不同生长期圆斑星鲽形态性状对体重影响的通径分析

圆斑星鲽(Verasper variegatus)作为中国鲽形目(Pleuronectiformes)养殖鱼类的重要代表种类,具有生长速度快,可食用部分多,肉质细嫩等特点。为了探究圆斑星鲽形态性状与体重的关系,本研究分别测定11月龄、14月龄和17月龄3个不同生长期圆斑星鲽的体重及全长(FL)、体长(BL)、体高(BH)、头长(HL)、头高(HH)、尾柄长(CL)、尾柄高(CH)、吻长(SL)共计8个形态性状,分别进行相关分析和通径分析,剖析形态性状对于体重的直接作用和间接作用;利用回归分析的方法,建立各个时期以形态指标为自变量,体重为因变量的最优线性回归方程。结果显示,1)不同生长阶段,影响体重的重点形态指标存在差异,影响11月龄圆斑星鲽体重的主要形态性状为体高和体长,14月龄阶段为全长、体高和头长,17月龄阶段为全长和体高;2)11月龄、14月龄和17月龄形态性状对体重(Y)的多元回归方程分别为:Y=-186.412+17.381XBH+10.517XBL,Y=-362.484+13.145XFL+20.172XBH+21.199XHL,Y=-816.147+24.121XFL+40.575XBH;3)除本研究所包括的形态指标外,体厚可能为另外一个影响圆斑星鲽体重的重要指标。本研究阐明了体重与形态指标间的相关关系,为圆斑星鲽的良种选育提供了生物学依据。     

鳜胃蛋白酶原基因cDNA全长的克隆与序列分析

利用RT–PCR和cDNA末端快速扩增法(RACE)克隆鳜(Siniperca chuatsi)胃蛋白酶原基因cDNA全长序列,并对该基因的结构特征和系统进化关系进行了分析。鳜胃蛋白酶原基因cDNA序列全长1367 bp,5′端非翻译区43 bp,3′端非翻译区187 bp,开放阅读框(ORF)1137 bp,共编码378个氨基酸。鳜胃蛋白酶原氨基末端存在信号肽和激活肽序列,序列中含有催化活性必需的2个天冬氨酸残基和构成二硫键的6个半胱氨酸残基。鳜胃蛋白酶原氨基酸序列与其他脊椎动物胃蛋白酶原氨基酸序列的同源性为59.9%～91.2%,表明胃蛋白酶原基因在脊椎动物的长期进化中比较保守。鳜胃蛋白酶原基因的成功克隆不仅为进一步研究该基因的时空表达奠定基础,而且为鱼类胃蛋白酶原的分子特征和进化提供了新的资料。     

The impact of temperature on nitrification rate in fixed film biofilters

The impact of temperature on nitrification rate was evaluated in this study through experimental tests, mathematical modeling and sensitivity analysis. The results show that the impact of temperature on fixed film nitrification rate is less significant than that predicted by the van't Hoff–Arrhenius equation. In a fixed film biofilter, the impact of temperature on nitrification rate due to DO (dissolved oxygen) limitation is different from that due to TAN (total ammonia nitrogen) limitation. Sensitivity analysis indicated that a temperature increment at 20 °C resulted in nitrification rate increase of 1.108% per °C and 4.275% per °C under DO and TAN limited conditions, respectively. Diffusion mass transport plays an important role in fixed film nitrification processes. Consequently, the effect of temperature on nitrification rate due to bacterial growth rate change in fixed film processes is greatly reduced compared with that of suspended growth processes. When oxygen is limited, the decrease in saturation DO concentration as temperature increases results in a negative temperature impact upon the nitrification rate.     

黄河陕西段浮游动物群落结构时空动态及与环境因子的关系

为了解黄河陕西段浮游动物群落结构时空动态及其与环境因子的关系,更好地进行水资源和水生态保护,于2013年7月至2014年5月在该河段设定了7个研究断面,对其浮游动物群落结构进行了4次调查,同时对15项水环境指标和同期浮游植物群落结构进行了监测和调查。结果显示,共检出浮游动物20种,其中原生动物4种,轮虫10种,枝角类3种,桡足类3种,夏季浮游动物种类数最多,为16种,冬季最少,仅有5种;浮游动物丰度和生物量变化范围分别为25～3 800个/L和0.00001～1.24 mg/L,春夏较大、秋冬较小,空间上整体呈现上游低、下游高的分布趋势;浮游动物优势种为小旋口虫(Spirostomum minus)、萼花臂尾轮虫(Brachionus calyciflorus)、前节晶囊轮虫(Asplanchna priodonta)、曲腿龟甲轮虫(Keratella valga)、裂足臂尾轮虫(Brachionus diversicornis)和微型裸腹溞(Moina micrura);浮游动物Shannon-Wiener指数均值为0.65～0.83,Margalef指数为1.08～2.49,Pielou均匀度指数为0.39～0.60;7个断面的浮游动物群落结构和环境因子的典范对应分析(CCA)结果表明,影响浮游动物丰度的主要环境因子为化学需氧量(COD)、总氮(TN)、pH值和重金属铬(Cr)。     

