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染色体精确分离是在纺锤体的正确组装和纺锤体检查点(spindle assembly checkpoint,SAC)的监控下完成的,对于哺乳动物卵母细胞来说,纺锤体的形成和SAC都是保证染色体精确分离的重要因素,如果染色体分离错误将直接导致自发性流产或其他出生缺陷。卵母细胞中心体缺失后,细胞依然能够依靠独立于中心体而围绕染色体成核的微管反向平行排列能形成双极纺锤体,即自我组装纺锤体。由微观组织中心(microtubue organizing center,MTOC)召集微管聚集,成熟促进因子(maturation promoting factor,MPF)维持两次减数分裂过程中纺锤体的形成过程,细胞静止因子(cytostatic factor,CSF)维持分裂中期结构,使纺锤体在染色体没有全部集合到赤道板时保持稳定。大体积的卵母细胞容易产生非整倍体,且卵母细胞中不含有中心体这一特殊性导致卵母细胞中是否存在SAC在很长一段时间内存在争议,但现在SAC是确保卵母细胞染色体精确分离的机制之一已被初步证明。在减数分裂中期染色体之间存在一种黏连,细胞会产生"等待-后期"信号抑制SAC活性,从而保持这种黏连稳定,直至所有染色体完成与纺锤体的连接,"等待-后期"信号失活,SAC启动,使染色体间的黏连失活,进而在纺锤体的作用下染色体分离。作者综述了减数分裂过程中纺锤体的特异性组装过程和纺锤体检查点的组成及作用机制,丰富了减数分裂的相关知识,并为减数分裂过程中非整倍体的形成机制提供依据。 相似文献
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雌性生殖细胞进行减数分裂时易发生染色体分离错误而产生非整倍体卵母细胞,其受精后会产生非整倍体胚胎,导致出生缺陷或胚胎致死,是影响哺乳动物繁殖的重要因素。卵母细胞在第一次减数分裂前期发生同源染色体联会,此时DNA双链断裂引发重组。重组时缺乏交叉、重组事件数量的减少及交叉靠近端粒或着丝粒导致染色体发生同向分离或不分离,从而产生非整倍体卵母细胞。减数分裂期间,当染色体的端粒共向于同一极或没有完全附着在纺锤体微管上时,纺锤体组装检查点(spindle assembly checkpoint,SAC)被激活,E3泛素连接酶APC/Cyclome (APC/C)沉默,保护分离酶抑制蛋白(securin)和细胞周期蛋白B (cyclin B)不被降解,从而抑制分离酶和染色体的分离。直到所有染色体与纺锤体实现稳定的双极定向并正确排列到赤道板上,SAC关闭,染色体正确分离。卵母细胞中SAC蛋白缺失,导致SAC不能有效地监测端粒在纺锤体上的正确附着,发生染色体分离错误,从而产生非整倍体卵母细胞。因此,通过现代分子技术手段解析非整倍体卵母细胞所涉及的机制是保护哺乳动物生育的重要目标。作者主要介绍了卵母细胞减数分裂的特点,详细阐述了卵母细胞非整倍体发生的染色体分离错误的分子机制,以期为开发卵母细胞非整倍体的治疗手段提供参考。 相似文献
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《畜牧与兽医》2015,(12):110-115
为探讨Aurora A激酶在猪卵母细胞成熟过程中的动态分布及其与细胞微管蛋白相关性,采用间接免疫荧光结合激光共聚焦显微成像技术,检测Aurora A蛋白的动态分布与亚细胞定位,然后分别使用Aurora A特异性抑制剂(MLN-8054)、微管蛋白抑制剂(秋水仙素)处理猪卵母细胞,研究Aurora A与细胞骨架分布的相关性。结果显示:在生发泡(GV)期,Aurora A主要分布在细胞质中,在第一次和第二次减数分裂中期,即MⅠ和MⅡ期,Aurora A则主要伴随着纺锤体分布,与纺锤体有着相似的亚细胞定位;使用Aurora A特异性抑制剂MLN-8054处理细胞后,与对照组相比,纺锤体形态异常的比例显著增加;使用秋水仙素处理细胞后,α-微管蛋白结构紊乱地分布在染色体周围或消失,而Aurora A蛋白或以异常形态伴随纺锤体分布,或消失。结果表明:猪卵母细胞成熟分裂过程中Aurora A与纺缍体微管的分布密切相关,并具有明显的阶段性特点,Aurora A可能通过参与调节纺锤体微管的组装进而参与猪卵母细胞减数分裂的调控。 相似文献
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蛋白激酶C(PKC)是一个广泛分布在真核细胞中的丝氨酸/苏氨酸蛋白激酶家族。它在卵母细胞的生发泡破裂(GVBD)、染色体凝集、MⅠ期纺锤体组装和第一极体排放等过程中起着重要的调节作用。PKC的活性变化调节着GVBD的发生,GVBD标志着第1次减数分裂的启动。PKC活性在卵母细胞成熟过程中逐渐升高,在第1次减数分裂中/后期转变时活性下降,使卵母细胞得以释放出第一极体,至此卵母细胞完成第1次减数分裂进入第2次减数分裂。作者就PKC在卵母细胞第1次减数分裂成熟过程中的作用综述如下。 相似文献
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《畜牧与兽医》2020,(11)
细胞周期检查点激酶1(Chk1)作为DNA复制检查点和DNA损伤反应的重要成员,在有丝分裂和减数分裂中都具有重要作用。为探究Chk1对猪卵母细胞减数分裂的影响,本研究首先采用免疫荧光染色和实时荧光定量PCR技术检测了Chk1在猪卵母细胞不同时期的表达和定位,随后利用chir-124抑制Chk1的表达,研究其对猪卵母细胞减数分裂的影响,以及相关基因的表达和纺锤体的变化。结果表明,Chk1在4个时期(GV、GVBD、MI、MII)均有表达,GV期主要定位在生发泡内,GVBD期主要定位在核周围,MI期和MII期主要定位在纺锤体上;用不同浓度的chir-124处理卵母细胞来抑制Chk1,发现0.5μmol/L的chir-124对卵母细胞生发泡破裂(GVBD)的影响最大,可显著提高猪卵母细胞处于GV-IV期的比例(P0.05),并且可显著提高卵母细胞达到GVBD期的比率(P0.05),但对后续的成熟没有显著影响;随后对MII期卵母细胞的基因表达进行检测发现,Chk1的抑制可调节cdk1、cdc25C、cyclin b1基因的表达,并使gwl基因的表达显著下降(P0.05),从而调节卵母细胞恢复减数分裂的进程;Chk1的表达会激活纺锤体组装检查点(SAC),阻止同源染色体分离,将猪卵母细胞定位在MI期,而减少Chk1的表达后,猪卵母细胞可渡过MI期,进入MII期。综上,在GV期使用chir-124抑制Chk1的表达可促进猪卵母细胞恢复减数分裂,并促进后续的成熟。 相似文献
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低温和冷冻保护剂(DMSO)对卵细胞的影响 总被引:3,自引:0,他引:3
实验以小鼠为动物模型 ,研究延长小鼠卵母细胞在含有冷冻保护剂的液体中的平衡时间、并且降低平衡时的温度是否能影响卵母细胞完成减数分裂时染色体的倍性。结果表明 :①在含有DMSO的液体中平衡卵母细胞的非整倍体率同对照组没有明显差异 ,但是卵母细胞在没有DMSO的液体中平衡 ,非整倍体率明显增加 ;②有DMSO时 0℃平衡15和 6 0min后卵母细胞非整倍体率没有发生明显变化 ;③卵母细胞在 1.5mol/L的DMSO液体中 2 4℃平衡 ,卵母细胞的非整倍体率明显增加。这些结果表明 :1.5mol/L的DMSO 0℃平衡对卵母细胞的染色体倍性有保护作用 相似文献
