Effects of dietary choline supplementation on growth performance,lipid deposition and intestinal enzyme activities of blunt snout bream Megalobrama amblycephal fed high‐lipid diet

This study aimed to investigate the effects of dietary choline supplementation on growth, lipid deposition and intestinal enzyme activities of Megalobrama amblycephala. Fish were fed four diets with two lipid levels (50 and 150 g kg^?1) and two choline supplementations (600 and 1600 mg kg^?1) for 8 weeks. Feed conversion ratio (FCR), viscerosomatic index (VSI), hepatosomatic index (HSI), intraperitoneal fat (IPF) ratio, whole‐body and muscle lipid contents, intestinal lipase activities and lipoprotein lipase (LPL) activities all increased significantly (P < 0.05) as lipid levels increased, whereas the opposite was true for whole‐body and muscle moisture contents and intestinal amylase activities. VSI, IPF ratio and whole‐body lipid contents all decreased significantly (P < 0.05) with increasing dietary choline supplementations. Weight gain, muscle moisture content all increased significantly (P < 0.05) with increasing dietary choline supplementations when dietary lipid levels reached 150 g kg^?1, whereas the opposite was true for FCR, IPF ratio, IPF and liver LPL activities. In addition, abnormal hepatocytes were found in the liver of fish fed 150 g kg^?1 lipid with 600 mg kg^?1 choline supplementation. The result of this study indicated that extra choline supplementation can improve growth performance, intestinal enzymes activities and reduce excessive lipid deposition of M. amblycephala fed high lipid.     

Resveratrol supplementation improves lipid and glucose metabolism in high-fat diet-fed blunt snout bream

Here, we aimed to investigate whether resveratrol (RSV) can ameliorate high-fat diet (HFD)-induced metabolic disorder in fish. Blunt snout bream (Megalobrama amblycephala) with average weight 27.99 ± 0.56 g were fed a normal fat diet (NFD, 5% fat, w/w), a HFD (11% fat), or a HFD supplemented with 0.04, 0.36, or 1.08% RSV for 10 weeks. As expected, fish fed a HFD developed hepatic steatosis, as shown by elevated hepatic and plasma triglycerides, raised whole body fat, intraperitoneal fat ratio and hepatosomatic index, and increased plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST). RSV supplementation lessened increases in body mass, whole body fat, and intraperitoneal fat, and alleviated development of hepatic steatosis, elevations of plasma triglyceride and glucose, and abnormalities of ALT and AST in HFD-fed fish. RSV supplementation increased SIRT1 messenger RNA (mRNA) expression and consequently hepatic mRNA expression of adipose triglyceride lipase (ATGL), carnitine palmitoyltransferase (CPT1a), and microsomal triglyceride transfer protein (MTTP), implying upregulation of lipolysis, β-oxidation, and lipid transport, respectively, in the liver. Conversely, hepatic lipoprotein lipase (LPL), sterol regulatory element-binding protein 1 (SREBP-1c), peroxisome proliferator-activated receptor γ (PPARγ), and ATP citrate lyase (ACLY) mRNA expression were decreased, implying suppression of fatty acid uptake, lipogenesis, and fatty acid synthesis. Additionally, RSV downregulated glucokinase (GCK) and sodium-dependent glucose cotransporter 1 (SGLT1) and upregulated glucose transporter 2 (GLUT2) mRNA expression, thus restoring normal glucose fluxes. Thus, RSV improves lipid and glucose metabolisms in blunt snout bream, which are potentially mediated by activation of SIRT1.     

