Molecule Characteristics And Expression Analysis Of Sex-related Gene Transformer-2α In The Different Tissues And Different Development Stages In Hyriopsis Schlegelii

Hyriopsis schlegelii was originated in Lake Biwa of Japan. It has better pear culture ability and disease resistance than other freshwater pearl mussels. In this study, a sex-related gene named Hs-Tra2α were cloned from Hyriopsis schlegelii by RACE-PCR. We also analyzed the molecule characteristics of Hs-Tra2α by using bioinformatics.The full-length cDNA sequence of Hs-Tra2α is 1051 bp, containing a 5’-terminal untranslated region(UTR) of 75 bp, a 3’- terminal UTR of 139 bp with a31 bp poly(A) tail and a conserved sequence(ATTAAA) as tailing signal, an open reading frame of 837 bp which encodes a hytrophilic polypeptide of 278 amino acids without signal peptide. The predicted molecular weight of the Hs-Tra2α was 32.72 kDa and the theoretical isoelectric point(pI) was 11.42, and it was located in the nucleus by analyzing subcellular localization. Domain analyses indicated that the Hs-Tra2α protein has a highly conserved RS Domain(rich in arginine and serine) in the C-terminal and N-terminal, a RRM Domain(RNA recognition motif) in the middle, the Linker sequence downsteam of the RRM domain which belongs to TRA2 family. The secondary structure of Hs-Tra2α protein was predicted by using Predict Protein online,and it showed that the polypeptide ecoded by Hs-Tra2α contained a lot of random-coil with alpha helix and beta folding arranged alternately in the RRM region. We also predicted its three-dimensional structure of Hs-Tra2α by using SWISS-MODEL, and we could find theβ1α1β2β3α2β4 structure clearly. Meanwhile, we constructed the phylogenetic tree of Hs-Tra2α based on amino acids sequence, the deduced amino acid sequence shares high homology with Crassostrea gigas, and it showed that the evolutionary status was quite conservative.The expression of Hs-Tra2α in different tissues in Hyriopsis schlegelii were analyzed by real-time PCR. The result showed that the Hs-Tra2α were widely distributed in different tissues. The expression level of Hs-Tra2α in the spermary was the highest, which was 53.67 times higher than that in the hemolymph, followed bythe ovary with the expression 23.47 times higher than that in the hemolymph. These results suggested that Hs-Tra2α could regulate many kinds of physiological functions and played a role in organogenesis in Hyriopsis schlegelii.Meanwhile, the expression of Hs-Tra2α in the different spermary and ovary development stages of Hyriopsis schlegelii were analyzed by real-time PCR. It showed that the Hs-Tra2α expressed universally in different development stages of spermary and ovary. Using the 1-year-old Hs-Tra2α expression value as a calibrator,the expression in the 2-year-old and 3-year-old spermary were about 30-fold. And the expression of Hs-Tra2α in the 3-year-old ovary was 10.66 times higher than that in the 1-year-old ovary. Then, the expression of Hs-Tra2α was down-regulated in the4-year-old and 5-year-old spermary and ovary. These results suggested the expression of Hs-Tra2α changed regularly along with the establishment, proliferation,growing, maturity of the gonads. We speculated that Hs-Tra2α participated in the sex differentiation and played a critical role in the proliferation, development, maturity of the gonads in Hyriopsis schlegelii.