Ubiquitin carboxyl-terminal hydrolase L1 contributes to the oocyte selective elimination in prepubertal mouse ovaries / 生理学报

Apoptosis of abnormal oocytes is essential for defective oocyte elimination during prepubertal ovary development, and the ubiquitin system regulates the cell apoptosis via the degradation of specific proteins. Ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) is a component of the ubiquitin system, and the UCH-L1-dependent apoptosis is important for spermatogenesis. In the present study, the change in the number of follicles and the expression of UCH-L1 in oocytes were determined in prepubertal mouse ovaries by immunohistochemical techniques. A significant decrease in the follicular pool was found in prepubertal mouse ovaries during the period of day 21 to day 28 after birth, and accordingly, the UCH-L1 protein expression was increased, to some degree in association with Jun activation domain-binding protein 1 (Jab1) and cyclin-dependent kinase inhibitor p27(Kipl). The increased UCH-L1 protein, together with the corresponding changes of Jab1 was detected in morphologically abnormal oocytes of prepubertal ovaries. Through the immunofluorescent colocalization, UCH-L1 was shown concentrating in abnormal oocytes, and a parallel change in Jab1 was also seen. The affinity analysis confirmed the interaction between UCH-L1 and Jab1 in ovaries. These results suggest that UCH-L1 plays an important role, possibly in association with Jab1 and p27(Kipl), in selective elimination of abnormal oocytes during mouse prepubertal development.

Developmental stage-dependence of cyclin B1 protein localization and gene expression in rabbit spermatogenesis / 生理学报

By means of in situ hybridization and immunohistochemistry, the protein localization and gene expression of cyclin B1 in spermatogenic cells were characterized during the spermatogenesis of rabbits. The results showed that the cyclin B1 mRNA in rabbit spermatogenic epithelium was expressed dominantly in primary spermatocytes. The expression was observed in round spermatids with a gradual decline in the process of metamorphosis of the spermatids, but not in elongated spermatids and sperms. Cyclin B1 protein was expressed in mitotic spermatogonia and meiotic spermatocytes and was observed predominantly in round and elongated spermatids. These results indicate that the expression of cyclin B1 mRNA and localization of cyclin B1 protein are dependent on the developmental stages of spermatogenic cells.