甘草次酸对团头鲂生长、脂肪沉积与抗氧化功能的影响

为探讨甘草次酸对团头鲂生长、脂肪沉积和抗氧化功能的影响,选取均体质量为(15.63±0.04)g的团头鲂幼鱼420尾,随机分在15个网箱中,分别以甘草次酸水平为0、0.15、0.30、0.45和0.60 g/kg的5种饲料投喂8周。结果发现,饲料添加甘草次酸对团头鲂增重率、特定生长率、饵料系数没有显著影响(P0.05)。甘草次酸可以显著降低实验鱼脏体比、肝体比、腹脂率及肝脏脂肪含量(P0.05),但对全鱼体组成和肌肉脂肪含量无显著影响(P0.05)。比对血浆脂肪代谢酶可见,0.30~0.60 g/kg甘草次酸添加组血浆总胆固醇含量较对照组显著下降(P0.05);而甘油三酯、游离脂肪酸和高密度脂蛋白胆固醇含量无显著变化(P0.05)。肝脏中脂蛋白酯酶、肝酯酶和总酯酶活性在添加甘草次酸后显著降低(P0.05);0.30~0.60 g/kg甘草次酸添加组脂肪酶活性显著高于其他各组(P0.05)。饲料添加甘草次酸可以显著提高肝脏超氧化物歧化酶活性和还原型谷胱甘肽含量,降低丙二醛含量(P0.05)。研究表明,饲料中添加0.30~0.45 g/kg甘草次酸时,显著降低了团头鲂内脏团的脂肪沉积,改善了鱼体脂肪分布,这可能是由于甘草次酸加强脂解作用,提高脂肪代谢酶活性导致的;饲料中添加甘草次酸也可显著提高团头鲂的抗氧化能力。     

Effects of dietary carbohydrate/lipid ratios on growth performance,body composition and glucose metabolism of fingerling blunt snout bream Megalobrama amblycephala

This study aimed to investigate the optimum dietary carbohydrate/lipid (CHO/L) ratio for fingerling blunt snout bream Megalobrama amblycephala (average initial weight: 6.61 ± 0.03 g). Six isonitrogenous and isoenergetic diets were formulated to contain various CHO/L ratios ranging from 1.62 to 24.20. Each diet was tested in four replicates for 10 weeks. Specific growth rate (SGR), feed conversion ratio and nitrogen and energy retention all improved significantly (P < 0.05) as dietary CHO/L ratios decreased from 24.20 to 5.64 but showed little difference (P > 0.05) as dietary CHO/L ratios ranged from 2.45 to 5.64. Hepatosomatic index increased significantly (P < 0.05) as dietary CHO/L ratios increased, whereas intraperitoneal fat ratio showed an opposite trend (P < 0.05). Opposite to moisture content, lipid content of whole body and carcass all increased significantly (P < 0.05) as dietary CHO/L ratios decreased. Liver lipid content showed little difference (P > 0.05) among all the treatments, while liver glycogen content increased significantly (P < 0.05) with increasing CHO/L ratios. High dietary carbohydrate enhanced the activities of liver hexokinase, pyruvate kinase and glucose‐6‐phosphate dehydrogenase but did not induce hyperglycaemia. Based on the second‐order polynomial regression analysis of SGR, the optimal dietary carbohydrate and lipid contents for fingerling blunt snout bream were 291.7 and 81.4 g kg⁻¹, respectively, with a corresponding dietary CHO/L ratio of 3.58.     

胆碱对高脂胁迫的团头鲂肝脏抗氧化、组织结构和免疫力的影响

以初始体质量(42.20±0.34)g团头鲂为研究对象,研究饲料中添加胆碱对高脂胁迫团头鲂肝脏抗氧化、组织结构和免疫力的影响。实验采用2×2因子设计方法,共配置2个脂肪水平(5%和15%)和2个胆碱水平(1200和2200 mg/kg)的等氮饲料4组。养殖实验在室内循环水系统中进行,养殖周期为8周。养殖实验结束后进行血液和肝脏生化指标、肝脏抗氧化指标和非特异性免疫指标等的检测分析,以及观察肝细胞的超微结构变化。结果显示,当饲料中添加1200 mg/kg胆碱时,随着脂肪水平的升高,团头鲂肝脏脂肪含量和甘油三酯浓度显著增加,而血浆中谷草转氨酶(AST)和谷丙转氨酶(ALT)活性则显著上升;肝脏中丙二醛(MDA)含量、总超氧化物歧化酶(t-SOD)活性、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GPX)活性等显著升高;血液中白细胞数、溶菌酶活性、总蛋白和球蛋白水平以及还原型谷胱甘肽(GSH)活性显著降低;超微结构观察到肝细胞中存在大量脂滴,伴随着细胞核变性、核膜残缺、线粒体水肿等异常现象。这些结果表明高脂日粮不仅导致肝细胞的结构和功能的损伤,而且造成肝脏氧化应激和机体免疫力的下降。在高脂饲料(15%脂肪)中添加2200 mg/kg胆碱,可显著降低肝脏脂肪含量、血浆谷草转氨酶(AST)和谷丙转氨酶(ALT)活性,显著降低肝脏丙二醛(MDA)含量、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性,并显著提高白细胞数和球蛋白水平以及还原型谷胱甘肽(GSH)活性,同时肝细胞形态及细胞器结构也趋于正常。研究表明,添加适量胆碱能够减少肝脏脂肪沉积,维持肝脏结构和功能的正常,并增强团头鲂抗氧化能力和机体免疫力,继而保持鱼体的健康。     

