大鼠睾丸生精小管上皮精子发生周期的PAS法判定

精子发生是一个包含生殖细胞成熟分裂的连续、复杂的动态过程,不同的生精小管,或同一生精小管不同区段的生精细胞的组合、分布均不相同。本文应用PAS染色法观察了大鼠睾丸生精小管上皮中各级生精细胞在精子发生过程的形态学变化特点。参照Clermont及Russell等制定的生精上皮时相的判定标准,根据生精上皮在精子发生过程中的各级生精细胞组合分布特点,把生精上皮分为ⅩⅣ个期。通过观察精子发生过程中生精上皮细胞组合的周期性形态变化特点,对精子发生过程进行精确划分,把精子发生这一连续、复杂的动态过程静止化,具体化,可以更加准确地描述和比较不同影响因素对生精小管上皮中各级生精细胞的组织学、病理学、毒理学变化。     

睾丸间质细胞在小鼠生精恢复过程中的作用

研究睾丸间质细胞对小鼠生精恢复过程的作用,可以为深入理解睾丸精原干细胞与其微环境(体)细胞间的相互关系提供实验证据。选取8周龄健康C57近交系成年雄性小鼠60只,腹腔注射22 mg/kg白消安建立小鼠精子发生受阻模型,随机分成1,2-二甲磺酸乙烷(ethane 1,2-dimethanesulphonate,EDS)处理组、氟他胺处理组和对照组,每组20只,3 d后分别给予EDS腹腔注射(100 mg/kg)、氟他胺埋植,对照组仅注射溶剂、埋植空管,分别在处理后的1个月内每周采样,Real-time RT-PCR检测CSF1、Gdnf、PLZF和Nanog m RNA表达水平,Gdnf蛋白水平表达,并在4周时进行睾丸组织HE染色,观察组织学变化并对相关指标进行量化分析。结果表明,小鼠睾丸间质细胞去除及雄激素受体阻断均能促进睾丸损伤后的生精恢复过程,但是,受体阻断的效果更强,说明间质细胞除了通过雄激素发挥作用外还直接对生精恢复起着一定的促进作用,这种促进作用可能是通过分泌CSF1等细胞因子来实现的。     

热敏蛋白TRPV1在小鼠睾丸生精小管中的表达特征

目的 明确热敏蛋白TRPV1在生后发育小鼠睾丸的表达和定位。方法 采用定量PCR和蛋白免疫印迹方法检测TRPV1在生后发育小鼠睾丸中的表达水平,采用免疫组织化学染色方法观察TRPV1在成年小鼠睾丸生精上皮不同周期的表达,采用免疫荧光双标染色分析TRPV1在成年小鼠睾丸各类生精上皮细胞中的定位。结果 荧光定量PCR和蛋白免疫印迹检测显示,TRPV1在小鼠出生后7 d的睾丸中已有表达,在21 d时其表达水平显著上升,在28 d达到顶峰,之后随小鼠发育至成年阶段其表达量逐渐降低;免疫组织化学染色显示,TRPV1在成年小鼠睾丸生精上皮的各个周期均有表达,并且从IV期开始表达量增加。免疫荧光双标染色显示,TRPV1在成年小鼠睾丸SOX9阳性的支持细胞、PLZF阳性的精原细胞和SYCP3阳性的精母细胞均有表达,并在初级精母细胞表达量较高。结论 TRPV1在小鼠睾丸生后发育的早期即开始表达,并且在生精上皮各类细胞中有广泛表达,提示其可能在生精细胞的发育过程中具有重要作用。     

乙烯利对青春期大鼠睾丸组织病理及生精细胞凋亡的影响

目的:探讨乙烯利对青春期大鼠睾丸组织病理及生精细胞凋亡的影响。方法:青春期雄性25日龄SD大鼠,分别以乙烯利浓度为2000 mg/kg、1000 mg/kg、500 mg/kg和生理盐水连续灌胃14和21天,分别取睾丸固定、包埋,以HE染色、末端转移酶标记技术(TUNE法)光镜观察睾丸的组织形态学变化、检测生精细胞凋亡情况。结果:低剂量组较对照组相比生精小管萎缩,生精细胞排列紊乱;中剂量和高剂量组较低剂量组相比,生精小管更加萎缩,生精细胞排列明显紊乱;接触乙烯利14天后高剂量组生精细胞凋亡指数与低剂量、对照组相比具有显著统计学差异(P0.01);高剂量与中剂量组相比无统计学差异(P0.05);中剂量和低剂量与对照组相比有显著统计学差异(P0.01);接触乙烯利21天后各组间比较均具有显著性差异(P0.01)。结论:乙烯利可导致大鼠生精细胞凋亡增加,生精能力下降,这可能是导致青年不育的原因之一。     

环磷酰胺对大鼠睾丸生精细胞凋亡的影响

观察环磷酰胺对大鼠睾丸组织学变化和生精细胞凋亡影响。用清洁级性成熟的15周龄雄性sD大鼠16只,体重300-350g。大鼠随机分为对照组和实验组,每组8只,实验组大鼠腹腔注射环磷酰胺,每天一次20mg／（kg·体重）,连续5d,对照组注射等量生理盐水;用药后两个月,以3％戊巴比妥钠（30mg／kg）麻醉,摘取一侧睾丸称重,4％多聚甲醛固定24h;     

