半干旱区农田杂草的生活史对策研究

2008-2009年通过利用当地常见的10种杂草种植于不同处理的农田,研究半干早区农田杂草群落结构以及10种杂草群落组分种对环境因子的响应,结果表明,1)同一物种在不同的气候环境下,可以表现出不同的生活史策略.蝇虫实、田旋花和金荞麦2008年生活史策略分别具有竟争型(C)对策属性、胁迫忍耐型(S)对策属性和中间型(C-...     

Immunogenicity of multiple-epitope antigen gene of HCV carried by novel biodegradable polymers

In order to develop a promising vaccine candidate utilizing a combined approach to induce both antibody production and T-cell activity, the DNA fragment containing MA of HCV with five conserved epitopes was synthesized. Two types of HCV vaccine candidates (the DNA type and DNA/polymers) were constructed using MA. PLA-PEG-PLA and PLGA-PEG-PLGA were synthesized and used as micelles with encapsulated plasmid pcDNA3.1(+)-MA. The preparation of copolymers, the cloning and analysis of recombinant plasmid DNA, in vitro expression, and immunogenicity in transgenic mice were evaluated in detail. The results indicated that even single immunization and oral immunization with DNA/polymers achieved satisfying immune responses in vivo tests. As biodegradable and nontoxic triblock copolymers, the novel copolymers demonstrated a great advantage, as they made long-term and single-immunizing vaccines possible; in addition, the copolymers showed a better adjuvant effect and scarcely any side effects.     

利用 HPLC 分析菠萝愈伤组织 DNA 甲基化水平

建立菠萝 DNA 甲基化水平的 HPLC 测定方法，分析菠萝愈伤组织 DNA 甲基化水平变化，为进一步研究菠萝 体细胞无性系变异机理奠定基础。通过对流动相和水解温度等条件的优化，建立菠萝 DNA 甲基化水平的检测方法。结 果表明，分离 C 和 5m-C 的最佳流动相为甲醇∶磷酸二氢钾∶三乙胺为 10∶90∶0.2（V/V），pH 3.0，DNA 的最佳水解 温度为 90 ℃。利用此体系分析菠萝愈伤组织和胚性愈伤组织的 DNA 甲基化变化，结果表明，菠萝愈伤组织在分化过 程中 DNA 总甲基化水平呈动态变化，变化范围为 5.14%~96.86%。此外，胚性愈伤组织甲基化水平低于非胚性愈伤组 织。推测 DNA 甲基化影响菠萝愈伤组织的分化及胚性愈伤组织的形成。     

Soil biodiversity and DNA barcodes: opportunities and challenges

Soils encompass a huge diversity of organisms which mostly remains to be characterized due to a number of methodological and logistical issues. Nonetheless, remarkable progress has been made in recent years toward developing strategies to characterize and describe soil biodiversity, especially thanks to the development of molecular approaches relying on direct DNA extraction from the soil matrix.Metabarcoding can be applied to DNA from any environment or organism, and is gaining increasing prominence in biodiversity studies. This approach is already commonly used to characterize soil microbial communities and its application is now being extended to other soil organisms, i.e. meso- and macro-fauna.These developments offer unprecedented scientific and operational opportunities in order to better understand soil biodiversity distribution and dynamics, and to propose tools and strategies for biodiversity diagnosis. However, these opportunities also come with challenges that the scientific community must face. Such challenges are related to i) clarification of terminology, (ii) standardisation of methods and further methodological development for additional taxonomic groups, (iii) development of a common database, and (iv) ways to avoid waste of information and data derived from metabarcoding. In order to facilitate common application of metabarcoding in soil biodiversity assessment, we discuss these opportunities and challenges and propose solutions towards a more homogeneous framework.     

