广东石灰岩柳叶蕨属植物分类与分布

柳叶蕨属为分布于石灰岩区域的一类较特别的植物。文献资料和野外调查表明,广东有柳叶蕨属植物共4种,其中3种为广东省分布新记录,即峨眉柳叶蕨、镰羽柳叶蕨和柳叶蕨,建议将这几种植物列为国家重点保护植物。     

鳞毛蕨科四个属的染色体数目

报道了鳞毛蕨科的4个属(毛枝蕨属Leptorumohra、石盖蕨属Lithostegia、黔蕨属Phanerophlebiopsis和柳叶蕨属Cyrtogonellum)6种植物的染色体数目及生殖方式。其中柳叶蕨Cyrtogonellum fraxinellum 'n'=123, 2n=123; 离脉柳叶蕨C. caducum 'n'=123; 斜基柳叶蕨C. inaequalis 2n=123; 四回毛枝蕨Leptorumohra quadripinnata n=41; 石盖蕨Lithostegia foeniculacea 2n=164; 长叶黔蕨Phanerophlebiopsis neopodophylla 2n=82。石盖蕨属、黔蕨属和柳叶蕨属的染色体数目为首次报道。结果表明这3个属的染色体基数和鳞毛蕨科中其他属一样均为x=41。细胞学证据支持将石盖蕨属、黔蕨属置于鳞毛蕨科的处理。本文还发现柳叶蕨属与贯众属Cyrtomium的一些种一样, 具有无融合生殖方式, 而其他3个属仅具有在蕨类植物中较为常见的有性生殖方式。     

柳叶蕨属的分类与分布

柳叶蕨属是鳞毛蕨科中一个小属,为秦仁昌教授1938年建立的。但50多年来,本属的分类与分布情况,很少为蕨类植物学家所了解。到目前为止,已知本属有8个种,主要分布中国西南部,仅1种-柳叶蕨Cyrtogonellum fraxinellum (Christ) Ching分布到越南北部。本文对属的形态特征加以描述,编制有分种检索表,并有本属的地理分布图。     

柳叶蕨属的新分类群

本文发表了柳叶蕨属的五个新种:峨眉柳叶蕨C.omeiense;相似柳叶蕨C.simile弓羽柳叶蕨C.salicifolium:镰羽柳叶蕨C.falcilobum;小柳叶蕨C.minimum     

鳞毛蕨科植物的系统发育: 叶绿体rbcL序列的证据

运用MEGA2和MrBayes 3.0b4软件包对105种鳞毛蕨类及近缘植物(其中新测定36种)的叶绿体DNA rbcL基因序列进行系统发育分析, 探讨了其主要分类群(属级水平)的系统演化关系。用最大简约法、邻接法和贝叶斯分析方法构建的系统树基本一致, 结果显示: (1)秦仁昌系统所定义的鳞毛蕨科Dryopteridaceae, 除了拟贯众属Cyclopeltis外, 均包含在两个单系群之中, 支持鳞毛蕨族Dryopterideae和耳蕨族Polysticheae的成立; 但是鳞毛蕨族还包含秦仁昌系统所定义的球盖蕨科Peranemaceae和三叉蕨科Tectariaceae肋毛蕨属Ctenitis的部分种类; 耳蕨族还包含产于美洲的Phanerophlebia属和Polystichopsis属; 确认石盖蕨属Lithostegia属鳞毛蕨族的成员, 且与复叶耳蕨属Arachniodes具有较近的亲缘关系。(2)拟贯众属与所分析的其他任何鳞毛蕨类植物的关系都比较疏远, 单独为一支。(3)秦仁昌系统所定义的球盖蕨科与肉刺蕨属Nothoperanema聚成一个分支, 属于鳞毛蕨族的成员。(4)鳞毛蕨属Dryopteris为多系类群, 耳蕨属Polystichum和贯众属Cyrtomium均为并系类群。(5)黔蕨属Phanerophlebiopsis、毛枝蕨属Leptorumohra和石盖蕨属与复叶耳蕨属构成一支; 柳叶蕨属Cyrtogonellum与Polystichum属和Cyrtomium属的部分种类聚成一支; 肉刺蕨属与球盖蕨科及鳞毛蕨属的部分种类聚成一支。对鳞毛蕨科的系统关系、球盖蕨科与鳞毛蕨科的系统关系、肋毛蕨属与鳞毛蕨科的系统关系以及中国或亚洲特有属(拟贯众属、肉刺蕨属、黔蕨属、毛枝蕨属、石盖蕨属和柳叶蕨属)的系统位置进行了讨论。     

