Maternal gamma (γ)‐tubulin is involved in microtubule reorganization during bovine fertilization and parthenogenesis

Publisher Website
Google Scholar
Abstract
In this study, γ-tubulin distribution was determined chronologically in conjunction with microtubule dynamics during bovine fertilization and parthenogenesis. In unfertilized bovine oocytes, γ-tubulin was identified in the cytoplasm, mainly in the cortex and concentrated in the meiotic spindle. Following sperm penetration, γ-tubulin in the cytoplasm was recruited by a sperm component. During pronuclear apposition, γ-tubulin was localized as spots at the spindle poles. γ-tubulin spots were observed in blastomeres of embryos cleaved in vitro. Following electrical stimulation, γ-tubulin and microtubule matrix were noted in oocyte cortex. In the late pronuclear stage, considerably less γ-tubulin and microtubules were detected in the cytoplasm. At the mitotic metaphase of parthenotes, γ-tubulin was recruited to the condensed chromatin and concentrated in the spindle. The γ-tubulin spots were not detected until the 8-cell stage of parthenotes. This suggests that maternal γ-tubulin is recruited by a sperm component to reconstitute the zygotic centrosome. In the absence of sperm components, the cell cycle-related assembly of γ-tubulin organizes microtubule nucleation for positioning the pronucleus and spindle protein of mitotic metaphase during the first cell cycle of bovine parthenotes. Mol. Reprod. Dev. 64: 438–445, 2003.