Alterations of liver histology and blood biochemistry in blunt snout bream Megalobrama amblycephala fed high-fat diets

In this study we examined the effects of high-fat diets on alterations in liver histology features and blood biochemistry parameters in blunt snout bream Megalobrama amblycephala. Fish were fed three diets containing 5, 10, and 15 % fat, respectively, for 6 weeks prior to the liver histology examination and blood biochemistry testing. The livers of fish fed the 5 % fat diet showed a normal structure, whereas those of the fish fed the diets with a higher fat content presented nucleus polarization and lipid vacuolization. Transmission electron microscopy examination revealed that the hepatocytes of fish fed the 15 % fat diet had undergone ultrastructural alterations involving the mitochondria, nucleus, and endoplasmic reticulum (ER). Alterations in the blood biochemistry were evaluated to determine whether the blood biochemistry changes could be correlated with the observed alterations in liver histology with the aim of assessing the suitability of the investigated blood parameters as rapid indicators of liver condition. Significantly higher levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities and of triglycerides and cholesterol were found in fish fed the 15 % fat diet. On the whole, the results clearly show that high fat intake resulted in fat accumulation and ultrastructural impairments of the mitochondria, nucleus, and ER. We conclude that blood sample measurements (AST, ALT, triglycerides, and cholesterol) could be used as a rapid test for determining liver status in blunt snout bream.     

饲料锌对团头鲂幼鱼生长性能、血清生化指标和抗氧化功能的影响

以酪蛋白和明胶为蛋白源,七水硫酸锌(Zn SO4·7H2O)为Zn源,分别配制成7种Zn含量(7.4 mg/kg、20.3 mg/kg、32.1 mg/kg、51.0 mg/kg、84.4 mg/kg、169.7 mg/kg、332.4 mg/kg)的半纯化饲料,投喂初始体重为(3.6±0.1)g团头鲂(Megalobrama amblycephala)12周,考察Zn对团头鲂幼鱼生长性能、血清生化指标和抗氧化功能的影响,确定团头鲂幼鱼对饲料Zn的需要量。结果表明,随着饲料Zn含量增加,团头鲂增重率、特定生长率和全鱼Zn含量呈先增加后稳定的趋势;全鱼水分含量显著降低(P0.05),粗蛋白含量显著增加。饲料Zn含量对团头鲂饲料系数无显著影响。饲料中添加Zn显著影响血清总蛋白、尿素氮、高密度脂蛋白胆固醇、总胆固醇以及甘油三酯含量,而对血清白蛋白含量和碱性磷酸酶活性无显著影响。随着饲料中Zn含量的增加,团头鲂肝丙二醛含量显著降低(P0.05),而肝过氧化氢酶和超氧化物歧化酶活性在各处理间均无显著差异。折线回归分析表明,团头鲂幼鱼(体重3.6~26.7 g)获得最佳生长时对饲料Zn需要量为32.6 mg/kg,获得最大鱼体Zn含量时Zn的需要量为47.6 mg/kg。本研究旨在确定团头鲂幼鱼对饲料中Zn的需要量,为配制团头鲂高效环保饲料提供科学依据。     

Effects of dietary linolenic acid on growth,fatty acid composition,immune function and antioxidant status of juvenile blunt snout bream,Megalobrama amblycephala

