广西壮族人群线粒体ＤＮＡ序列遗传多态性分析

测定了８３例广西壮族人的线粒体ＤＮＡ（mtDNA）第一高变区５１５bp的序列,并从这一母系遗传标记的角度对壮族人群的起源和群体的遗传结构进行了探讨,在所测定的８３个个体中,共检测到６６个单倍型,包括７１个多态位点,显示了高度的遗传多样性,对单倍型的系统发育分析表明：壮族人群内部存在一定的分化,不同地区的壮族人群在mtＤＮＡ遗传变异上有一定的差异,其中柳州和河池地区的个体有一半以上属于聚类簇Ⅱ,而南宁和百色地区的个体属于聚类族Ⅰ的较多,结合已相关报道的人群比较分析显示,壮族和我国北方民族群体亲缘关系较远,而与南方的少数民族及南方汉族亲缘关系较近,壮族人群中单倍型辐射型体分布,系统树中壮族人群与其他人群聚类先后次序都表明壮族是一个较为典型的南方群体。     

云杉矮槲寄生遗传多样性及其群体遗传结构分析

该研究采用CTAB法提取云杉矮槲寄生(Arceuthobium sichuanense)的基因组DNA,利用ITS1片段的序列信息对中国9个不同地理群体的62份云杉矮槲寄生样本的遗传多样性及群体遗传结构进行分析。结果表明:(1)62条ITS1序列共定义16个单倍型(H1~H16),表现出较低的遗传多样性水平(h=0.678 5,π=0.005 9),而群体间的遗传多样性水平则表现出较大差异(h=0~1.000 0,π=0~0.009 4);AMOVA分析显示云杉矮槲寄生群体内的遗传变异占到51.37%,群体间为48.63%。(2)Network单倍型网络分析表明,单倍型H1和H12较为古老,且所有群体对2种单倍型无共享现象;单倍型H1是广布单倍型,存在于青海和甘肃的6个群体中,单倍型H12仅在四川的2个群体中有分布。(3)基于最大似然法(ML)构建的群体聚类和中介邻接法构建的单倍型网络图均显示,四川的3个群体为独立类群,区别于青海、甘肃群体,且甘肃和青海的群体之间没有明显分化。该研究首次报道了云杉矮槲寄生遗传多样性和遗传结构,为进一步研究其进化及后续的病害防控提供了一定的参考。     

日本囊对虾4个地理群体线粒体16S rRNA序列及遗传结构分析

对我国东南沿海日本囊对虾(Marsupenaeus japonicus)的4个地理群体广东群体(GD)、台湾群体(TW)、福建群体(FJ)和浙江群体(ZJ)的线粒体16S rRNA基因片段进行PCR扩增,对产物进行测序后分析。经比对获得470bp的核苷酸分析序列,发现了16个变异位点,得到了10种单倍型。广东、台湾、福建和浙江群体的核苷酸多样性依次分别为0.0008、0.0010、0.0051、0.0015,各群体均存在独有的单倍型和共有单倍型。群体遗传距离分析表明各群体间保持着一定的遗传差异,其中福建群体与其他群体之间存在着较远的遗传距离并保持了较高的遗传多样性。另外,利用其423bp的16S rRNA同源序列探讨了对虾科6个属共12种对虾的系统进化关系,囊对虾属与沟对虾属亲缘关系较近聚为一支,其他4个属的10种对虾聚为一支。     

长江中下游湖泊短颌鲚线粒体控制区遗传多样性分析

为探明长江中下游不同湖泊中短颌鲚(Coilia brachygnathus)遗传多样性水平和遗传分化程度,以洞庭湖、长湖、巢湖3个地理群体作为研究对象,采用线粒体控制区序列为分子标记,分别应用软件Dna SP 5.0、Arlequin3.1.1、MEGA5.0和Network 5.1进行了遗传参数统计和单倍型间分子变异分析(AMOVA),构建邻接系统树及单倍型网络图。对长江中下游短颌鲚野生群体的遗传多样性和遗传结构进行分析。结果显示,用来分析的1 236 bp D-loop区序列中共90个变异位点,54个简约信息位点。长江中下游3个地理群体中共发现58个单倍型,单倍型多样性(h)范围0.949~0.982,核苷酸多样性范围0.004 99~0.006 21,说明长江中下游3个湖泊短颌鲚地理群体具有较高的遗传多样性水平。3个短颌鲚地理群体遗传分化指数(Fst)为0.265 95,呈现出中等程度的分化水平,主要表现在巢湖群体与其他群体之间处于中等程度分化水平。依据遗传距离构建系统发育树及单倍型网络图也出现相类似结果。     

基于线粒体控制区序列的黄河上游厚唇裸重唇鱼种群遗传结构

采集黄河上游厚唇裸重唇鱼(Gymnodiptychus pachycheilus)甘肃玛曲群体,测定其线粒体DNA控制区序列,并从GenBank中下载青海玛多和贵德等3地2个群体的同源序列,分析该物种的遗传多样性、遗传结构及其演化历史.从81条729 bp序列中,检测到26个变异位点(占3.57％),碱基序列总的单倍型多样性为0.844,核苷酸多样性为0.0054,界定了34个单倍型,有1个广布单倍型H2,占所有样品的38.27％.单倍型网络图图显示单倍型没有明显的亲缘地理格局,H2处于中心,呈星状发散,系统发育分析没有显示出单倍型与地理位置的对应关系.AMOVA分析显示变异主要来自地理区内群体间,歧点分布和中性检测显示厚唇裸重唇鱼近期经历了种群扩张.分析表明黄河上游3地种厚唇裸重唇鱼种群未出现分化,建议应作为一个整体进行保护.     

