idella)

A study was undertaken to determine the effect of dietary lipid level on growth, feed efficiency and body chemical composition of juvenile grass carp. Seven isonitrogenous diets (400 g kg^?1 crude protein) containing seven dietary lipid level (0, 20, 40, 60, 80, 100 and 120 g kg^?1 dry matter) were fed to triplicate groups of 40 fish with initial weight 6.52 g, for 70 days. No obvious and assured essential fatty acid deficiency symptom appeared in fish fed the lipid‐free diet. Excess dietary lipid level (100 and 120 g kg^?1) resulted in decreased feed intake. The best growth performance and feed utilization was observed in fish fed 20–40 g kg^?1 dietary lipid. The fish fed a lipid‐free diet had the lowest protein efficiency and protein retention. Growth performance and feed utilization increased with the increasing dietary lipid levels up to 40 g kg^?1 dietary lipid. Higher dietary level (above 40 g kg^?1) made growth performance and feed utilization decrease and no protein sparing effect was observed. Lipid retention decreased as dietary lipid level increased. Mesenteric fat index (MFI) increased, hepatosomatic index (HSI) decreased with dietary lipid level. The increased MFI and simultaneous decrease lipid retention can be explained by differences in growth. The effect of dietary lipid levels on the chemical composition of tissues was significant only for whole body and muscle. The excess lipid content of liver in all groups was regarded as a slight symptom of fatty liver, which was partly identified by microscopic structural study and lower plasma lipid indexes, comparing to the initial plasma data. In conclusion, grass carp is a fish with low energy requirement and excess dietary lipid level should be avoided.     

Effects of dietary non‐protein energy source levels on growth performance,body composition and lipid metabolism in herbivorous grass carp (Ctenopharyngodon idella Val.)

A study was conducted to determine the effects of dietary non‐protein energy sources on growth, tissue lipid accumulation and lipid metabolism‐related genes expression of grass carp. Triplicate groups of fish were fed for 9 weeks on four isonitrogenous (300 g kg^?1) experimental diets with four levels of non‐protein energy (6.52 kJ g^?1 control diet, 5.32 kJ g^?1 high‐CEL diet, 8.46 kJ g^?1 high‐CHO diet and 8.53 kJ g^?1 high‐LIP diet respectively). Increasing dietary non‐protein energy source levels did not improve the growth, and the high‐CEL diet reduced the growth of grass carp. The high‐CHO diet tended to induce high hepatosomatic index, with high fat and glycogen content of liver. However, the high‐LIP diet caused the high mesenteric fat index, but did not increase liver fat. The mRNA abundance and activities of hepatic lipogenic enzymes were significantly increased in the high‐CHO diet group, whereas the opposite tendencies were observed in the high‐LIP diet group. Peroxisome proliferator‐actived receptor‐α (PPARα) in liver and PPARγ in mesenteric adipose tissue were up‐regulated in the high‐CEL diet group. Lipoprotein lipase (LPL) gene expression was significantly increased both in liver and mesenteric adipose tissue of fish fed the high‐LIP diet, while the LPL gene expression was up‐regulated in liver but down‐regulated in mesenteric adipose tissue of fish fed the high‐CEL diet. These findings suggest that an increase in dietary non‐protein energy sources alters the genes expression of lipid metabolism and increased lipid deposition.     

Effects of dietary chlorogenic acid on growth,flesh quality and serum biochemical indices of grass carp (Ctenopharyngodon idella)

The study was to investigate effects of dietary chlorogenic acid (CGA) on growth performance, flesh quality and serum biochemical indices of grass carp (95.1 ± 0.3 g) (Ctenopharyngodon idella) fed seven different diets, including control diet, Eucommia ulmoides (EU)‐supplemented diet (20 g kg^–1) and CGA‐supplemented diets containing 100, 200, 400, 600 and 800 mg/kg CGA. Contents of collagen and alkaline‐insoluble collagen in muscle and skin were significantly increased by dietary CGA and EU (p < .05). Total essential amino acids (TEAA) and total amino acids (TAA) in muscle of grass carp fed EU diet or 400, 600 and 800 mg/kg CGA diet were significantly higher than those of fish fed control diet and 100 and 200 mg/kg CGA diet (p < .05). Fish fed 200–800 mg/kg CGA showed significantly lower muscle crude lipid content than EU, control and 100 mg/kg CGA groups (p < .05). Fish fed CGA‐supplemented diets (100–800 mg/kg) had significantly higher muscle fibre density and lower muscle fibre diameter than control group (p < .05). In conclusion, supplementation of CGA improved flesh quality of grass carp, and supplemental level of CGA for improving flesh quality and growth was estimated to be 400 mg/kg diet.     

