异源四倍体鲫鲤的受精细胞学

异源四倍体鲫鲤的成熟卵子处于第二次减数分裂中期,精子通过受精孔进入卵内。精子入卵以来,受精孔立即被受精塞堵住。受精后8min,受精卵出现明显的精子星光,同时进入第二次减数分裂后期,即将排出第二极体;13min时,精子头部开始膨胀,趋向核化;18min时,雌雄原核均已形成,并向胚盘中央靠近;23min时,雌,雄原核开始接触;33min时,雌,雄原核完全融合成为一个合子核;38min时,受精卵开始第一次卵裂,53min后分裂形成两个子核。该研究证明异源四倍体鲫鲤和大多数二倍体鱼一样,具有正常的受精细胞学程序,受精方式为单精受精。     

可口革囊星虫受精过程及早期卵裂的细胞学变化

为探究可口革囊星虫(Phascolosoma esculenta)受精过程中精子入卵、极体排放、雌雄原核的形成与结合以及早期卵裂的特点,为胚胎发育机制研究奠定基础及指导人工育苗,显微观察了可口革囊星虫卵母细胞的形态;用荧光染色剂HOECHST33258对已固定的成熟卵及受精卵进行染色的方法,在荧光显微镜下观察了可口革囊星虫受精过程及第一与第二次卵裂的细胞学变化。成熟卵呈椭圆形,卵膜较厚,核区偏位,染色体排列整齐。在水温30℃-31℃、盐度23条件下,授精后5min-10min,精子完成入卵;授精后10min-20min,完成第一次减数分裂、释放第一极体;授精后20min-30min,完成第二次减数分裂、放出第二极体,部分受精卵的第一极体分裂为二;授精后30min-40min,雌、雄原核形成,并相互靠近向卵中央迁移;授精后40min-50min,雌、雄原核在卵中央结合成合子核;授精后50min-70min及70min-90min分别完成第一及第二次卵裂。可口革囊星虫的受精过程及早期卵裂的细胞学特点为:1)成熟卵是处在第一次减数分裂中期的初级卵母细胞,具有受精能力;2)精子入卵位点是随机的,存在多精入卵现象;3)雌、雄原核以融合方式结合成合子核;4)第一及第二次卵裂均为经裂、不等裂。     

异源四倍体鲫鲤的受精细胞学

异源四倍体鲫鲤的成熟卵子处于第二次减数分裂中期,精子通过受精孔进入卵内.精子入卵以后,受精孔立即被受精塞堵住.受精后8 min,受精卵出现明显的精子星光,同时进入第二次减数分裂后期,即将排出第二极体;13 min时,精子头部开始膨胀,趋向核化;18 min时,雌雄原核均已形成,并向胚盘中央靠近;23 min时,雌、雄原核开始接触;33 min时,雌、雄原核完全融合成为一个合子核;38 min时,受精卵开始第一次卵裂,53 min后分裂形成两个子核.该研究证明异源四倍体鲫鲤和大多数二倍体鱼一样,具有正常的受精细胞学程序,受精方式为单精受精.     

红鲫与湘江野鲤杂交的受精细胞学研究

红鲫成熟卵直径680—720μm;卵膜孔为精子入卵的唯一通道,包括前庭和精孔管两部分;精孔管内径约5μm。湘江野鲤精子头部直径约2.5μm。在通常情况下,红鲫卵为单精受精。尽管红鲫与湘江野鲤不同属,但杂交仍具有正常的受精细胞学程序。红鲫卵子处于第二次成熟分裂中期接受湘江野鲤精子入卵,精子入卵5min后,出现明显的精子星光;15min后,雄性原核及雌性原核形成;25min后,雌、雄性原核融合;30min后、开始卵裂,发现1个受精卵切片上有4个即将融合的原核,这可能是由于双精受精所致。     

鲫鲤杂种一代(F_1)自交二代(F_2)的受精细胞学研究

荷包红鲫 (♀ )×湘江野鲤 (♂ )杂交产生的杂种一代 ( F1)成熟卵的直径为1 .0～ 1 .2 5mm;为单受精孔卵 ,一般只允许单个精子入卵 ;成熟卵在受精前处于第二次减数分裂中期 ;鲫鲤杂种一代的雄性部分可育 ,能产生正常的精子 ;杂种一代的受精方式为单精受精 ,具有正常的受精细胞学程序 .受精 30 s后 ,精子通过受精孔进入卵质 ;5min后 ,精子产生明显星光 ;1 5min后 ,精子头部膨大核化 ,最后形成雄性原核 ,与此同时 ,雌性原核也开始形成 ;2 5min后 ,雌、雄原核向胚盘中央靠近 ,然后彼此接触 ,最后融合为合子核 ;40 min后 ,开始第一次卵裂 ,在一个受精卵第一次卵裂中期的切片上看到了一个三极纺锤体 .     

