Shin Mi-Ra, Kim Nam-Hyung
Department of Animal Sciences, Chungbuk National University, Cheong Ju, Chungbuk, Korea.
Mol Reprod Dev. 2003 Apr;64(4):438-45. doi: 10.1002/mrd.10280.
In this study, gamma-tubulin distribution was determined chronologically in conjunction with microtubule dynamics during bovine fertilization and parthenogenesis. In unfertilized bovine oocytes, gamma-tubulin was identified in the cytoplasm, mainly in the cortex and concentrated in the meiotic spindle. Following sperm penetration, gamma-tubulin in the cytoplasm was recruited by a sperm component. During pronuclear apposition, gamma-tubulin was localized as spots at the spindle poles. gamma-tubulin spots were observed in blastomeres of embryos cleaved in vitro. Following electrical stimulation, gamma-tubulin and microtubule matrix were noted in oocyte cortex. In the late pronuclear stage, considerably less gamma-tubulin and microtubules were detected in the cytoplasm. At the mitotic metaphase of parthenotes, gamma-tubulin was recruited to the condensed chromatin and concentrated in the spindle. The gamma-tubulin spots were not detected until the 8-cell stage of parthenotes. This suggests that maternal gamma-tubulin is recruited by a sperm component to reconstitute the zygotic centrosome. In the absence of sperm components, the cell cycle-related assembly of gamma-tubulin organizes microtubule nucleation for positioning the pronucleus and spindle protein of mitotic metaphase during the first cell cycle of bovine parthenotes.
在本研究中，结合牛受精和孤雌生殖过程中的微管动力学，按时间顺序确定了γ-微管蛋白的分布。在未受精的牛卵母细胞中，γ-微管蛋白存在于细胞质中，主要位于皮质，并集中在减数分裂纺锤体中。精子穿透后，细胞质中的γ-微管蛋白被精子成分募集。在原核并置期间，γ-微管蛋白定位在纺锤体极处呈斑点状。在体外分裂的胚胎的卵裂球中观察到γ-微管蛋白斑点。电刺激后，在卵母细胞皮质中发现了γ-微管蛋白和微管基质。在原核晚期，细胞质中检测到的γ-微管蛋白和微管明显减少。在孤雌生殖细胞的有丝分裂中期，γ-微管蛋白被募集到浓缩染色质中并集中在纺锤体中。直到孤雌生殖细胞的8细胞期才检测到γ-微管蛋白斑点。这表明母体γ-微管蛋白被精子成分募集以重建合子中心体。在没有精子成分的情况下，γ-微管蛋白与细胞周期相关的组装组织微管成核，以便在牛孤雌生殖细胞的第一个细胞周期中定位原核和有丝分裂中期的纺锤体蛋白。
