Essential amino acids supplementation to practical diets affects growth,feed utilization and glucose metabolism‐related signalling molecules of blunt snout bream (Megalobrama amblycephala)

Six diets were formulated to investigate the success of fish meal (FM) replacement by plant proteins; diet 1 reflected a commercial feed (8% FM), diet 3 contained 4% FM, and diet 5 was devoid of FM. Whereas, diet 2, diet 4, and diet 6 reflected diet 1, diet 3, diet 5, respectively, and supplemented with essential amino acid (EAA). At the end of 8‐week trial, there was no significant difference in survival rate. Significantly higher final weight, weight gain rate, and specific growth rate were recorded in the group fed diet 2 compared with the other treatments (except diet 4) (p < 0.05). Feed conversion ratio of fish fed diet 2 was significantly lower than those fed diets 1, 3, and 5 (p < 0.05). The lowest feed intake and highest protein efficiency rate were found in fish fed diet 2 (p < 0.05). There was no significant difference in whole body compositions between treatments. Plasma aspartate transaminases, alanine aminotransferase, and glucose were significantly affected by dietary treatments (p < 0.05), while plasma protein and albumin contents were not influenced by the treatments. The relative expression of target of rapamycin (TOR) and phosphatidylinositol 3‐kinase, regulatory subunit 1 (alpha) (PIK3R1) in fish fed diet 3 (4% FM) were significantly down‐regulated compared with those fed diet 6 for TOR and diets 4 and 6 for PIK3R1 (p < 0.05). Insulin receptor substrate 1 (IRS‐1) and janus kinase 3 (JAK3) expressions were fluctuated, with the higher levels in fish fed diets 4 and 6. In conclusion, the findings of this study indicate that plant protein mixture supplemented with EAA could be used to substitute FM in practical diet for Megalobrama amblycephala.     

Growth and ontogenetic development of digestive functionality in black Amur bream (Megalobrama terminalis)

The function of digestive physiology during ontogenetic development is essential to ensure high survival and growth rates. In order to evaluate the digestive physiological capacity of the black Amur bream (Megalobrama terminalis), changes of morphology and digestive enzyme activity (trypsin, lipase, amylase, pepsin, leucine aminopeptidase and alkaline phosphatase) in larvae were examined from hatching to 40 days after hatching (DAH). Results indicated that fluctuation patterns differed between the total and specific activities of the digestive enzymes. The total activities of these six enzymes gradually increased throughout the fish growth. The specific activity of trypsin peaked at 5 DAH and then decreased dramatically, while it increased remarkably again from 8 to 10 DAH and remained stable level after 20 DAH. Pepsin activity was first examined in M. terminalis at 15 DAH and gradually elevated towards the end of the experiment. The specific activity of lipase displayed obvious peaks at 5 and 20 DAH. For the amylase, its specific activity reached plateau at 4 DAH, underwent sharp decrease, and remained stable after 20 DAH. In addition, we found that the specific activity of alkaline phosphatase raised significantly from hatching to 5 DAH, and tended to keep slight fluctuation after 15 DAH. From the above, we concluded that the specific activities of digestive enzymes in the larvae varied constantly from 3 to 20 DAH and turned relatively stable after 20 DAH. The present study provides effective information that is useful to improve the seedling cultivation and the technology for healthy breeding.     

团头鲂tf和tfr1a基因启动子克隆及转录调控分析

为探索鱼类转铁蛋白基因tf和转铁蛋白受体基因tfr1a的转录调控机制,本实验以团头鲂为研究对象,在其全基因组数据库中获取tf和tfr1a基因序列,对2个基因候选启动子区转录因子结合位点及CpG岛进行预测,通过PCR方法克隆得到tf和tfr1a基因近端启动子区不同长度片段,连接至pGL3-Basic/pEGFP-1载体,瞬时转染入Hela细胞,并采用双荧光素酶报告基因检测系统进行检测。结果发现,团头鲂tf基因启动子区无CpG岛位点,而tfr1a基因启动子区有2个CpG岛位点。成功构建9个tf和10个tfr1a不同长度启动子片段的重组质粒,经双荧光素酶报告基因系统检测发现,tf启动子核心区域为-268^+56 bp,且-1 308^-1 102 bp片段可能存在正调控该基因表达的转录因子结合位点;tfr1a启动子核心区域为-224^+48 bp,且+48^+92 bp可能存在抑制该基因转录的负调控元件,而-1 229^-1 219 bp区域可能存在促进tfr1a基因表达的正调控转录因子结合位点。     

团头鲂肠道肝胰脏消化酶的初步研究

本文采用动力学方法测定了团头鲂肝胰脏淀粉酶和肠道蛋白酶、淀粉酶的活性分布及pH值对各消化酶活性的影响,结果表明:食糜中的蛋白酶、淀粉酶活性沿消化道从前至后逐渐减弱,而肠黏膜中各消化酶活性则基本上是由前到后逐渐增加。在pH值6.0～9.0范围内,肠道蛋白酶活性在pH为8.6时为最大,在pH值6.2～8.6范围内,肝胰脏和肠道淀粉酶活性在pH值7.8时为最大。     

