加拿大披碱草×野大麦三倍体杂种染色体的分子原位杂交鉴定

加拿大披碱草与野大麦 2个四倍体多年生禾草杂交产生的属间杂种F1为三倍体 (2n =3x =2 1) ,丢失了与亲本染色体基数相同的 7条染色体。为查明该杂种F1的染色体构成 ,应用基因组分子原位杂交方法 ,将父本(♂ )野大麦基因组 (H1H1H2 H2 )DNA用荧光生物素标记作为探针 ,以母本 (♀ )加拿大披碱草基因组 (SSHCHC)DNA作为封组 ,对杂种F1根尖细胞有丝分裂中期的染色体DNA进行原位杂交。结果表明 :三倍体杂种F12 1条染色体中 ,有 14条出现偏黄色荧光信号 ,来自父本 (♂ )野大麦H1H2 基因组有 7条出现橙红色荧光信号 ,来自母本 (♀ )加拿大披碱草S基因组、加拿大披碱草HC 基因组的 7条染色体丢失。     

栽培稻与疣粒野生稻杂种F1代的基因组原位杂交鉴定

生物素标记的疣粒野生稻总DNA作探针,未标记的栽培稻总DNA封阻,对栽培稻与疣粒野生稻杂种F1体细胞染色体进行基因组原位杂交（Genomic in situ hybridization,简称GISH）分析。FITC检测表明,杂种细胞中来自瘛发粒野生稻的染色体有较多的黄色或黄绿色荧光信号,来自栽培稻的染色体只检出很少的信号。每条疣粒野生稻染色体上信号点所占的总的区域只是染色体的一小部分,表明疣粒野生稻染色体与栽培稻染色体的DNA序列大部分是同源的。     

基因组原位杂交鉴定牛筋草AA基因组在穇子染色体上的分布及探针长度优化方法

采用基因组原位杂交(Genomic in situ hybridization,GISH)方法研究了牛筋草(Eleusine indica)AA基因组在穇子(E.coracana)染色体上的分布,并探讨了AA、BB基因组的同源关系。用超声波破碎法进行预剪切,以缺口平移法标记的牛筋草总DNA为探针,BB基因组的E.floccifolia(Forssk.)Spreng.总DNA为封阻,与AABB基因组穇子的中期染色体进行杂交。结果表明,牛筋草AA基因组分布在穇子的18条染色体上。不加封阻或加过量封阻均不能鉴别AA基因组,说明AA和BB基因组间的分化程度不大,双方共享的重复序列较多。牛筋草与E.floccifolia总DNA分别用超声波破碎2 min和3 min后,可得到峰值为300-750 bp的DNA片段,这说明不同物种的超声波破碎时间需要调整,以获得合适长度的探针。     

用RAPD技术鉴定小麦属间不对称体细胞杂种

用随机引物扩增多态DNA(RAPD)技术对三种不同组合:小麦(Triticum aestivum)( )簇毛麦(Haynaldia villosa);小麦( )羊草(Leymus chinensis)和小麦( )高冰草(Agropyron elongatum)的属间不对称杂种进行分子鉴定,不同杂种植株的基因组经随机引物扩增后,均出现双亲的多态特异产物,证实它们含有双亲的基因组。将引物OPJ-12扩增的高冰草多态特异产物(分子量为0.77bp的DNA片段)分离纯化并标记作探针,用Southern杂交证明了小麦( )高冰草杂种经OPJ-12扩增的0.77kbp特异片段与高冰草这一片段具有同源性。本文结果证明,RAPD技术可作为小麦属间不对称体细胞杂种的一种快速、简便、有效的分子鉴定方法。     

基因组原位杂交鉴定栽培稻与广西药用野生稻杂交后代染色体构成

广西药用野生稻 (Oryza officinalis)具有多种优良特性 ,是水稻遗传育种的重要种质资源之一。本实验以 Biotin标记的药用野生稻总 DNA作探针 ,未标记的栽培稻 (Oryzasativa)总 DNA作封阻 ,以 HRP- DAB系统进行信号检测 ,对栽培稻与广西药用野生稻的杂种F1植株的根尖染色体制片进行基因组原位杂交。采用封阻比例 1∶ 2 0～ 30时 ,杂交效果较为理想 ,药用野生稻的 1 2条染色体显深棕色 ,而栽培稻的 1 2条染色体着色很浅。在有丝分裂间期的细胞核中 ,也检测到大量杂交信号分布于核的周边。     

