蕨配子体发育及卵发生的显微结构观察

运用显微观察技术对蕨(Pteridium aquilinum var. latiusculum)配子体发育和卵发生进行了研究。结果表明：(1)蕨孢子黄褐色,四面体形,具三裂缝,接种后3～7 d萌发,经丝状体和片状体阶段发育成原叶体,成熟原叶体雌雄异株或同株。(2)蕨颈卵器产生于生长点下方的表面细胞(颈卵器原始细胞),该细胞经2次分裂形成3层细胞,其上层和下层细胞发育为颈卵器壁细胞,中间细胞为初生细胞,它经2次不等分裂产生3个细胞,分别为卵细胞、腹沟细胞和颈沟细胞;刚产生时,此3个细胞紧贴颈卵器壁,细胞质内液泡较多,随着发育,卵细胞和腹沟细胞之间产生了分离腔,但二者通过孔区相连,在卵细胞上表面可观察到卵膜;此后,颈沟细胞和腹沟细胞逐渐退化,颈卵器壁细胞内具有黑色颗粒物质。连续切片观察发现,成熟卵细胞上表面中央具有受精孔。卵发生的细节尚需超微结构的研究。     

地钱颈卵器发育和卵发生的显微观察及细胞化学研究

对地钱（Marchantia polymorpha）颈卵器发育和卵发生过程进行了显微观察和细胞化学的研究,颈卵器起始于原始细胞,该细胞呈乳突状,经横分裂产生基细胞和顶细胞,顶细胞经3次纵斜向分裂和1次横分裂产生初生细胞,初生细胞是颈卵器内的第一个细胞,经横分裂产生中央细胞和颈沟母细胞,前者产生1个腹沟细胞和1个卵细胞,后者最终产生4个颈沟细胞。颈卵器的成熟表现为颈部显著伸长和腹部膨大,卵细胞成熟时具有不规则的核,细胞质内含有丰富的囊泡和颗粒物,卵细胞周围充满粘性物质,细胞化学研究表明,该粘性物质为多糖,卵细胞质中深染色的颗粒可能为脂类物质,腹沟细胞自产生后就逐渐退化,颈沟细胞的退化迟于腹沟细胞,其数量通常为4个,偶尔可见5个颈沟细胞或具有双核的现象。     

乌蕨配子体发育及卵发生的显微观察

采用光学显微镜对乌蕨的配子体发育及卵发生的过程进行了研究,以阐明蕨类植物颈卵器发育特征,为揭示蕨类植物有性生殖机制以及鳞始蕨科的演化提供依据。结果表明:(1)乌蕨孢子黄褐色,具单裂缝,表面平滑或呈疣状纹饰;孢子接种12d萌发,萌发类型为书带蕨型,原叶体发育类型为铁线蕨型。(2)半薄切片观察表明,乌蕨颈卵器产生于原叶体生长点下方的表面细胞,即颈卵器原始细胞,该细胞经过两次分裂形成纵向3层细胞,最上层细胞发育为颈卵器的颈部壁细胞,中间层细胞即初生细胞再经过两次不等分裂产生颈沟细胞、腹沟细胞和卵细胞,此三细胞最初紧密贴合,随着颈卵器的发育,卵细胞与腹沟细胞间从两侧向中间产生分离腔,且腹沟细胞与颈沟细胞开始退化;分离腔逐渐向中间扩大,直至出现孔状结构,即受精孔;颈卵器发育后期,在卵细胞上表面形成染色较深的卵膜,颈沟细胞与腹沟细胞退化成絮状物。     

水蕨颈卵器的形成与发育

主要运用电子透射显微镜技术对水蕨（Ceratopteris thalictroides（L．）Brongn）颈卵器形成与发育进行了研究。结果表明：水蕨颈卵器是由原叶体分生组织内颈卵器原始细胞形成的。该原始细胞经2次分裂形成3层细胞,上下两层发育成颈卵器颈部与底部的壁细胞,中层为初生细胞。初生细胞是颈卵器内雌配子发生的第一个细胞,该细胞经2次不等分裂形成1个卵细胞,1个腹沟细胞、1个双核的颈沟细胞。本研究首次阐明了水蕨颈卵器内细胞的发育顺序和特征。     

水蕨颈卵器的形成与发育

主要运用电子透射显微镜技术对水蕨(Ceratopteris thalictroides(L.)Brongn)颈卵器形成与发育进行了研究。结果表明:水蕨颈卵器是由原叶体分生组织内颈卵器原始细胞形成的。该原始细胞经2次分裂形成3层细胞,上下两层发育成颈卵器颈部与底部的壁细胞,中层为初生细胞。初生细胞是颈卵器内雌配子发生的第一个细胞,该细胞经2次不等分裂形成1个卵细胞,1个腹沟细胞、1个双核的颈沟细胞。本研究首次阐明了水蕨颈卵器内细胞的发育顺序和特征。     

