家蚕基因组中SnoRNA（Box C/D）的生物信息学分析与研究

【目的】探索生物信息方法在家蚕基因组 snoRNA 预测中的应用，了解snoRNA在家蚕基因组的分布和结构特征。【方法】利用已有和自行设计的生物信息工具对家蚕基因组中Box C/D snoRNA 进行预测和手工校正。【结果】获到家蚕基因组中的 70 个 snoRNA 和 56 个推测的甲基化位点。结构分析发现 D′box 和末端茎环结构的不保守性；分析 snoRNA 在基因组上的分布，未发现普遍的成簇分布的现象，且内含子和基因间隔区的 snoRNA 数目接近；预测得到的家蚕 Box C/D snoRNA 与已报道果蝇 Box C/D snoRNA进行相似性分析，表明两个物种的 Box C/D snoRNAs 在一级结构上存在较大的差异。【结论】基于结构特征预测的方法有利于逐步揭示家蚕基因组中存在的 snoRNA 信息；但与家蚕同源关系较近的物种，其 snoRNA 在序列上可能有较大变化，故可能不适合以序列同源来对其进行预测。     

The extent and pattern of Eucalyptus regeneration in an agricultural landscape

The process of natural regeneration is critical for sustaining remnant native vegetation and the ecosystem services it supports. We quantified the extent and pattern of Eucalyptus regeneration within remnant vegetation in a fragmented agricultural landscape in south-eastern Australia. Eucalyptus regeneration was absent at 42% of sites. Using an information-theoretic approach, we explored 13 possible models of Eucalyptus regeneration across multiple scales. The explanatory variables in the four models with empirical support (and their summed Akaike weights) were: grazing intensity (1.0), native ground cover (0.99), remnant area (0.83), tenure (0.67), canopy cover (0.21) and vegetation type (0.11). Averaging across these four models we predicted that the probability of Eucalyptus regeneration was highest (0.95) in relatively unmodified remnant native vegetation, that is, remnant vegetation on public land where grazing was light and the understorey was dominated by native plants. In contrast, the predicted probability of Eucalyptus regeneration was lowest (0.12) in small remnants on private land where grazing was heavy. Our results suggest that a large proportion of all remnant native vegetation in this landscape will disappear under existing land management and farming practices. Reducing grazing pressure within intensively grazed remnants appears to be the single most effective management intervention that will mitigate this threat. This will require a shift in conservation priorities away from large, intact remnants where regeneration does not appear to be affected, to poorer quality remnants—often small remnants or scattered trees—where regeneration is typically absent.     

一种快速鉴定Femu2p C2H2蛋白与TTGGGT BOX相互作用的EMSA实验法

分析了电泳迁移率（EMSA）技术研究进展及其优缺点,并在此基础上进行实验方法改进.通过检测TTGGGT Box及其突变体与Femu2p-C2H2蛋白的相互作用,探索并总结出一套快速、简便、经济适用的EMSA实验法,该方法可用于DNA结合蛋白和其相关的DNA结合序列相互作用的特异性竞争反应分析.     

Dormant Season Grazing: Effect of Supplementation Strategies on Heifer Resource Utilization and Vegetation Use

Grazing dormant forage under low-input heifer development strategies typically exposes cattle to low-quality forage. Protein supplementation while grazing dormant range can enhance heifer growth and reproductive performance. We examined resource utilization of heifers and the effects of dormant season grazing on residual vegetation characteristics under two supplementation management strategies. Approximately 100 weaned composite heifer calves were randomly selected and placed into one of two supplementation treatments in each of 2 yr, one receiving a free access 62% crude protein self-fed concentrate and the other receiving a daily hand-fed 20% crude protein cake. Grazing occurred from December (2015 and 2016) through March (2016 and 2017). Thirty transects were randomly located within each pasture for measuring vegetation quality and structure before and after grazing. Daily space use and behavior was evaluated for 21 individuals within each treatment using global positioning system (GPS) collars and resource utilization functions. Heifers supplemented with concentrated protein spent more time grazing per day than heifers supplemented with cake (6.92 ± 0.18, 6.24 ± 0.17 h). Relative use by heifers in the cake treatment was negatively related to horizontal distance from the supplement delivery site early to midwinter ($\stackrel{?}{\overline{\beta }}$ = ? 0.41 ± 0.16, ? 0.53 ± 0.17). Both treatments selected grazing locations relative to standing biomass of perennial grasses ($\stackrel{?}{\overline{\beta }}$ = 0.0005 ± 0.00004) and crude protein ($\stackrel{?}{\overline{\beta }}$ = 0.12 ± 0.007). However, resource selection was highly variable among individuals for both supplementation treatments. We found no treatment effects on pre-post grazing differences in residual cover of litter, grass, forbs and shrubs (P > 0.24). However, the time period when grazing occurred had an effect on residual vegetation conditions (P < 0.01). Our results indicate high levels of variability in grazing site selection by heifers, suggesting future research should incorporate individual animal measurements in an attempt to account for individual animal variability.     