小鼠生精周期判定方法的改进

目的探讨一种可以在普通HE染色或苏木精复染标本上对精子发生周期进行简单划分的方法。方法应用PAS染色法与普通HE染色法相对照,对比观察小鼠睾丸各级生精上皮在精子发生不同时期的形态学变化特点。结果参照Clermont及Russel等制定的生精上皮时相的判定标准,把小鼠生精上皮分为XⅡ个期。结论通过对比总结,可以在普通HE染色或苏木精复染标本上对精子发生周期进行简单划分,并进一步辨别各型生精细胞。     

生精冲剂对白消安致生精障碍大鼠恢复精子发生及其机理的研究

为研究生精冲剂对精子发生的作用,我们随机将30只雄性SD大鼠分为正常组、药物组和对照组.后2组通过腹腔注射白消安制备成生精障碍模型大鼠.药物组每天灌胃生精冲剂,对照组灌胃等量的生理盐水.连续30 d后,测定血清FSH、LH、T水平和睾丸组织切片观察的结果显示,药物组大鼠血清中3种激素的水平与对照组相比差异显著(P＜0.05),并可在睾丸组织切片的曲细精管中,观察到大量的精原细胞和圆形精子细胞,而对照组中只有少量的精原细胞,半定量RT-PCR分析结果表明,生精冲剂促进了GDNF表达.因此,生精冲剂对精子发生有明显的促进作用.     

siRNA抑制哺乳动物细胞内Rab9 GTPase表达的研究

构建Rab9 GTPase siRNA表达载体,观察siRNA对哺乳动物细胞内Rab9 GTPase表达的抑制作用,为应用Rab9 GTPase siRNA表达载体进行抗麻疹病毒感染研究奠定基础。根据Rab9 GTPase基因的mRNA序列设计合成2对靶向Rab9 GTPase基因的寡核苷酸,克隆到表达载体pSUPER.neo EGFP,通过双酶切和序列分析对重组表达载体进行鉴定。将鉴定为阳性的重组表达载体转染B95a细胞株,通过逆转录聚合酶链反应(RT-PCR)和免疫印迹技术(Western-blot)检测B95a细胞内Rab9 GTPase mRNA和蛋白的表达水平。双酶切和序列分析表明成功构建了Rab9 GTPase siRNA表达载体,RT-PCR和Western-blot技术实验表明重组表达载体可显著抑制B95a细胞内Rab9 GTPase mRNA和蛋白的表达(最高抑制率分别为89.4%±0.5%和87.6%±0.7%),而对照组则没有变化。结果表明,成功构建了Rab9 GTPase siRNA表达载体,该表达载体可有效地抑制Rab9 GTPase在哺乳动物细胞内的表达。     

Regulation of autophagy by the Rab GTPase network

Autophagy (macroautophagy) is a highly conserved intracellular and lysosome-dependent degradation process in which autophagic substrates are enclosed and degraded by a double-membrane vesicular structure in a continuous and dynamic vesicle transport process. The Rab protein is a small GTPase that belongs to the Ras-like GTPase superfamily and regulates the vesicle traffic process. Numerous Rab proteins have been shown to be involved in various stages of autophagy. Rab1, Rab5, Rab7, Rab9A, Rab11, Rab23, Rab32, and Rab33B participate in autophagosome formation, whereas Rab9 is required in non-canonical autophagy. Rab7, Rab8B, and Rab24 have a key role in autophagosome maturation. Rab8A and Rab25 are also involved in autophagy, but their role is unknown. Here, we summarize new findings regarding the involvement of Rabs in autophagy and provide insights regarding future research on the mechanisms of autophagy regulation.     

Rab GTPase function in Golgi trafficking

The Rab, ARF, and Arl members of the Ras superfamily of small GTPases work together to control specific intracellular trafficking pathways. Here we focus on their roles in protein transport to and within the Golgi apparatus.     

Ric1-Rgp1 Complex Is a Guanine Nucleotide Exchange Factor for the Late Golgi Rab6A GTPase and an Effector of the Medial Golgi Rab33B GTPase

Rab GTPases are master regulators of membrane trafficking events and template the directionality of protein transport through the secretory and endocytic pathways. Certain Rabs recruit the guanine nucleotide exchange factor (GEF) that activates a subsequent acting Rab protein in a given pathway; this process has been termed a Rab cascade. We show here that the medial Golgi-localized Rab33B GTPase has the potential to link functionally to the late Golgi, Rab6 GTPase, by its capacity for association with Ric1 and Rgp1 proteins. In yeast, Ric1p and Rgp1p form a complex that catalyzes guanine nucleotide exchange by Ypt6p, the Rab6 homolog. Human Ric1 and Rgp1 both bind Rab6A with preference for the GDP-bound conformation, characteristic of a GEF. Nevertheless, both Ric1 and Rgp1 proteins are needed to catalyze nucleotide exchange on Rab6A protein. Ric1 and Rgp1 form a complex, but unlike their yeast counterparts, most of the subunits are not associated, and most of the proteins are cytosolic. Loss of Ric1 or Rgp1 leads to destabilization of Rab6, concomitant with a block in Rab6-dependent retrograde transport of mannose 6-phosphate receptors to the Golgi. The C terminus of Ric1 protein contains a distinct binding site for Rab33B-GTP, supporting the existence of a Rab cascade between the medial and trans Golgi. This study thus identifies a GEF for Rab6A in human cells.     

