Molecular cloning of two tropomyosin family genes and expression analysis during development in oriental river prawn, Macrobrachium nipponense

This paper reports that Slow-tonic S2 tropomyosin (Sst) and Slow tropomyosin isoform (Sti) was highly expressed in androgenic gland transcriptome of Macrobrachium nipponense, which may play crucial roles in sexual differentiation to maleness. In this study, two Sst and Sti gene homologues designated as Mnsst and Mnsti were cloned and characterized from a freshwater prawn M. nipponense. The full-length cDNA of Mnsst and Mnsti consists of 997 bp and 1926 bp, respectively, with an ORF of 852 bp encoding 284 amino acids, and the similarity in ORF reached to 95.82%. The deduced amino acid sequences of Mnsst and Mnsti shared the highest identity with Slow-tonic S2 tropomyosin and Slow tropomyosin isoform of Homarus americanus. Real-time quantitative RT-PCR showed that the Mnsst and Mnsti genes were expressed in different tissues with the highest level of expression in the androgenic gland, implying that these two genes may be related to sex-determination in M. nipponense. Real-time quantitative RT-PCR revealed that in addition, Mnsst and Mnsti were speculated to be related with embryonic organogenesis of M. nipponense, especially for the formation of complete mouthpart and digestive organ and stimulating larval changes of morphology and initiate metamorphosis, the results of present study implied that the two genes may play complex and important roles in sex differentiation of M. nipponense. Thus, we isolated two candidate genes that may advance the studies of sex-determination mechanism in M. nipponense and even the whole crustacean species, as well as promoting the all-male population culture of M. nipponense.