猪戊型肝炎研究进展

我国为猪戊肝发病率比较高的地区之一,曾发生戊型肝炎的多次爆发或大面积的流行,并可传播给人类,与人的生活密切相关,回顾猪戊肝炎病毒结构特征研究,流行方式、临床症状及病理变化等,为猪戊型肝炎未来的诊断提供参照。文章收集国内外文献资料查询酶联免疫吸附试验(ELISA)、免疫电子显微镜(IEM)、免疫荧光实验(IFA)、荧光定量RT-PCR法对防治猪戊型肝炎进行研究,对其作了分析、比较和汇总。为猪戊型肝炎病毒提供了有效诊断方式以及防御措施。对猪戊型肝炎仍需养殖者认真护理,一旦确诊为动物戊型肝炎,应立即对其进行隔离治疗。     

三种计算机辅助工程软件在农业机械虚拟设计中的组合运用

阐述了Pro/E(三维建模软件)、ADAMS(动力学仿真分析软件)和ANSYS(有限元分析软件)各自的特点,并以水稻直播机的设计为例,详细介绍了三种软件联合运用的方法和步骤。     

基于ADAMS的勺式玉米精密排种器的动态仿真

在利用Pro/E软件建立勺式玉米精密排种器三维实体模型的基础上,将排种器实体模型导入机械系统仿真分析软件ADAMS中进行仿真分析.在仿真分析过程中,对排种器施加了与实际播种过程一致的运动约束和受力约束.仿真结果直观地显示了排种器工作时所完成的种子充种、清种和投种过程,并给出了排种器转角和种子受力变化的曲线,为排种器的改进设计提供了参考依据.     

基于Pro/E的发动机曲柄连杆机构运动仿真

通过对曲柄连杆机构的运动分析,得到活塞的运动方程。运用Pro/E对发动机单体进行三维实体建模与装配;运用Pro/E的Mechanism模块对其进行运动学分析,得到可视化的发动机单体运动过程图形;同时,与运用MATLAB进行的数值模拟结果进行了比较。     

检测马西尼罗热病毒抗体的重组E蛋白-ELISA的建立

摘要：重组质粒pET-E转化宿主菌 BL21，经1.0mmol/L IPTG 诱导，外源基因以包含体的形式获得高效表达。通过Western blotting 检测证明表达产物具有良好的抗原性。以纯化后表达产物作为诊断抗原包被酶标板建立了检测WNV抗体的间接ELISA方法。结果表明，抗原的最佳稀释度为8.6ug/mL，血清的最佳稀释度为1：100，待检血清阳性标准初步定为：OD490nm＞2.1×OD490阴性。用此方法检测了450 份血清样品，结果全为阴性。     

Genetic analysis of grain mold resistance in white seed sorghum genotypes

Grain molds in rainy season sorghums can cause poor grain quality resulting in economic losses. Grain molds are a major constraint to the sorghum production and for adoption of the improved cultivars. A complex of fungi causes grain mold. Information on genetics of grain mold resistance and mechanisms is required to facilitate the breeding of durable resistant cultivars. A genetic study was conducted using one white susceptible, three white resistant/tolerant sources, and one colored resistant source in the crossing programme to obtain four crosses. P₁, P₂, F₁, BC₁, and BC₂, and F₂ families of each cross were evaluated for the field grade and threshed grade scores, under sprinkler irrigation. Generation mean analyses and frequency distribution studies were carried out. The frequency distribution studies showed that grain mold resistance in the white-grained resistance sources was polygenic. The additive gene action and additive × additive gene interaction were significant in all the crosses. Simple recurrent selection or backcrossing should accumulate the genes for resistance. Epistasis gene interactions were observed in colored resistance × white resistance cross. Gene interaction was influenced by pronounced G × E. Pooled analysis showed that environment × additive gene interaction and environment × dominant gene interaction were significant. The complex genetics of mold resistance is due to the presence of different mechanisms of inheritance from various sources. Evaluation of segregating population for resistance and selection for stable derivatives in advanced generations in different environments will be effective.     

Regression analysis of genotype x environment interaction in sweet potato

Summary Two experiments, each involving a set of 10 sweet potato clones, were conducted for three years at 4 sites (Ekona, Ebolowa, Nkolbisson, and Bambui Plain) in Cameroon. Data obtained were subjected to analysis of variance to determine the presence of genotype x environment (G x E) interactions, and to regression analysis to assess the performance of clones across anvironments. Environments were assessed in two ways: (i) the mean response of all clones (dependent assessment), and (ii) the average performance of a different set of clones (independent assessment).The first experiment (Expt 1) produced higher yields but had fewer stable clones than the second (Expt 2).The analysis of variance revealed that the clones interacted significantly with environments for all traits.The study has identified high yielding and stable sweet potato clones for distribution to growers in the major areas of cultivation in the tountry. Despite slight differences in numbers of clones judged stable by the various regression indices in the two methods of environmental assessments, the rankings of clones on the basis of their linear regression coefficients were similar. In a developing country like Cameroon, with limited resources and where sophisticated equipment for obtaining physical or biological measures of the environment may be lacking, the mean performance of genotypes may still be the most reliable measure of environment in evaluating the stability of performance of crop cultivars.     

高压静电场杀菌效果研究

利用自行研制的直流高压静电场装置针对大肠杆菌进行了杀菌实验研究,结果表明,电压、处理时间是影响电场杀菌作用的主要因素.在极板间距D=3 cm,电压20 kV,处理时间45 min的务件下,大肠杆菌的致死率达到98.7%.     

Genetic analysis of tocopherol content and composition in winter rapeseed

The improvement of the nutritional value and the stability properties of rapeseed oil is partly hindered by the lack of information on the genetic control of tocopherols. The objectives of this investigation were to characterize the inheritance of tocopherols by using two factorial mating designs (North Carolina Design II, NC_II). The first (NC_II‐A) was produced with two sets of nine parents each, one selected for high and the other for low total tocopherol contents. In the second (NC_II‐B), each set consisted of six parents, which were either high or low for the α/γ‐tocopherol ratio. Parents and F₁ hybrids from both experiments were tested under field conditions in 1998 and 1999 using a completely randomized design with two replications. Only small differences were detected between mean values of parents and F₁ hybrids. General combining ability (GCA) variation in both experiments was highly significant (P < 0.01) for all tocopherol traits. Significant specific combining ability (SCA) effects were only detected for a‐tocopherol in NC_IIA and therefore for the α‐/γ‐tocopherol ratio. These results indicate that tocopherol contents and composition are controlled mainly by genes with additive effects. Interactions of F₁ hybrids and GCA effects with the environment were significant for only tocopherol contents and not for tocopherol composition.