A nine‐week feeding trial was performed to determine the dietary linolenic acid (LNA; 18:3n–3) requirements of juvenile blunt snout bream. Six iso‐nitrogenous, semi‐purified diets were prepared with different concentrations of LNA (0–25 g/kg). Dietary LNA had no significant effects on survival rate. However, final fish weight, weight gain (WG), specific growth rate (SGR) and feed efficiency ratio (FER) increased with increasing dietary LNA concentrations up to 20 g/kg. Dietary LNA increased muscle LNA and total n‐3 polyunsaturated fatty acid (PUFA) contents, but decreased total saturated fatty acid content. Fish fed 20 g/kg LNA had the highest plasma alkaline phosphatase activity, total protein, albumin and white blood cell count levels. Additionally, fish fed 20 g/kg LNA had higher triglyceride levels than control fish. Plasma glucose increased with increasing dietary LNA concentrations. Superoxide dismutase and glutathione peroxidase activities significantly increased with increasing dietary LNA concentrations up to 15 g/kg. Based on SGR and FER, the optimal dietary LNA requirements of juvenile blunt snout bream were 17.5 and 15.6 g/kg respectively.     

Effects of dietary docosahexaenoic acid on growth performance,fatty acid profile and lipogenesis of blunt snout bream (Megalobrama amblycephala)

Six diets were designed to investigate the effects of dietary docosahexaenoic acid (22:6n‐3; DHA) levels (0.5, 1.3, 2.3, 4.2, 8.1 and 15.9 g/kg diets) on growth performance, fatty acid profile and expression of some lipogenesis‐related genes of blunt snout bream (Megalobrama amblycephala). Fish (average weight: 26.40 ± 0.11 g) were randomly fed one of six diets for 8 weeks. Results indicated that the final body weight (FBW) and specific growth rate (SGR) of fish fed 1.3 g/kg DHA were significantly higher than other groups except for the 2.3 g/kg DHA (p < .05). Compared with other groups, the number of lipid droplet clusters of the liver stained with oil red O in the 2.3 g/kg DHA group was the highest, which was consistent with the lipid contents of whole body and liver. The DHA proportion in liver and muscle significantly increased with the increasing dietary DHA levels (p < .05), which reflected fatty acid profiles of diets. The highest mRNA expressions of acetyl‐CoA carboxylase α (ACCα), fatty acid synthase (FAS) and sterol regulatory element‐binding protein‐1 (SREBP‐1) occurred in the 1.3 g/kg DHA group, followed by 2.3 g/kg DHA. In summary, the supplementation of 1.3–2.3 g/kg DHA could improve growth performance and lipogenesis, and the dietary DHA could improve DHA and PUFA proportion in liver and muscle.     

Effects of dietary selenium on the growth,selenium status,antioxidant activities,muscle composition and meat quality of blunt snout bream,Megalobrama amblycephala

An 8‐week feeding trial was performed to investigate effects of dietary selenium (sodium selenite, Na₂SeO₃; selenium nanoparticle, Nano‐Se; selenium yeast, Se‐yeast) on the growth, selenium status, antioxidant activities, muscle composition and meat quality of blunt snout bream. Na₂SeO₃ and Nano‐Se were supplemented at 0.2 mg Se kg^?1, and Se‐yeast was supplemented at 0.1, 0.2, 0.4 and 0.8 mg Se kg^?1 in basal diet; no Se was added as a control. The results indicated that groups of 0.2 and 0.4 mg kg^?1 Se‐yeast had significantly higher weight gain and Nano‐Se, 0.2, 0.4 mg kg^?1 Se‐yeast had significantly lower feed conversation ratio compared with the control group. The Se concentrations of whole body, muscle and liver linearly increased with increasing dietary Se‐yeast levels. Group of 0.4 mg kg^?1 Se‐yeast significantly increased activities of catalase and glutathione peroxidase. Muscle colour of Nano‐Se, 0.2, 0.4 mg kg^?1 Se‐yeast groups, the water‐holding capacity of 0.4, 0.8 mg kg^?1 Se‐yeast groups showed significant differences compared with the control group. The results suggest that Se‐yeast and Nano‐Se had a better growth performance than Na₂SeO₃ at 0.2 mg Se kg^?1, and supplementing appropriate Se‐yeast in diet can increase antioxidant activities and enhance meat quality of blunt snout bream.     

