Molecular cloning and characterization of a novel Y-box gene from Sepiella maindroni

Y-box proteins are a family of highly conserved nucleic acid binding proteins that interact with genome and transcription product to modulate the transcriptional and translational processes. In the present study, a complete mRNA of Y-box binding protein (designated SmYB) was obtained from Sepiella maindroni by amplification of flanking sequences. The full size of SmYB cDNA was 1502 bp, including 99 bp at the 5. untranslated region (UTR), a 3' UTR of 821 bp with a poly (A) tail, and an open reading frame of 582 bp, encoding a polypeptide of 193 amino acids with the predicted molecular weight of 16.48 kDa. The conserved cold-shock domain and two known RNA binding motifs identified in SmYB strongly suggested that SmYB was a new member of Y-box proteins. Quantitative real-time PCR was performed to examine the expression of SmYB mRNA in various tissues, embryos, and its temporal expression in liver after cold shock. The mRNA transcript of SmYB was detected in all examined tissues, with the highest expression level in testis and ovary. SmYB was abundant in early developmental stages of S. maindroni embryos but diminished in the late post-embryonic development. In addition, cold-shock treatment upregulated the transcription of SmYB mRNA in liver. These results demonstrated that SmYB is involved in embryonic development of S. maindroni and its tolerance to acute low temperatures.