Effects of dietary lipid source on fatty acid composition,expression of genes involved in lipid metabolism and antioxidant status of grass carp (Ctenopharyngodon idellus)

This study determined the effect of different lipid sources on growth, feed use, lipid metabolism and antioxidant status of grass carp (Ctenopharyngodon idellus). Juvenile fish (56.9 ± 4.7 g) were divided into four triplicate groups and fed diets containing 30 g/Kg of fish oil (FO), olive oil (OO), peanut oil (PO) and linseed oil (LO), respectively, for 60 days. Weight gain and feed conversion ratio were not significantly different between the dietary groups, but we observed changes in the fatty acid composition of muscle and intraperitoneal fat reflecting the fatty acid profile of the dietary lipid source. In the hepatopancreas, the highest mRNA level of fatty acid translocase CD36 (FAT/CD36) and carnitine palmitoyl transferase (CPT‐1A) was both observed in the FO group. In muscle, the expression of FAT/CD36 and CPT‐1A in the LO group was significantly higher than that in other groups, except for CPT‐1A in the PO group. In addition, the lowest and highest content of malondialdehyde in serum was observed in OO and FO groups, respectively. In summary, dietary lipid source altered the fatty acid composition, potential uptake (FAT/CD36) and oxidation (CPT‐1A) of fatty acids, and antioxidant status of grass carp, which should be considered when selecting a lipid source.     

Effect of dietary carbohydrate‐to‐lipid ratios on growth performance,body composition,nutrient utilization and hepatic enzymes activities of herbivorous grass carp (Ctenopharyngodon idella)

Six isonitrogenous (390 g kg^?1) and isoenergetic (16.2 kJ g^?1) diets with varying carbohydrate : lipid (CHO : L) ratios (202.5–1.74), were fed to triplicate groups of 25 fish in indoor recirculation system. Over 8‐week‐growth trial, best weight gain (WG), specific growth rate, feed conversion ratio, protein efficiency ratio and protein production value (P < 0.05) were observed in fish‐fed diets with CHO : L ratio of 7.5. Fish fed either the lowest (1.7) or highest (202.5) CHO : L ratio tended to produce lower (P < 0.05) growth and feed conversion efficiencies. The values of viscerosomatic index, hepatosomatic index and intraperitoneal fat ratio increased as dietary CHO : L ratios decreased. There were no significant differences in whole body and liver crude protein among dietary treatments. Whole body and liver lipid increased as CHO : L ratios decreased. Plasma cholesterol and triacylglyceride levels increased linearly as dietary CHO : L ratios decreased. Activities of glucokinase and pyruvate kinase were stimulated by elevated levels of dietary carbohydrate; however, activities of lipase (LPS) and alkaline phosphatase were stimulated by elevated levels of dietary lipid. Based on a second‐order polynomial regression analysis of WG against dietary carbohydrate and lipid levels, 275 g kg^?1 of carbohydrate and 59 g kg^?1 of lipid, corresponding to a CHO : L ratio of 4.7, in a diet holding 390 g kg^?1 of crude protein and 16.3 kJ g^?1 of gross energy, proved to be optimal for grass carp. These results indicated that utilization of dietary lipid and carbohydrate was moderate in grass carp, but the fish were a little more capable of utilizing lipid compared with carbohydrate.     

不同脂肪源饲料对草鱼稚鱼生长的影响

不同脂肪源饲料对草鱼稚鱼生长的影响刘玮，徐萍，任本根，龚纲明（江西省科学院生物资源研究所，南昌３３００２９）关键词草鱼，鱼饲料，必采脂肪酸ＥＦＦＥＣＴＳＯＦＤＩＥＴＳＣＯＮＴＡＩＮＩＮＧＤＩＦＦＥＲＥＮＴＬＩＰＩＤＳＯＮＧＲＯＷＴＨＯＦＪＵＶＥＮＩＬ...     

