两种木莲属植物的花器官发生与发育

用扫描电镜观察桂南木莲(Manglietia chingii Dandy)和木莲(Manglietia fordiana Oliv.)两种木莲属植物的花器官发生及发育过程。结果显示,两种植物的花被片皆为向心发生,木莲的花被片3基数3轮,而桂南木莲的花被片4轮,前3轮3基数,第4轮普遍存在退化现象。雄蕊与心皮皆多枚,螺旋状向心发生。两种植物花发育的特殊之处在于花被片为轮状不同时发生,即从发生位置上看为3基数轮生,但同一轮花被片之间在发生时间上存在差异。这种花被片的轮状不同时发生可能是螺旋状发生向轮状发生演化的一个过渡阶段,这对探讨被子植物花器官发生与发育的演化具有重要意义。     

四福花花部解剖及维管系统的研究

对四福花(Tetradoxa omeiensis)花部进行了详细的解剖观察。其花部整齐,较少特化,维管系统愈合程度较五福花低。其萼与花冠同数,比率始终为1。我们认为四福花应居于科内原始位置。此外,四福花作为一个原始类型,有助于说明五福花”萼与花冠”的本质及演化的可能途径。     

红花檵木与檵木花数性表型变异研究

红花木与木花的数性结构有很大差异 ,木 4数性花占 96 2 %(花瓣、雄蕊、退化雄蕊、萼片均为 4数 ) ;野生红花木 4数性花约占 5 0 %;红花木栽培类型以 5数性花居多 ,不同类型品种花的数性结构亦有差异 ,总体变异规律为 :近期栽培品种双面红类 5数性花 >中期栽培品种透骨红类 >早期栽培品种嫩叶红类。利用花的数性表型变异探讨了品种的演化历史和新品种选育的前景。     

百合科扭柄花属一个新的染色体基数

对中国云南西部和西北部分布的腋花扭柄花Streptopus simplex的4个居群进行了细胞学研究。生长在云南西北香格里拉县(原中甸县)碧塔海和小中甸冷杉林中的腋花扭柄花两个居群的体细胞染色体数目为2n=2x=18,而生长在高黎贡山的福贡县片马和贡山县的灌丛中的植物体细胞染色体数目则为2n=2x=14。2n=14为腋花扭柄花一个新的染色体数目,x=7为扭柄花属一个新的染色体基数。香格里拉碧塔海和小中甸两个居群的核型公式分别为2n=4m+8sm+4st和2n=8m+2sm+6st,染色体逐渐变小;贡山和福贡片马两个居群的核型公式分别为2n=14=4m+10sm和2n=14=7m+7sm,其中第一对中部着丝粒的染色体显著大于其余染色体。由于x=8是扭柄花属最常见的染色体基数,因此可认为x=8是腋花扭柄花的染色体原始基数,x=7的数目是衍生的;x=7居群染色体的一条大染色体可能是由x=8的染色体的两条st型染色体的着丝粒发生了罗伯逊易位而来。     

四福花染色体核型的分析

四福花[Tetradoxa ometensis (Hara)C.Y.Wu]体细胞具有36个染色体。其核型组成为2n=36=6m+14sm+4st+12t,即具有3对中部着丝点染色体,7对亚中部着丝点染色体,2对亚端部着丝点染色体和6对端部着丝点染色体。 四福花染色体核型分析表明,与传统对五福花科植物染色体具9基数的认识不同,其基数应为X=18。与Noguchi所发现的具18基数的三倍体五福花的核型相比较,二者在核型组成及染色体结构上都有明显差异。     

商陆属中五基数花起源于三基数花的新证据——非洲商陆的花器官发生

运用扫描电镜和石蜡切片方法对非洲商陆Phytolacca dodecandra L′Her.的花器官发生过程及花器官各部分的位置排列进行了观察。结果表明：非洲商陆萼片5枚,以螺旋向心方式发生;没有观察到花瓣原基的发生;雄蕊为螺旋离心方式发生,前4枚雄蕊分2对出现在对萼位置,但此后发生的雄蕊的发生顺序明显区别于其他种;心皮4-5枚,与内部雄蕊互生。本文探讨了时空因素对花器官发生的影响,基于对非洲商陆花器官发生的观察,否定了“商陆属源于二轮雄蕊样式”的假说,并为商陆属中“五基数花起源于三基数花”的观点提供了新的证据。     

檵木与红花檵木的解剖结构研究

对7个不同地点的野生檵木、野生红花檵木、栽培红花檵木花的解剖结构进行了研究,浏阳大围山野生檵木花的数性遗传结构与其它地区的野生檵木有较大差异,4数性花和5～6数性花各占50%;红花檵木野生和栽培类型均以5数性花数量居多,不同于文献记载的檵木属植物4数性花的分类属征(每朵花花瓣、雄蕊、退化雄蕊及萼片均为4数).利用花的结构遗传变异探讨了红花檵木的起源和品种演化历史.     

五福花科花部形态的变异式样及其系统学意义

由于四福花Ｔｅｔｒａｄｏｘａ顶花、侧花均为典型的４数花,并被认为是科内最原始的属,因而长期以来关于五福花Ａｄｏｘａ“总苞一萼”还是“萼一花冠”的争议得到了彻底解决。根据本研究,五福花顶花和侧花的变异痃较五福花科另外３个分类群要高得多。五福花顶花和侧花的变异率分别为２０％和３６１％。通过后位雄蕊的退化和两则相邻花瓣的融合,雄蕊和花瓣从６数至３数的减少系列仅存在于五福花中。本文假设五福花科顶花和侧花的     

眼子菜的花器官发生

运用扫描电镜观察了眼子菜的花器官发生过程。结果表明：花原基从花序轴的基部开始以三数 交互轮状的方式发生,在花原基发生的早期具有明显的苞片原基形成。花器官是以向心的方式发生的, 二枚侧方花被片原基首先形成,紧接着产生二枚中间花被片。四枚雄蕊分两轮分别在与侧方花被和中 间花被相对的位置发生,四枚雄蕊原基在发生时均呈长条形。上述四轮花被和雄蕊虽然在时间上以二 数轮状的方式发生,但在空间上花被片和雄蕊各自分别排成一轮。最后,二个心皮原基在花原基顶端略 偏于一侧并与雄蕊相间的位置同时发生。有些花的二枚心皮原基发生后其中一枚很早即停止生长或仅 有一枚心皮原基形成。本文结果支持了眼子菜属心皮数目逐渐向简化的方向演化的观点。在花原基早期发育的过程中苞片原基的存在表明眼子菜属植物成熟花中缺乏苞片是简化的结果。     

青城细辛的花器官发生

利用扫描电镜观察了青城细辛（Asarum splendens）的花器官发生过程。青城细辛的花器官为轮状结构,向心发生,依次为两轮3基数的花被原基,两轮6基数的雄蕊原基和一轮6基数的心皮原基。两轮花被原基互生,只有外轮（先发生的一轮）花被原基完全发育,而内轮（后发生的一轮）花被原基在发育过程中逐渐退化。两轮雄蕊原基为离心发生：位于内侧的一轮雄蕊原基先发生,每两个原基正对第一轮发生的花被原基,外侧的一轮雄蕊原基后发生,与内轮雄蕊原基互生。心皮与内侧的一轮雄蕊互生。     

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.