Possible use of Brachionus plicatilis (O.F. Müller) as food for freshwater cyprinid larvae

The use of the euryhaline rotifer Brachionus plicatilis as food in raising freshwater fish larvae was tested with the Japanese ornamental carp, koi (Cyprinus carpio) and a breed of bait fish (Carassius sp.).Providing rotifers in addition to granulated food improved significantly the growth rate of fish larvae and also, in the case of ornamental koi, their survival. Growth rate in terms of increase in length was found to fit a simple empirical formula similar to a power growth curve. The curve fits results obtained with bait fish (R²=0.85) better than those with Japanese koi (R²=0.76). The coefficients of growth for each treatment (β_i) were used to evaluate the contribution of rotifers to the larval growth. The improvement in growth was found to correlate with the quantity of rotifers, being higher with the larger quantity offered (2400 larva⁻¹ day⁻¹). In bait larvae, results obtained from measuring length were supported in weight measurements taken on day 8, but not by those recorded on day 11. Between day 8 and day 11, these larvae were fed on granulated food only.Preliminary results indicate that yeast-fed rotifers were superior to algae-fed ones when supplied to bait fish larvae in equal quantities, in addition to granulated food.     

Metamorphosis of larvae of Crassostrea virginica fed microencapsulated diets

This paper reports the results of two feeding experiments in which oyster larvae (Crassostrea virginica) were grown to metamorphosis on microencapsulated diets, and provides the first successful case of culturing oyster larvae to metamorphosis on an artificial diet. Five to 25% of the larvae fed microencapsulated diets grew to the “eyed” stage in 22–25 days. About 2–20% of these “eyed” larvae metamorphosed and settled and 25–40% of these settled larvae produced spat (> 0.05 mm). Two concentrations of two microencapsulated diets were tested; results indicated that diet concentration affects larval growth and development.Microcapsules with capsule walls made of a lipid mixture containing ethyl cellulose and stearic acid improved the retention of water-soluble components. Capsules were more stable at low temperature (5°C) than at higher temperatures (22 and 28°C). Inclusion of lipid algal extract in gelatin-acacia capsules promoted better growth of larvae than those not containing the algal extract. This suggests that attractants or phagostimulants could play an important role in microencapsulated diets.     

兔病毒性出血症病毒基因组3''端非编码区的分子克隆及生物信息学分析

采用3′RACE方法对兔病毒性出血症病毒(RHDV)JX／CHA／97株基因组3′端全序列进行了扩增、克隆和测序,并利用ONAstar和DNAman软件分析了RHDV JX／CHA／97株与各参比毒株3′NCR的序列同源性,用RNA structure软件对3′NCR的二级结构进行了预测和分析。结果表明,所扩增的目的基因片段长1500 bp,包括部分VP60基因序列、ORF2基因、3′端非编码区(3′Non Coding Region,3′NCR)和poly(A)尾巴,其中 3′NCR位于ORF2终止密码子TAG之后,长59 bp,poly(A)至少含有27个A;3′NCR序列具有较高的同源性 (93．5％-100％);3′NCR二级结构可以形成2个潜在的茎-环结构(SL1和SL2),其中SL2具有一定的保守性,其形状和形成位置与poly(A)尾巴的长度关系不大,但是SL1的结构和形成位置与poly(A)尾巴的存在与否密切相关,提示poly(A)尾巴与3′NCR高级结构的稳定性以及基因组复制有一定关系。     

The effect of nearly closed RAS on the feed intake and growth of Nile tilapia (Oreochromis niloticus), African catfish (Clarias gariepinus) and European eel (Anguilla anguilla)

One of the challenges that Recirculating Aquaculture Systems (RAS) are still facing is the risk that in RAS fish grow less than in flow-through systems due to the accumulation of substances originating from feed, fish or bacteria associated with the water re-use. The present study investigated whether RAS with high and low accumulation levels of these substances affect feed intake and growth of Nile tilapia Oreochromis niloticus, African catfish Clarias gariepinus, and European eel Anguilla Anguilla. One-hundred and twenty individuals of each species were used (start body weights: Nile tilapia 264.8 ± 8.3 g; African catfish 253.2 ± 2.1 g and European eel 66.6 ± 1.3 g). For a period of 39 days, growth and feed intake were compared between high and low accumulation RAS. HIGH accumulation RAS was designed for maximal accumulation of substances in the water by operating the system at nearly-closed conditions (30 L/kg feed/d), using mature biofilters and high feed loads; and (2) LOW accumulation RAS was designed to be a proxy for flow-through systems by operating at high water exchange rates (1500 L/kg feed/d), new biofilters and low feed load. HIGH accumulation RAS induced a reduction in feed intake (42%) and growth (83%) of Nile tilapia, as compared to systems that are a proxy for flow-through conditions. This effect was not observed in European eel and African catfish. The cause of this reduced feed intake and growth rate of Nile tilapia is still unclear and should be addressed in further studies.     

