花生凝集素受体在中华绒螯蟹生精细胞的分布

以中华绒螯蟹为材料,应用凝集素印迹法检测中华绒螯蟹生精细胞中的花生凝集素受体.以凝集素组织化学技术为手段,采用生物素标记的花生凝集素对中华绒螯蟹精子发生过程中花生凝集素受体进行了标记,研究精子发生过程中花生凝集素受体的分布特征.结果表明,中华绒螯蟹生精细胞中的花生凝集素受体的分子质量为72 ku;精子发生过程中,不同的生精细胞膜有不同程度的阳性标记.精原细胞质膜上有较强的阳性标记,呈深棕色;精母细胞的质膜阳性标记减少;精细胞与精母细胞染色程度相似.PNA受体在生精细胞中分布,可能与生殖细胞发育以及生殖细胞之间或者生殖细胞与体细胞之间的信息传递有关.精子质膜、顶体区域也有阳性标记,这可能与精卵识别及结合等受精过程息息相关.     

类固醇激素受体在扬子鳄睾丸表达的免疫细胞化学研究

用免疫细胞化学方法对雄激素受体(AR)、雌激素受体(ER)和孕激素受体(PR) 在扬子鳄睾丸中进行定位研究.结果表明,三种类固醇激素受体在扬子鳄睾丸中都有分布:雄激素受体在睾丸的肌样细胞和支持细胞中呈阳性反应,雌激素受体在睾丸的间质细胞中呈 阳性反应,孕激素受体在睾丸的生精细胞中呈阳性反应.推测结果表明,雄激素受体在扬子 鳄精子发生过程有重要作用;雌激素受体可能在扬子鳄睾丸发育过程中影响睾丸间质细胞雄性激素的分泌,进而调节生精过程和精子发育成熟,孕激素受体可能通过转换成AR和ER来对精子发生进行调节.这些结果为证明性类固醇激素参与调节扬子鳄性腺生殖内分泌调控提供了重要的形态学新证据.     

剑尾鱼精巢的显微和超微结构观察

对性成熟卵胎生鱼类剑尾鱼(Xiphophorus helleri)的精巢进行了显微和超微结构的观察.结果显示,剑尾鱼具一对索状精巢,其内部呈小管型.精巢内每一精小囊的生殖细胞发育同步,从精子发生到成熟精子的形成,精小囊逐渐由小管盲端向中央腔方向移动,在迁移过程中逐渐发育.剑尾鱼的精子发生经过精原细胞,初级精母细胞,次级精母细胞,精细胞及变态精子、成熟精子等阶段.剑尾鱼成熟精子分为头部、中段、尾部3个部分.     

Boule基因在精子发生过程中的作用

精子发生是一个复杂的细胞分化过程,生精细胞经过有丝分裂和减数分裂产生单倍型的精细胞,精细胞再经过复杂的形态变化而形成成熟的精子。这一过程需要众多基因表达的精确调控。目前已发现了一些与男性不育相关的候选基因,这些候选基因中的DAZ(Deleted in azoospermia)基因家族在精子发生过程中发挥关键性的调控作用。Boule基因是2001年发现的DAZ家族的新成员,是人类精子发生过程中重要的调控因子。Boule表达的改变或BOULE蛋白的缺乏可引起减数分裂阻滞和精子生成障碍,从而导致无精子症并产生不育。     

哺乳动物精原干细胞移植研究进展

精原干细胞(SSCs)移植是将正常动物或转基因、突变动物的生精细胞移入受体睾丸曲精小管,供体细胞中的SSCs在受体睾丸内存活、迁移、定居、增殖,从而启动精子发生,甚至产生有受精能力精子的一项新技术. 该技术为探讨精子发生机理、重建不育个体的精子发生、生产转基因动物等提供了新的途径. 文中就SSCs移植时供(受)体的条件、供体SSCs在受体睾丸内的活动过程及SSCs移植的应用等进行了评述.     

