中华刺蕨和长耳刺蕨配子体发育研究

采用光镜观察,对中华刺蕨和长耳刺蕨配子体发育进行了观察研究.结果表明:中华刺蕨和长耳刺蕨的孢子和配子体发育特征相似,孢子均两侧对称,单裂缝,孢子萌发方式为书带蕨型;配子体经丝状体、片状体发育为心形原叶体,毛状体多产生于幼原叶体生长点两侧边缘,为多细胞棒状,原叶体发育方式为槲蕨型;幼原叶体阶段即可产生精子器,而颈卵器只产生于大型心形原叶体生长点下方,性器官发育类型为薄囊蕨型,卵受精后发育成孢子体.该研究结果支持秦仁昌将刺蕨属和实蕨属独立为实蕨科的观点.     

阔叶鳞盖蕨和粗毛鳞盖蕨(碗蕨科)配子体发育的研究

以腐殖土为基质,对阔叶鳞盖蕨Microlepia patyphylla（D．Don）J．Sm．和粗毛鳞盖蕨M.strigosa（Thunb．）Presl进行了孢子繁殖;利用光学显微镜观察和记录了它们的孢子萌发和配子体发育过程。结果表明,两者的孢子及配子体性状极为相似：孢子同型,三裂缝,萌发慢;孢子萌发需要光,萌发方式为书带蕨型Vittaria-type;配子体生长慢,发育类型为铁线蕨型Adiantum—type;原叶体心形或其他形状,无毛状体,多数为雌雄异株。性器类型为薄囊蕨型Leptosporangiate-type。它们既具有大量的原始性状,也具有少数进化性状。与阔叶鳞盖蕨相比,粗毛鳞盖蕨的配子体发育特征更为原始。说明粗己鳞盖蕨的系统位置更加低下。首次观察到阔叶鳞盖蕨中细胞自然死亡时的叶绿体聚集现象。粗毛鳞盖蕨原叶体老化时叶绿体呈现规则的、相互镶嵌的多边形的形状以及在正常光照下粗毛鳞盖蕨某些细胞中的部分叶绿体成链珠状排列等现象。     

海金沙配子体发育及卵发生的显微观察

用光镜观察海金沙(Lygodium japonicum)配子体发育和卵发生。海金沙孢子为四面体形,具三裂缝,孢子萌发方式为密穗蕨型(Anemia-type);配子体的发育形态多样,通常丝状体长至3~5个细胞时通过顶细胞纵分裂发育为片状体,进而发育为心形原叶体,在心形原叶体上可产生精子器和颈卵器。但在培养过程中也可产生10个细胞以上的丝状体,这种丝状体发育成的片状体和原叶体形态通常不规则,只产生精子器,不产生颈卵器。原叶体发育是铁线蕨型(Adiantum-type),性器官是薄囊蕨型(Leptosporangiate-type)。切片观察海金沙颈卵器产生于生长点下方表面细胞,经两次分裂形成了顶细胞、初生细胞和基细胞。其中初生细胞再经两次不等分裂产生卵细胞、腹沟细胞和颈沟细胞,此时三个细胞紧密相连,随发育,颈沟细胞和和腹沟细胞退化,卵周围形成了分离腔,光镜观察显示成熟卵细胞上无典型卵膜形成,未观察到受精孔的结构。     

亮毛蕨的配子体发育特征及其系统学意义

采用原生境土培养方法对亮毛蕨(Acystopteris japonica)进行培养,并对其配子体发育过程进行了观察。结果表明:亮毛蕨植物的孢子二面体型,极面观为椭圆形,赤道面观肾形,单裂缝,无周壁,外壁具棒状纹饰,孢子萌发为书带蕨型(Vittaria-type),原叶体发育为铁线蕨型(Adiantum-type)。丝状体4～7个细胞,片状体小楔状,仅3～5个细胞宽,成熟原叶体心形,裸露,初生假根具叶绿体,颈卵器较短;配子体发育较迅速,假根具分枝和膨大,精子器囊由3个壁细胞构成,颈卵器略弯曲。本研究首次观察到亮毛蕨的颈卵器壁细胞内含有球形颗粒,但其功能不详。亮毛蕨的配子体发育过程兼有原始和进化的特点。在适宜的光照和温度下,土壤培养亮毛蕨原叶体的成苗率达95%以上,移栽成活率达89%以上。     

石灰岩地区蕨类植物低头贯众的配子体发育研究

采用原生境腐殖土对低头贯众[Cyrtomium nephrolepioides (Christ) Cop.]孢子进行培养,在显微镜下详细观察了其配子体发育的全过程.结果表明:低头贯众孢子深棕褐色,二面体形,极面观椭圆形,孢子萌发不具假根或为书带蕨型(Vittaria-type);丝状体由3～8个细胞构成;片状体上偏斜具毛状体,宽达10个细胞;原叶体的发育为叉蕨型(Asplenium-type).成熟的原叶体为对称心形,具乳头状毛状体,假根分叉,根尖膨大,精子器壁由3细胞构成和颈卵器弯曲等表现出进化的特征,但假根含有叶绿体又表现了原始的系统学特征.研究认为孢子萌发较慢,假根尖膨大和毛状体等似乎是该种配子体对石灰岩土壤特殊生境的适应对策.     