A total-continuous portal vein fistula in gastrointestinal and toxicology research

A method for the total collection of portal vein blood over extended periods has been developed. The method has been applied in gastrointestinal toxicology research involving rats. The method facilitated quantitative recovery of portal vein blood for 120 min for measurement and identification of absorbed radiolabeled components derived from a toxic lipphilic pesticide placed in the lumen of the small intestine. The method can be applied to any substance—nutrient, anutrient, xenobiotic chemical, or endocrine factor—absorbed into the portal vein from the gastrointestinal tract. The method (a) provides for collection of compounds absorbed from the gastrointestinal tract before distribution to nondigestive tissues (i.e., liver), (b) allows measurement of the compounds absorbed without the need to monitor flow rate, and (c) facilitates accumulation of sufficient material from the total portal circulation for analyses when submicrogram quantities are absorbed. The latter two features are important but impossible to attain with small samples of portal blood and are crucial in research with minute quantities of substrate. These features become requirements in metabolism and toxicology research. The method involves replacement of the portal blood with a suspension of perfluorohydrocarbons to substitute for the major functions of natural blood. The total-continuous portal vein fistula makes it possible to investigate metabolic and transport phenomena in live animals which previously could be explored only by in vitro methods. The method may be applied to conscious animals with further refinements.     

面对WTO,北京市发展都市农业的必要性与策略

北京市发展都市农业,是与现阶段生产力发展水平相适应的,具有重要意义.加入WTO后,北京市都市农业面临的机遇与挑战并存.为此,应采取切实可行的"绿箱"政策,重视高新技术、信息技术在都市农业中的作用,注重产业结构调整,加强农产品的标准化工作,从而提高北京都市农业的竞争力.     

晋中市农业人口分布的分形研究

本文运用分形理论,以山西省晋中市为研究区域,结合统计分析和GIS技术,测算了其农业人口分形维数的盒子维数和关联维数,讨论了晋中市内各县市的农业人口分布的分形特征和分形规律。结果表明,农业人口分布呈现了自然科学所特有的分形特征———人口分形;不同地域人口分布情况直接受当地地形地貌的影响。     

SFB‐based S‐haplotyping of apricot (Prunus armeniaca) with DHPLC

Most cultivars that belong to the Rosaceae are self‐incompatible and depend on cross‐pollination. The pollen donor and pollen recipient have to flower synchronously and must be genetically compatible. Genetic compatibility is governed by the S‐locus, which holds the S‐RNase and S‐haplotype‐specific F‐Box (SFB) genes. Thus, the S‐genotype of cultivars is an important feature and is characterized molecularly by the S‐RNase and SFB alleles which are distinctive for each S‐haplotype. Here, we report the usage of DNA chromatography (denaturing high‐performance liquid chromatography – DHPLC) for identifying the S‐genotypes of European apricots on the basis of their SFB alleles. DHPLC is amenable to high‐throughput automation, and therefore is valuable for breeding and for high‐quality plant typing in the nursery.     

Box-Cox变换在谷物破碎敏感性研究中的应用

利用Ｂｏｘ－Ｃｏｘ变换,分别得到玉米和大豆破碎敏感性与水分、风温、风速的单因素模型,为进行干燥过程中玉米和大豆破碎敏感性的模拟打下了基础。利用计量经济学中Ｂｏｘ－Ｃｏｘ变换建立谷物干燥品质模型是一个新的尝试,取得了显著的效果,为复杂关系的建模找到了一个可行的方法。