中国明对虾精子发生过程中H4蛋白的免疫定位

以真核生物细胞核碱性蛋白H4的高度保守性为依据,利用改良的胶体金电镜免疫定位技术,研究中国明对虾精子发生过程中细胞核碱性蛋白H4的变化特征.发现从精原细胞至精母细胞的细胞质中有H4蛋白的合成,其用于该阶段细胞核染色质的构建;精细胞变态过程中,初期的早些时候有细胞质合成的H4蛋白进入前顶体囊,从初期的晚期开始,细胞核中H4蛋白向顶体囊转移,变态中期转移最强烈,晚期呈减弱趋势,最终导致成熟精子细胞核中不存在碱性蛋白H4.中国明对虾成熟精子细胞核中碱性蛋白H4的缺失是其呈非浓缩核状态的原因之一.     

多肠目薄背涡虫生殖细胞发生的组织学研究

将薄背涡虫（Notoplana humilis）制成石蜡切片,通过光学显微镜观察其生殖细胞的发生过程．结果表明：薄背涡虫的精巢可划分为6个时相,每个时相的生精细胞组合图像不同,精子发生先后经历精原细胞、初级精母细胞、次级精母细胞、精细胞和精子;卵子发生先后经历卵黄发生前期的卵母细胞、卵黄发生期的卵母细胞、成熟的卵母细胞以及受精卵．对精子发生过程中各级生精细胞的特征以及卵子发生过程中各级卵细胞的特征进行了描述．     

蟋蟀雄性生殖系统的结构和精子发生

研究了蟋蟀雄性生殖系统的结构和精子发生的动态过程 .成熟的雄性生殖系统主要由一对精巢 ,一对输精管 ,一对附腺 ,一对储精囊和一根射精管组成 .精巢乳白色由许多精巢管盘曲组成 ,精巢管包括原精区、生长区、成熟区和变形区四个区域 .其主要特点是处于不同发育时期的精母细胞呈放射状密集排列在圆球形的育精囊中 .精子发生的动态是 :一龄期 ,精巢小管仅具一些精原细胞 ;二～三龄期 ,精原细胞不断通过有丝分裂增殖 ;四龄期 ,初级精母细胞形成 ,并由减数分裂形成次级精母细胞 ;五龄期 ,精细胞大量形成 ,并变形成为精子 .其主要特点是成虫期的精巢管中存在所有各期生殖细胞 ,当下端的精子成熟时 ,上端部分的精母细胞再发育形成精子 ,表明从五龄开始蟋蟀便能连续不断地产生精子     

中国龙虾Panulirus stimpsoni(Holthuis)的精子发生

本文报导了光学显微镜、透射电子显微镜和扫描电子显微镜研究中国龙虾Panuliurus stimpsoni(Holthuis)精子发生的结果。
中国龙虾的精子发生经过精原细胞、初级精母细胞、次级精母细胞、精细胞和精子。成熟分裂前期由细线期、偶线期、粗线期、双线期和终变期组成。精细胞的变态经过早期精细胞、顶体颗粒期、顶体囊期、顶体分化期和成熟精子。精子属非典型精子,没有鞭毛,不能运动。在扫描电镜中,成熟精子呈绒毛球状。在透射电镜片中,每个精子有核、板层区和顶体。核内有分散的染色质和微管。突起从核发出,核中的微管也伸进突起,顶体和板层区也见到突起。板层区包含有大量的膜和少量退化的线粒体。由高尔基复合体产生的顶体可以分成均质部、旋涡部、晶体部和绒毛部。     

中国龙虾Panulirus stimpsoni(Holthuis)的精子发生

本文报导了光学显微镜、透射电子显微镜和扫描电子显微镜研究中国龙虾Panuliurusstimpsoni(Holthuis)精子发生的结果。中国龙虾的精子发生经过精原细胞、初级精母细胞、次级精母细胞、精细胞和精子。成熟分裂前期由细线期、偶线期、粗线期、双线期和终变期组成。精细胞的变态经过早期精细胞、顶体颗粒期、顶体囊期、顶体分化期和成熟精子。精子属非典型精子,没有鞭毛,不能运动。在扫描电镜中,成熟精子呈绒毛球状。在透射电镜片中,每个精子有核、板层区和顶体。核内有分散的染色质和微管。突起从核发出,核中的微管也伸进突起,顶体和板层区也见到突起。板层区包含有大量的膜和少量退化的线粒体。由高尔基复合体产生的顶体可以分成均质部、旋涡部、晶体部和绒毛部。     

