云南元江普通野生稻(Oryza urfipogon Griff)遗传多样性分析及保护策略研究

用SSR方法对云南元江普通野生稻3个自然居群进行30个位点的遗传多样性分析.结果表明,元江普通野生稻具有较高的遗传变异水平(Ap＝2.6,Hs=0.77),且群体遗传分化系数较大,GST为41.08%,即在遗传变异总量中41.08%存在于居群间.本文还通过对云南元江普通野生稻遗传多样性特点的分析,提出了保护策略.     

广西武宣濠江流域普通野生稻居群遗传多样性及保护研究

选用平均分布于水稻基因组的24对SSR引物,对沿河分布最长的广西武宣濠江流域的12个普通野生稻居群343份材料的遗传结构进行研究.结果表明:(1)该地普通野生稻遗传多样性丰富.24个位点共检测到206个等位变异,平均等位变异数A＝8.7083,有效等位变异数Ae＝3.7117;(2)该地普通野生稻居群具有较高的遗传分化和一定频率的基因流.群体遗传分化系数Gst＝0.2659,基因流Nm＝0.6901,表明26.59%的遗传变异存在于居群间;(3)SSR标记使普通野生稻居群中一些稀有等位变异得以显现.206个等位变异中,65个等位变异仅出现在1个或2个居群中,且频率较低,其中12个等位变异只出现在居群B中;(4)通过聚类分析和主坐标分析(PCO),下游居群A和B遗传关系较近,中游居群C比较独特,单独成为一类,中游居群D、E、F和G遗传关系较近,中游居群H、I和J及上游居群K和L遗传关系较近.根据上述分析结果,建议对濠江下游和中游具有代表性的居群(即居群B、D和H)的普通野生稻进行重点保护.     

我国北回归线区域普通野生稻遗传多样性和遗传结构研究

选择分布于水稻染色体组的26对SSR引物,对集中分布于广西来宾市北回归线附近的13个普通野生稻居群的342份材料进行遗传多样性和遗传结构研究。结果表明,该地区的野生稻无论在种内(A=9.154,Ae=4.446,I=1.547,He=0.671)还是居群水平上(P=95%,A=4.219,Ae=2.394,I=0.905,He=0.476)遗传多样性都十分丰富,高于同类研究水平。供试居群的遗传分化系数Gst为0.30,表明30%的遗传变异存在于居群间,大部分遗传变异存在于居群内。居群间的遗传一致度变化范围为0.332~0.903,且居群间地理距离越近,遗传一致度越高,说明北回归线附近的普通野生稻居群符合"隔离-距离"模型。综合上述研究结果和我国野生稻保护现状,建议对居群G13和G06实施优先保护。     

SSR 在琼海和三亚两普通野生稻居群中的遗传变异

通过分析37个SSR座位在琼海与三亚两普通野生稻(Oryza rufipogon)居群中的遗传变异, 结果表明, SSR座位在三亚普通野生稻居群中的变异高于其在琼海普通野生稻居群中的变异。根据遗传相似性和遗传距离公式得到琼海与三亚普通野生稻居群间的遗传相似性为0.6385, 遗传距离为0.4486 cM。Wright的FST检验结果表明, 这37个SSR座位在两居群之间存在着中等程度的遗传分化, FST=0.3909。此分化结果主要是由两居群间弱的基因漂移导致的(Nm=0.3895)。     

利用SRAP标记研究海南野生稻的遗传多样性与遗传分化

利用8对多态性较好的SRAP引物对海南120份普通野生稻、55份疣粒野生稻和26份药用野生稻进行扩增,在检测到的219个位点中,普通野生稻的多态性位点率为74.89％,疣粒野生稻为42.47％,药用野生稻25.11%。香农指数以普通野生稻最高0.3277,疣粒野生稻为0.2044,药用野生稻最低0.1113。UPGMA聚类分析结果显示供试材料与地理来源相一致,相关性强,各居群个体间没有出现任何交叉。根据居群间的遗传分化系数,普通野生稻群体的基因多样性为0.2135,群体内的平均基因多样性大于居群间的基因漂变,说明普通野生稻居群遗传分化不显著,遗传多样性主要来自于居群内,基于群体杂合度和居群遗传多样性指数特点,认为实施保护策略时,优先保护遗传多样性最丰富的WDL和WDA居群。疣粒野生稻居群存在中等程度的遗传分化,建议原生境保护;药用野生稻居群数量较少,建议原生境保护。     