中国对虾受精过程中精卵核的细胞学变化

中国对虾精子以其棘部顶端随机附着在卵上,精子在凝胶膜形成后,第一极体排出前入卵,精子入卵后,絮状的精核经过重建形成雄原核,中国对虾卵子排放时处于第一次成熟分裂的中期,卵子入海水时,纺锤体的长轴与质膜平行,卵子激活后,纺锤体的长轴开始旋转,旋转至纺鲑体长轴与质膜垂直时,由纺锤丝牵引着染色体向两极移动,外侧的染色体由质膜包裹形成第一极体,受膜举起后,由次级卵母细胞排放出第二极体,此后,单倍雌核重建形成雌原核,雄原核形成早于雌原核,雌雄原核于卵子中央联会形成联合核,受精后的50分钟纺锤丝牵关染色体称向两极,质膜内缢断裂形成两个细胞的胚胎。     

中华鲟受精细胞学研究

中华鲟(Acipenser sinensis Gray)的成熟卵具有一层放射膜及二层卵黄膜。在动物极有9—15个受精孔。每一受精孔有一大的入口(12.7—13.9μm直径)及一细长的受精管道(1.2—1.3μm直径)。 进入受精孔的许多精子只能按序入卵。其中只有一个精子的头部膨大核化,最后形成雄性原核。同时活跃的卵子也形成雌性原核。雌、雄原核彼此接触,最后融合成合子核,随后分成两个子核。 中华鲟的受精方式为多精入卵,单精受精。     

泥鳅精子和卵子结构及受精过程的细胞学观察

研究旨在探讨泥鳅精子受精时限及为其人工繁殖提供基础资料。采用光镜、电镜技术对泥鳅（Misgurnus anguillicaudatus）精子、卵子和不同时间段的受精卵进行了观察。结果显示:泥鳅精子头部无顶体,主要为核占据,核凹窝较浅,中段具不对称的袖套,尾部轴丝为9+2结构,无侧鳍。卵子动物极卵膜仅有一受精孔,受精孔为深凹陷、短孔道型。在20-21℃水温条件下,授精后3s,精子开始穿过精孔管或已经进入卵子;授精后5-8s,形成精子星光;授精后70s,卵子处于第二次减数分裂后期;授精后6-8min,第二极体形成,等待排出;授精后20-25min,雌雄原核融合;授精后25-30min,受精卵进入第一次有丝分裂中期;授精后40-45min,第一次有丝分裂结束,二细胞形成。研究表明:成熟卵子精孔管内口径（2.2860.364）m,而精子头部直径与其接近,单精受精;入水后150s内可受精。     

栉孔扇贝(♀)×虾夷扇贝( ♂ )受精细胞学观察

采用Bouin氏液固定、石蜡包埋、切片 ,用苏木精 伊红染色 ,在光学显微镜下观察栉孔扇贝 (♀ )与虾夷扇贝 (♂ )杂交的受精细胞学过程。尽管栉孔扇贝与虾夷扇贝同科不同属 ,但它们的杂交仍具有正常的受精细胞学程序。栉孔扇贝卵子处于第一次成熟分裂中期时接受虾夷扇贝的精子入卵 ,精卵混合后 6min精子入卵 ;8～ 1 0min精核略微膨胀 ;2 5～ 3 0min排出第一极体 ;1h左右 ,雌雄原核同时形成 ;1小时 3 0分钟左右 ,雌雄原核融合 ;2h左右开始卵裂。杂交过程中的精子入卵行为较本交迟缓 ,但杂交后代仍能正常发育     

斜带石斑鱼(♀)×鞍带石斑鱼(♂)受精细胞学的组织切片观察

人工诱导雌核发育二倍化的关键是掌握极体排出和卵裂的时机,掌握该规律最直接的方式即进行受精细胞学的研究。以鞍带石斑鱼(Epinephelus lanceolatus)为父本,斜带石斑鱼(Epinephelus coioides)为母本,通过人工授精获得受精卵,收集受精后不同时刻的卵子,经Smith′s液固定、石蜡包埋、切片、苏木精-伊红染色和显微组织观察。结果表明:受精后第30~60 s精子入卵;第3 min精子星光出现;第5 min卵子排出第二极体;第7~15 min雌雄原核相互靠近,并最终融合;第15 min以后合子核开始分裂。鞍带石斑鱼精子进入斜带石斑鱼卵子的时间与多数硬骨鱼类比较没有显著差别;但是,第二极体排出及第一次卵裂的时间较早。研究展示了斜带石斑鱼与鞍带石斑鱼杂交的受精细胞学的基本发育过程,并为后续的人工诱导石斑鱼雌核发育研究提供了理论依据。     

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.