拟目乌贼精子发生和精子的超微结构

应用扫描电镜和透射电镜观察了拟目乌贼(Sepia lycidas)精子的发生过程和超微结构。结果表明,精子发生经历了精原细胞、初级精母细胞、次级精母细胞、精细胞和成熟精子5个阶段,其中精细胞可以分为Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ5个时期,精细胞Ⅱ期又可分为前期和后期。细胞核经历了一个横向收缩、纵向拉长的过程,由圆形或椭圆形,变为不规则的纺锤形、稍弯曲的长柱形;核内染色质由絮状,变为絮块状、致密颗粒状、细纤维状、粗纤维状和片层状,直至高电子密度均质状;顶体由圆形,变为头盔形、圆锥形、倒"U"字形,直至子弹头形;线粒体由空泡状经过融合和迁移,变为内嵴丰富的椭球形,形成不完全包围鞭毛的线粒体距。成熟精子全长101.28μm,由头部和尾部组成,头部呈长辣椒状,长7.73μm,宽1.51μm,由顶体和细胞核组成;尾部细长,为93.18μm,为典型的"9+2"结构,由中段、主段和末段三部分组成。     

大鲵精子结构研究

为了解大鲵精子超微结构,应用扫描电镜和透射电镜开展了大鲵精子形态结构研究。结果显示:大鲵精子由头部、颈部和尾部3部分组成。精子总长216.36μm±9.93μm(n=30),头部长65.80μm±3.70μm(n=30),颈部较短,多不明显,尾部长153.52μm±3.22μm(n=30)。头部由顶体、穿孔器和细胞核组成;颈部包括核窝、近端中心粒及远端中心粒、线粒体、轴丝和轴纤维;尾部无明显分段,由轴丝、轴纤维、轴丝旁纤维和波动膜组成。大鲵精子内线粒体较少,可能与精子运动缓慢、精子活力维持时间短有关;成熟过程中精子细胞头部包围的胞质分泌物中含有一定数量的线粒体。     

墨西哥湾扇贝精子的超微结构

报道了墨西哥湾扇贝成熟精子在SEM和TEM下的超微结构观察结果。墨西哥湾扇贝的精子为典型的原生型,精子全长约43～45μm,头部长约2．1～2．4μm。精子主要由头部、中段和尾部三部分组成。头部顶体明显突出,呈倒V形;顶体下方为细胞核,细胞核近似卵圆形。在细胞核内部或边缘,能观察到有一个或几个形状较为规则的核泡。中段的主要结构有线粒体和中心体,中段的横切面有4个线粒体围绕在中心体的周围。尾部细长,尾部鞭毛横切面为典型的“9 2”结构。     

白肛海地瓜精子发生及形态的超微结构

通过透射和扫描电镜观察了白肛海地瓜(Acaudina leucoprocta)的精子发生过程及其形态结构,揭示了白肛海地瓜精子发生时期一系列变化,其精子发生分为精原细胞、初级精母细胞、次级精母细胞、精细胞、成熟精子5个时期。精原细胞体积最大。精母细胞染色质开始凝集。精细胞前顶体颗粒形成。白肛海地瓜成熟精子的超微结构为原生型,由头部、中部、尾部组成,头部圆形,最前端为顶体,核染色质凝集成团块状,中部是线粒体和中心粒复合体融合成1个超大结构,尾部长约60μm,尾部鞭毛横切面为典型的"9+2"型结构。     

川陕哲罗鲑精子超微结构及形态学研究

对川陕哲罗鲑Hucho bleekeri Kimura精子采用扫描电子显微镜及透射电子显微镜进行观察,结果显示:精子由头部、中片和尾部组成;精子全长41.07μm±2.18μm,头部长2.76μm±0.15μm,头部前端和后端的宽度分别为1.88μm±0.18μm和2.08μm±0.20μm;尾部长34.74μm±5.01μm。头部呈卵圆形,无顶体,主要由细胞核组成;中片由1个不规则的圆球状线粒体及袖套结构组成;线粒体直径为0.82μm±0.08μm;尾部呈细长形,并由一个过渡区域分为前端和末端,尾部内部主要由轴丝组成,轴丝为典型的"9+2"结构,外部有不对称性分布的侧鳍结构。结果表明,川陕哲罗鲑精子类型较为原始,属于硬骨鱼类中的TypeⅠ类型。     

虾夷扇贝精子的超微结构

用扫描和透射电镜研究了虾夷扇贝(Patinopecten yessoensis)精子的超微结构.虾夷扇贝精子为典型的原生型,全长50μm左右,头部长约3 μm.精子主要由头部、中段和尾部三部分组成.头部顶体突出,呈倒"V"形;顶体下方为精核,电子密度较高且占头部大部分,具有核前窝(anterior nuclear fossa)、核后窝(posterior nuclear fossa)和植入窝(implantation fossa);4～5个近圆形的线粒体围绕着中心粒复合体形成精子的中段.尾部细长,尾部鞭毛横切面为典型的"9 2"结构.     

