Relative importance of seed‐tuber and soilborne inoculum in causing black dot disease of potato

Controlled‐environment and field experiments were done to quantify the individual contribution of seed‐tuber and soilborne inoculum of Colletotrichum coccodes in causing black dot disease of potato tubers. Seed‐tuber and soilborne inocula of C. coccodes were quantified using an existing real‐time PCR assay and related to subsequent incidence and severity of disease. In four field trials, a controlled‐environment experiment and through the monitoring of 122 commercial crops, seed‐tuber inoculum was found to be relatively less important than soilborne inoculum in causing black dot, and the level of seed‐tuber inoculum did not significantly affect either the incidence or severity of disease or the percentage of progeny tubers deemed unmarketable. By contrast, soilborne inoculum had the potential to result in high levels of disease and the level of C. coccodes soil infestation (pg DNA g^?1 soil) was found to have a significant effect. At soil infestation levels below 100 pg DNA C. coccodes g^?1 soil, 7% of commercial crops had an incidence of black dot greater than 20%, increasing to 40% and 57% of crops at levels of 100–1000 pg g^?1 and >1000 pg g^?1 soil, respectively. These arbitrary threshold levels for soilborne inoculum related to disease risk are discussed. Interpretation of disease risk based on inoculum levels must, in the future, be informed by agronomic variables and potential control strategies.     

一种快速高效适于橡胶树叶片AFLP分析的DNA提取方法

以近200个巴西橡胶树种质材料（品种及无性系）幼嫩叶片为材料．采用改良的cTAB法对其基因组总DNA的提取进行了研究。结果表明,该方法提取的DNA溶液无色透明,DD260／DD280的比值均为1．8～2．0,1％琼脂糖凝胶电泳为清晰的一条带,无降解现象,KNA去除干净,能被限制性内切酶完全消化;其AFLP分析（引物EcoRI-TA／MseI—CTT）条带清晰,多态性好,说明此方法提取的巴西橡胶树幼嫩叶片基因组总DNA较适于AFLP分析。     

一种快速微量提取柑橘早期胚基因组DNA的方法（英文）

[目的]建立一种快速微量提取柑橘基因组DNA的方法。[方法]采用优化的CTAB微量提取法,以20.0,10.0,5.0,2.5mg的早期杂种胚为材料进行基因组DNA的提取,并对其DNA进行质量检测和SSR验证。[结果]该方法简单易行,所需材料少,提取的DNA纯度较高,OD260nm/OD280nm在1.800～2.000,可满足SSR等以PCR扩增为基础的试验需要。[结论]建立的方法可以用于快速微量提取柑橘基因组DNA。     

蒙古马mtDNA D-loop区遗传多样性与多重母系起源

【目的】对蒙古马mtDNA D-loop区247bp序列进行遗传多样性分析,探讨蒙古马的起源。【方法】采用PCR方法、测序技术及生物信息学方法,将本试验所测得的21匹蒙古马的mtDNA D-loop区序列,与GenBank中公布的43条蒙古马的对应序列,及世界范围内家马、普氏野马和内蒙古地区古马的mtDNA D-loop区序列一起进行系统发育分析。【结果】蒙古马具有39种单倍型,37个多态位点,核苷酸多样度(π)为0.02756±0.00967,单倍型多样度(h)为0.979±0.007,表明蒙古马mtDNA遗传多样性非常丰富。引用世界家马、古马、普氏野马和蒙古马共1074条mtDNA D-loop序列及本研究中21条mtDNA D-loop序列,共同进行系统发育分析,结果显示,蒙古马分布于A、B、C、D、E和F支系。【结论】蒙古马为多重母系起源,且与国内古马的母系起源几乎一致,推测蒙古马可能是中国北方家马的重要母系来源。     

Applying molecular genetic tools to tiger conservation

The utility of molecular genetic approaches in conservation of endangered taxa is now commonly recognized. Over the past decade, conservation genetic analyses based on mitochondrial DNA sequencing and microsatellite genotyping have provided powerful tools to resolve taxonomy uncertainty of tiger subspecies, to define conservation units, to reconstruct phylogeography and demographic history, to examine the genetic ancestry of extinct subspecies, to assess population genetic status non-invasively, and to verify genetic background of captive tigers worldwide. The genetic status of tiger subspecies and populations and implications for developing strategies for the survival of this charismatic species both in situ and ex situ are discussed.     

仿火箭电泳应用于单细胞凝胶电泳技术的优势(摘要)(英文)

[目的]研究仿火箭电泳应用于单细胞凝胶电泳技术,为单细胞凝胶电泳技术寻求另一种可行的电泳方法提供参考。[方法]将仿火箭电泳方法应用于单细胞凝胶电泳技术,检验单细胞水平上的DNA损伤,并与传统的电泳方法比较,分析其优劣势。[结果]在细胞DNA未受损状态下,2种电泳方法所得的结果一致;而在细胞DNA受到损伤时,传统的电泳方法下一些细胞的慧尾发散出现漂移,仿火箭电泳方法得到的慧尾图像集中且未发生偏移。[结论]仿火箭电泳方法较传统的电泳方法存在一定优势。     

不同寄主植物上茶黄硬蓟马mtDNACOⅠ序列分析

采用线粒体DNACOⅠ基因片段作为分子标记,对11个不同寄主上的茶黄硬蓟马(Scirtothrips dorsalis Hood)进行系统发育研究,获得655bp的线粒体DNACOⅠ基因片段。序列分析结果表明,不同寄主上茶黄硬蓟马mtDNACOⅠ的遗传距离在0~0.046之间,平均遗传距离为0.012。其中遗传距离最大的是木棉,遗传距离为0.046;杧果、荔枝、鳄梨、番荔枝、龙眼、咖啡无差异,遗传距离为0。基于COⅠ构建的11种寄主上茶黄硬蓟马之间的系统发育MP树显示:杧果、荔枝、鳄梨、番荔枝、龙眼、咖啡、花生、茶树紧密的聚合在一起;辣椒、台湾相思、木棉各为一支。     

信用评级机构监管的演化动态博弈分析

清代士子一旦中举,即失去了原有的官学学生资格,但举人仍有读书应试之需。于是,至清代晚期,各地出现由官府创建的专课举人的书院,专门招收举人,开展应试教育。与此不同,有的书院则兼课举人,并由官府设立孝廉课,专课举人。从总体上而言,专课举人和兼课举人的书院以培养生徒参加会试、殿试为目的,不仅在考课时模拟会试、殿试,而且在经费的投入、对考课的重视程度上,都超过了同一地区的其他书院,使肄业于书院的举人在竞争激烈的会试、殿试中脱颖而出的几率明显提高。