抗白粉病小偃麦异代换系的细胞学和RAPD鉴定

利用细胞学和RAPD方法,对从长穗偃麦草与普通小麦复合杂交后代中选育的抗白粉病小麦种质系山农87074－526和山农87074－551进行了鉴定。结果表明,两种质系的根尖细胞染色体数目均为2n=42,花粉母细胞减数分裂中期I（PMC MI）染色体构型为2n=21Ⅱ;二者杂交F1 PMC MI染色体构型亦为2n=21Ⅱ,两种质系分别与小麦中国春的杂种F1 PMC MI染色体构型均为2n=20Ⅱ 2I,说明两种质系为相同的双体异代系。在苗期和成株期两种质系对白粉病15号菌种均表现免疫,其白粉病抗性为显性,并且来自长穗偃麦草,抗白粉病基因位于它们所含的偃麦草染色体上。从80个随机引物中,筛选出2个引物OPE13和OPH15能在两种质系中稳定地扩增出长穗偃麦草亲本的特异DNA片段。     

抗条锈病小偃麦双体异附加系山农87074-519的鉴定

综合利用抗性接种鉴定、细胞学分析、SSR分子标记和基因组原位杂交(GISH)技术相结合的方法,对从长穗偃麦草与小麦复合杂交后代中选育的抗条锈病种质系山农87074-519进行了鉴定。结果表明,山农87074-519的根尖细胞染色体数目2n=44,花粉母细胞减数分裂中期I(PMCMI)绝大多数细胞内可观察到22个二价体,平均染色体构型2n=44=21.82Ⅱ 0.36Ⅰ,它与普通小麦中国春杂种F1的多数花粉母细胞内染色体构型为2n=21Ⅱ 1Ⅰ,因此它是1个附加了1对长穗偃麦草染色体的双体异附加系;以假鹅冠草St基因组总DNA作探针进行原位杂交发现山农87074-519的44条染色体中有2条出现黄绿色杂交信号,且杂交信号遍布整条染色体,证明其附加的长穗偃麦草染色体为St基组;利用SSR分子标记技术,在170对SSR引物中筛选出特异引物BARC165,它能稳定地在山农87074-519中扩增出长穗偃麦草特异标记BARC165268;将长穗偃麦草中BARC165的特异扩增片段克隆测序后制备成探针进行原位杂交,可在山农87074-519的间期染色体和有丝分裂中期染色体检测到杂交信号。山农87074-519综合农艺性状较好,对条锈病免疫,其抗性基因为显性,且位于附加的长穗偃麦草St基组染色体上,暂将其表示为YrSt。该种质系在小麦的遗传改良中具有重要利用价值。     

小偃麦异代换系山农0095辐照花粉后代的细胞学及SSR标记分析

本研究采用^60Co-γ射线辐照小偃麦异代换系山农0095花粉,对其M1、M2代的细胞遗传学特点进行分析,结果表明：M1、M2代均出现频率不同和染色体数目不等（2n=41、2n=40和2n：39）的染色体数目变异类型;在两个世代的花粉母细胞减数分裂过程中．普遍观察到单价体、多价体、染色体片段、落后染色体、染色体桥及微核等现象,说明辐射有效地促进了染色体数目和结构的改变,有可能导致染色体易位重组。利用已建立的山农0095中中间偃麦草染色体的特异SSR标记BARC159240对M2代进行检测,结果发现大部分M2单株仍含有该标记位点,说明这些植株仍然具有标记位点的中间偃麦草染色体特异区段：少部分单株虽然保留了该位点．但缺少普通小麦中的条带．这些单株可能发生了染色体重组。     