菲律宾蛤仔的精子发生和精子超微结构

用透射电镜研究了菲律宾蛤仔(Ruditapes philippinarum)精子结构和精子发生过程中细胞形态结构的变化及细胞器的演变规律。菲律宾蛤仔雄性生殖细胞的形态由椭圆形渐变为辣椒状,细胞核的形态由椭圆形逐渐拉长,渐变为锥形。染色质的凝集经历：小颗粒团块状一较大颗粒均匀状一粗颗粒均匀状的过程。线粒体在演化过程中数量先增多后逐渐减少,嵴数逐渐增多,电子密度和体积逐渐增大。高尔基体在初级精母细胞期已经发育,随后的各期中发育良好,分泌旺盛。精细胞Ⅱ期,高尔基体分泌的潴泡开始融合,形成前顶体囊。精细胞Ⅲ期,高尔基体的分泌物仍不断融合。精细胞分化的后期,前顶体囊逐渐发育形成顶体。菲律宾蛤仔成熟精子呈长辣椒状,为原生型,由头部、中段和尾部构成。头部的顶体为细长柱形,末端渐细,电子密度较小;细胞核为锥形;中段线粒体4个,尾部鞭毛为典型的“9 2”型结构。此外在成熟精子线粒体环横切面有一特殊“风车状”结构。     

中国淡水蛏精子发生的超微结构研究

利用透射电镜观察了中国淡水蛏的精子发生和精子结构。描述了精子发生过程中各细胞形态结构的变化;揭示了细胞核、线粒体和项体等的演变过程。中国淡水蛏的精子经过精原细胞、初级精母细胞、次级精母细胞和精子细胞,最终限育为成熟的精子。精子为典型的原生型,由头部、中段和尾部构成。项体复合体位于精子头部前端,呈“⊥”形,精核近圆形;中段包括２个中心粒和４或５个紧密排列的椭圆形线粒体;尾部鞭毛断面为典型的“９＋２”     

平疣桑椹石磺精子结构观察

通过电光学显微镜和透射电子显微镜观察了平疣桑椹石磺精子的形态及其超微结构。平疣桑椹石磺成熟精子属于进化型,由头部、中段和末段组成。头部由顶体和精核构成,顶体长约0.7μm,呈细奶嘴状,内含物分布均匀,电子密度稍低于细胞核。顶体基部与精核前端紧密相连,无间隙。精核长约3.8μm,宽约1.0μm,核质高度浓缩,电子密度高,无核泡,纵切似辣椒状,核后端内凹形成核后窝。中段加长,结构复杂,线粒体演化成线粒体鞘,螺旋状包绕轴丝。精子末段由轴丝及包绕轴丝的质膜组成,轴丝为典型的“9＋2”结构。比较了平疣桑椹石磺精子与相关腹足类精子结构的异同,进一步证实了腹足纲贝类精子结构之间的区别主要在于顶体有无及形态,精核的长短与外形、中段线粒体的数目及其排列方式等。     

大鳞副泥鳅精子结构研究

用光学显微镜和透射电子显微镜对大鳞副泥鳅精子的结构进行研究。结果表明,大鳞副泥鳅的精子主要分为头部、中段和尾部;头部无顶体,在光学显微镜下近圆形,在透射电子显微镜下纵切亦近圆形,主要由细胞核组成,核内染色质致密,核内有核空泡,核外可见清晰核膜,核外可见细胞质,细胞质很少且紧贴细胞核,细胞质外是质膜,质膜在细胞质外呈波浪状;头部后端有一较浅的植入窝,约占核的1/4,植入窝的长轴几乎与细胞核的长轴平行,植入窝内有中心粒复合体;精子的中片与头部无明显分割,位于头部的后方,由中心粒复合体和袖套组成,袖套两边不对称,中心粒复合体由近端中心粒和远端中心粒组成,近端中心粒与远端中心粒之间呈一钝角;精子尾部无侧鳍,可分为主段和末段,尾部主段具有典型的＂9＋2＂的轴丝结构。精子头长为（1.79±0.28）μm,中片长为（1.86±0.42）μm,尾长为（28.06±2.78）μm,全长为（31.65±2.82）μm。     

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.