芦笋种质资源遗传多样性的RAPD分析

采用RAPD技术对国内外43个芦笋品种的遗传多样性进行分析.从60个随机引物中筛选出12个有效引物,共扩增出183条DNA片段,其中170条为多态性条带,约占总数的92.92%;平均每个引物扩增DNA带数超过15条.结果表明,43份材料的Nei氏相似系数分布在0.407～0.931之间,平均为0.765,可见遗传多样性相对偏低.对所有材料进行聚类分析,在Coefficient=0.77处划等值线,可将参试样品划分为8大类群.其中Jwc1、Purple Passion、鲁芦笋1号等6个品种各单独列为1个类群,其余的被分为2个类群.     

粤糖系列甘蔗亲本表型性状遗传多样性分析

为了解粤糖系列甘蔗亲本遗传关系,提高粤糖系列甘蔗亲本的利用效率,本研究利用35个表型性状对106份粤糖系列甘蔗亲本和10份中国主栽甘蔗品种进行了遗传多样性、聚类分析等研究。结果表明,粤糖系列甘蔗亲本平均多样性信息指数、基因多样性指数分别为0.782±0.082、0.438±0.039,遗传多样性水平较高。叶片宽度和曝光后茎色多样性非常丰富。遗传相似性系数变幅在0.388~0.829,基于遗传相似性系数的聚类分析将参试材料分成2个大类群6个亚类群及5个亚亚类群。20世纪80年代粤糖亲本多样性指数最高,基于遗传距离的聚类分析将7个群体分为3个类群(Ⅰ、Ⅱ、Ⅲ),中国主栽甘蔗品种单独成为一个类群。以上结果为甘蔗遗传育种亲本的选择、杂交组合配制及核心种质构建提供帮助。     

蓖麻品种遗传多样性与亲缘关系的SRAP分析

利用SRAP技术对81份蓖麻品种材料亲缘关系进行了分析,实验选用20对SRAP引物组合,在81份蓖麻材料中共扩增出263条带,多态性条带计214条,多态性条带比率（PPB）为81.37%,遗传相似系数变幅范围在0.32558～0.92973,显示了蓖麻品种的遗传多样性较丰富。从分子聚类结果分析表明,在相异系数0.43为阈值时,可将81份蓖麻材料分为4个类群L1-1、L1-2、L1-3和L1-4;若在相异系数0.287为阈值时,又可将L1-4大类群分为两个亚类群L2-1和L2-2。从聚类图得知,聚在同一亚类群的蓖麻品种大多数所处的地域相近或者是由同一育种单位所选育,其类内的品种基因型遗传相似系数较高,类间的品种遗传差异相对较大,该分子聚类树状图可为蓖麻栽培种种质资源遗传多样性与亲缘关系在育种的利用上提供科学依据。     

利用ISSR标记分析福云(半)同胞系茶树品种(系)的遗传多样性和亲缘关系

福鼎大白茶和云南大叶茶是茶树育种中的骨干亲本,利用这两个亲本选育了许多优良的品种(系).本研究利用ISSR标记技术分析了40个福云(半)同胞系茶树品种(系)的遗传变异水平和亲缘关系.14个ISSR引物在供试品种(系)间共扩增出251条谱带,多态性条带的比率为96.4%.引物的PIC值平均为0.94,Rp值平均为29.35,表明引物扩增位点的高多态性和对品种的强辨别能力.40份供试品种(系)的基因多样性指数(H)为0.35,Shannon信息指数(1)为0.52.按母本来源和育种机构对供试品种(系)进行分组分析,结果表明不同品种(系)组间的遗传多样性水平比较接近,遗传变异主要存在于组内品种(系)的个体之间,不同组间基因交流明显.供试品种(系)间的相似系数介于0.52～0.75,根据相似系数矩阵按UPGMA法对40个供试品种(系)进行聚类分析,构建了不同品种(系)间的亲缘关系树状图.福鼎大白茶在树状图中形成单独的分支,在树状图的根基处,其它品种(系)根据遗传距离聚类成不同的类群.来源于同一育种单位的部分茶树品种(系)聚类在同一类群中,但未发现按母本来源区分的独立类群.总之,通过ISSR标记分析,可在基因组水平上进一步了解福云(半)同胞系茶树品种(系)间的遗传变异水平,并进一步明确其亲缘关系,为今后福云(半)同胞系在茶树育种上的有效利用提供依据.     