药用植物乌蕨配子体发育的观察

药用植物乌蕨(Stenoloma chusanum(L.)Ching)配子体发育周期短而迅速,是一种研究蕨类配子体世代的生理生态和分子生物学等特征的理想试验材料.本文采用原生境腐殖土培养方法对乌蕨的孢子进行人工培养,观察并记录其孢子萌发和配子体发育的过程.结果表明:乌蕨孢子呈黄色,单裂缝,二面体形;孢子萌发为书带蕨型(Vittaria-type).丝状体4～6个细胞,有时具二叉分枝.片状体为长楔形,达6～8个细胞宽.成熟的原叶体为对称心形,裸露,发育为槲蕨型(Drynaria-type),并且具备一定的营养繁殖能力.原叶体上的假根为单细胞且不含叶绿体.精子器为盖裂开放,颈卵器短而直立.利用孢子培养的方法对乌蕨种苗进行人工繁殖,将为保护性开发利用这一重要药用资源奠定基础.     

水鳖蕨配子体系统学特征的培养观察

在光学显微镜下观察了水鳖蕨(Sinephropteris delavayi(Franch.)Mickel)配子体发育的详细过程。水鳖蕨孢子培养6 d左右萌发;原丝体单列细胞,或发育出2~3个分支;片状体生长点不明显,成熟配子体近心形。本文还讨论了其生长点、毛状体及性器的发育特点,结果支持Mickel将水鳖蕨独立成属的观点。     

旱生蕨类植物金毛裸蕨配子体发育及其生态意义

采用光学显微镜对旱生金毛裸蕨(Gymnopteris vestita)配子体发育的全过程进行了观察。结果显示,(1)旱生金毛裸蕨孢子三裂缝,成熟时黄褐色,接种后10～15d萌发,萌发类型为书带蕨型。原叶体母细胞首先形成单列的丝状体,其后配子体发育明显区别于非旱生的蕨类,金毛裸蕨配子体发育最明显的特征是形成大量的分枝,通常单列的丝状体基部细胞可通过细胞纵分裂形成丝状分枝,这些分枝又可进一步产生新的分枝,分枝的末端可形成片状体,这些片状体又可产生分枝丝状体或片状体,最终整个配子体可发育为群丛。有时,单列的丝状体也可直接发育为片状体,然而这些片状体并不发育为原叶体而是产生大量的丝状分枝。当群丛形成时,在丝状体或片状体表面可产生数量较多的精子器,但在人工培养条件下并没有发现颈卵器。如果培养条件适宜,配子体可进行营养繁殖,持续较长时间,老的片状体上可产生新的丝状体。金毛裸蕨位于群丛外的大型心形原叶体可进行无配子生殖产生孢子体。金毛裸蕨的配子体发育特征,包括多分枝、发达的营养繁殖及无配子生殖现象的发生,表明了金毛裸蕨配子体群丛的形成是对于旱生环境的一种适应性。     

细辛蕨配子体发育的研究

利用光学显微镜详细观察和记录了细辛蕨[Boniniella ikenoi(Makino)Hayata]配子体发育过程,为细辛蕨属(BoniniellaHay.)的系统学研究积累基础资料.结果表明:孢子单裂缝,赤道面观半圆形,极面观椭圆形;接种7 d左右孢子萌发,14~20 d形成4~7个细胞的丝状体,丝状体阶段容易受到真菌的侵染;70 d左右,配子体发育成熟,多为雌雄同株,原叶体细胞中叶绿体的分布因光强的不同而改变.并对细辛蕨配子体各发育阶段的系统学意义、抗逆性及光诱导叶绿体运动的生理学机制进行了讨论.     

下延叉蕨和芽胞叉蕨配子体发育的研究

利用光学显微镜详细观察了叉蕨属(Tectaria)下延叉蕨(Tectaria decurrens)和芽胞叉蕨(T.fauriei)的配子体发育过程,记录了配子体各发育阶段的特征。结果表明:(1)下延叉蕨和芽胞叉蕨的孢子均为单裂缝,具周壁,由周壁形成纹饰,孢子极面观椭圆形,赤道面观豆形或肾形。(2)孢子萌发方式为向心型。(3)原叶体发育方式为三叉蕨型。(4)成熟原叶体心脏形,两翼向斜上方扩展。(5)均具单细胞和多细胞毛状体,在丝状体或片状体阶段出现。研究认为,从配子体发育角度看,叉蕨属是较进化的陆生真蕨类;毛状体的类型、位置和出现时间等特征在叉蕨属种间存在差异,可作为该属种间分类的特征。     

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.