突脉金丝桃的花器官发生及其系统学意义

利用扫描电镜（SEM）观察了突脉金丝桃（Hypericum przewalskii）（金丝桃科）的花部器官发生发育过程。结果表明,突脉金丝桃2枚苞片原基首先发生,花原基在苞片原基的包裹中完成发育。在苞片原基发生后,5枚萼片原基沿2/5圆周依次发生。萼片原基发生近完成时,5枚雄蕊—花瓣共同原基在萼片原基之间的角隅处近同时发生,此后,雄蕊—花瓣共同原基下部向外伸展形成花瓣原基,上部向上凸起形成与花瓣原基相对的雄蕊原基,之后雄蕊原基由内向外依次分化发育产生次生雄蕊原基,随着次生雄蕊原基的发育和数目的增多,形成了5束雄蕊。次生雄蕊原基发生的同时,5枚心皮原基近同时发生。突脉金丝桃雄蕊束的发生方式表明,金丝桃属的雄蕊束可能起源于5基数的单轮雄蕊。金丝桃科与藤黄科植物花瓣及雄蕊原基发生方式的显著不同,支持了APG Ⅲ系统将金丝桃亚科从藤黄科中独立为金丝桃科的观点。     

长角凤仙花（凤仙花科）的花器官发生和发育

以不同发育时期的长角凤仙花Impatiens longicornuta Y.L.Chen（凤仙花科Balsaminaceae）为材料,利用扫描电镜技术观察了其花器官的分化及其发育过程。长角凤仙花为两侧对称花,具2枚侧生萼片,唇瓣囊状,旗瓣具鸡冠状突起,雄蕊5枚,子房上位,5心皮5室。其花器官分化顺序为向心式,萼片—花瓣—雄蕊—雌蕊原基。2枚侧生萼片先发生,然后近轴萼片（即唇瓣）原基和2枚前外侧萼片原基近同时发生;但是这3枚萼片原基的发育不同步,远轴的2枚前外侧萼片原基的发育渐渐滞后,然后停止发育,最后渐渐为周围组织所吸收,直至消失不见。花瓣原基中,旗瓣原基最先发生,4个侧生花瓣原基相继成对发生,且之后在基部成对愈合形成翼瓣;5枚雄蕊原基几乎同时发生,5个心皮原基轮状同时发生。本文结果支持凤仙花属植物为5基数的花,并进一步证实了唇瓣的萼片来源;此外,研究结果表明花器官早期发育资料对植物系统与进化研究具有重要参考价值。     

吉祥草的花部器官发生及其系统学意义

利用扫描电镜（SEM）观察了吉祥草（Reineckia carnea）（铃兰科）的花部器官发生发育过程。吉祥草花被片、雄蕊的发生方式是由近轴端向远轴端发生的逆单向型（reversed unidirection）,花发育后期花被片合生形成花被筒,花丝与之贴生。伴随花被片、雄蕊发生,三枚心皮也由近轴向远轴方向相继发生,随后彼此合生发育。花序顶部的花易发生花器官数目变异。结合早期花原基形态以及花器官数目变异情况分析,吉祥草的花被片与雄蕊可能是由共同原基分化而成。从花部器官发生式样和花被筒形成时间两方面比较吉祥草属、白穗花属和铃兰属的特征发现,三属中,铃兰属处于相对进化的位置,而白穗花属比吉祥草属更为原始。     

泽苔草的花器官发生

本文用扫描电镜观察了泽苔草的花器官发生过程,观察结果表明：花萼以螺旋状方式向心发生,花瓣以接近轮状方式近同时发生,不存在花瓣雄蕊复合原基。雄蕊和心皮均以轮状向心方式发生,6枚雄蕊分两轮分别在对萼和对瓣的位置先后发生,至发育的后期排成一轮,但仍分别处于对萼和对瓣的位置;随后发生的第一轮3个心皮原基与3枚萼片相对,第二、三轮心皮原基分别为1~3个,与前一轮心皮相间排列向心发生。本文首次揭示了泽苔草花被的外轮3个萼片螺旋状发生方式,这种螺旋状方式很可能是泽泻科植物的花部结构在进化过程中适应环境而保留下来的一种较原始的叶性特征。     

水筛的花器官发生

利用扫描电镜首次对水筛[Blxa japonica(Miq.)Maxim.ex Asch.et Guerk.]花器官的发生进行了观察。结果显示：萼片原基以轮关方式向心发生;花瓣原基轮状近同时发生,与萼片基基交替排列;雄蕊原基以对萼的形式轮关发生,与花瓣原基轮状近同时发生,与萼片原基交替排列;雄蕊原基以对萼的形式轮状发生,与花瓣原基交替排列;花柱原基在整个花的发育过程中发生较晚,以对瓣的形式轮状发生,与雄蕊原基交替排列。与同科其它属的花比较,水筛的花为两性,辐射对称,胚珠多数,体现了较原始的特征。花各部数目均为3,进化程度居于中间水平。该属花各部轮状发生,子房下位,心皮合生,体现了本科在泽泻亚纲中花部结构进化的特征。     

