Expression analysis and tissue distribution of two 14-3-3 proteins in silkworm (Bombyx mori)

14-3-3 proteins, which have been identified in a wide variety of eukaryotes, are highly conserved acidic proteins. In this study, we identified two genes in silkworm that encode 14-3-3 proteins (Bm14-3-3ζ and Bm14-3-3ε). Category of two 14-3-3 proteins was identified according to phylogenetic analysis. Bm14-3-3ζ shared 90% identity with that in Drosophila, while Bm14-3-3ε shared 86% identity with that in Drosophila. According to Western blot and real time PCR analysis, the Bm14-3-3ζ expression levels are higher than Bm14-3-3ε in seven tissues and in four silkworm developmental stages examined. Bm14-3-3ζ was expressed during every stage of silkworm and in every tissue of the fifth instar larvae that was examined, but Bm14-3-3ε expression was not detected in eggs or heads of the fifth instar larvae. Both 14-3-3 proteins were highly expressed in silk glands. These results suggest that Bm14-3-3ζ expression is universal and continuous, while Bm14-3-3ε expression is tissue and stage-specific. Based on tissue expression patterns and the known functions of 14-3-3 proteins, it may be that both 14-3-3 proteins are involved in the regulation of gene expression in silkworm silk glands.