维生素E对高脂饲料养殖大菱鲆生长、脂类代谢和抗氧化性能的影响

选用750尾初体质量为(114.2 ± 6.5) g的大菱鲆 (Scophthalmus maximus L.), 随机分成5组, 每组3个重复, 每重复50尾鱼, 分别投喂在高脂基础饲料中添加0(D-0)、120 (D-120)、240(D-240)、480 (D-480)和960 mg/kg (D-960) 的DL-α-生育酚醋酸酯5种试验饲料养殖110 d, 考察维生素E(VE)对高脂饲料养殖大菱鲆生长、脂类代谢和抗氧化性能的影响。结果表明, D-240组大菱鲆末均质量最高, 且显著高于D-0组(对照组)(P<0.05), 与其他组差异不显著(P>0.05); D-120组和D-240组饲料系数显著低于D-0组(P<0.05), 但蛋白质效率显著高于D-0组(P<0.05)。D-0组和D-960组血清总胆固醇、甘油三酯、低密度脂蛋白胆固醇和谷丙转氨酶显著高于其他各组(P<0.05), 而D-0组和D-960组高密度脂蛋白胆固醇则显著低于其他各组(P<0.05); 随着饲料VE添加水平的增加, 大菱鲆肝脂蛋白脂酶(LPL)活性有降低的趋势; 脂肪酸合成酶(FAS)活性, 有先增加后降低的趋势。大菱鲆肝总抗氧化酶、超级氧化歧化酶和过氧化氢酶活性, 均随VE添加水平的升高有先升高后下降的趋势, 而丙二醛含量的变化趋势则相反; 随着饲料VE水平的增加, 大菱鲆肝VE积累量有显著升高的趋势(P<0.05), 肌肉VE的积累量先升高后恒定在一个水平。综上所述, 在高脂饲料中添加适量的维生素E (有效含量124~243 mg/kg) 能改善大菱鲆生长性能、饲料利用效率、鱼肝体指数、脏体指数, 调节和改善血脂代谢, 可调控机体脂肪代谢酶活性, 提高机体组织VE积累量和肝抗氧化功能。本研究旨在通过考察添加不同水平的VE对高脂胁迫下大菱鲆生长、脂类代谢酶、抗氧化能力的影响, 为VE在高脂胁迫下的合理使用及以VE营养调控鱼类脂肪代谢和改善抗氧化功能提供参考依据。

     

苯磷硫胺对饲喂高糖饲料团头鲂血浆生化指标及肝糖脂代谢的影响

为了探究苯磷硫胺对饲喂高糖饲料团头鲂(Megalobrama amblycephala)的血清生化指标及肝糖脂代谢的影响,随机选取360尾体重(45.25±0.34)g的团头鲂幼鱼,进行12周的养殖实验,期间分别投喂6种饲料[对照组C:30％糖水平;高糖组HC:43％糖水平;高糖组+不同苯磷硫胺添加量:43％糖水平+0...     