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牛卵母细胞的成熟与激活 总被引:4,自引:0,他引:4
本文综述了牛卵母细胞生长成熟过程和卵母细胞激活的形态学变化,并从分子调控机制上进行探讨。卵母细胞成熟经历了四个阶段:(1)减数分裂启动及在核网期的阻滞;(2)卵母细胞生长期;(3)减数分裂的恢复;(4)减数分裂在MⅡ停滞。一些细胞因子和小分子物质参与并调控这一过程的完成,卵母细胞激活的形态学标志是释放第二极体并形成原核,其实质是形成减数分裂向有丝分裂的转变。 相似文献
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Panpan Cui Benazir Abbasi Defeng Lin Rong Rui Shiqiang Ju 《Reproduction in domestic animals》2020,55(5):584-593
As common overexpression of Aurora A in various tumours, much attention has focused on its function in inducing cancer, and its value in cancer therapeutics, considerably less is known regarding its role in the first cleavage division of mammalian embryos. Here, we highlight an indispensable role of Aurora A during the first mitotic division progression of pig embryos just after meiosis. The expression and spatiotemporal localization of Aurora A were initially assessed in pig embryos during the first mitotic division by Western blot analysis and indirect immunofluorescent staining. Then, the potential role of Aurora A was further evaluated using a highly selective Aurora A inhibitor, MLN8054, during this mitotic progression in pig embryos. Aurora A was found to express and exhibit a specific dynamic intracellular localization pattern during the first mitotic division in pig embryos. Aurora A was diffused in the cytoplasm at the prophase stage, and then exhibited a dynamic intracellular localization which was tightly associated with the chromosome and spindle dynamics throughout subsequent mitotic phases. Inhibition of Aurora A by MLN8054 treatment led to the failure of the first cleavage, with the majority of embryos being arrested in prophase of the mitotic division. Further subcellular structure examination showed that Aurora A inhibition not only led to the failure of spindle microtubule assembly, but also resulted in severe defects in chromosome condensation, accompanied by an obvious decrease in p-TACC3(S558) expression during the prophase of the first mitosis. Together, these results illustrated that Aurora A is crucial for both spindle assembly and chromosome condensation during the first mitotic division in pig embryos, and that the regulation of Aurora A may be associated with its effects on p-TACC3(S558) expression. 相似文献
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Roles of microtubules and microfilaments in spindle movements during rat oocyte meiosis 总被引:1,自引:0,他引:1
Ai JS Wang Q Li M Shi LH Ola SI Xiong B Yin S Chen DY Sun QY 《The Journal of reproduction and development》2008,54(5):391-396
Spindle movements, including spindle migration from the center to the cortex of oocytes during first meiosis and spindle rotation during second meiosis, are required for asymmetric meiotic divisions in many species. However, little is currently known in relation to the rat oocyte. To explore how spindles move and the mechanism controlling spindle movements in rat oocytes, we observed the spindle dynamics during the two meiotic divisions in the rat oocyte by confocal microscopy. Drugs that depolymerize microtubules or microfilaments were employed to further determine the roles of these two cytoskeletons in spindle movements. The results showed that peripheral spindle migration took place during first