饲料中添加不同水平的维生素D3对草鱼幼鱼生长和体成分的影响

本文以酪蛋白和脱脂豆粕为蛋白源,糊精为糖源,玉米油和豆油为脂肪源的半纯化饲料为基础饲料,研究维生素D3对草鱼(Ctenopharyngodon idellus)幼鱼生长及体成分的影响。维生素D3共设0,100,200,500,1000,2000,3000 IU/kg 7个添加梯度,每一梯度设3个重复,每个重复放养60尾初始体质量(3.86±0.34)g的草鱼,在(26.9±3)℃的流水系统中养殖8周。结果显示:维生素D3对草鱼幼鱼增重率、特定生长率、饲料系数、存活率、体水分、粗蛋白质、粗脂肪含量和血清钙浓度没有显著性影响(P>0.05);对照组和添加100 IU/kg维生素D3的试验组中,草鱼幼鱼的粗灰分显著低于其它试验组(P<0.05);与对照组相比,饲料中添加维生素D3对全鱼钙磷含量、血清磷离子浓度以及碱性磷酸酶活性影响显著(P<0.05)。根据维生素D3对全鱼钙磷含量的影响,草鱼幼鱼饲料中维生素D3适宜的添加量为1000 IU/kg。     

半滑舌鳎促滤泡激素基因全长cDNA的克隆与组织表达分析

从半滑舌鳎Cynoglossus semilaevis Günther脑垂体中提取总RNA,利用RT-PCR和RACE技术首次克隆得到半滑舌鳎促滤泡激素（FSH）基因全长cDNA序列。半滑舌鳎FSHcDNA全长为541bp,开放阅读框为393bp,编码130个氨基酸（GenBank序列登录号：JQ277933）。发现一个N-糖基化位点：24～27NTT。与其他脊椎动物的FSH成熟肽氨基酸序列同源性比较表明,半滑舌鳎FSH与鲽形目和鲈形目鱼类FSH同源性为42％～49％,与鲤形目和高等脊椎动物FSH同源性为27％～319/5。用MEGA4．0软件构建了NJ树,获得的进化树表明,半滑舌鳎FSH与其他鱼类FSH聚类,亲缘关系较近。实时荧光定量组织表达分析表明,FSHmRNA除在垂体中大量表达外,其他组织也有表达,尤以脑、性腺表达量较高。半滑舌鳎FSHmRNA在垂体以外组织中的广泛表达,暗示FSH可能具有广泛的生理功能。     

国内虹鳟代表性养殖群体的高通量SNP芯片检测及遗传分析

本研究旨在对国内虹鳟(Oncorhynchus mykiss)代表性养殖群体开展全基因组水平的遗传评估。利用57K单核苷酸多态性(single nucleotide polymorphism,SNP)芯片,检测了来自不同地域的6个虹鳟养殖群体样本共计48尾,包括黑龙江虹鳟、黑龙江金鳟、四川虹鳟、四川金鳟、北京虹鳟和北京金鳟,共获得有效SNP位点50201个,在中国虹鳟中的多态比例达到97.7%,表明该芯片虽然基于美国和挪威虹鳟群体设计,但对中国群体同样具有良好的适用性。各群体最小等位基因频率均值为0.240~0.267,与国外主流养殖群体相近,黑龙江虹鳟、四川虹鳟和北京虹鳟群体内遗传多样性丰富,多态位点比例为83.6%~84.9%,与国外主流养殖群体相近,而黑龙江金鳟、四川金鳟和北京金鳟,多态位点比例相对较低,在60.2%~76.9%范围内。应用6个中国虹鳟群体和2个美国虹鳟群体数据开展系统发育分析、主成分分析和群体遗传结构STRUCTURE分析,结果显示8个群体可分为3个祖源类群,其中3个金鳟群体为遗传联系较紧密的一个类群,黑龙江虹鳟和北京虹鳟为一个类群,而四川虹鳟与2个美国虹鳟群体为一个类群,部分中国养殖群体中有显著离群个体存在,表明群体遗传背景不均一。本研究表明,高密度SNP芯片在我国虹鳟养殖群体遗传分析中具有广泛的应用前景,能够为种质资源评估、本土化良种培育、制种和引种工作提供基因组水平的参考信息。     

基于县域单元的我国水稻生产时空动态变化

水稻是我国最重要的粮食作物之一, 阐明近几十年来水稻的时空动态变化特征, 对于优化水稻布局、促进水稻生产的可持续发展具有重要意义。本研究基于1985年以来的县域水稻生产数据, 分析了我国水稻产量、面积和单产的时空动态变化特征和水稻生产重心迁移轨迹, 在此基础上量化了水稻面积和单产对总产的贡献度。结果发现, 我国水稻产量变化以49年周期为主, 21年为辅, 面积变化周期为26年, 单产变化周期为60年; 1985—2015年间, 在水稻种植区域内, 近50%地区产量上升, 约70%播种面积减少, 80%以上区域单产增加; 我国水稻产量、面积重心分别向东北方向迁移229 km和225 km, 而东北稻作区产量、面积重心分别向北偏东方向迁移238 km和242 km; 我国水稻生产主导因素中单产占比由56.3%下降至28.3%, 面积由34.7%上升至63.1%。结果表明, 全国各稻作区单产提升、东北早熟单季稻区面积增加、华中双单季稻区和华南双季稻区面积减少是我国水稻种植面积变化的主要特征。因此, 合理布局我国水稻的种植面积和持续提高的水稻单产是稳定和提升我国水稻产量的主要措施, 充分利用光热资源、提高机械化程度和比较效益是促进我国水稻生产发展的关键途径。     

Bacillus subtilis SPB1 biosurfactant: Production optimization and insecticidal activity against the carob moth Ectomyelois ceratoniae

Bacillus subtilis SPB1 was shown to produce a lipopeptide biosurfactant. The insecticidal activity of this biosurfactant was evaluated against Ectomyelois ceratoniae Zeller, a moth pest of stored dates in Tunisia. The LC₅₀ and LC₉₀ values after six days of contact were 152 μg/g and 641 μg/g, respectively. To promote an economical production of this highly effective bioinsecticide, statistical experimental designs and response surface methodology were employed to optimize the concentrations of agro-industrial residues and humidity, for lipopeptide biosurfactant production by B. subtilis SPB1 under solid state fermentation. The optimal medium leading to a production yield near to 28 mg of crude lipopeptide preparation per g of wet solid material was composed of a mixture of 4.34 g of tuna fish flour and 5.66 g of potato waste flour with a moisture content of 76%.