Pacific Oyster (crassostrea Gigas) Cdk1 And Cyclin B3, Gene Cloning And Its Role In Gonadal Development Of A Preliminary Study

Cyclin B and cyclin dependent kinase 1(CDK1, CDC2, p34, p34cdc2), which play a central role in the cell cycle and meiosis maturation modulation network, are the regulatory and catalytic subunit of M-phase/maturation promoting factor (MPF), respectively.In our study, we cloned the cDNA sequence of the above two genes for the first time in Pacific oyster. The full length of cdk1 cDNA is 2 018 bp including a 909 bp CDS encoding a peptide of 302 amino acids (aa) with all the features of CDK1: the predicted weight 34 KD, the three phosphorylation/dephosphorylation sites (T14, Y15, T161), the conserved binding domain PSTAIRE with cyclin B and GXGXXG&K33 with ATP etc.. The cDNA of cyclin B3 is 2 383 bp including a 1 293 bp CDS encoding a 430 aa peptide with predicted weight 47.8 KD, the features of which are also consist with B3-type cyclin: the cyclin box in the middle, the typical destruction box RXAFGXIXN in N-terminal with a Lys-rich zone downstream and the target domain of cAMP-dependent Kinase PKA FLRRXAK in C-terminal. Both domain analysis and multiple alignments showed that these two sequences were the homologues of cdk1 and cyclin B3, respectively.We also obtained the genome structure of cdk1 and cyclin B3. The 6 294 bp cdk1 genome sequence includes 8 exons and 7 introns, with the"GT-AG"boundary in the intron edge; the 5'UTR in cDNA was abrupt by a 442 bp intron, which may be important to the expression regulation. The length of cyclin B3 genome sequence is 5 347 bp owning 10 exons and 9 introns, which also agreed with the rule in exon and intron juncture. The number and size of these two genes are coincidence with their place in evolution. One result needed pay attention is the frequent appearance of ploy G,ploy C and ploy T structure in 1 500 bp zone above exon1, which may be an effective way for their transcription regulation.We analyzed the expression character of cdk1 and cyclin B3 among different tissues or gonads with different maturation level. The result showed that cdk1 and cyclin B3 were present in all tissue but specially expressed in gonads with significant difference compared to other tissues (P<0.05); the expressed level increased in the process of gonad maturation. These features suggested that differential expression of cdk1 and cyclin B3 is closely related to meiotic maturation and may be important to mitosis of early development of embryo.