我国草鱼野生群体D-Loop序列遗传变异分析

利用线粒体DNA的D-Loop区序列, 对来自长江水系(邗江、吴江、九江、石首、木洞和万州)、珠江水系(肇庆)和黑龙江水系(嫩江)的8个草鱼野生群体开展了遗传变异分析。在424尾鱼中检测到34个变异位点, 34个单倍型, 单倍型多样性介于0.4740.708。群体间Kimura双参数遗传距离介于0.00200.0049。长江下游3个群体间遗传距离最近, 遗传分化不显著(P0.05); 肇庆群体与长江上游3个群体遗传距离较近, 与九江群体遗传分化不显著(P0.05); 嫩江群体与长江上游2个群体遗传距离较近, 与万州群体遗传分化不显著(P0.05)。遗传距离与地理距离存在极显著正相关(R=0.61, P0.01)。分子方差分析显示, 不同流域间遗传变异占总变异26.24%, 差异极显著(P0.01)。34个单倍型分为2个分支, 分化极显著(FST=0.644, P0.01), 推测分化时间为第四纪更新世纪晚期。       

基于mtDNA-COI基因序列的雷氏按蚊分子群体遗传结构研究

【目的】探讨我国雷氏按蚊Anopheles lesteri的群体差异和分化程度。【方法】采用PCR方法, 从分子水平鉴别了采自我国和韩国的雷氏按蚊共9个群体139个样本, 扩增其线粒体DNA细胞色素氧化酶亚基Ⅰ基因, 并进行序列测定和分析。【结果】本研究共获得49个单倍型, 各单倍型呈高水平的平行演化, 来自云南群体的单倍型显示是扩张的源头。分子变异等级分析(AMOVA)的计算结果显示, 群体内变异占总变异的比例（64.95%）大于群体间（35.05%）, FST值为0.3504, 各群体间出现遗传分化。Mantel检验结果显示基因流水平与地理距离呈负相关关系（R²＝0.1322）, 群体遗传结构符合距离隔离模型。【结论】雷氏按蚊韩国和辽宁群体与其他分布地群体间差异大, 已出现明显分化, 我国其他分布地群体间的遗传差异小。     

我国部分黄牛品种线粒体D-loop区遗传多样性与起源分化

为了解我国地方黄牛品种线粒体DNA的遗传变异情况, 文章测定了16个地方黄牛品种206个个体线粒体D-loop区的全序列, 共检测到101个变异位点; 99种单倍型, 其中73种是普通牛单倍型, 26种是瘤牛单倍型; 平均核苷酸差异为22.6920, 单倍型多样度为0.9320, 核苷酸多样度为0.0227, 表明我国黄牛品种遗传多样性非常丰富。构建的NJ进化树显示16个品种来源于两大母系: 普通牛和瘤牛; 构建的Network图表明73种普通牛单倍型可以分为3大单倍型群; 26种瘤牛单倍型分为5种单倍型群, 推测我国瘤牛在迁移过程中, 至少经历了4次群体扩张事件。通过分析比较地方黄牛品种与内罗门牛共有的 H3单倍型, 发现其中只有16%的序列与内罗门牛的H3单倍型非常相似, 其余84%的序列均发生了鸟嘌呤变异, 推测这些变异很可能是我国瘤牛固有的变异。     

我国水牛地方品种线粒体D-loop区遗传变异与起源分化

测定了我国24个地方水牛品种和2个引进水牛品种共311个个体的线粒体DNA D-Loop区序列.结果表明我国水牛遗传多样性非常丰富,共检测到256个突变位点,132种单倍型,单倍型多样度Hd为0.9288.构建的NJ系统树表明中国水牛都属于沼泽型,并且主要为2个母系起源,分别命名为SA支系和SB支系,所研究的每个地方水牛群体中2个支系都存在.SB支系中还存在两个分化也比较明显的小分支,称为SBI和SBII.所有单倍型中,H2单倍型出现频率最高,且只在24个地方品种中存在,说明H2单倍型是我国地方水牛特有的标志单倍型,也是一种古老的单倍型.中国水牛应是在本土独立驯化的.     

基于线粒体COI基因分析钩手水母的群体遗传结构

钩手水母(Gonionemus vertens)为大西洋和太平洋广布种, 是我国习见的有毒水母种类之一。本文对采自黄渤海海域4个地理群体的104个钩手水母线粒体COI基因序列进行扩增, 并结合GenBank上其他182个钩手水母同源序列进行序列变异分析。在286个基因序列中共检测出52个多态位点, 定义了14种单倍型。总群体的单倍型多样性和核苷酸多样性分别为0.743 ± 0.012和1.046% ± 0.097%, 与其他几种大型水母相比, 钩手水母总群体的遗传多样性处于较高水平。AMOVA结果显示, 60.17%的分子变异源于群组间, 13.37%的分子变异源于群体内, 26.46%的分子变异源于组内群体间, 群组间、群体内和组内群体间的遗传分化均极显著。F_st值统计检验表明, 中国厦门群体与乐亭、东营、烟台、大连群体间存在显著的遗传分化, 大连与东营、烟台群体间也存在显著的遗传分化。系统分析结果显示, 钩手水母群体间存在2个明显的单倍型谱系分支。不同的钩手水母地理群体间具有复杂的遗传模式, 钩手水母复杂的生活史、扩散能力、地理隔离和海流分布可能是影响钩手水母遗传结构的重要因素。     

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.