SSR在琼海和三亚两普通野生稻居群中的遗传变异

通过分析37个SSR座位在琼海与三亚两普通野生稻（Oryza rufipogon）居群中的遗传变异,结果表明,SSR座位在三亚普通野生稻居群中的变异高于其在琼海普通野生稻居群中的变异。根据遗传相似性和遗传距离公式得到琼海与三亚普通野生稻居群间的遗传相似性为0．6385,遗传距离为0．4486cM。Wright的啪验结果表明,这37个SSR座位在两居群之间存在着中等程度的遗传分化,FST=0．3909。此分化结果主要是由两居群间弱的基因漂移导致的（Nm=0．3895）。     

广东高州7个普通野生稻居群遗传结构的SSR分析

利用32对SSR引物对来自全部7个自然居群的217份广东高州普通野生稻（简称＂高野＂）材料进行遗传结构、多样性和遗传聚类分析。结果表明,高野各居群因遗传结构存在差异而相对独立,但各居群之间由于存在基因渗透又具有一定的相似性。高野总体多样性指数（Ht）为0.65,居群内的多样性（HS=0.431）略大于居群间的多样性（DS=0.392）,二者差异并不显著。居群间的遗传分化系数（GST）为0.611,说明高野群体的遗传差异是由居群内和居群间的遗传分化共同作用的结果。其中A、B、E居群间,D、F、G居群间遗传相似性较高,C居群与其它居群之间存在较大差异。根据7个居群的遗传结构,结合其地理分布状况,认为遗传多样性最大的B和E居群以及遗传分化最小的C居群应作为重点对象进行保护。     

广东高州7个普通野生稻居群遗传结构的SSR分析

利用32对SSR引物对来自全部7个自然居群的217份广东高州普通野生稻(简称“高野”)材料进行遗传结构、多样性和遗传聚类分析。结果表明, 高野各居群因遗传结构存在差异而相对独立, 但各居群之间由于存在基因渗透又具有一定的相似性。高野总体多样性指数(Ht)为0.65, 居群内的多样性(HS=0.431)略大于居群间的多样性(DS=0.392), 二者差异并不显著。居群间的遗传分化系数(GST)为0.611, 说明高野群体的遗传差异是由居群内和居群间的遗传分化共同作用的结果。其中A、B、E居群间, D、F、G居群间遗传相似性较高, C居群与其它居群之间存在较大差异。根据7个居群的遗传结构, 结合其地理分布状况, 认为遗传多样性最大的B和E居群以及遗传分化最小的C居群应作为重点对象进行保护。     

广东高州普通野生稻(Oryza rufipogon Griff)的遗传多样性和居群遗传分化研究

利用30对SSR引物对广东高州普通野生稻3个群体进行了遗传多样性分析和居群遗传分化研究.结果表明,30对引物中只有20对表现出多态,多态位点比率P为66.7%;在20个多态位点中共检测出81个等位变异,平均等位变异数(Ap)为4.05 个;3个群体总的遗传多样性(Ht)为0.61,其中,居群内的遗传多样性为居群间的遗传多样性的3倍多,说明总的遗传多样性主要来自居群内;虽然居群间的遗传分化系数(G ST)较低,仅为0.2427,但当遗传相似系数临界值增加时,3个群体在聚类图上相对独立 ,说明3个群体既存在着高度的遗传相似性,又具有一定程度的遗传分化,可以作为3个居群进行原生境保护.     

广西普通野生稻群体结构解析与核心种质构建

利用覆盖水稻12条染色体的64个分子标记,对广西境内已发现的283个野生稻自然居群按居群取样原则采集4173份代表性样本进行遗传结构分析并构建核心种质。结果显示,64个标记位点共检测出1180个等位变异,平均等位变异数为18.4375,Shannon指数为1.7367,Nei's多样性指数0.7182,表明广西普通野生稻资源遗传多样性十分丰富。同时,基于广西普通野生稻群体结构,构建了包含351份种质的广西普通野生稻核心种质,占原样本数的8.41%。广西普通野生稻核心种质,代表广西普通野生稻的多样性和特异性,为野生稻遗传资源的深入研究提供基础,从而为水稻育种提供应用信息。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.