pH值对黄鳍鲷主要消化酶活性的影响

研究了pH值对黄鳍鲷肝、胃、肠3个部分主要消化酶(蛋白酶、脂肪酶和淀粉酶)比活的影响。结果显示,黄鳍鲷肝脏、胃和肠道蛋白酶最适pH值分别为:7.0、2.8和7.4,脂肪酶最适pH值分别为:7.2、7.6和7.6,淀粉酶最适pH值分别为4.8、5.2和6.8。胃蛋白酶的最适pH在酸性范围,肝和肠的最适pH值都在中性偏碱性范围。淀粉酶的最适pH值都在酸性范围,脂肪酶的最适pH都在碱性范围。     

3个水域黄鳍鲷线粒体DNA D-loop基因序列多态性研究

利用PCR技术扩增海南海口市、福建厦门市和广东珠海市3个地理群体海捕黄鳍鲷线粒体D-loop基因片段，测定了该基因片段580bp序列。结果发现，3个地理群体内和群体间都存在丰富的DNA序列多态性，共检测到33个多态性核苷酸位点(5．7％)，24个个体具有22种单倍型(haplotype)。UPGMA法构建的分子系统树中，海南群体内所有的单倍型聚成一支，福建与广东的单倍型混杂在一起，聚成一支。从序列差异的分析中得出，海南群体与福建和广东群体的亲缘关系较远；福建群体和广东群体亲缘关系较近。     

温度对黑鳍棘鲷耗氧率与排氨率的影响

对体重为240.9±27.1 g的黑鳍棘鲷在不同水温(10℃、15℃、20℃、25℃、30℃)条件下的耗氧率和排氨率进行了测试分析。结果表明:黑鳍棘鲷在一定温度范围内的耗氧率和排氨率均随温度的升高而升高,但当水温超过一定值后,其耗氧率和排氨率均随温度的升高而下降。在实验条件下,黑鳍棘鲷的耗氧率与温度的回归方程为Y=-0.489 7X2+27.39X-147.39;排氨率与温度的回归方程为Y=-0.009 3X2+0.508 2X-1.247;耗氧率的最大值为235.61μg/g.h(温度为28.0℃),排氨率的最大值为5.70μg/g.h(温度为27.3℃)。黑鳍棘鲷快速生长期的最适温度为25~28℃。     

Daily age and food habits of Lateolabrax latus larvae and juveniles occurring in the innermost shallow waters of Uwajima Bay, Japan

ABSTRACT:   Daily age and food habits of Lateolabrax latus larvae and juveniles were investigated at two different habitats in Uwajima Bay, western Shikoku, Japan. In the shallow zone at Miura, which contained eelgrass beds, larvae occurred from January and were collected abundantly in March. The size, age, and hatch-date distributions suggested that late-hatched specimens stay longer than early-hatched specimens at this station. On the contrary, in the intertidal flats of the Kunomura River mouth larvae were rarely collected, but juveniles were collected in relative abundance from April. The distributions in the intertidal flats station suggested that specimens had migrated from another location and then resided in the intertidal flats. Spatial and temporal trophic variations increased remarkably with metamorphosis, and thus, the spatial differences in growth rate were considered in relation to the trophic diversity of prey items. Our results suggest that the nursery environment, nursery utilization pattern, and food habits of early life stages of L. latus show remarkable flexibility. From the similarity of these ecological aspects with L. japonicus , which is a closely related species, we suggest the important role of the interspecific competition to the realized niche difference between Lateolabrax congeners.     

茶跗线螨空间分布型及理论抽样技术研究

在田间调查的基础上,运用聚集度指标法、Iwao回归分析法及Talor幂指数法对茶跗线螨在茶园中的空间分布型、理论抽样数技术进行研究,同时根据1wao的理论抽样数模型确定了茶跗线螨的最适理论抽样数。结果表明：茶跗线螨在茶园中的空间分布为聚集分布,基本成分为个体群,个体间相互吸引,个体群在茶园中呈聚集分布。同时其聚集程度随种群密度的增加而增强。根据各项聚集度指标得出茶跗线螨田间调查的理论抽样数公式为：N=t2/D2（12.557/m＋0.340）.本研究结果为茶园茶跗线螨预测预报及防治提供了科学依据。     

