Characterization and expression analysis of a cyclin B gene from black tiger shrimp (Penaeus monodon).

The open reading frame of black tiger shrimp (Penaeus monodon) cyclin B (Pmcyclin B) was identified, based on cDNA sequence registered in GenBank (accession No. EF015590). The target sequence was 1206 bp, corresponding to 401 amino acids. Two conserved signature sequences of the cyclin B gene family were found in the Pmcyclin B deduced aa sequence. Temporal expression of Pmcyclin B in different tissues, including ovary, lymphoid organ, brain, blood, muscle, heart, gill, hepatopancreas, and intestine, were quantified by quantitative real time PCR. Messenger RNA expression levels of Pmcyclin B were greatest in the ovary, compared to other tissues (P < 0.05). Temporal expression of Pmcyclin B in the ovary at six different developmental stages was investigated by real-time PCR; no significant difference was observed (P < 0.05). Recombinant Pmcyclin B protein and its polyclonal antibody were successfully produced. Western blot analysis revealed differential expression of Pmcyclin B in ovaries in developmental stages II to IV; a positive signal (45 kDa) was observed in all ovarian stages assessed, but was most intense at stage III. Pmcyclin B protein was assessed by immunohistochemistry and was localized to the cytoplasm of prophase oocytes at stage II and enriched in the nuclei of pro-metaphase oocytes at stages III and IV. Results from this study indicate that Pmcyclin B is constitutively expressed and plays an important role in ovarian maturation in P. monodon.