北方山溪鲵精巢支持细胞的显微与超微结构观察

用光镜和电镜观察了山溪鲵精巢内支持细胞的显微和超微结构．结果表明，在精原细胞增生期，支持细胞间存在镶嵌连接，与精原细胞增生以及生精小囊的体积变大相适应；在精子形成期，支持细胞具有典型的类固醇激素分泌特征；精子成熟后，支持细胞退化．并对生精细胞和支持细胞的关系进行了讨论．     

中华大蟾蜍蝌蚪发生类坏死的皮肤在恢复过程中Con A受体的变化研究

本研究以中华大蟾蜍后肢芽期的蝌蚪为材料,以0.001/molL 氨水处理皮肤使之发生类坏死.运用荧光标记的凝集素刀豆球蛋白 A(Con A)结合半薄切片技术观察了皮肤发生类坏死后恢复过程中 Con A 受体的变化.结果发现:正常皮肤表面细胞质膜下,细胞质和基膜中有一些Con A 受体分布.经类坏死处理后,表面细胞内出现了一层团块状分布的 Con A 受体,基底细胞膨大,一类膨大的细胞中仅细胞核和质膜上有 Con A 受体分布,另一类细胞中核和质均有 Con A受体分布.类坏死处理后1h,表面细胞内团块状分布的 Con A 受体变成小颗粒排列在质膜下,表皮细胞质中 Con A 受体较多,基膜中也出现较多的 Con A 受体;类坏死处理3h 表面细胞,基底细胞和基膜中 GonA 受体的分布和1h 的相似:类坏无处理后5h,Con A 受体逐渐减少并恢复正常.结果表明,生发类坏死的皮肤在恢复过程中 Con A 受体对保持结构的完整性及正常的生理功能具有重要的意义.     

Hormonal regulation of peptide receptors and target cell responses.

Regulation of plasma membrane receptors for peptide hormones by the prevailing ligand concentration often causes altered target cell function. Receptor number is determined by hormone-induced changes in membrane conformation, irreversible ligand binding, and processing of ligand-receptor complexes during hormone action.     

Heterogeneity of membrane phospholipid mobility in endothelial cells depends on cell substrate

Cellular growth control and differentiation have been shown to be dependent on both cell-cell and cell-substrate contacts. Interactions of cells with extracellular material are critical events during embryonic development and maintenance of tissue function. Plasma membrane receptors have been described for components of the extracellular matrix such as fibronectin, laminin and various collagen types. Transmembrane signalling has been shown to be influenced by the lateral mobilities of the plasma membrane constituents. The interaction of cells with their extracellular matrix could thus have a significant effect on the mobility properties of the plasma membrane components. Here we have studied the dynamic properties of fluorescent membrane phospholipids in bovine endothelial cells using fluorescence recovery after photo-bleaching measurements. At this molecular level we find that the phospholipid lateral diffusion coefficient is dependent on the substrate upon which cells are allowed to adhere (collagen, fibronectin or a natural basement membrane) and on the topography of the cell (basal versus apical plasma membrane).     

Regulation of AMPA receptor lateral movements

An essential feature in the modulation of the efficacy of synaptic transmission is rapid changes in the number of AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) receptors at post-synaptic sites on neurons. Regulation of receptor endo- and exocytosis has been shown to be involved in this process. Whether regulated lateral diffusion of receptors in the plasma membrane also participates in receptor exchange to and from post-synaptic sites remains unknown. We analysed the lateral mobility of native AMPA receptors containing the glutamate receptor subunit GluR2 in rat cultured hippocampal neurons, using single-particle tracking and video microscopy. Here we show that AMPA receptors alternate within seconds between rapid diffusive and stationary behaviour. During maturation of neurons, stationary periods increase in frequency and length, often in spatial correlation with synaptic sites. Raising intracellular calcium, a central element in synaptic plasticity, triggers rapid receptor immobilization and local accumulation on the neuronal surface. We suggest that calcium influx prevents AMPA receptors from diffusing, and that lateral receptor diffusion to and from synaptic sites acts in the rapid and controlled regulation of receptor numbers at synapses.     

