Our study was conducted to clarify what happens in wing discs during the metamorphosis of wing discs in the last larval instar of B. mori. Overviewing the ecdysone-dependent and -independent genes during wing metamorphosis will lead to a better understanding of insect metamorphosis. For this, we constructed four cDNA libraries from different stages of wing disc of B. mori, and expression patterns were compared among different developmental stages. The expression profile from each stage of the wing disc EST database in Bombyx mori reflected morphological changes. The wing disc showed dynamic morphogenesis during the preparatory stage of metamorphosis in 4-5 days, and these morphological changes matched to the wing disc ESTs in the SilkBase. Genes of high frequency in V4 reflect the evidence that V4 is the transition stage to cell proliferation. Genes of high frequency in the W0 stage reflect the abundance of proliferating cells and the feature of the beginning of differentiation in W0. Genes of high frequency in W2 reflect the dynamic morphogenesis of the W2. Genes of high frequency in W3 reflects the secreting and cuticle-producing feature of W3. We isolated ecdysone responsive genes through EST DataBase and microarray analysis: genes coding for peptidase, protease, cuticle protein. Developmental profiles, hormone responsiveness, genomic analysis of these cuticle protein genes were operated, and five groups of the cuticle protein genes having different developmental profile and hormone reponsiveness were identified. By genomic analysis, gene clustering was observed.
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