云贵高原及横断山区莲座蕨科植物地理分布

依据云南大学植物标本馆蕨类植物标本室(PYU)和国内主要标本馆保存的莲座蕨科植物标本,以及多年来积累的研究资料,建立该科植物在云南的产地GIS数据库。以此为基础,分析云南莲座蕨科植物空间分布的多样性和特有性,及其在云贵高原及横断山区的地理分布特征。研究结果如下：① 云南莲座蕨科植物种类丰富,分布海拔范围为100~2400m;② 滇东南是莲座蕨科植物分布的多样性和特有性中心,其多样性由滇东南向西、北方向递减;③ 云南有莲座蕨科2个属分布,即莲座蕨属(Angiopteris)和原始莲座蕨属(Archangiopteris),其中原始莲座蕨属的物种多样性较低而特有性较高。初步分析了该科植物中5个广布种和1个高山峡谷种分布格局的成因,以及5个特有种的发生史,推断广布种的分布格局形成于第四纪冰期之前,高山峡谷种的分布格局形成于第三纪之后,而特有种的主要成因可能是自然杂交和边缘效应。     

凤尾蕨属植物在中国的分布新资料

凤尾蕨属植物具有较高的观赏价值和药用价值。弄清其在我国的分布状况,有利于资源的开发利用。本文报道了台湾凤尾蕨Pteris taiwanensis Ching ex Ching et S. H. Wu为中国大陆分布新记录,另外11种凤尾蕨属植物为省新记录,分别是海南凤尾蕨、指叶凤尾蕨、多羽凤尾蕨、大明凤尾蕨、细弱凤尾蕨、线羽凤尾蕨、栗柄凤尾蕨、单叶凤尾蕨、细羽凤尾蕨、三叉凤尾蕨和鸡冠凤尾蕨。并证实凤仪凤尾蕨Pteris dalhousiae Hook.没有分布至中国。     

湖北鳞毛蕨属植物的地理分布及区系特征

对湖北鳞毛蕨后植物的地理分布和区系特点进行了研究。鳞毛蕨后植物广布于世界各地,该后的分布和多样性中心位于中国西南部和东喜马拉雅山区;另一中心则位于日本,中国东南部和南部。鳞毛蕨后是一个自然的北温带分布属。中国有鳞毛蕨后植物134种(包括7变种),西南地区(云南、四川、贵州等)是国产鳞毛蕨属植物分布最集中的地区。区系分析表明：湖北鳞毛蕨后植物种类比较丰富,有36种,主要分布于鄂西北和鄂西南山区,是构成湖北森林植物区系林下草本植物的主要成分之一;地理成分比较复杂,种的分析显示出以中国一日本分布和中国持有分布为主的特点;与相邻省鳞毛蕨属植物区系的关系比较密切;区系过渡性明显。     

膜叶铁角蕨属的形态系统学研究

膜叶铁角蕨属隶属于铁角蕨科,全世界约有30种,我国分布有18种,是该属植物的分布中心之一。到目前为止,膜叶铁角蕨属的物种数目和物种分类还存在很大争议,一些物种的界限和定义还模糊不清,为了得到一个自然的膜叶铁角蕨属分类系统,还需要对膜叶铁角蕨属的物种分类做进一步研究。该文在前人研究的基础上,对膜叶铁角蕨属10种植物的形态特征,包括孢子形态特征、叶柄和根状茎上的鳞片形态特征、叶片形态、羽片形状以及叶脉特征等进行详细观察分析,探讨了各个形态特征间的关系以及膜叶铁角蕨属植物的物种分类。结果表明:膜叶铁角蕨属植物的叶片及羽片等形态特征存在很大区别,叶柄和根状茎上的鳞片以及孢子形态的种间差异虽然不大,但其在大小、形状、颜色等方面的细微差别仍可作为部分种类的鉴定依据。该研究结果为膜叶铁角蕨属植物的物种分类及进一步研究提供了重要依据。     

中国燕尾蕨属(Cheiropleuria C.Presl)植物修订

通过研究燕尾蕨属(Cheiropleuria C.Presl)植物的标本和文献,对过去国内标本馆及文献中有关燕尾蕨属植物的报道进行了订正,确认中国产燕尾蕨属植物2种,即广泛分布在我国华南地区的全缘燕尾蕨(C.integrifolia)和仅产海南的燕尾蕨(C.bicuspis)。     

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.