PURIFICATION AND CDNA CLONING OF EVOLUTIONALLY CONSERVED LARVAL CUTICLE PROTEINS OF THE SILKWORM, BOMBYX-MORI

A specific set of structural proteins termed larval cuticle proteins ( LCPs) accumulates in integuments during larval development of the silk worm, Bombyx mori., Two major larval cuticle proteins, LCP17 and LCP22 , were purified from the guanidine hydrochloride extract of the larval cuticle, and specific antibodies were raised against these proteins, Immunoblot analysis revealed that both LCPs are actively synthesized d uring larval intermolt stages, whereas the LCP17 epitope is also sligh tly but significantly detectable in pupal integuments, cDNA clones for LCPs were isolated by immunoscreening of the cDNA expression library constructed from larval epidermal mRNA, Predicted amino acid sequences of LCP17 add LCP22 are homologous to cuticle proteins from other; ins ect species, including Manduca sexta, Drosophila melanogaster and Locu sta migratoria. This fact suggests that these cuticle protein genes or iginated from a common ancestral gene and have been conserved during e volution. Northern blot hybridization demonstrated that the expression of LCP17 as well as LCP22 mRNA is controlled in a stage-specific mann er in the epidermis of the final instar larvae, suggesting a common re gulatory mechanism for transcription of these two intermolt genes, (C) 1997 Elsevier Science Ltd, All rights reserved.