부산대학교 도서관

Until the onset of anaphase, sister chromatids are bound to each other by a multi-subunit protein complex called cohesin. Since chromosomes in meiosis behave differently from those in mitosis, the cohesion and separation of homologous chromosomes and sister chromatids in meiosis are thought to be regulated by meiosis-specific cohesin subunits. Actually, several meiosis-specific cohesin subunits, including Rec8, STAG3 and SMC1β, are known to exist in mammals; however, there are no reports of meiosis-specific cohesin subunits in other vertebrates. To investigate the protein expression and localization of cohesin subunits during meiosis in non-mammalian species, we isolated cDNA clones encoding SMC1α, SMC1β, SMC3 and Rad21 in the medaka and produced antibodies against recombinant proteins. Medaka SMC1β was expressed solely in gonads, while SMC1α, SMC3 and Rad21 were also expressed in other organs and in cultured cells. SMC1β forms a complex with SMC3 but not with Rad21, in contrast to SMC1α, which forms complexes with both SMC3 and Rad21. SMC1α and Rad21 were mainly expressed in mitotically dividing cells in the testis (somatic cells and spermatogonia), although their weak expression was detected in pre-leptotene spermatocytes. SMC1β was expressed in spermatogonia and spermatocytes. SMC1β was localized along the chromosomal arms as well as on the centromeres in meiotic prophase I, and its existence on the chromosomes persisted up to metaphase II, a situation different from that reported in the mouse, in which SMC1β is lost from the chromosome arms in late pachytene despite its universal presence in vertebrates. [Copyright &y& Elsevier]