高脂日粮添加胆汁酸对大口黑鲈生长性能、脂代谢和胆汁酸代谢的调节作用

为探究胆汁酸对高脂饲料饲喂下大口黑鲈(Micropterus salmoides)生长生理、脂代谢和胆汁酸代谢的影响, 配制基础饲料(脂肪含量 10.6%, 对照组 C)、高脂饲料(脂肪含量 17.5%, 高脂组 HF)、高脂饲料+300 mg/kg 胆汁酸 (HFB1)、高脂饲料+600 mg/kg 胆汁酸(HFB2)、高脂饲料+900 mg/kg 胆汁酸(HFB3) 5 种试验饲料。将 750 尾大口黑鲈随机分为 5 组, 每个组设置 3 个平行缸, 每缸 50 尾, 进行 7 周养殖实验。结果表明: 高脂饲料显著降低大口黑鲈生长性能, 而添加胆汁酸后可改善高脂饲料对大口黑鲈生长的不利影响。饲喂高脂饲料组血浆和肝脏中甘油三酯 (TG)含量显著升高(P＜0.05)。添加胆汁酸后, 肝脏中 TG 含量显著降低(P＜0.05), 而血浆中 TG 含量在胆汁酸添加量为 900 mg/kg 时显著下降(P＜0.05)。肝脏和血浆中总胆酸(TBA)含量随着胆汁酸添加量的升高而显著增加(P＜0.05)。 胆汁酸添加量为 600 mg/kg 时, 肝脏中法尼醇 X 受体基因(fxr)表达量上调(P＜0.05), 胆汁酸合成和转运相关基因 (cyp7a1、bsep、asbt)均显著上调(P＜0.05)。同时对脂代谢相关基因表达进行检测, 发现 fxr 诱导 shp 的表达, 抑制肝脏中 srebp1 及脂肪合成相关基因(fas、acc2)的表达。此外, 胆汁酸增加肝脏中脂肪分解和 β 氧化相关基因(lpl、 hl、hsl、cpt1、acox1)的表达水平。综上所述, 高脂饲料中添加胆汁酸可改善大口黑鲈生长性能, 通过 FXR/SHP/ SREBP1 信号通路调节脂质代谢, 并促进胆汁酸合成和循环, 本研究为进一步研究胆汁酸在鱼类中的营养调控作用奠定了基础。     

Effects of dietary supplementation of fructooligosaccharide on growth performance,body composition,intestinal enzymes activities and histology of blunt snout bream (Megalobrama amblycephala) fingerlings

A feeding trial was conducted to investigate the effects of dietary fructooligosaccharide (FOS) on growth performance, body composition, intestinal enzymes activities and histology of fingerling Megalobrama amblycephala. A total of 1200 fish (1.42 ± 0.01 g) were fed diets containing graded levels of FOS (0, 0.5, 1, 2, 4 and 8 g kg⁻¹ diet) for 8 weeks in a recirculating system indoor. The weight gain, specific growth rate (SGR) and survival rate were all improved in dietary supplementation of FOS fed fish. Increasing FOS levels resulted in both higher whole‐body lipid and lower moisture contents, whereas ash and protein contents showed no significant differences among all the treatments. Intestinal amylase, protease, Na⁺, K⁺‐ATPase, alkaline phosphatase, γ‐glutamyl transpeptidase and creatine kinase activities all increased with dietary FOS levels up to 4 g kg⁻¹ (P < 0.05). Transmission electron microscopy analysis indicated that microvilli length in the mid‐intestine was significantly increased with increased dietary FOS levels (P < 0.05). In conclusion, dietary supplementation of FOS could confer benefits on growth performance, intestinal digestive and absorptive ability, histology of fingerling Megalobrama amblycephala.     

饲料中添加串叶松香草对团头鲂幼鱼生长性能、抗氧化能力和脂肪代谢的影响

[目的]本实验旨在探讨饲料中添加串叶松香草对团头鲂幼鱼生长性能、抗氧化能力和脂代谢的影响。[方法]实验选取240尾初始体重为(3.85±0.5)g团头鲂幼鱼,随机分为4组,每组3个重复,每重复20尾鱼。各组分别投喂串叶松香草添加水平为0%(对照组)、2%、4%和6%的实验饲料,饲喂8周后测定鱼体生长性能、肌肉组成、血液生化、肝肠抗氧化和肝脏脂代谢相关基因表达。[结果]研究发现,相较于对照组,4%和6%串叶松香草组的增长率、特定生长率显著降(P<0.05),6%组的终末均重显著降低(P<0.05),饵料系数显著增加(P<0.05)。在抗氧化能力方面,2%串叶松香草组肠道过氧化氢酶(CAT)、超氧化物歧化酶(SOD)显著高于对照组(P<0.05)。在脂肪沉积和代谢方面,4%和6%串叶松香草组肌肉粗脂肪含量显著高于对照组(P<0.05)。4%和6%串叶松香草组肠道脂肪酶活性显著低于对照组(P<0.05)。6%串叶松香草组血清中的甘油三酯(TG)、胆固醇(TC)、高密度脂蛋白(HDL-C)、低密度脂蛋白(LDL-C)均显著高于对照组(P<0.05)。4%和6%串叶松香草组肝脏中脂肪合成基因fas、srebp1c的表达量显著升高(P<0.05)。同时,6%串叶松香草组肝脏中脂肪分解基因lpl、cpt1a、pparβ的表达量显著下降(P<0.05)。应激24h后2%串叶松香草组累积死亡率低于对照组,肝脏SOD活性显著高于对照组(P<0.05)。[结论]总之,在饲料中添加2%的串叶松香草对团头鲂幼鱼的生长和饲料利用无不利影响,并且能够提高肠道的抗氧化能力,而当添加量增加至4%和6%时会抑制鱼体生长,并引起团头鲂幼鱼脂肪沉积。[意义]本研究结果为串叶松香草在水产动物饲料中的应用提供了参考。     

