Molecular cloning, expression pattern analysis, and in situ hybridization of a Transformer-2 gene in the oriental freshwater prawn, Macrobrachium nipponense (de Haan, 1849).

In this study, we isolated a full-length cDNA sequence from Macrobrachium nipponense and investigated its gene function. We named the gene Mntra-2a because of high similarities and close evolutionary divergence with arthropod tra-2. The full-length cDNA of Mntra-2a was 1293 bp, consisting of a 212 bp 5' UTR, a 268 bp 3' UTR, and an ORF of 813 bp encoding 270 amino acids. It contained an RNA recognition motif and a linker region. Real-time PCR analysis showed that Mntra-2a was highly expressed in the gonads of both males and females. Further in situ hybridization analysis showed that Mntra-2a was mainly located in oocytes and spermatocytes. During embryogenesis, Mntra-2a expression was higher in the cleavage and nauplius stages. During the ovarian reproductive cycle, Mntra-2a expression reached a peak at OvaryV and decreased to the lowest level at OvaryIV. These results indicated that Mntra-2a probably played important roles in embryonic development and early gonad development in M. nipponense. Our results provide basic information for further functional studies of tra-2 in M. nipponense.