Expression Analysis Of Sox2in Chlamys Farreri During Early Development And Gonad Development

SOX2, as an important transcription factor, has been revealed to play severalroles in embryogenesis, neurogenesis, development of the lens and formation of theinduced pluripotent stem cells in vertebrates.In this study, a commercially important aquatic bivalve, the scallop Chlamysfarreri was employed, and a full-length cDNA sequence of C. farreri sox2(Cf-sox2)was cloned by RACE. Furthermore, its spatio-temporal expression pattern wasanalyzed in embryos, larvae, adult tissues and gonads during the early developmentand reproductive cycle by semi-quantitative RT-PCR, real-time RT-PCR and wholemount in situ hybridization techniques. The main results are as follows:The full-length sequence of Cf-sox2cDNA was2194bp with an open readingframe encoding327amino acids which contained the HMG-box of SOX family andthe SOXp motif of SOXB1subfamily. Two structures of SOX2in vertebrates, thepoly-Gly in N terminal and the Ser-rich in C terminal, were not found in Cf-SOX2.Quantitative real-time RT-PCR detected that the Cf-sox2mRNA is maternal.Expression level of Cf-sox2increased significantly in cleavage embryos than that offertilized eggs, and reached the maximum in blastula; and then decreased significantlyafter gastrula, and touched the bottom in umbo larva. Whole mount in situhybridization showed that positive hybridization signals were diffuse in the centralregion of embryos before gastrula, and then the signals were concentrated in larvae atdifferent developmental stages. In trochophore, the signals were located in middle andtop; and in veliger larva, the strong signals were restricted in viscera mass. In umbolarva, weak signals were located possibly in presumptive visceral ganglia and pedalganglia. This expression pattern is similar with that of mammal, implying that theCf-sox2might play a role in the regulation of early development in C. farreri.Semi-quantitative RT-PCR determined that the Cf-sox2was mainly expressed intestis, ovary and adductor muscle of adult at proliferative stage and growing stage, and weakly expressions in mantle and gill were also found, however, no visibleexpression was detected in other organs. In situ hybridization detection of adultgonads revealed that the Cf-sox2was located in germ cells and follicle cells of allstages, while intensity of the signals was different among these cells, whichsuggesting that the Cf-sox2may play roles in the adult tissue function maintenanceand gametogenesis.