三疣梭子蟹几丁质酶基因的克隆及其在蜕皮过程中的表达分析

为探究几丁质酶基因在三疣梭子蟹蜕皮过程中的生理作用,本研究通过转录组测序和RACE技术克隆了三疣梭子蟹几丁质酶基因（PtChi）cDNA全长（登录号：KF914663）,并通过荧光定量PCR（qRT-PCR）技术研究了该基因在三疣梭子蟹不同组织及不同蜕皮阶段的表达情况。结果表明,(1)PtChi基因cDNA全长2 200 bp,包括5’非编码区（5’-UTR）16 bp、3’-UTR 714 bp和开放阅读框1 470 bp,编码489个氨基酸,预测分子量和等电点为53.97 ku和4.76。(2)BlastP 结果显示,PtChi推导氨基酸序列与已知甲壳动物Chi-3的一致性为61%~96%,系统进化树分析表明PtChi与其他甲壳动物Chi-3聚为一支。(3)qRT-PCR结果显示PtChi基因在C期三疣梭子蟹肝胰腺中表达水平最高,胃、大颚器、心脏和眼柄中PtChi-mRNA表达水平依次降低,在其他组织中PtChi-mRNA表达量最低,且表达水平无显著差异。(4)不同蜕皮阶段,PtChi在肝胰腺、肠、胃和大颚器4种组织中的表达变化模式有所不同,肝胰腺中PtChi-mRNA表达水平在AB期最高,C期最低,暗示PtChi可能参与三疣梭子蟹蜕皮后期对病原体的免疫防御;肠中的PtChi-mRNA表达水平在E期最高,C期最低,推测PtChi参与蜕皮过程中肠道围食膜的分解和免疫功能;胃中PtChi表达水平在C期最高,暗示其参与了食物消化。以上结果表明,本研究克隆的PtChi可能为甲壳动物Chi-3型,其准确生理学功能及其在蜕皮过程中的调控机制有待进一步深入研究。     

洋河水库流域面源污染负荷空间分布特征

为探究洋河水库流域面源污染的空间分布特征,基于气象、土地利用、农业管理等数据资料,计算2013年洋河水库流域农村生活污水、固体废弃物、畜禽养殖流失、化肥流失、水土流失污染和城镇地表径流污染6种污染来源中总氮（TN）、总磷（TP）、氨氮（NH3-N）、化学耗氧量（COD）4个污染物指标排放负荷,并通过GIS空间分析反映流域内的污染分布情况。结果表明,畜禽养殖污染物排泄量对研究区污染负荷贡献最大,年产生量约51621.34 t,入河量2961.52 t,占比分别为92%和85%;从总量上看,洋河水库流域的面源污染负荷分布在西洋河支流区域范围;单位面积负荷量最大的区域是迷雾河支流区域范围。据此确定了西洋河和迷雾河流域为今后洋河水库流域面源污染重点治理的区域,此研究结果可为洋河水库流域面源污染防治及消减提供理论依据。     

Improvement in recruitment of Japanese sardine with delays of the spring phytoplankton bloom in the Sea of Japan

To evaluate the impact of temporal variation of primary productivity on the recruitment of Japanese sardine (Sardinops melanostictus) in the Sea of Japan, the phenology of sea surface phytoplankton abundance was estimated from 8 day multiple satellite (SeaWiFS, MODIS‐Aqua, MERIS, and VIIRS) derived sea surface chlorophyll (SSChl) a concentrations from January 1998 to December 2015. Because relationships between SSChl a and in situ chlorophyll a concentrations were significantly different among periods based on the satellite combinations used, maximum and minimum SSChl a concentrations of 1 year were relativized as 1 and 0, respectively. Spatio‐temporal variation of relativized SSChl a concentrations was determined by using empirical orthogonal function (EOF) analysis. Scores in the first EOF mode denoted the basin‐scale variations of SSChl a concentrations in the Sea of Japan, and the major peak from the end of February to the end of May displayed the spring bloom. The logarithm of recruitment per spawner (LNRPS) for sardine was positively affected by delays in the start and end dates of the spring phytoplankton bloom. The delay of the date of the lowest sea surface temperature contributed to the delay of the end of the spring bloom during the period 1998–2015 and elevated the LNRPS during the period 1982–2015. Sardine spawns in the southern Sea of Japan from April to May, hence, delays of the spring bloom prolonged its overlap with sardine larval periods, and thus improved the recruitment of Japanese sardine in the Sea of Japan.     

Identification and phylogenetic analysis of Babesia parasites in domestic dogs in Nigeria

The present study examined the presence of Babesia parasites in 104 domestic dogs in Nigeria. Sequentially, Babesia parasites infecting domestic dogs underwent genetic and phylogenetic analyses. The results of nested PCR based on the Piroplasmida 18S rRNA gene illustrated that 13.5% (14/104) of the samples were positive. The obtained positive samples determined the nucleotide sequences of the 18S rRNA genes. In the genetic and phylogenetic analyses, four of five nucleotide sequences were similar to Babesia canis rossi, and one sample exhibited a close similarity to a Babesia sp. isolated from a raccoon in Hokkaido, Japan. The present study revealed the widespread presence of B. canis rossi among domestic dogs in Nigeria.     

农网配电线路损耗分析

配电网起着输送和分配电能的作用,线路损耗给供电企业造成很大的成本投入,降低能源的利用率。分析配电网线路损耗的原因,提出降低线路损耗的具体措施,以期为配电网节能降耗、安全运行提供参考。     

沥青混凝土桥面铺装早期损坏原因分析

对钢筋混凝土桥柔性桥面铺装的早期病害及其原因进行了分析与研究,总结了当前国内桥面铺装结构分析的主要方法,提出了用有限元分析需要注意的一些问题,指出了今后的主要研究方向.