Identification and Expression Analysis of Ras Gene in Silkworm, Bombyx mori

Ras proteins play important roles in development especially for cell proliferation and differentiation in various organisms. However, their functions in the most insect species are still not clear. We identified three ras cDNAs from the silk worm, Bombyx mori. These sequences corresponded to three Ras of Drosophila melanogaster, but not to three mammalian Ras (H-Ras, K-Ras, N-Ras). Subsequently, the expression profiles of ras were investigated by quantitative real-time PCR using whole body of individuals from the embryonic to adult stages, and various tissues of 4th and 5th instar larvae. Each of three Bombyx ras showed different expression patterns. We also showed membrane localization of their products. These results indicate that the three Bombyx Ras are functional and have different roles.