睾丸支持细胞功能的研究进展*

摘要: 支持细胞位于睾丸曲细精管内皮,作为与生精细胞接触的惟一体细胞,在生精过程中起着至关重要的调控作 用。支持细胞在精子发生过程中可为精子细胞提供结构支持; 他分泌的各种蛋白质参与精子发生所需物质的转 运; 同时支持细胞表达一些膜蛋白,促进局部免疫豁免形成,为精子发生提供有利的微环境; 再者,支持细胞通过发 挥粘附与吞噬作用,清除精子发生中凋亡的精子细胞。随着研究的深入,近年来对支持细胞又有了新的认识。     

Basement membrane polarizes lectin binding sites of Drosophila larval fat body cells

Vertebrate epithelial cells in monolayers are asymmetrical in that their apical and basal membranes differ in morphology and function. That this cell polarity depends on the presence of tight junctions can be demonstrated by labelling one surface of a cell monolayer in culture with fluorescent lectins and lipid probes, and subsequently observing whether the labels disperse to the opposite cell surfaces. Here we report on a differential distribution of binding sites for the lectin wheat germ agglutinin (WGA) on the cells of Drosophila melanogaster larval fat body, and show that the pattern is correlated with the structural association between the cell surfaces and their overlying basement membrane.     

Ca2+ signalling between single L-type Ca2+ channels and ryanodine receptors in heart cells

Ca2+-induced Ca2+ release is a general mechanism that most cells use to amplify Ca2+ signals. In heart cells, this mechanism is operated between voltage-gated L-type Ca2+ channels (LCCs) in the plasma membrane and Ca2+ release channels, commonly known as ryanodine receptors, in the sarcoplasmic reticulum. The Ca2+ influx through LCCs traverses a cleft of roughly 12 nm formed by the cell surface and the sarcoplasmic reticulum membrane, and activates adjacent ryanodine receptors to release Ca2+ in the form of Ca2+ sparks. Here we determine the kinetics, fidelity and stoichiometry of coupling between LCCs and ryanodine receptors. We show that the local Ca2+ signal produced by a single opening of an LCC, named a 'Ca2+ sparklet', can trigger about 4-6 ryanodine receptors to generate a Ca2+ spark. The coupling between LCCs and ryanodine receptors is stochastic, as judged by the exponential distribution of the coupling latency. The fraction of sparklets that successfully triggers a spark is less than unity and declines in a use-dependent manner. This optical analysis of single-channel communication affords a powerful means for elucidating Ca2+-signalling mechanisms at the molecular level.     

Appearance of new variants of membrane skeletal protein 4.1 during terminal differentiation of avian erythroid and lenticular cells

The erythrocyte plasma membrane is lined with a network of extrinsic proteins, mainly spectrin and actin, which constitute a reticulum tethered to the intrinsic anion transport protein of the lipid bilayer through a linker protein, ankyrin. Protein 4.1 forms a stable ternary complex with spectrin and actin, thereby strengthening the reticulum and anchoring it directly to the lipid bilayer or to another intrinsic protein, glycophorin. It has been found recently that spectrin, ankyrin and protein 4.1 are not erythrocyte-specific; this has elucidated further the mechanisms of plasma membrane assembly and modelling during the differentiation of diverse tissues. We have shown previously that protein 4.1 in chickens is most abundant in erythrocytes and lens cells, but is scarce or absent from other spectrin-rich cell types. In addition, it exists as a family of related polypeptides showing differential expression in these two tissues, suggesting variant-specific functions. Here we show that the pattern of protein 4.1 variants changes during the terminal differentiation of erythroid and lenticular cells, with novel variants appearing in postmitotic cells. The accumulation of these variants may lead to the final stabilization of the plasma membrane skeletons of these cells.