野生和近交稀有鮈鲫的遗传多样性

用RAPD技术对稀有鮈鲫近交10代及3个野生群体的遗传多样性和群体间差异进行了研究。无论从多态位点的比例、个体间的共带率还是从多样性指数来看,近交10代的遗传多样性极低。在226个RAPD位点中,野生群体有近半数的位点是多态的,Shannon多样性指数在0.2911～0.3235间,表明自然群体保持了较丰富的遗传多样性。近交10代与野生群体间遗传差异十分明显。野生群体间在11～19个位点上的表型频率存在显著差异,总遗传多样性的91.33%来自群体内,8.67%来自于群体间。     

毛乌素沙地根茎灌木羊柴的遗传多样性和克隆结构

采用淀粉凝胶电泳技术对毛乌素沙地根茎灌木羊柴（ＨｅｄｙｓａｒｕｍｌａｅｖｅＭａｘｉｍ．）８个群体的遗传多样性和克隆结构进行了初步研究。利用１０个酶系统１５个等位酶位点的检测表明,羊柴群体具有较高的遗传变异水平,多态位点百分率Ｐ＝３７．０,等位基因平均数Ａ＝１．４８,平均期望杂合度Ｈｅ＝０．１０１;但８个群体间的分化很小（Ｆｓｔ＝０．０６７）;固定沙丘群体和半固定沙丘群体在等位酶水平上的变异性无显著差异。通过７个多态位点的研究表明,羊柴群体中的克隆多样性很高（Ｄ＝０．９１５６）,但不同克隆在规模上相差很大。同时,群体间的克隆分化较大,广布基因型仅占３．２％。克隆空间结构的分析表明,羊柴的基株分布为游击型构型,克隆之间的镶嵌明显。     

苍术（Atractybeslancea（Thunb．）DC．）种内遗传多样性分析

分析了苍术（Ａｔｒａｃｔｙｌｏｄｅｓｌａｎｄｅａ（Ｔｈｕｎｂ．）ＤＣ．）５种等位酶（ＭＤＨ,ＧＤＨ,ＰＰＯ,ＳＯＤ,ＰＥＲ）１２个位点上２５个等位基因的分化特征。结果表明：群体内多态位点比例平均为０．６１,每个位点的平均杂合率为０．２６,每个位点发现的平均等位基因数为１．７８。苍术种内基因多样性的８６％产生在群体内,群体间分化的明显效果为１４％。所有配对组合,群体间的平均遗传距离是０．１１,遗传同一性是０．９０。说明苍术种内变异很大。同时探讨茅苍术的分类位置,认为茅苍术不是苍术和白术的杂交种。     

苍术DNA分离及RAPD遗传多样性分析

用新鲜的或－７５℃保存的苍术〔Ａｔｒａｃｔｙｌｏｄｅｓｌａｎｃｅａ（Ｔｈｕｎｂ．）ＤＣ．〕叶片提取ＤＮＡ,产量分别为４０ｎｇ／ｍｇ鲜重和１０ｎｇ／ｍｇ鲜重左右,分离出的ＤＮＡ的ＯＤ２６０／ＯＤ２８０值均大于１９,可用于ＲＡＰＤ试验。用８种引物对苍术４个居群的ＤＮＡ进行扩增,单个１０碱基的引物扩增出的ＲＡＰＤ标记在１～１５之间,多态位点百分率南苍术为４７５０％,北苍术为４５４０％,遗传相似度值南苍术为０８５,北苍术为０８７。结果表明,南苍术的遗传多样性略高于北苍术。     

螅状独缩虫(Cachesium polypinum)遗传多样性的RAPD分析

用随机扩增多态ＤＮＡ（ＲＡＰＤ）技术对武汉的汉口（ＣＰ－１）、汉阳（ＣＰ－２）和武昌（ＣＰ－３）三个地区缘毛类的螅状独缩虫（Ｃａｃｈｅｓｉｕｍ ｐｏｌｙｐｉｎｕｍ）进行了遗传多样性分析。结果表明：这种动物存在广泛的变异,三个地域群体之间的遗传相似度为０．６５２２－０．７３８５（平均值为０．６９２１）,各群体之间遗传相似度大小依次为：ＣＰ－２－ＣＰ－３〉ＣＰ－１－ＣＰ－２〉ＣＰ－１－ＣＰ－３。本文对     