Effect of dietary bile acids on growth,body composition,lipid metabolism and microbiota in grass carp (Ctenopharyngodon idella)

To investigate the effects of dietary bile acids (BA) on growth and metabolism of lipid in grass carp (Ctenopharyngodon idella, C. idella) at high dietary lipid level, a basal diet (50 g kg^–1 lipid, 5L group) was supplemented with 20 g kg^–1 soybean oil (70 g kg^–1 lipid, 7L group); then, 0.06 g/kg BA was added in 7L diet to form the third diet (7L+BA group). The 96 C. idella (69.86 ± 6.24 g) were divided into three groups (duplicate per group) and fed three diets, respectively, for 8 weeks, and then, growth and lipid metabolism were determined. Results showed that growth of fish in 7L+BA group was significantly higher than 5L and 7L groups. The lipid level in whole body, hepatopancreas and muscle of grass carp in 7L+BA group were significantly lower than 7L group. Relative expression of lipid catabolism genes in hepatopancreas and muscle of 7L+BA group was significantly higher than 5L group. The amount of microbiota in intestine of fish in 7L+BA group was significantly higher than the other two groups. The present results indicated that BA in 7L diet improved growth of fish by increasing protein synthesizing, decreasing lipid content in fish body and by regulating amount of microbiota in intestine of fish.     

草鱼C1qC基因的克隆及表达分析

为了研究C1qC基因在草鱼(Ctenopharyngodon idella)免疫过程中所起的作用,利用RT-PCR和RACE方法克隆获得了C1qC基因cDNA全长序列,经序列分析表明,所克隆的C1qC cDNA全长为916 bp,包括开放阅读框(open reading frame,ORF)735 bp,5′端非编码区(untranslated region,UTR)89 bp和3′端非编码区(UTR)92 bp。735 bp的ORF共编码244个氨基酸,相对分子量为26 162.5 U。同源性分析表明,草鱼与斑马鱼(Danio rerio)的相似度最高,达到71%。经草鱼呼肠孤病毒(grass carp reovirus,GCRV)诱导后,草鱼C1qC基因在鳃、皮肤、肌肉、肝、中肾、心脏、头肾等组织中的mRNA表达水平均显著上调。在草鱼胚胎发育的各个阶段都能检测到C1qC mRNA的表达,说明该基因可能在草鱼胚胎和鱼苗的免疫反应和早期发育中起重要作用。本研究将为今后在草鱼免疫功能方面深入研究C1qC基因提供基础资料。     

Effects of dietary geniposidic acid on growth performance,flesh quality and collagen gene expression of grass carp,Ctenopharyngodon idella

This study was conducted to investigate the effects of dietary geniposidic acid (GA) on growth performance, flesh quality and collagen gene expression of grass carp (Ctenopharyngodon idella). The fish with an initial body weight of 47.1 ± 0.8 g were fed one of the seven diets, including control diet, Eucommia ulmoides (EU)‐supplemented diet (20 g/kg) and GA‐supplemented diets (200, 400, 600, 800 and 1,000 mg/kg GA) for 75 days. The growth performance and muscle proximate composition showed no difference among groups (p > .05). Dietary GA (200–1,000 mg/kg) increased the contents of total collagen and alkaline‐insoluble collagen in skin (p < .05), and high supplementation of GA (600–1,000 mg/kg GA) and EU increased the contents of total collagen, alkaline‐insoluble collagen and total amino acids (p < .05), but reduced the lipid level in muscle (p < .05). In collagen gene expression, EU and 200–1,000 mg/kg GA increased COL1A1 expression in muscle and skin (p < .05), but the expression of COL1A2 was increased only by high supplementation of GA (1,000 mg/kg, or 800–1,000 mg/kg) (p < .05). In conclusion, dietary GA improved the flesh quality of grass carp, and the supplementation level was estimated to be 600 mg/kg diet.     

Dietary arginine requirement of juvenile grass carp Ctenopharyngodon idella (Valenciennes in Cuvier & Valenciennes, 1844)

This experiment was conducted to estimate the optimum requirement of arginine for juvenile grass carp Ctenopharyngodon idella. Six isonitrogenous (38%) and isoenergetics (16 MJ kg^?1) semi‐purified diets containing casein and gelatine with graded level of arginine (0.93, 1.20, 1.51, 1.84, 2.10 and 2.41 g 100 g^?1 DM) were formulated. Each diet was randomly assigned to triplicate groups of 25 fish each tank (initial weight: 3.84 ± 0.01) for 10 weeks. The highest weight gain (WG, %) was recorded when arginine level was 2.10% of the diet. Dietary arginine level higher than 1.84% significantly increased the protein contents of whole body. Whole body amino acid composition of juvenile grass carp was not significantly affected by the dietary arginine level. Plasma‐free arginine level was increased linearly with increasing of arginine level in the diets, and the plasma‐free ornithine level was significantly higher when the dietary arginine level was 2.41% compared with other groups. Quadratic model analysis of SGR data indicated that the minimum recommended dietary arginine requirement for grass carp was 2.17% of the diet, corresponding to 5.71% of dietary protein.     

