Identification of novel genes expressed highly and selectively in the corpora allata of the silkworm, Bombyx mori (Lepidoptera: Bombycidae)

Juvenile hormone (JH) has crucial roles in insect physiology, including development, reproduction, and polyphenism. JH is synthesized in the corpora allata (CA) from acetyl-CoA through 13 enzymatic steps, which can be divided into the early mevalonate pathway and the late JH branch pathway. Genes for these 13 enzymes have been identified in several insect species, although the three genes for the first three steps in the late pathway are unclear in many insect species. Information about the regulatory mechanism of JH biosynthesis in the CA has been accumulated in previous researches, but the process is not fully understood. In this study, we identified two genes that are expressed highly and selectively in the CA of the silkworm, Bombyx mori (L.) (Lepidoptera: Bombycidae), through the screening using EST library, DNA microarray, and qRT-PCR analyses. These genes showed developmental expression patterns that correlate well with the fluctuation pattern of JH biosynthetic activity in the CA, suggesting important roles in JH biosynthesis or its regulation.