香鱼嗜水气单胞菌人工染病后血液生理生化指标变化

从患病香鱼的体腔液中分离获得嗜水气单胞菌病原,经培养稀释的菌液,腹腔注射人工感染健康香鱼,出现典型的出血症后,进行血液生理生化指标的测定。结果发现,病鱼红细胞数量为(1.21±0.08)×1012个/L,血栓细胞数量(189.00±5.19)×1012个/L,较健康香鱼红细胞[(2.41±0.16)×1012个/L]、血栓细胞[(380.0±20.00)×1012个/L]呈极显著降低(P0.01),血红蛋白含量呈显著减少(P0.05),而白细胞数量却显著增加(P0.05)。染病香鱼总蛋白为(47.56±2.63)g/L,健康鱼为(49.23±3.06)g/L,经检验无显著差异;而碱性磷酸酶、Cl-、Ca2+等3项血液生化指标值均呈极显著减少(P0.01),乳酸脱氢酶呈极显著增加(P0.01)。     

驼背鲈消化系统组织学与组织化学研究

采用形态解剖、组织学及组织化学方法,分别用HE和AB-PAS染色法对驼背鲈(Cromileptes altivelis)的消化系统进行了研究。结果表明:驼背鲈食道内表面分布较多宽大的粘膜褶;胃分为贲门部、盲囊部和幽门部,贲门部胃小凹和胃腺最多,盲囊部厚度最大;前、中、后肠粘膜褶丰富,后肠粘液细胞密度最大;幽门与前肠交界处有幽门盲囊10~13个,结构与前肠相似。食道,胃,前、中、后肠及幽门盲囊均以分泌中性粘多糖的Ⅱ型粘液细胞为主。驼背鲈消化系统的结构表现出与其肉食性习性相适应的特点。     

驼背鲈血细胞的超微结构

利用电镜技术对驼背鲈（Cromileptes altivelis）外周血细胞的超微结构进行了研究。结果表明,电镜下可区分6种类型的细胞：红细胞、粒细胞、单核细胞、淋巴细胞、血栓细胞和浆细胞。红细胞呈圆形或椭圆形,可见线粒体、少数囊泡;根据细胞中的颗粒形态大小和细胞核的形态,可将粒细胞分为4种类型：I型粒细胞、II型粒细胞、III型粒细胞和IV型粒细胞。单核细胞圆形,表面较平整,偶有伪足伸出,空泡多见;淋巴细胞的胞质少,仅在细胞核边缘处形成薄薄的一层,细胞器少;血栓细胞异染色质丰富,沿核膜呈带状分布,胞质中有较多大小不等的空泡和少量的线粒体;浆细胞中粗面内质网成层分布包绕在核周围。此外可见到嗜曙红细胞吞噬红细胞、血栓细胞成群聚集分布的现象。     

驼背鲈肝脏结构的光镜和透射电镜观察

采用HE、Mallory氏三色法、Heidenhain氏Azan染色,PAS反应,组织块银浸染方法,对组织切片染色处理,应用光学显微镜和透射电镜对驼背鲈肝脏的显微和超微结构进行了观察,结果表明驼背鲈肝组织中肝细胞界限不明显,不存在双核现象,有暗细胞和亮细胞之分,胞质中细胞器丰富,有大量的线粒体、内质网和溶酶体,高尔基体很难观察到,仅在胆小管和狄氏间隙的附近发现。此外,在肝血窦的附近观察到成纤维细胞、枯否氏细胞和贮脂细胞。肝组织中胆管数量众多包括肝叶中央胆管、支胆管、小叶间胆管和小叶内胆管,并且在中央静脉附近偶见辐射状排列的肝细胞索。     

驼背鲈线粒体细胞色素b基因的序列分析

采用PCR—DNA测序技术，对驼背鲈线粒体DNA细胞色素b（Cytb）基因全序列进行分析。获得长度为1141bp的Cytb基因片段，序列碱基组成平均是T为29．1％，C为32．3％，A为23．2％，G为14．0％，A＋T的碱基百分比总体上略大于C＋G，平均值分别是52．3％和46．3％。与其它鱼类相同基因片段碱基序列含量相似。在由核苷酸推导的氨基酸中，亮氨酸（Leu）所占的比例最高，为16．03％。     