团头鲂“浦江1号”一个RAPD标记的SCAR转化

从100个10bp寡核苷酸引物的扩增带中，筛选出了3个RAPD特异扩增带，即团头鲂“浦江1号”群体所具有的S37^277bp、S11^2660bp带，以及对照群体所具有的S28^946bp带。该3条RAPD特异扩增带经回收、克隆和测序，并根据部分序列信息分别设计了3对各20bp的正向引物和反向引物。用3对引物分别在“浦江1号”群体和对照群体中进行PCR扩增，分别产生了Sc-1(248bp)、Sc-2(540bp，460bp)和Sc-3(320bp)4个SCAR扩增带。其中，Sc-2(540bp，460bp)和Sc-3(320bp)3个SCAR扩增带在“浦江1号”和对照群体中均呈阳性，不能有效地区分这2个群体；而Sc-1产生的248bp带仅在“浦江1号”群体中出现，对照群体中未出现此扩增带。采用大样本对该Sc-1标记(248bp)进行验证，结果发现，在团头鲂“浦江1号”良种群体的分布频率高达91．1％(82／90)以上，而在淤泥湖原种群体中的分布频率为14．3％(8／56)，Sc-1标记在良种群体中的高频率，可作为检测团头鲂“浦江1号”良种的一个重要的分子遗传特征指标；另外，该Sc-1标记在团头鲂“浦江1号”群体中的高出现频率，也说明了在长期(16年)和高强度(0．03％～0．04％选择率)的选育过程中，团头鲂“浦江1号”已大大提高了某些优良性状基因的等位基因频率。     

Anti-stress properties and two HSP70s mRNA expressions of blunt snout bream (Megalobrama amblycephala) fed with all-plant-based diet

The influence of all-plant-based diet on fingerling blunt snout breams (Megalobrama amblycephala) was tested by examining growth performance, anti-stress properties and related gene expression. Healthy fish were randomly divided into triplicate groups per dietary treatment and fed with different formulated diets. The results showed that both weight gain, specific growth rate and protein efficiency ratio of all-plant-based diet group were significant higher than those of the control (p < 0.05). In contrast, FCR of all-plant-based diet group was significantly lower than that of the control (p < 0.05). Therefore, all-plant-based diets could not affect the growth performance of blunt snout breams. Compared to the control group, the lysozyme levels in serum and mucus, and glutamic-oxaloacetic transaminase activities in serum and liver decreased significantly (p < 0.05). In contrast, the glutamic-pyruvic transaminase activities in serum and liver increased significantly (p < 0.05). For blunt snout breams fed with all-plant-based diets, the superoxide dismutase activities in mucus, serum and liver as well as catalase activity in serum and liver were decreased significantly (p < 0.05) comparing with that of the control group. But malondialdehyde contents were higher (p < 0.05) in serum and liver than that of control group. The expression of HSC70 mRNA increased significantly (p < 0.05) in blunt snout breams fed with all-plant-based diet, whereas the HSP70 mRNA expression decreased significantly (p < 0.05) when compared with control group. In conclusion, all these results indicated that the application of all-plant-based diet could decrease the anti-stress properties (non-specific immunity, stress resistance and antioxidant ability) and HSP70 mRNA expression in blunt snout breams fingerling. Although all-plant-based diets could not affect the growth performance of blunt snout breams, the application of all-plant-based diet should be discreet in the production practice.