多径衰落信道下OFDM系统的符号同步方法研究

由于在正交频分复用（OFDM）的系统中存在符号时间同步误差，为了消除这种误差，提出了工作在多径衰落信道的符号时间频移（STO）估计方法，即基于CP的符号时间偏移估计和基于训练符号的符号时间偏移估计，通过仿真对基于循环序列（CP）估计技术的最大似然法（ML）和基于训练符号的最小均方差异法（Classen）两类性能比较分析，在无载波频移条件下，ML算法精确度更高，当存在载波频移时，Classen算法精确度更高。     

广东省主要红树林植物DNA条形码评价

为评估DNA条形码对鉴定红树林植物的通用性和有效性,在广东红树林分布区域共计采集红树林植物16科22属23种,共144个样品,并进行DNA条形码测序。结果表明:选择的rbcL、matK和trnH-psbA 3个DNA片段的PCR扩增成功率分别为100%、80.29%±8.49%、99.38%±1.25%。测序成果率最高为rbcL 100%,trnH-psbA次之94.57%±5.06%,matK最低75.04%±6.26%。表明rbcL和trnH-psbA片段在红树林群落中都具有较好的通用性。应用BLAST和NJ Tree两种方法计算红树植物的物种识别率。BLAST结果表明,单片段中trnH-psbA的物种识别率最高,为84.48%±12.09%,rbcL次之,matK最低。NJ Tree分析显示单片段中rbcL的物种识别率最高,为66.65%±17.35%;trnH-psbA片段次之,matK片段最低。两张分析方法都显示多个片段组合使用时,rbcL或trnH-psbA是提高物种平均识别率的主要片段。利用单片段rbcL即可获得平均节点支持率最高的红树植物系统发育树,且能准确区分不同树种。trnH-psbA片段可以识别rbcL片段不能识别的物种,可以作为补充片段。综合比较,推荐rbcL、trnH-psbA作为红树林植物DNA条形码片段。     

七星瓢虫对草地贪夜蛾低龄幼虫的捕食能力评价

为了评估七星瓢虫Coccinella septempunctata对重大入侵害虫草地贪夜蛾Spodoptera frugiperda（J.E.Smith）的防控效果，本试验在室内条件下开展了七星瓢虫对草地贪夜蛾1龄、2龄幼虫的捕食功能反应和种内干扰研究。结果表明：七星瓢虫对草地贪夜蛾幼虫的捕食功能反应均符合HollingⅡ模型，七星瓢虫对草地贪夜蛾1龄幼虫的日最大捕食量、瞬时攻击率和处理时间分别为233.100头、1.204和0.103 h；对草地贪夜蛾2龄幼虫的日最大捕食量、瞬时攻击率和处理时间分别为41.220头、1.075和0.582 h。七星瓢虫的搜寻效应随猎物密度的增加而逐渐降低。七星瓢虫对草地贪夜蛾的捕食作用受到较强的种内干扰。试验证明七星瓢虫对草地贪夜蛾具有较好的控害效果，可用于对草地贪夜蛾的防控实践。     

转基因玉米TC1507质粒DNA标准物质的研制

标准物质具有特定量值、均匀性和稳定性三大典型特征,也是其作为测量标尺的依据。转基因生物标准物质是我国转基因产品标识制度顺利实施的关键技术支撑之一。文章以转基因玉米TC1507为对象,制备了转化体特异性的新型质粒DNA标准物质pTC1507,并对其均匀性、稳定性、量值进行了评价和测定。测试结果表明,制备的质粒DNA标准物质具有良好的瓶间和瓶内均匀性,pTC1507稳定性可靠,可以在-20 ℃稳定放置6个月以上。经过测序和实时荧光定量PCR定值以及不确定度评估,pTC1507标准物质的量值是1.01±0.053。均匀性、稳定性和量值结果表明,研制的转基因玉米TC1507质粒分子标准物质符合标准物质的典型要求,可以代替传统的基体标准物质应用于转基因玉米检测,解决传统标准物质获取困难、制备复杂、成本高等不足。     

DNA条形码技术在中药领域的应用

DNA条形码技术可对物种进行快速自动鉴定,具有鉴定准确、结果稳定、操作简便、适用广泛等特点,目前在中药领域应用较多。从DNA条形码技术在中药材鉴定、种植、流通、市场监管、中成药鉴定和药用植物种质资源调查等中药领域的多个方面进行综述,并探讨DNA条形码技术在中药领域的优势和不足,以期为DNA条形码技术在中药领域的研究提供新的思路。