黄藤染色体核型及基因组大小分析

为探究黄藤(Daemonoropsjenkinsiana)染色体核型和基因组的大小,采用体细胞染色体常规制片法与显微摄影技术相结合的方法,对黄藤染色体进行了核型分析,同时以番茄(Lycopersicon esculentum)为内标,应用流式细胞术对黄藤叶片基因组大小、DNA含量和DNA倍性进行了测定。结果表明,黄藤茎尖是理想的染色体制片材料;黄藤的染色体数为2n=24,核型公式为K(2n)=1M+17m+5sm+1st,核型类型为2C;核型不对称系数61.20%;黄藤的DNA含量为1.57 pg,基因组大小为1 539.53 Mb,黄藤的DNA倍性为二倍体(2n)。这是首次报道黄藤的核型和基因组大小,为深入开展黄藤属及其近缘属植物的核型和基因组比较分析提供了参考依据。     

自身基因组原位杂交揭示植物基因组重复DNA沿染色体的分布

重复DNA沿染色体的分布是认识植物基因组的组织和进化的要素之一。本研究采用一种改良的基因组原位杂交程序,对基因组大小和重复DNA数量不同的6种植物进行了自身基因组原位杂交(self-genomic in situ hybridization,self-GISH)。在所有供试物种的染色体都观察到荧光标记探针DNA的不均匀分布。杂交信号图型在物种间有明显的差异,并与基因组的大小相关。小基因组拟南芥的染色体几乎只有近着丝粒区和核仁组织区被标记。基因组相对较小的水稻、高粱、甘蓝的杂交信号分散分布在染色体的全长,但在近着丝粒区或近端区以及某些异染色质臂的分布明显占优势。大基因组的玉米和大麦的所有染色体都被密集地标记,并在染色体全长显示出强标记区与弱标记或不标记区的交替排列。此外,甘蓝染色体的所有近着丝粒区和核仁组织区、大麦染色体的所有近着丝粒区和某些臂中间区还显示了增强的信号带。大麦增强的信号带带型与其N-带带型一致。水稻自身基因组原位杂交图型与水稻Cot-1DNA在水稻染色体上的荧光原位杂交图型基本一致。研究结果表明,自身基因组原位杂交信号实际上反映了基因组重复DNA序列对染色体的杂交,因而自身基因组原位杂交技术是显示植物基因组中重复DNA聚集区在染色体上的分布以及与重复DNA相关联的染色质分化的有效方法。     

花椰菜与黑芥种间体细胞杂种的获得和鉴定

利用非对称体细胞杂交技术, 获得芸薹属花椰菜(Brassica oleracea var. botrytis)与黑芥(B. nigra)的种间杂种, 实现了野生种质抗病基因向甘蓝类蔬菜作物的渗透。以具有良好再生能力的花椰菜下胚轴原生质体作为融合受体, 具有抗黑腐、黑胫和根肿病优良性状的黑芥叶肉原生质体作为融合供体, 用不同强度的UV射线处理后, 利用PEG方法诱导供、受体原生质体融合。培养后获得170棵再生植株, 选取来自40个不同愈伤组织的40棵单株进行形态学观察及RAPD和SRAP分子标记检测, 结果表明其中30棵为体细胞杂种。染色体计数显示, 约23%杂种植株的染色体数目小于供、受体染色体数之和。用流式细胞仪测定DNA含量显示, 杂种植株DNA含量是受体的2-4倍, 20%杂种植株DNA含量小于供、受体之和。     

基因组原位杂交的新进展及其在植物中的应用

基因组原位杂交 ( Genomic in situ hybridization GISH)是 2 0世纪 80年代末发展起来的一种原位杂交技术。它最初应用于动物方面的研究[1 ] ,但很快被植物方面所借用 ,并且使用频率高于动物方面的研究。它采用来自一个物种的总基因组 DNA作为标记探针 ,用另一物种的总基因组 DNA以适当的浓度进行封阻 ,在靶染色体上进行原位杂交。在封阻DNA和标记 DNA探针之间 ,封阻 DNA优先与一般序列杂交 ,剩下的特异性序列主要被标记探针所杂交。在此基础上 ,人们先后发展了荧光基因组原位杂交、多色基因组原位杂交和比较基因组原位杂交等技术 ,…     

利用栽培稻C0t-1DNA和基因组DNA比较分析斑点野生稻和短药野生稻基因组

通过荧光原位杂交(FISH)利用来源于A基因组栽培稻的中高度重复序列C0t-1DNA和基因组DNA作为探针,对栽培稻、斑点野生稻和短药野生稻进行了比较基因组分析。结果发现C0t-1DNA杂交信号主要分布在这3种染色体的着丝粒、近着丝粒和端粒区域,在斑点野生稻染色体上的信号多于短药野生稻,与gDNA作为探针FISH的结果相一致,说明A和B基因组间的亲缘关系明显近于A和F基因组。确定了含有中高度重复序列的C0t-1DNA用于属内种间关系研究的可行性,并根据C0t-1DNA的FISH结果进行了染色体核型分析。     

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.