meiosis and spindle rotation took place during second meiosis in the rat oocytes. Microfilament inhibitor inhibited both spindle migration and spindle rotation, and depolymerization of microtubules inhibited spindle rotation. Severe depolymerization of microtubules inhibited spindle migration, while migration was achieved by partial but not complete depolymerization of microtubules. We thus conclude that microfilaments are important for both spindle migration and spindle rotation and that spindle microtubules are essential for spindle movements in rat oocytes. 相似文献
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Meng XQ Fan HY Zhong ZS Zhang G Li YL Chen DY Sun QY 《The Journal of reproduction and development》2004,50(1):97-105
Gamma-tubulin, a member of the tubulin superfamily, is a peri-centriolar component which is considered to be essential for microtubule nucleation. The dynamics of gamma-tubulin during mouse oocyte meiotic maturation, fertilization, and early cleavage as well as the co-localization of gamma-tubulin and alpha-tubulin during the formation of the meiotic I spindle were studied by confocal microscopy. We found that gamma-tubulin was evenly distributed in the germinal vesicle (GV) stage oocyte. After germinal vesicle breakdown (GVBD) gamma-tubulin dots were localized in both the cytoplasm and the vicinity of the condensed chromosomes, and aligned at both poles of the meiotic spindle at prometaphase I and metaphase I. At anaphase I and telophase I, gamma-tubulin was detected between the separating chromosomes, while it was absent in the midbody. At the MII stage, gamma-tubulin was again accumulated at the spindle poles. Alpha-tubulin had a similar distribution pattern as gamma-tubulin in the cytoplasm and radiated from gamma-tubulin foci close to the chromosomes during the meiotic spindle formation. After fertilization, gamma-tubulin was translocated from spindle poles to the area between separating chromatids and distributed around the pronuclei. It aggregated into some dots during the interphase, but was distributed on the mitotic spindle poles in early embryos. Our results suggest that gamma-tubulin is essential for microtubule nucleation and spindle formation during mouse oocyte meiosis, fertilization, and early embryo cleavage. 相似文献
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Tomioka I Mizutani E Yoshida T Sugawara A Inai K Sasada H Sato E 《The Journal of reproduction and development》2007,53(4):835-842
The present study was conducted to demonstrate the spindle formation and behavior of chromosomes and microtubules during first division in reconstructed rat embryos produced by somatic cell nuclear transfer (SCNT) with cumulus cell nuclei. To demonstrate the effect of oocyte aging after ovulation on the cleavage of SCNT embryos, micromanipulation was carried out 11, 15 and 18 h after injection of hCG. SCNT oocytes were activated by incubation in culture medium supplemented with 5 microM ionomycin for 5 min followed by treatment with 2 mM 6-dimethylaminopurine (6-DMAP) in mR1ECM for 2-3 h. For immunocytochemical observation, the SCNT embryos were incubated with monoclonal anti-alpha-tubulin antibody and then fluorescein isothiocyanate (FITC)-conjugated goat anti-mouse