The Legionella pneumophila GTPase Activating Protein LepB Accelerates Rab1 Deactivation by a Non-canonical Hydrolytic Mechanism

GTPase activating proteins (GAPs) from pathogenic bacteria and eukaryotic host organisms deactivate Rab GTPases by supplying catalytic arginine and glutamine fingers in trans and utilizing the cis-glutamine in the DXXGQ motif of the GTPase for binding rather than catalysis. Here, we report the transition state mimetic structure of the Legionella pneumophila GAP LepB in complex with Rab1 and describe a comprehensive structure-based mutational analysis of potential catalytic and recognition determinants. The results demonstrate that LepB does not simply mimic other GAPs but instead deploys an expected arginine finger in conjunction with a novel glutamic acid finger, which forms a salt bridge with an indispensible switch II arginine that effectively locks the cis-glutamine in the DXXGQ motif of Rab1 in a catalytically competent though unprecedented transition state configuration. Surprisingly, a heretofore universal transition state interaction with the cis-glutamine is supplanted by an elaborate polar network involving critical P-loop and switch I serines. LepB further employs an unusual tandem domain architecture to clamp a switch I tyrosine in an open conformation that facilitates access of the arginine finger to the hydrolytic site. Intriguingly, the critical P-loop serine corresponds to an oncogenic substitution in Ras and replaces a conserved glycine essential for the canonical transition state stereochemistry. In addition to expanding GTP hydrolytic paradigms, these observations reveal the unconventional dual finger and non-canonical catalytic network mechanisms of Rab GAPs as necessary alternative solutions to a major impediment imposed by substitution of the conserved P-loop glycine.     

Giantin interacts with both the small GTPase Rab6 and Rab1

The interaction of small GTPases of the Rab family and coiled coil proteins of the golgin family has been reported for example for the Rab1 GTPase and p115, GM130 and Giantin. We now show that Rab6A, a GTPase that controls retrograde trafficking within the Golgi back to the endoplasmic reticulum is also able to bind to Giantin in vivo and in vitro pointing to an interesting complex formation between Giantin and two different Rab GTPases. In Saccharomyces cerevisiae a genetic interaction between Ypt1 and Ypt6 has already been demonstrated, but in this paper we were able to describe that the mammalian Rab GTPases are able to interact on the same golgin protein, Giantin.     

Rab34 GTPase mediates ciliary membrane formation in the intracellular ciliogenesis pathway

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The small GTPase Rab5 homologue Ypt5 regulates cell morphology,sexual development,ion-stress response and vacuolar formation in fission yeast

Inner-membrane transport is critical to cell function. Rab family GTPases play an important role in vesicle transport. In mammalian cells, Rab5 is reported to be involved in the regulation of endosome formation, phagocytosis and chromosome alignment. Here, we examined the role of the fission yeast Rab5 homologue Ypt5 using a point mutant allele. Mutant cells displayed abnormal cell morphology, mating, sporulation, endocytosis, vacuole fusion and responses to ion stress. Our data strongly suggest that fission yeast Rab5 is involved in the regulation of various types of cellular functions.     

Rab13 is upregulated during osteoclast differentiation and associates with small vesicles revealing polarized distribution in resorbing cells

Osteoclasts are bone-resorbing multinucleated cells that undergo drastic changes in their polarization due to heavy vesicular trafficking during the resorption cycle. These events require the precise orchestration of membrane traffic in order to maintain the unique characteristics of the different membrane domains in osteoclasts. Rab proteins are small GTPases involved in regulation of most, if not all, steps of vesicle trafficking. The investigators studied RAB genes in human osteoclasts and found that at least 26 RABs were expressed in osteoclasts. Out of these, RAB13 gene expression was highly upregulated during differentiation of human peripheral blood monocytic cells into osteoclasts. To study its possible function in osteoclasts, the investigators performed immunolocalization studies for Rab13 and various known markers of osteoclast vesicular trafficking. Rab13 localized to small vesicular structures at the superior parts of the osteoclast between the trans-Golgi network and basolateral membrane domain. Rab13 localization suggests that it is not involved in endocytosis or transcytosis of bone degradation products. In addition, Rab13 did not associate with early endosomes or recycling endosomes labeled with EEA1 or TRITC-conjugated transferrin, respectively. Its involvement in glucose transporter traffic was excluded as well. It is suggested that Rab13 is associated with a putative secretory function in osteoclasts.