阔叶鳞盖蕨配子体发育及卵发生的研究

采用显微镜和透射电镜对阔叶鳞盖蕨(Microlepia platyphylla)的配子体发育和卵发生过程进行了观察,以阐明其卵发生的细胞学机制,探讨其演化地位。阔叶鳞盖蕨孢子褐色,四面体形,具三裂缝,接种5~10d后孢子萌发,经丝状体和片状体阶段发育为心形原叶体,原叶体发育是铁线蕨型,通常为雌雄异株,精子器产生于不规则配子体的表面,颈卵器产生于心形原叶体生长点的下方,性器官是薄囊蕨型。卵发生研究表明,阔叶鳞盖蕨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3个细胞通过胞间连丝紧密相连,随发育,腹沟细胞与卵细胞间形成了分离腔,但在孔区处始终通过胞间连丝相连,成熟卵细胞上形成了卵膜和受精孔,卵核表面产生了核外突,通过比较表明阔叶鳞盖蕨卵发生与蕨（Pteridium aquilinum）卵发生相似。     

阔鳞瘤蕨(水龙骨科)卵细胞发育超微结构观察

水龙骨科是蕨类植物中最进化的类群,该文采用超微技术对水龙骨科的阔鳞瘤蕨(Phymatosorus hainanensis)卵发育过程进行观察,以完善薄囊蕨植物卵发生的资料,为揭示蕨类植物的有性生殖及演化机制奠定基础。结果表明:(1)幼卵、颈沟细胞、腹沟细胞通过胞间连丝紧密连接。(2)发育过程中,卵与腹沟细胞之间细胞壁显著加厚,将卵细胞与腹沟细胞隔离。(3)在壁的下方产生分离腔,内含大量不定形物质,但卵细胞与腹沟细胞在中间处始终相连。(4)分离腔中的不定形物质沉积在卵细胞质膜外形成了一层加厚的卵膜,而在连接区(孔区)处不形成卵膜,该位置最终形成了受精孔。(5)卵细胞核变得高度不规则,近成熟时卵核产生了大量的核外突。     

扇叶铁线蕨配子体发育及卵发生的显微观察

采用显微观察技术对扇叶铁线蕨配子体发育和卵发生进行了研究.结果显示:(1)扇叶铁线蕨孢子黄褐色,四面体形,具三裂缝,孢子接种后4～7 d萌发,经丝状体和片状体阶段发育为心形的原叶体,成熟原叶体雌雄同株,在原叶体基部产生精子器,在原叶体生长点下方产生颈卵器.(2)切片观察表明,扇叶铁线蕨颈卵器产生于生长点下方的表面细胞(颈卵器原始细胞),该细胞经2次分裂形成3层细胞,其上层细胞发育为颈卵器颈部壁细胞,中间细胞为初生细胞,它经2次不等分裂产生3个细胞--卵细胞、腹沟细胞和颈沟细胞;刚产生时, 3个细胞紧贴颈卵器壁,随着发育,卵细胞和腹沟细胞之间产生了分离腔,同时在卵细胞上表面形成了染色深的卵膜;此后,颈沟细胞和腹沟细胞逐渐退化,在颈沟内产生大量不定形物质,受精作用观察表明,该物质能够吸引精子进入颈卵器.(3)连续切片观察发现,成熟卵细胞上表面卵膜中央具有受精孔,表明受精孔在同型孢子蕨类卵细胞中可能是普遍存在的.     

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。     

阔鳞瘤蕨颈卵器形成与卵发生的初步研究

运用光学显微镜与透射电镜对阔鳞瘤蕨（Phymatosorus hainanensis(Noot.) S.G.Lu）颈卵器形成和卵发生进行了研究。阔鳞瘤蕨颈卵器产生于雌配子体生长点下方分枝毛状体内侧。切片观察表明颈卵器起源于配子体表面的原始细胞,该细胞经两次不等分裂形成3个细胞,上下两个细胞分别发育为颈卵器的颈部与底部壁细胞,中间的细胞为初生细胞,含有较丰富的细胞器。初生细胞进行两次不等分裂产生颈沟细胞、腹沟细胞与卵细胞。成熟颈卵器内颈沟细胞和腹沟细胞退化,卵细胞上表面产生受精孔。本研究阐述了阔鳞瘤蕨颈卵器形成和卵发生的细胞学过程,对阐明蕨类植物雌性生殖器官的发育特征有一定的科学意义。     

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.