抗白粉病耐盐小麦-中间偃麦草附加系‘山农120211’的鉴定

以中间偃麦草(Thinopyrum intermedium,2n=42)与普通小麦‘烟农15’杂交,从其杂种后代中选育出一个细胞学稳定的二体异附加系‘山农120211’,该研究对其细胞学和主要性状特点进行了鉴定。白粉病抗性鉴定结果表明,‘山农120211’成株期对白粉病的田间抗性为免疫,苗期对白粉病菌种E09表现为免疫。以耐盐品种‘山融3号’为对照进行苗期耐盐性鉴定表明,‘山农120211’耐盐级别为2级(较强)。细胞学鉴定表明:‘山农120211’根尖细胞染色体数目为2n=44,PMC MI染色体构型为2n=22Ⅱ,具有高度的细胞学稳定性。以拟鹅观草基因组DNA为探针,‘烟农15’DNA为封阻,在‘山农120211’的根尖有丝分裂细胞中检测到2条染色体具有明显的杂交信号,确定其为二体异附加系。利用该实验室筛选的71对E组染色体特异分子标记,对‘山农120211’分析显示,标记BE494262在中间偃麦草和‘山农120211’中可以稳定扩增出1条440bp特异带,而‘烟农15’中缺少此带,BE494262可作为‘山农120211’中附加中间偃麦草染色体的特异标记。利用二倍体长穗偃麦草和一套中国春-长穗偃麦草异附加系(1Ee~7Ee),进一步将BE494262定位在2Ee染色体,确定‘山农120211’所附加的中间偃麦草染色体为2Ee染色体。     

普通小麦与长穗偃麦草杂种及其衍生材料的细胞遗传学特性

对十倍体长穗偃麦草(Thinopyrum ponticum)与普通小麦杂交F1及其与普通小麦回交BC1F1的形态学和细胞学特性进行了分析。结果表明,长穗偃麦草与普通小麦‘兰考矮早八’衍生F1(‘兰考小偃麦’)的根尖细胞染色体数为56条;花粉母细胞减数分裂中期Ⅰ染色体构型平均值为19.81Ⅰ+15.78Ⅱ+0.75Ⅲ+0.59Ⅳ;基因组荧光原位杂交(GISH)显示,兰考小偃麦中含有35条完整的长穗偃麦草和21条小麦染色体。‘兰考小偃麦’/‘科育818’和‘兰考小偃麦’/‘Cp02-3-5-5’杂交F1的根尖细胞染色体数及其所遗传的长穗偃麦草染色体数分别为50~52和16~22条,且存在染色体易位;花粉母细胞减数分裂中期Ⅰ平均染色体构型为14.54Ⅰ+17.40Ⅱ+0.55Ⅲ+0.14Ⅳ,平均49.4%的细胞出现多价体(三价体或四价体)。这些材料为创造小麦-长穗偃麦草新种质奠定了基础。     

小麦-簇毛麦种质系‘山农030713＇的细胞学和SSR鉴定

利用形态学、细胞学以及SSR标记技术对从硬簇麦和Am3的杂种后代中选育的种质系‘山农030713＇进行了鉴定,结果表明：种质系‘山农030713＇大田生长整齐一致,农艺性状较好,且对白粉病免疫;其根尖细胞染色体数目为2n=42,花粉母细胞减数分裂中期Ⅰ（PMC M Ⅰ）染色体构型为2n=21Ⅱ;它与普通小麦的杂种F1PMC MⅠ多数细胞中形成21个二价体,且常有四价体出现,可能伴有染色体的结构变异;SSR分析证明‘山农030713＇基本染色体组成为AABBDD,引物Xgwm99-1A在‘山农030713＇中扩增出簇毛麦的特异带,表明‘山农030713＇中有来自于簇毛麦的遗传物质,此特异带可作为识别‘山农030713＇的SSR标记.综合形态学、细胞学和SSR分析结果推测,‘山农030713＇可能是一个小麦-簇毛麦易位系.     