Comparison study of three compounds in Eucommia ulmoides on growth,flesh quality of grass carp (Ctenopharyngodon idella)

This study was conducted to compare the growth‐promoting and flesh quality ‐improving effects of three active compounds in Eucommia ulmoides (EU) on grass carp (Ctenopharyngodon idella). Four iso‐nitrogenous diets supplemented with 400 mg/kg inclusion of geniposidic acid (GA), chlorogenic acid (CGA), geniposide (GP) and their combination (GA:CGA:GP = 1:1:1, the mixture) were prepared and fed to grass carp (47.1 ± 0.6 g) for 75 days. The results indicated that weight gain was increased by 5.22%, and feed conversion ratio decreased by 0.07 by dietary CGA (p < 0.05). In flesh quality, the four supplementations significantly increased muscle fibre density, total collagen and alkaline‐insoluble collagen in skin, and reduced steaming loss of flesh. In addition, dietary CGA, GP and the active compounds mixture further increased total collagen, alkaline‐insoluble collagen and amino acid in flesh. In collagen genes expression, the expression of COL1A1 in muscle and skin was significantly promoted by the supplementation of GA, CGA, GP and their combination (p < 0.05). In conclusion, the supplementation of GA, CGA, GP and their combination improved the flesh quality of grass carp, and the growth was increased by CGA. CGA played more important roles in growth‐promoting and flesh quality‐improving effects than GP and GA.     

Variability in the chemical composition of different cottonseed and sunflower meals influences their digestibility when fed to grass carp (Ctenopharyngodon idella)

In the present study, it was examined whether variability in chemical composition of different cottonseed (Nazilli‐M39, Nazilli‐84 and Çukurova‐1518) meals (CSMs) and sunflower (Sanbro, Isera and Coban) meals (SFMs) had any effects on digestibility when fed to grass carp. Protein and energy digestibility of CSMs (83.2–86.8%; 88.7–92.5%) and SFMs (78.9–83.1%; 88.4–92%) had a coefficient of variation of 1.96% (CSMs) and 1.52% (SFMs) for protein and 1.93% (CSMs) and 1.82% (SFMs) for energy digestibility. Sum of amino acids digestibility of CSMs (83.1–86.5%) and SFMs (78.9–83.4%) had a coefficient of variation of 1.85% and 2.47%, respectively. Protein and energy digestibility of CSMs and SFMs was significantly positive affected by a range of compositional features including protein or sum of amino acids and phosphorus content, and significantly negative affected by fiber and carbohydrate contents in the test ingredients. This suggested that fiber and carbohydrate contents of CSMs and SFMs may also be influencing the nutritional value of its own protein or sum of amino acids. In conclusion, the relationship between plant protein meals protein content and its digestible value provides a good support for the development of a system of grain segregation by protein content and ingredient pricing according to that protein content.     

不同脆化阶段草鱼肌肉的显微结构观察和质构特性分析

脆肉鲩作为广东特色水产品之一,其养殖中常出现"不脆"、"半脆"现象,严重制约其产业发展。为探索可鉴定脆度的指标,文章结合生产(饲喂120 d蚕豆+30 d饲料),每30 d采集1次肌肉,检测其感官脆度、肌纤维结构、质构特性的变化。随着脆化时间增加,蚕豆组草鱼感官脆度不断增加(P0.05),肌纤维直径逐渐减小、密度逐渐增大(P0.05);60 d后蚕豆组草鱼质构特性(硬度、弹性、咀嚼性、内聚性、胶黏性)均显著高于对照组(P0.05)。转投30 d饲料对感官脆度、肌纤维结构、质构特性均无显著影响(P0.05)。相关性分析表明,硬度、弹性、咀嚼性、胶黏性与感官脆度的相关性更高(R~20.90,P0.05)。结果表明,硬度、弹性、咀嚼性、胶黏性可用于脆肉鲩的脆度评价,转投30 d饲料不影响其脆度。     

南美白对虾和草金鱼、草鱼等池塘混养技术初探

为探索南美白对虾与鱼类的新型混养模式,于2020年5月—10月在上海市青浦区某合作社开展了南美白对虾和草金鱼、草鱼等的池塘混养试验.试验结果显示:0.33 hm2(5亩)试验池塘共收获南美白对虾2070 kg,平均规格83尾/kg,平均销售价格37.7元/kg,销售收入78040元;共收获草金鱼430 kg,平均规格2...     