IgG. Cleavage rates were significantly higher for oocytes collected after 15 and 18 h rather than for those collected 11 h after injection of hCG (56 and 53%, respectively vs. 28%; P<0.05). Premature chromosome condensation occurred before activation of the SCNT oocytes, but adequate spindle formation was only rarely observed. The distribution of microtubules in SCNT embryos after activation was different from those of fertilized and parthenogenic oocytes, i.e., a dense microtubule organization shaped like a ring was observed. Eighteen to 20 h post-activation, most SCNT embryos were in the 2-cell stage, but no nucleoli were clearly visible, which was quite different from the fertilized oocytes. In addition, first division with and without small cellular bodies containing DNA was observed in the rat SCNT embryos in some cases. The present study suggests that reorganization of transferred nuclei in rat SCNT embryos may be inadequate in terms of formation of the mitotic assembly and nucleolar reorganization. 相似文献
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Petrunewich MA Trimarchi JR Hanlan AK Hammer MA Baltz JM 《The Journal of reproduction and development》2009,55(1):30-38
ERK-type MAP kinase activity is required for normal first meiotic (MI) metaphase spindle dynamics and first polar body formation at the MI/MII transition, and for MII arrest until egg activation. MEK and MAPK, however, remain active until meiosis is completed and pronuclei form, but whether MEK/MAPK activity affects MII spindle function during egg activation has been unknown. Polarized light microscopy revealed that the MII spindle rapidly (within approximately 15 min) lost birefringence upon treatment of the egg with U0126, indicating decreased organization at the molecular level upon MEK inhibition. In contrast, birefringence rapidly increased when MPF was inhibited with roscovitine, and this was similar to the increased birefringence previously shown after fertilization or parthenogenetic activation with Sr(2+). Confocal microscopy indicated that many spindles in U0126-activated eggs had failed to rotate or were dissociated from the egg cortex. Subsequently, abnormally-located midbodies were evident in U0126-induced parthenogenotes. Thus, MEK/MAPK activity is required to maintain the ordered structure of the MII spindle and for normal spindle dynamics during second polar body formation. 相似文献
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Since the pig is not only an important farm animal, but also a model animal for biomedical applications, the development of reproductive technologies in this species has been very important. In vitro oocyte maturation and fertilization (IVM-IVF) are basic techniques for a number of oocyte- or embryo-related technologies. The practical aspects for pig oocyte IVM-IVF have been reviewed, while the molecular mechanisms underlying oocyte meiotic maturation and fertilization have not been well summarized, although accumulating data have been obtained in recent one decade. This review will focus on what is known about the molecular mechanisms of porcine oocyte maturation and fertilization such as first meiosis resumption, meiotic spindle assembly, second meiosis metaphase (MII) arrest during oocyte maturation, sperm-egg recognition and fusion, sperm acrosome reaction, second meiosis resumption, sperm chromatin decondensation, and pronucleus formation during fertilization, as well as the establishment of polyspermy block. 相似文献