厚颌鲂外周血细胞形态及细胞化学特征研究

采用血细胞常规染色和细胞化学染色对厚颌鲂(Megalobrama pellegrini)外周血细胞形态及细胞化学特征进行观察。结果显示:厚颌鲂外周血细胞可分为红细胞、血栓细胞、单核细胞、淋巴细胞和三种类型粒细胞。红细胞有幼稚、成熟和衰老三种形态,其中幼稚和衰老红细胞较少见;血栓细胞数量最多,其次是淋巴细胞。粒细胞中Ⅰ型和Ⅱ型较常见,Ⅲ型粒细胞少有。细胞化学染色显示幼红细胞、血栓细胞和淋巴细胞均呈ACP弱阳性;单核细胞呈ACP和ANAE阳性;Ⅰ型粒细胞是嗜中性粒细胞,POX、ACP和ANAE阳性;Ⅱ型粒细胞是PAS-GL,PAS强阳性和ACP阳性;Ⅲ型粒细胞是Ⅰ型粒细胞的晚期形态。厚颌鲂的PAS-GL可能是嗜酸性/嗜碱性粒细胞,而不是嗜碱性粒细胞的前体。     

广东鲂全人工繁殖的研究

本文研究了广东鲂人工繁殖的鱼苗在池塘育成亲鱼的方法，用ＬＲＨ－Ａ２与ＤＯＭ混合催们效果最优，人工授精的关键是效应时间的掌握，本研究提出广东鲂最小性成熟年龄为２龄，属一年我次产卵鱼类，可进行一次２次性成熟产卵，胚胎发育程序与家鱼基本相似，胚胎发育最适水温范围约为２４－２８℃，临界水温上、下限分别为３１℃和２０℃。     

Induction of interspecific allo-tetraploids of Megalobrama amblycephala♀×Megalobrama terminalis♂ by heat shock

Interspecific allo-tetraploidy was induced by a combination of hybridization of Megalobrama amblycephala ♀× Megalobrama terminalis ♂ and thermal shock. A thermal shock at 40 °C for 2 min applied to eggs 33 or 26 min (τ₀: 1.40) after fertilization resulted in a significantly ( P <0.01) higher yield of allo-tetraploids than hybrid crosses without heat shock. The yield of allo-tetraploids in embryos from mid-gastrula to hatching stages was 15.7–24.4% in different thermal shock treatment groups. The allo-tetraploidy rate in 330-day-old juveniles was 9.3% and 6.7% in different year treatment groups. After 2 years of rearing, allo-tetraploidy males attained sexual maturity with milk-like milt at the age of 2+, while allo-tetraploidy females at the age of 2+, and even at 3+, did not show any signs of sexual maturation exhibiting obviously delayed maturity. Only a few allo-tetraploidy females (three individuals) showed maturation characters at the age of 4+ and these females were induced to spawn.     

厚颌鲂的年龄结构及生长特性

以鳞片作为鉴定年龄的材料,对龙溪河厚颌鲂(Megalobrama pellegrini)种群开展年龄结构与生长特性的研究。结果表明,厚颌鲂鳞片年轮结构呈疏密切割型,年轮特征显著,可用于年龄鉴定,3~4月是年轮形成高峰时间。种群由0~7龄共8个龄组组成,以低龄个体为主,1~3龄个体占83.14%,体长分布主要集中在130~250 mm间(77.71%)。体质量分布主要集中在50~250 g(64.33%)。群体总性比为♀∶♂=1∶1.03,符合1∶1理论比值。体长和鳞径呈直线关系,体长和体质量呈幂函数关系且幂指数接近3,属于匀速生长类型,因此用Von Bertalanffy方程描述其生长特性,相关生长参数分别为:渐近体长L∞=488.89 mm,渐近体质量W∞=2486.96 g,k=0.1648,t0=-0.5453龄。体质量生长拐点Ti=6.40龄,对应体长、体质量分别为Lt=333.14 mm,Wt=746.06 g。厚颌鲂的总体生长性能逊于同属其他鱼类。     

饲料中添加枯草芽孢杆菌对团头鲂幼鱼生长性能、肝脏抗氧化指标、肠道菌群结构和抗病力的影响

本试验旨在研究饲料中添加枯草芽孢杆菌对团头鲂幼鱼生长性能、肝脏抗氧化指标、肠道菌群结构和抗病力的影响。选取初始体重为(1.81±0.01)g的团头鲂幼鱼360尾,随机分为4组(每组3个重复,每个重复30尾),分别饲喂添加0(T0组,作为对照组)、2×10~7(T1组)、2×10~8(T2组)、2×10~9CFU/g枯草芽孢杆菌(T3组)的等氮等脂饲料。试验期为8周。结果表明:1)与对照组相比,T1组和T2组团头鲂幼鱼的增重率、特定生长率显著升高(P0.05),且T1组的饲料系数显著降低(P0.05)。2)与对照组相比,T1组团头鲂幼鱼的肝脏抗氧化酶(超氧化歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶)活性显著升高(P0.05),同时该组肝脏丙二醛含量显著降低(P0.05)。3)各组全鱼水分、粗蛋白质、粗脂肪和粗灰分含量均无显著差异(P0.05)。4)变性梯度凝胶电泳(DGGE)图谱显示摄食不同添加量枯草芽孢杆菌饲料的团头鲂幼鱼的肠道菌群结构发生了改变。5)采用嗜水气单胞菌对鱼体进行攻毒,各组96 h后的累积死亡率未产生显著差异(P0.05),但T1组和T2组的累积死亡率低于对照组和T3组。由此可见,饲料中添加2×10~7CFU/g的枯草芽孢杆菌能够提高团头鲂幼鱼的生长性能、抗氧化能力,并改变肠道菌群结构,但对其体成分和抗病力没有显著影响。     

湖北淤泥湖团头鲂优良性状及种质研究

本文采用比较分析的方法,阐明了团头鲂的淤泥湖种群与其它种群相区别的形态特征,以及该种群的优良经济性状及种质.