不同养殖模式对驼背鲈生长的影响

采用相同的饵料,分别在工厂化流水车间和池塘的网箱中放养全长(13.50±0.88)cm,体质量(31.78±7.73)g的驼背鲈各500尾,1年后,车间养殖的驼背鲈全长增至(25.71±1.65)cm,体质量为(260.05±45.99)g;池塘养殖的驼背鲈全长为(26.89±1.90)cm,体质量为(330.00±44.91)g。结果表明,驼背鲈在池塘网箱中的生长速度快于在工厂化流水车间网箱中的生长速度(P0.05)。     

微卫星DNA鉴别克隆香鱼

实验应用微卫星DNA检测技术，分析了I至Ⅶ组共42尾香鱼的Pal-1*和Pal-2*两个基因座位的基因型。结果显示Ⅱ、Ⅲ、Ⅳ和Ⅶ组共22尾在两个基因座位上均为纯合，是基因型完全相同的克隆鱼，并且Ⅶ组l0尾为人工诱导成功的雌核发育二倍体，而I为混入本克隆的其它类型的香鱼；V组9尾为I与海产香鱼的子代；Ⅵ组10尾为Ⅱ或Ⅲ与海产香鱼的子代。     

Dietary ascorbic acid requirement of juvenile ayu (Plecoglossus altivelis)

To investigate dietary ascorbic acid (AA) requirement of juvenile ayu (Plecoglossus altivelis) weighing 1.27 ± 0.02 g, eight diets were formulated with graded levels (0, 20, 40, 80, 160, 320, 640 and 1280 mg AA kg^?1) of AA supplied as ascorbyl polyphosphate. Each experimental diet was fed to four‐replicate groups to apparent satiation three times a day for 8 weeks. At the end of the feeding trial, fish fed AA‐deficient diet showed visible AA deficiency signs and low survival. Based on the four‐parameter saturation kinetics model, the calculated AA requirement levels for each dose‐dependent response [weight gain, hepatic AA concentration, hydroxyproline (HyPro) concentration in skin and HyPro concentration in backbone] were 116, 226, 47 and 35 mg kg^?1, respectively. Based on the maximal growth performance, a level of 116 mg AA kg^?1 was recommended for commercial diet of juvenile ayu. To maintain tissue HyPro saturation and avoid AA deficiency symptoms, the minimum required dietary AA level was 47 mg kg^?1. Hepatic AA saturation was considered as the most stringent criterion for determination of AA requirement.     

Effects of dietary protein and lipid level on growth and body composition of juvenile ayu (Plecoglossus altivelis) reared in seawater

A 3 (protein levels, 380, 460 and 520 g kg^–1 diet) × 2 (lipid levels, 65 and 140 g kg^–1 diet) factorial experiment with three replicates was conducted. Weight gain, feed efficiency and daily feed intake were not significantly affected by dietary protein level, but were by dietary lipid level. Weight gains of fish fed 65 g lipid kg^–1 diet were significantly, or slightly, higher than for 140 g lipid kg^–1 diet at all protein levels. Daily protein intake was significantly affected by both dietary protein and lipid levels ( P  < 0.002). Daily lipid intake was not significantly affected by dietary protein level, but was by dietary lipid level ( P  < 0.001). Protein efficiency ratio was significantly affected by dietary protein level ( P  < 0.02), but not by dietary lipid level. Protein efficiency ratio tended to improve with the decrease of dietary protein level at the same lipid level. Moisture, protein and lipid contents of whole fish were significantly affected by dietary lipid level ( P  < 0.01). Increased dietary lipid did not improve growth or feed efficiency, but increased body fat deposition. It was concluded that the optimum dietary protein and lipid level for growth of juvenile ayu may be 380 and 65 g kg^–1 diet, respectively, when fish were fed to satiety three times daily in seawater.