芝麻核心收集品中育成品种（系）的遗传多样性分析

利用SRAP分子标记技术对中国芝麻核心收集品的育成品种(系)进行遗传多样性分析,结果表明,14对引物组合在18份芝麻育成品种(系)间共扩增出稳定清晰的条带193条,其中多态性带124条,占64.2%.通过聚类分析和主坐标分析,表明育成品种(系)的遗传基础存在一定的多样性,但遗传相似系数较大(0.5342～0.9688),遗传距离较近.该研究结果表明,在芝麻育种的亲本选配中应积极引入地方种质、国外种质等,以拓宽遗传基础.     

美国引种辣椒的ISSR分析

采用ISSR分子标记技术对30个美国引种辣椒样品的遗传多样性进行研究,为选配辣椒杂交育种亲本选择提供了参考。根据加拿大哥伦比亚大学公布的100条随机引物,从中筛选出多态性强、重复性好的20条ISSR引物进行标记。共扩增出217条带,多态性百分率为67.3%。结果表明其遗传相似系数在0.5330-0.8302之间,在水平GS=0.6350可将其分为三类。表明ISSR分子标记进行辣椒遗传多样性的分析是可行的。辣椒品种间具有较丰富的遗传多样性。并为辣椒品种的选育和种质资源的保护提供理论依据。     

SSR标记分析国家北方花生区试品种的遗传多样性

利用10对SSR引物对参加我国北方区域试验的27份花生品种进行PCR扩增分析,共扩增出57条带,其中45条呈现多态,多态性比率为78.95%.引物的多态性信息含量(PIC)变幅为0.417～0.857,平均值为0.688.27个品种间的遗传相似系数在0.311～0.962之间,平均为0.651.聚类分析结果表明,27个参试花生品种在遗传相似系数0.61处分为3个类群,同一类型的参试品种优先聚为一类,同一地区或同一育种单位提供的品种往往首先聚为一类.系谱分析表明亲本来源相近的品种优先聚在一起,利用农家品种和辐照诱变材料对于拓宽花生遗传基础发挥作用较明显.SSR分析结果基本上与系谱相吻合.     

平榛种质资源坚果农艺性状鉴定与评价研究

平榛是我国重要的榛属植物资源,为鉴定、评价和保护平榛种质资源,提高其利用效率,采用主成分分析和聚类分析方法对99份平榛种质资源坚果的主要农艺性状进行了鉴定和综合评价。结果表明:平榛种质资源坚果的24个性状具有丰富的遗传多样性;10个数量性状的主成分分析确定了4类影响因子,反映了育种选择方向及潜力;基于各种质间形态性状的遗传差异,将99份平榛种质划分为5大类群,第Ⅰ类群可作为选育果面光滑品种的育种和候选亲本材料,第Ⅱ类群可作为选育大粒型、适宜机械化加工的育种和候选亲本材料,第Ⅲ类群具有作为市场产品的潜力,第Ⅳ类群可作为选育圆形、果面无条纹的育种和候选亲本材料,第Ⅴ类群可作为选育高丰产性品种的育种和候选亲本材料。上述研究为平榛种质资源的评价、保护和选优工作提供了基础数据。     

黑龙江省近年审定水稻品种基于SSR标记的遗传多样性分析

为评估黑龙江省水稻品种的遗传基础,利用24个用于水稻DNA指纹图谱构建的SSR标记以及其他均匀分布于水稻12条染色体的38个SSR标记,对黑龙江省近年审定的73个水稻常规稻品种进行遗传多样性分析。结果表明,在62个SSR标记位点中,共检测到142个等位基因,平均每个标记2.3个,多态性比率平均为71.0%,多态性频率变幅为0~0.775,平均值为0.246。供试品种间两两遗传相似系数的平均值为0.759,变幅为0.622~0.966,且96.4%的品种间遗传相似系数在0.66~0.86之间,表明供试的73个品种亲缘关系较近。通过SSR标记基因型聚类分析将这些品种划分为6个类群,与系谱分析趋势一致,类群间的差异主要表现在生育期和米质方面。综上所述,黑龙江省近年审定的水稻品种遗传基础狭窄,在育种中需要导入新的种质资源,加强种质资源创新,以期丰富水稻品种的遗传多样性,进一步提高水稻产量和抗性。     

采用RAPD技术探讨花椒的遗传多样性及其与环境的关系

采用RAPD分子标记方法分析11个花椒品种的遗传多样性,以及遗传多样性与环境因素的相关性。从60条随机引物中筛选出10条引物,共扩增出67条带,平均每个引物扩增出6．7条,其中56条具有多态性,多态比例为84％。根据品种间的遗传距离构建的聚类分析树状图,11个花椒品种的相似系数在0．08-0．92之间,可分为2个类群,这种分类与花椒的叶的外形分类结果一致。不同地域种植的同一品种材料遗传距离较大,显示花椒的遗传多样性与地域分布有关系。     

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.