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Polo‐like kinase 1 inhibition results in misaligned chromosomes and aberrant spindles in porcine oocytes during the first meiotic division
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Y Liao D Lin P Cui B Abbasi C Chen Z Zhang Y Zhang Y Dong R Rui S Ju 《Reproduction in domestic animals》2018,53(1):256-265
Polo‐like kinase 1 (Plk1), a type of serine/threonine protein kinase, has been implicated in various functions in the regulation of mitotic processes. However, these kinase's roles in meiotic division are not fully understood, particularly in the meiotic maturation of porcine oocytes. In this study, the expression and spatiotemporal localization of Plk1 were initially assessed in the meiotic process of pig oocytes by utilizing Western blotting with immunofluorescent staining combined with confocal microscopy imaging technique. The results showed that Plk1 was expressed and exhibited a dynamic subcellular localization throughout the meiotic process. After germinal vesicle breakdown (GVBD), Plk1 was detected prominently around the condensed chromosomes and subsequently exhibited a similar subcellular localization to α‐tubulin throughout subsequent meiotic phases, with particular enrichment being observed near spindle poles at MI and MII. Inhibition of Plk1 via a highly selective inhibitor, GSK461364, led to the failure of first polar body extrusion in porcine oocytes, with the majority of the treated oocytes being arrested in GVBD. Further subcellular structure examination results indicated that Plk1 inhibition caused the great majority of oocytes with spindle abnormalities and chromosome misalignment during the first meiotic division. The results of this study illustrate that Plk1 is critical for the first meiotic division in porcine oocytes through its influence on spindle organization and chromosome alignment, which further affects the ensuing meiotic cell cycle progression. 相似文献
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Jibak LEE 《The Journal of reproduction and development》2013,59(5):431-436
Meiosis is a key step for sexual reproduction in which chromosome number is halved
by two successive meiotic divisions after a single round of DNA replication. In the
first meiotic division (meiosis I), homologous chromosomes pair, synapse, and
recombine with their partners in prophase I. As a result, homologous chromosomes are
physically connected until metaphase I and then segregated from each other at the
onset of anaphase I. In the subsequent second meiotic division (meiosis II), sister
chromatids are segregated. Chromosomal abnormality arising during meiosis is one of
the major causes of birth defects and congenital disorders in mammals including human
and domestic animals. Hence understanding of the mechanism underlying these unique
chromosome behavior in meiosis is of great importance. This review focuses on the
roles of cohesin and condensin, and their regulation in chromosome dynamics during
mammalian meiosis. 相似文献