黄鳍鲷肌肉中弹性蛋白酶基因全长克隆及生物信息学

研究表明弹性蛋白酶(elastase, Ela)参与调控嗜水气单胞菌引起的细菌性溃疡病,对控制鱼类养殖中免疫疾病有重要作用。本研究根据已报道脊椎动物的Elas基因序列设计特异性引物,通过RT-PCR和RACE技术克隆获得黄鳍鲷Ela基因(AlEla)cDNA序列全长,并对其进行生物信息学分析。结果显示,AlEla基因全长为946 bp,包含807 bp的开放阅读框,编码269个氨基酸,含有16个氨基酸信号肽的亲水性稳定膜外蛋白,定位于细胞外基质,具有3个O-糖基化和15个磷酸化的潜在位点。编码的成熟AlEla蛋白预测相对分子质量27 509 u,等电点为6.05。氨基酸序列同源性比对发现,AlEla与鲷和鲆的Elas2的同源性为84.76%～99.26%,处于系统进化树上同一分支,表明它们的亲缘性相近。AlEla具有Elas的保守结构,如Tryp-SPc结构域、丝氨酸蛋白酶催化三联体、保守的半胱氨酸残基以及在C端含有GDSGGPL序列等,揭示该酶有丝氨酸蛋白酶的催化活性。对AlEla蛋白的二级结构分析显示,α-螺旋、β-转角、β-折叠和无规则卷曲所占的比例分别为17.84%、7.06%、24.54%和50.56%。三级结构分析推测α-螺旋和β-折叠对于AlEla蛋白的空间构象可能有着重要作用。本研究从黄鳍鲷肌肉中成功克隆AlEla基因并分析其生物信息学特征,为后续研究AlEla参与调控鱼类免疫疾病的机制提供理论基础。     

黄鳍鲷幼鱼对几种不同糖源的利用

本研究用来评价黄鳍鲷幼鱼对饲料中葡萄糖、麦芽糖、糊精、玉米淀粉和预糊化玉米淀粉的利用。本试验饲料为6种等氮(粗蛋白:45%,干重)等脂(粗脂肪:9%,干重)的半纯化饲料,其中对照组糖源为纤维素。每种饲料设3个平行。试验鱼初始体重为(3.57±0.13)g(平均值±均差)。试验鱼饲养在含18个水族箱的循环系统中。水温保持在(27±1)℃。试验周期为8周。本试验用来评价黄鳍鲷幼鱼对饲料中不同糖源利用的指标为生长指标、饲料效率、蛋白质效率和肝脏的6-磷酸葡萄糖脱氢酶、苹果酸脱氢酶、异柠檬酸脱氢酶和葡萄糖-6-磷酸脱氢酶。试验结果表明,黄鳍鲷幼鱼体增重、特定生长率、肝体比、肠系膜脂肪体比、饲料效率、蛋白质效率、肝脂肪合成有关酶活性和全鱼、肌肉、肝脏组成均受到饲料中不同糖源的显著影响。预糊化玉米淀粉和麦芽糖组比其它糖源组显著具有更好的体增重和特定生长率,但与对照组没有显著性差异。黄鳍鲷幼鱼生长和体增重与饲料中糖源的复杂性没有相关性。饲喂预糊化淀粉和对照饲料鱼的饲料效率和蛋白质效率显著比其它组高。饲料中糖的添加增加了黄鳍鲷幼鱼的肝体比,但对照组肝体比与糊精组,玉米淀粉组没有显著性差异。预糊化玉米淀粉组肠系膜脂肪体比比其它饲料组要高。结论:基于体增重和特定生长率为指标,饲料中添加25%预糊化玉米淀粉和麦芽糖可以提高黄鳍鲷幼鱼的生长。另外,玉米淀粉预糊化显著提高了黄鳍鲷对玉米淀粉的利用。     

Allozyme variation and stock structure in the black bream, Acanthopagrus butcheri (Munro) (Sparidae) in southern Australia: implications for fisheries management, aquaculture and taxonomic relationship with Acanthopagrus australis (Günther)

An investigation of allozyme variation at 32 loci in the black bream, Acanthopagrus butcheri (Munro), and the yellowfin bream, Acanthopagrus australis (Günther), revealed heterozygosities (H) equal to 0.035 and 0.065, respectively, and polymorphism (P_0.95) equal to 0.067 and 0.200, respectively. The genetic data confirm the very high level of genetic similarity previously found between the two species, but nevertheless also support their recognition as separate species. The finding of only limited allozyme differentiation at three polymorphic loci amongst six black bream samples from south-eastern Australia is consistent with the existence of a single panmictic population in this region. This would require that adult black bream have a greater capacity to survive in near-shore marine environments than previously realised and that dispersal between estuaries is more extensive than was shown by tagging studies. In contrast, significant differences were found at two loci between black bream from south-eastern Australia and a sample from south-western Australia. The degree of genetic divergence between stocks in south-eastern and south-western Australia suggests that only local brood stock should be used for aquaculture or re-stocking as a precaution until further investigations with DNA-based techniques are conducted. The genetic divergence detected supports separate management for populations in Western Australia and Victoria.