凉水国家自然保护区天然红松林遗传变异的RAPD分析

采用随机扩增多态ＤＮＡ（ｒａｎｄｏｍ ａｍｐｌｉｆｉｅｄ ｐｏｌｙｍｏｒｐｈｉｃＤＮＡ ＲＡＰＤ）技术,研究了凉水国家自然保护区天然红松林的遗传变异水平及其分布规律。１６个１０ｂｐ长度的随机引物在８个实验样地内７２个个体中共检测了９６个位点,其中５５个是多态位点。在种水平上,红松的多态位点比率为Ｐ＝５８．５１％;Ｎｅｉ’ｓ遗传变异指数为Ｈ＝０．２８６８;Ｓｈａｎｎｏｎ’ｓ指数为Ｉ＝０．３６５４,所     

松嫩草原羊草种群遗传分化的研究

通过等位酶技术,综合分析了松嫩原理１１个羊草种群的遗传多样性及遗传分化指标,深入剖析了灰绿型和黄绿型两种叶色类型羊草种群之间的遗传差异：两类种群在等位基因频率、非平衡位点和Ａ、Ｐ、Ｈe及固定指数Ｆ上明显不同,两类种群间有极明显的遗传分化。黄绿型种群的Ａ、Ｐ、Ｈe皆低于灰绿型;黄绿型Ｆ＜０,灰绿型Ｆ＞０,这种差异主要表现在ＤＩＡ－１、ＰＧＭ、ＳＫＤ和ＡＣＰ等位点上;两类种群间的遗传分化主要发生在ＡＤＨ、ＤＩＡ－２和ＰＧＭ等位点上。种群间的遗传距离与地理距离之间没有相关。     

毛乌素沙地柠条群体分子生态学 初步研究：RAPD证据

毛乌素沙地柠条群体是一个杂种带。为了进一步阐明分子变异和基因流与生境或生态过渡带的联系,应用ＲＡＰＤ标记开展了柠条群体的分子生态学研究。根据ＲＡＰＤ数据利用Ｓｈａｎｎｏｎ信息指数估计了６个柠条群体的遗传多样性,发现大部分的分子变异存在于柠条群体之内（８２．４％）,只有少部分的分子变异存在于群体之间（１７．６％）。又利用Ｎｅｉ指数统计了ＲＡＰＤ数据,也证实了大部分的遗传变异存在于群体之内。柠条锦鸡儿群体与中间锦鸡儿群体的遗传分化系数和遗传距离都很小。以上结果都肯定了柠条群体间和种间的基因流动。无论是从多态位点比率还是群体的遗传多样性来看,硬梁和硬梁覆沙群体是最小的,滩地覆沙群体则具有较高的水平。某些ＲＡＰＤ扩增片段的频率在柠条群体间有规律的变化也许具有着特殊的生态学意义,更可能是中性突变的随机固定。根据以上研究可以得出下列结论：①通过比较Ｓｈａｎｎｏｎ指数和Ｎｅｉ指数的统计结果,可以认为,对于异交植物来讲,Ｓｈａｎｎｏｎ指数在统计ＲＡＰＤ数据方面有用。②毛乌素沙地柠条群体之间存在着强大的基因流,物种的杂交性与生态过渡性一致     

三个地理群体赤眼鳟遗传多样性的RAPD分析

利用RAPD技术对宿鸭湖、青龙湖和丹江口水库3个野生赤眼鳟群体的遗传多样性进行分析.9个RAPD引物共获得93个扩增位点,其中多态位点56个,多态位点比例为60.22%.3个群体的多态位点比例分别为53.01%、54.12%和57.95%,遗传距离分别为0.1548、0.1613和0.1764,Shannon信息指数分别为0.2249、0.2318和0.2437.群体间遗传距离以宿鸭湖和青龙湖群体最近(0.1257),青龙湖与丹江口水库群体最远(0.1416).结果表明3个赤眼鳟群体的遗传多样性均较丰富,但群体间地理遗传分化差异并不明显.     

盐渍条件下野大豆群体的遗传分化和生理适应：同工酶和随机扩增多态D…

黄河三角洲野大豆盐渍群体的耐盐性高于附近的正常群体。群体内个体间耐盐能力差别很大。盐渍群体有比最耐盐的栽培大豆品种耐盐能力高得多的个体,也有对盐相当敏感的植株。同工酶分析表明群体内高水平多态性,但酶谱与抗性没有相关性。盐渍与正常群体间的遗传一致性高达０．９６。用改良的随机扩增多态ＤＮＡ（ＲＡＰＤ）方法,１０个引物扩增得出群体内多态位点百分数为６８／１８８＝０．３６。看来,绝大多数位点与耐盐能力无关     

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.