Title: Microtubule organization during egg cleavage without sperm centrosome
Abstract: ObjectiveIn most mammalian fertilization, the sperm introduces the centrosome, which acts as a microtubule organizing center (MTOC) and is essential for pronuclear movement. However, there are several number of egg cleavage without sperm centrosome in nature. (e.g. parthenogenesis, making clone animals). This study was conducted to test the hypothesis that mammalian oocytes are capable of forming a functional centrosome required to assemble microtubules in order to move female pronucleus in the absence of sperm centrosomal components.DesignAnimal experiments.Materials and methodsExperiment 1: We used bovine parthenotes in this study. We detail the dynamics of microtubules and the distribution of g-tubulin, assumed to be a major component of the maternal centrosome, during the first interphase of bovine parthenogenesis. Our results also identify an interaction between microtubule organization and female pronuclear movement in bovine parthenotes. Experiment 2: Microtubule organization and early embryonal development were compared between rabbit zygotes following Piezo-ICSI with and without sperm centrosome.ResultsIn bovine parthenotes, microtubule patterns correlated well with pronuclear movement to the cell center. Microtubules aggregated at regions of g-tubulin, but g-tubulin did not localize to a spot until the first interphase of bovine parthenogenesis. These findings indicate that g-tubulin is responsible for microtubule organization as the maternal centrosome. The maternal centrosome then organizes cytoplasmic microtubules to move the female pronucleus into the cell center. In rabbit ICSI with and without sperm centrosome, the sperm aster formation was observed 2–3 hr after ICSI with intact sperm. In contrast, microtubules were organized between the male and female pronucleus without a nucleation site in the eggs after ICSI with an isolated sperm head. The first mitotic spindle was organized in eggs following ICSI with an isolated sperm head, as observed in eggs following ICSI with an intact sperm.ConclusionsWe propose that the maternal centrosome plays a role as a functional centrosome, despite the lack of a sperm contribution making this structure less competent for microtubule organization in comparison with centrosomes containing sperm centrosomal components. Correlation/collaboration between maternal/paternal centrosome will be examined. ObjectiveIn most mammalian fertilization, the sperm introduces the centrosome, which acts as a microtubule organizing center (MTOC) and is essential for pronuclear movement. However, there are several number of egg cleavage without sperm centrosome in nature. (e.g. parthenogenesis, making clone animals). This study was conducted to test the hypothesis that mammalian oocytes are capable of forming a functional centrosome required to assemble microtubules in order to move female pronucleus in the absence of sperm centrosomal components. In most mammalian fertilization, the sperm introduces the centrosome, which acts as a microtubule organizing center (MTOC) and is essential for pronuclear movement. However, there are several number of egg cleavage without sperm centrosome in nature. (e.g. parthenogenesis, making clone animals). This study was conducted to test the hypothesis that mammalian oocytes are capable of forming a functional centrosome required to assemble microtubules in order to move female pronucleus in the absence of sperm centrosomal components. DesignAnimal experiments. Animal experiments. Materials and methodsExperiment 1: We used bovine parthenotes in this study. We detail the dynamics of microtubules and the distribution of g-tubulin, assumed to be a major component of the maternal centrosome, during the first interphase of bovine parthenogenesis. Our results also identify an interaction between microtubule organization and female pronuclear movement in bovine parthenotes. Experiment 2: Microtubule organization and early embryonal development were compared between rabbit zygotes following Piezo-ICSI with and without sperm centrosome. Experiment 1: We used bovine parthenotes in this study. We detail the dynamics of microtubules and the distribution of g-tubulin, assumed to be a major component of the maternal centrosome, during the first interphase of bovine parthenogenesis. Our results also identify an interaction between microtubule organization and female pronuclear movement in bovine parthenotes. Experiment 2: Microtubule organization and early embryonal development were compared between rabbit zygotes following Piezo-ICSI with and without sperm centrosome. ResultsIn bovine parthenotes, microtubule patterns correlated well with pronuclear movement to the cell center. Microtubules aggregated at regions of g-tubulin, but g-tubulin did not localize to a spot until the first interphase of bovine parthenogenesis. These findings indicate that g-tubulin is responsible for microtubule organization as the maternal centrosome. The maternal centrosome then organizes cytoplasmic microtubules to move the female pronucleus into the cell center. In rabbit ICSI with and without sperm centrosome, the sperm aster formation was observed 2–3 hr after ICSI with intact sperm. In contrast, microtubules were organized between the male and female pronucleus without a nucleation site in the eggs after ICSI with an isolated sperm head. The first mitotic spindle was organized in eggs following ICSI with an isolated sperm head, as observed in eggs following ICSI with an intact sperm. In bovine parthenotes, microtubule patterns correlated well with pronuclear movement to the cell center. Microtubules aggregated at regions of g-tubulin, but g-tubulin did not localize to a spot until the first interphase of bovine parthenogenesis. These findings indicate that g-tubulin is responsible for microtubule organization as the maternal centrosome. The maternal centrosome then organizes cytoplasmic microtubules to move the female pronucleus into the cell center. In rabbit ICSI with and without sperm centrosome, the sperm aster formation was observed 2–3 hr after ICSI with intact sperm. In contrast, microtubules were organized between the male and female pronucleus without a nucleation site in the eggs after ICSI with an isolated sperm head. The first mitotic spindle was organized in eggs following ICSI with an isolated sperm head, as observed in eggs following ICSI with an intact sperm. ConclusionsWe propose that the maternal centrosome plays a role as a functional centrosome, despite the lack of a sperm contribution making this structure less competent for microtubule organization in comparison with centrosomes containing sperm centrosomal components. Correlation/collaboration between maternal/paternal centrosome will be examined. We propose that the maternal centrosome plays a role as a functional centrosome, despite the lack of a sperm contribution making this structure less competent for microtubule organization in comparison with centrosomes containing sperm centrosomal components. Correlation/collaboration between maternal/paternal centrosome will be examined.