Molecular and functional characterization of nucleoside diphosphate kinase (nm23) gene in oriental river prawn Macrobrachium nipponense during ovarian development

nm23 belongs to nucleoside diphosphate kinase superfamily?a group of multifunctional regulatory proteins. In this study, Macrobrachium nipponense nm23 (Mnnm23) complementary DNA (cDNA) was isolated and characterized. Full-length cDNA of Mnnm23 measured 829bp, with a 531bp open reading frame encoding for 177 amino acids (aa). Specific functional sites of Mnnm23 aa sequence were highly conserved with those in other decapod crustaceans. Mnnm23 transcripts were ubiquitously distributed in various tissues. Expression level of Mnnm23 was highest in stage I ovaries and gradually decreased as ovaries developed. After Mnnm23 knockdown by RNA interference, expression levels of Cyclin B and cyclin-dependent kinase 2 in ovaries increased in comparison with that of vehicle control (VC); vitellogenin and vitellogenin receptor transcripts in ovaries and gonadosomatic indexes of prawn reached peak values in advance during ovarian cycle in comparison with VC. In histological observation, more advanced oocyte and ovarian development were observed in prawns after Mnnm23 knockdown in comparison with that of VC. These results suggest that Mnnm23 is involved in ovarian development in M.nipponense and possibly functions in hindering rapid oocyte and ovarian maturation of this prawn species.