Effects of dietary glutamine supplementation on growth performance,antioxidant status and intestinal function in juvenile grass carp (Ctenopharyngodon idella)

Glutamine (Gln) is a conditionally essential free amino acid that has been widely used in aquaculture. The present study showed that appropriate levels of dietary Gln could significantly improve growth performance and increase lipase and trypsin activity, mucosal thickness (MT) and the number of lymphocytes. The levels of glycine (Gly) in the 6 g/kg Gln group, threonine (Thr) in the 12 g/kg group and lysine (Lys) in the 6 and 9 g/kg group were increased significantly, while glutamate (Glu) and serine (Ser) concentrations decreased significantly with increasing dietary Gln levels from 3 to 12 g/kg. Moreover, the 12 g/kg dietary Gln level could improve the concentration of malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GSH‐PX) and the total antioxidant capacity (T‐AOC). In addition, 3 g/kg Gln upregulated the gene expression of aminopeptidase N (APN), caudal‐related homeobox gene (CDX2), L‐type amino acid transporter 2 (LAT2), oligopeptide transporter 1 (PEPT1), specificity proteins 1 (SP1) and 3 (SP3), and peroxisome proliferator‐activated receptor α (PPAR‐α) but downregulated PPAR‐γ gene expression compared to that in the control group. Taken together, these findings suggest that Gln could improve the growth performance, antioxidant status and intestinal function of grass carp.     

Dietary α‐linolenic acid affects lipid metabolism and tissue fatty acid profile and induces apoptosis in intraperitoneal adipose tissue of juvenile grass carp (Ctenopharyngodon idella)

A 56‐day feeding trial was conducted to elucidate the effects and mechanism action of dietary α‐linolenic acid (ALA, 18:3n‐3) on lipid accumulation and fatty acid profile of muscle, hepatopancreas and intraperitoneal fat (IPF) in juvenile grass carp using three isonitrogenous and isoenergetic semi‐purified diets containing 0.0% (control group), 1.0% and 2.0% ALA, respectively. The lowest intraperitoneal fat (IPF) ratio was found in 2.0% group. In the muscle, hepatopancreas and IPF, docosahexaenoic acid (DHA, 22:6n‐3) and eicosapentaenoic acid (EPA, 20:5n‐3) contents increased with the increase in dietary ALA. In the IPF, caspase 3, caspase 8 and caspase 9 showed the highest activities in 2.0% group, while the value of Bcl‐2/Bax (B‐cell leukaemia 2/Bcl‐2‐associated X protein) reached the lowest. Meanwhile, swelling of the IPF mitochondria was observed in 2.0% group. The gene expressions of fatty acid desaturase (FAD) and fatty acid elongase (ELO) in the hepatopancreas and muscle showed significantly higher levels in the treatment groups, whereas an opposite trend was existed in the IPF. Fatty acid synthase (FAS), sterol regulatory element binding protein‐1c (SREBP‐1c) in the IPF and hepatopancreas reached the lowest in 2.0% group. Overall, dietary ALA could promote n‐3 highly unsaturated fatty acids (HUFAs) synthesis and suppress the accumulation of lipid by decreasing the expression of related genes and promoting the apoptosis in IPF.     

Differential expression of lipid metabolism‐related genes and miRNAs in Ctenopharyngodon idella liver in relation to fatty liver induced by high non‐protein energy diets

To explore the mechanism of fatty liver formation induced by high non‐protein energy diets in grass carp (Ctenopharyngodon idella), basal diet and high‐energy diets were fed to juvenile grass carp for 9 weeks. The experimental groups fed on high‐energy diets which included a high‐lipid diet (H‐LIP), a high‐carbohydrate diet (H‐CHO) and a high‐lipid and carbohydrate diet (H‐CL). The control group fed on basal diet. Growth performance, liver fat accumulation, serum biochemical indexes and the expression levels of lipid metabolism‐related genes (SREBP‐1, PPARγ, FAS, ACC1, and LPL) and miRNAs (miR‐33, miR‐122, and miR‐370) were examined at the end of the feeding trial. There were no significant differences in growth rate and feed efficiency among the four groups. However, significant increase in mesenteric and liver fat contents, and lipid droplets in the liver was induced by high‐lipid and high‐carbohydrate diets. There were significant differences in serum biochemical indicators such as AST/ALT, GLB, TG and TP, and liver fatty acid composition between the control and experimental groups. The expression levels of SREBP‐1, PPARγ, FAS, ACC1 and LPL were upregulated, while CPT‐1 was downregulated with the high‐energy treatments. Additionally, the expression levels of miR‐33, miR‐122 and miR‐370 in the liver were higher in the three high‐energy treatments than those in the control (P < 0.05). The results suggest that modifications of lipid metabolism‐related genes and miRNAs may be involved in fatty liver formation induced by high non‐protein energy diets in grass carp.