偃麦草与小偃麦染色体组构成的细胞遗传学研究在Ⅴ.硬粒小麦与中间偃麦草杂交及回交的细胞遗传学研究

获得了硬粒小麦(2n=6x=28、AABB)与中间偃麦草(2n=6x=42、NNE_1E_1E_2E_2)杂种F_1及回交后代材料。统计分析杂种F_1及回交一代PMC MI染色体配对构型,认为中间偃麦草具较远缘的同亲关系(distant homologous)染色体组。由三价体出现频率分析,中间偃麦草不含小麦的B染色体组,建议用NE_1E_2为其染色体组公式。根据回交一代及其自交后代染色体数目,分析了六倍体小偃麦这一人工新物种的形成过程。     

小麦-中间偃麦草双体异附加系的鉴定

利用形态学、细胞学、A-PADE和RAPD方法,对5个小麦-中间偃麦草(Thinopyrum intermedium)双体异附加系Line 1、Line 4、Line 10、Line 14和Line 15进行了鉴定。细胞学鉴定结果表明,它们根尖细胞染色体数目为2n=44,花粉母细胞减数分裂中期Ⅰ(PMCMⅠ)染色体构型为2n=22 Ⅱ,具有高度的细胞学稳定性;形态学鉴定和A-PADE电泳分析证明,Line 1和Line 15可能附加了中间偃麦草第7部分同源群的染色体,Line 10和Line 14可能附加了中间偃麦草第1部分同源群的染色体,Line4则可能同时存在多种染色体变异;RAPD分析表明,在供试的100个随机引物中,有5个引物S21、S29、S57、S121和S152能够在亲本中间偃麦草和双体异附加系中稳定扩增出特异带型,并可作为异附加系所附加染色体的特异RAPD标记。     

兼抗白粉、条锈病小偃麦渗入系CH7124抗性遗传及细胞学鉴定

CH7124是通过八倍体小偃麦TAI8335与感病小麦杂交、回交育成的兼抗白粉病、条锈病的小偃麦种质系。利用抗性接种鉴定、细胞学和基因组原位杂交(GISH)技术相结合的方法,对CH7124的抗性来源、遗传方式及细胞学特征进行了分析和鉴定。结果表明,CH7124在苗期和成株期对条锈菌系CYR29、CYR31、CYR32、CYR33和白粉菌系E09、E20、E21、E26表现为免疫或近免疫,其抗性来自中间偃麦草,受1对显性核基因控制;CH7124的根尖细胞染色体数目为2n=42,花粉母细胞减数分裂中期I(PMC MI)绝大多数细胞内可观察到21个二价体,平均配对构型为2n=0.30 I+20.79 II+0.04 III;与普通小麦中国春、绵阳11的杂种F1中,有80%以上的花粉母细胞可观察到2n=21Ⅱ的染色体构型,其平均配对构型均为2n=21II。说明CH7124具有与普通小麦相似的染色体结构和规则的配对构型。由于利用以中间偃麦草总DNA为标记探针的原位杂交未观察到可见的外源DNA杂交信号,进一步证明CH7124是一个小麦-中间偃麦草的隐形异源渗入系。     

中间偃麦草的GISH分析

以染色体组为E^eE^e的二倍体长穗偃麦草（Thinopyrum elongatum,2n=2x=14)、染色体组为E^bE^b的二倍体比萨偃麦草（Th.bessarabicum,2n=2x=14）、染色体组为StStStSt的四倍体拟鹅冠草（Pseudoroegneiria strigosa,2n=4x=28)的总基因组DNA为探针,对中间偃麦草（Th.intermedium)进行GISH分析。结果表明,中间偃麦草是由2个亲缘关系较近的染色体组、1个亲缘关系较远的染色体组构成;中间偃麦草所含的亲缘关系较近的染色体组分别与二倍长穗偃麦草染色体组E^e、比萨偃麦草染色体组E^b、以及1个亲缘关系较远的染色体组与拟鹅冠草染色体组St基本相似,但不完全一样,因此,中间偃麦草的染色体组用E^etE^etE^btStSt表示。     

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.