养殖密度对半滑舌鳎成鱼生长的影响

采用单因素试验方法,研究了不同养殖密度对半滑舌鳎生长的影响。试验设置400、500、600尾,池三种养殖密度梯度,选择同源、同批次且体重均为600g左右的半滑舌鳎成鱼在闭合式循环养殖系统中养殖153d。结果表明：不同养殖密度对半滑舌鳎体重的增长有显著影响（P〈0．05）,低密度组、中密度组和高密度组半滑舌鳎的体重平均增长量分别为671．35g、650．94g、474．07g,高密度组显著低于低、中密度组（P〈0．05）。随养殖密度的增大,半滑舌鳎的生长呈现减慢的趋势,并且出现了生长离差。分析表明,500尾,池的乔殖富度在实际养殖生产中较为适宜。结果提示,养殖密度是影响半滑舌鳎生长的一个重要因素,过高的密度会抑制半滑舌鳎的生长。     

半滑舌鳎(Cynoglossus semilaevis) c-Jun基因的克隆及免疫应答分析

半滑舌鳎(Cynoglossus semilaevis)AP-1家族转录因子c-Jun基因(Jun proto-oncogene)及其在免疫应答中的作用尚无报道.本研究根据半滑舌鳎转录组数据库中预测的c-Jun序列,通过RACE技术和PCR扩增方法获得了半滑舌鳎c-Jun基因cDNA全长2093 bp,CDS区域共981 bp,编码326个氨基酸,5'UTR区域377 bp,3'UTR区域735 bp.SMART分析显示,C-JUN蛋白具有2个结构域:AP-1家族典型结构域Jun,以及高度保守的亮氨酸拉链结构域(BRLZ).经蛋白多序列同源比对、系统进化树分析,发现半滑舌鳎c-Jun与虹鳟(Oncorhynchus mykiss)c-Jun亲缘关系最近.实时荧光定量PCR分析显示,c-Jun基因在半滑舌鳎不同组织中普遍表达,在卵巢中表达量最高.鳗弧菌(Vibrio anguillarum)人工感染半滑舌鳎后,c-Jun基因在肝脏、脾脏、头肾、小肠、鳃、血液中表达量都出现不同程度上调,其中,鳃中变化最明显:感染12h后表达量达到0h时的13.20倍.使用LPS、PGN、PolyI:C和WGP病原模拟物刺激半滑舌鳎外周血淋巴细胞,结果显示,WGP诱导c-Jun基因上调表达,而LPS与PolyI:C均下调基因表达.以上实验结果表明,c-Jun基因在半滑舌鳎的免疫防御中发挥重要作用.     

Effect of taurine enrichment in rotifer (Brachionus sp.) on growth of larvae of Pacific bluefin tuna Thunnus orientalis (Temminck & Schlegel) and yellowfin tuna T. albacares (Temminck & Schlegel)

To investigate the dietary effect of taurine on the larval stage of tuna species, Pacific bluefin tuna (PBF) and yellowfin tuna (YFT), larvae were reared until 16 days after hatching (dAH) and 14 dAH, respectively, and replicate samples were fed either non‐taurine‐enriched rotifers (T‐0) or rotifers enriched with 800 mg taurine L^?1 (T‐800). Most PBF and YFT larvae were at the preflexion stage until 7 and 8 dAH, and there were no differences in the growth performance and total protein content of larvae between the T‐0 and T‐800 groups (t‐test; P > 0.05). Thereafter, however, for larvae of both species, these parameters in the T‐800 group significantly increased with enhanced notochord development compared to those in T‐0 group (t‐test; P < 0.05). Except for the RNA content in PBF larvae, there were no significant differences in changes of DNA and RNA content with larval growth between the T‐0 and T‐800 groups, but both PBF and YFT larvae showed increased protein DNA^?1 and protein RNA^?1 ratios in the T‐800 group compared to the T‐0 group after notochord flexion. This indicates that taurine is an important nutrient for the rapid growth of early stage PBF and YFT larvae, and we conclude that the growth improvement of PBF and YFT larvae by dietary taurine supplementation is due to the increase in protein synthesis efficiency after notochord flexion.     

高寒地区红豆草苜蓿不同栽培模式生产性能比较研究

在甘肃省甘南州合作市那吾乡高寒牧区,进行了甘肃红豆草和阿尔冈金紫花苜蓿单播和混播模式下的生产性能比较试验,结果表明:甘肃红豆草和阿尔冈金苜蓿混播是高寒牧区建立优质多年生豆科牧草人工草地的最佳技术模式,其次为单播红豆草,单播苜蓿产量最低.混播第2年干草产量达到12 136 kg/hm2,分别比单播红豆草和单播苜蓿提高14...     

Relationships among yellowfin and skipjack tuna, their prey-fish and plankton in the tropical western Indian Ocean

Stomach contents of yellowfin (Thunnus albacares) and skipjack (Katsuwonus pelamis) tuna caught by trolling and purse seining in the tropical western Indian Ocean, together with those of the prey-fish found in their stomachs, have been analysed. Epipelagic fish are the main prey of these tunas, whereas no vertically migrating fish, which inhabit subsurface layers at night, have been found in their stomachs. These tunas are thus considered day-feeders. Purse-seine-caught tunas, which belong to large schools, have a much higher number of prey-fish in their stomachs than tunas caught by trolling on small schools. Similarly, prey-fish from purse-seine tunas have a much higher number of plank-tonic prey in their stomachs than those from troll-caught tunas. Therefore, these tunas adopt a wandering strategy in small schools when food resources are scarce and form large schools when they are abundant. The planktonic organisms found in the stomachs of prey-fish are described by taxa and sizes; they represent the fraction of the planktonic biomass actually supporting the stock of tuna. Size ratios between the three links tuna-prey-fish-plankton are very high, suggesting that these tunas benefit from a short food chain which is probably efficient from the energetic point of view.     

Estimation of the period sensitive for the development of abnormal morphology in brown sole <Emphasis Type="Italic">Pseudopleuronectes herzensteini</Emphasis> fed live food enriched with docosahexaenoic acid

The aim of the present study was to clarify the effect of a feeding regimen of live food enriched with docosahexaenoic acid (DHA) on the rates of abnormal morphology in larval brown sole Pseudopleuronectes herzensteini. Live foods were enriched with oil emulsion to produce both high-DHA and low-DHA content. Larvae in group 1 (control) were fed low-DHA-content live foods throughout the experiment. Conversely, larvae in group 2 were fed high-DHA live foods from 15 days post-hatching (dph), when larvae were D stage. Larvae in group 3 were fed high-DHA live foods from 25 dph, when larvae consisted mainly of E stage. The occurrence of normal morphology development in group 2 was significantly higher (P < 0.05) than those of groups 1 and 3, suggesting that normal morphology of brown sole is determined during the critical larval period (D–E stages).     

Characterization of Vibrio tapetis strains isolated from diseased cultured Wedge sole (Dicologoglossa cuneata Moreau)

The first isolation of Vibrio tapetis from Wedge sole (Dicologoglossa cuneata) is reported. The bacterium was recovered from ulcers of ailing cultured fish, from two different outbreaks occurred in spring 2005. The four isolates found (a200, a201, a204 and a255) were biochemically, genetically and serologically characterized and diagnosis was confirmed by PCR V. tapetis specific primers and multilocus sequencing analysis (MLSA). The isolates constituted a homogeneous phenotypic and genotypic group, being distinct to the already serological and genetic groups defined within the species. A virulence evaluation of the isolate a255 was also carried out; however this strain was unable to induce disease in fry and juvenile Wedge sole.