Abstract:The vasa gene is a member of the DEAD-box family of proteins and plays a key role in the formation of germ cells in eukaryotes. In this study, we cloned the full length (2438 bp) of Octopus sinensis vasa cDNA (Os-vasa) via rapid amplification of cDNA end (RACE) methods. With an open reading frame (ORF) of 2067 bp, encoding 688 amino acids, a 5′UTR of 128 bp, a 3′UTR of 244 bp, and included an A-tail. Based on ExPASy, Signal4.1, TMHMM, and SMART biological analysis, the ORF encoded a putative protein, with a predicted molecular weight of 76 580.53 Da, and the theoretical isoelectric point was 5.89. No signal peptide site was detected, and there was a significant signal in the transmembrane region; therefore, it was presumed to be an intracellular protein, and not a membrane protein. There were two domains, DEXDc and HELICc, and nine conserved motifs of the DEAD-box family, indicating that the cDNA cloned in this study belonged to the family of vasa. Real-time fluorescence quantitative PCR was used to analyze the expression patterns of the Os-vasa gene at different stages of the embryo and larva, in the ovaries at two growth stages, and in specific tissues for males and females. The results showed that the Os-vasa gene was especially expressed in the gonads, and the expression level in the ovary was significantly higher than that in the testis; vasa mRNA was expressed in both immature and mature ovaries, and the transcript level of the immature stage was evidently higher than the mature stage, revealing that the Os-vasa gene might play an important role in the development process and the maintenance of ovarian functions. Os-vasa gene transcripts were detected at whole embryonic developmental stages, were weakly expressed first 10 days, and gradually increased from the 13th day to the highest level on the 19th day. In the larval stages, vasa exhibited the lowest and highest expression on the 8th day post-hatching and the 20th day, respectively. The findings of this study can provide information for the study of primordial germ cell origin and migration and differentiation, and can contribute to the understanding of ovarian development and oogenesis of O. sinensis.