驴蹄草属和金莲花属(毛茛科)花器官的形态发生及系统学意义

利用扫描电镜观察了驴蹄草Caltha palustris L.和川陕金莲花Trollius buddae Schipcz.花器官的发生和发育过程。结果显示:驴蹄草和川陕金莲花的所有花器官均螺旋状向心式发生、向心式发育,花器官的螺旋状发生方式在毛茛科Ranunculaceae可能是一种基本式样;苞片、萼片与其他花器官原基的形状明显不同,显示苞片、萼片与其他花器官在系统发生上有所不同;川陕金莲花的花瓣在早期延迟发育且基部具囊,花瓣的延迟发育在毛茛科具花瓣的属中非常普遍,而花瓣基部的囊类似于耧斗菜属Aquilegia一些植物;两个属雄蕊群一纵列雄蕊中的小孢子均向心式发育,这种发育方式在毛茛科可能为基本类型。两个属植物的心皮原基均为对折式,在发育过程中,驴蹄草心皮顶端沿腹缝线形成下延的柱头组织,川陕金莲花不形成明显的柱头组织。根据花形态发生和发育特点,并结合其他研究成果,认为这两个属不应当属于同一个族。     

基于扫描电镜技术的天葵属(毛茛科)花器官发生研究

毛茛科天葵属为东亚特有类群,但其花器官的发生过程仍不清晰。该研究利用扫描电子显微镜观察了天葵［S. adoxoides (DC.) Makino］花器官的发生过程,以揭示毛茛科花形态的多样性和演化规律,为进一步探讨天葵属与近缘类群的亲缘关系提供发育形态学证据。结果表明：(1)天葵萼片、花瓣和雄蕊均为螺旋状发生,轮状排列;不育雄蕊的数目和位置不定,心皮轮状发生。(2)天葵萼片原基为宽阔的新月形,其他花器官为窄的半球形。(3)天葵花发育后期,花瓣有延迟发育现象,花瓣原基基部发育为浅囊状,心皮原基马蹄形对折,胚珠倒生、双珠被、具胎座附属物。(4)天葵属与耧斗菜属、尾囊草属的花发育性状存在相似性,支持分子系统学证据的三者近缘的观点;天葵属的花性状的特殊表现为：花直径较小,雄蕊、不育雄蕊和心皮数目较少,花器官没有形成明显的直列线,内珠被较长等。     

掌叶木的花器官发生及其系统学意义

利用扫描电子显微镜和光学显微镜观察了掌叶木的花器官发生过程。观察结果表明: 花序原基最先发生, 然后形成两个大小不一的花原基; 萼片原基的发生不同步, 螺旋状向心发生; 4-5枚花瓣原基以接近轮状方式近同时发生; 不存在花瓣-雄蕊复合原基; 7-8枚雄蕊原基为近同时发生, 其生长较花瓣原基快; 心皮原基最后发生, 3枚心皮原基为同时发生。花为单性花。在雌花中, 子房膨大而雄蕊退化。在雄花中, 雄蕊正常发育, 子房退化。讨论了掌叶木花器官发生和发育的系统学意义。     

一种新型矮牵牛花发育突变体的研究

报道了新发现的一种矮牵牛(Petunia hybrida L.)花发育突变体,命名为efficient(eff),并对这一突变体进行了形态学和遗传学分析。eff突变体主要表现为雌蕊心皮数目的增加和雄蕊上长出花瓣状结构,同时,雄蕊、花瓣和萼片数亦有增多,但营养器官无变化。心皮数目的增加导致雌蕊柱头和子房体积的显著增大,并形成较大的果实。雄蕊上花瓣的形成对花粉的产生无明显影响。扫描电镜观察发现,eff突变体在花器官原基形成时发生了相应数目的增加及特征的变化。遗传学分析表明,突变的表现型符合孟德尔单基因遗传规律。     

黄连属(毛茛科)花的形态发生

本文运用扫锚电子显微镜（SEM）观察了黄连属（Coptis）植物花的形态发生和发育过程,结果表明,该属植物所有的花部器官均为螺旋状发生,雄蕊为向心式发育,花瓣原基有微弱的延迟发育,心皮原基为对折型（即马蹄形）,子房为半封闭类型,子房柄是在发育过程中形成的。通过与其它具T．型染色体类群在花形态发生上的比较,认为黄连属表现出了某些原始的性状,这一结果与分子系统学研究认为黄连属为毛莨科的基部类群的结论一致。     

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.