Molecular cloning, expression profiles and subcellular localization of cyclin B in ovary of the mud crab, Scylla paramamosain

Abstract

A full-length cDNA of cyclin B was isolated from ovary of the mud crab (Scylla paramamosain) in this study. This transcript encodes a polypeptide of 401 amino acids, which is highly homologous to cyclin B protein family. Reverse transcription-PCR (RT-PCR) showed that cyclin B mRNA was expressed at highest levels in ovary of the mud crab. During the ovarian maturation process, real-time RT-PCR revealed that the abundance of cyclin B mRNA increased from the second stage (early-developing stage) to the fourth stage (nearly-ripe stage) and reached the peak level at the fifth stage (ripe stage). This result indicates the identified cyclin B gene might be related to the cell proliferation in ovary, both mitotically and meiotically. Immunohistochemistry showed that cyclin B protein was localized in the cytoplasm of prophase oocytes at the second stage while enriched in the nuclei of pro-metaphase oocytes at the fourth stage. It suggests the tested cyclin B protein might play different roles in ovary at the two stages.