A family of bacteria-regulated, cecropin D-like peptides from Manduca sexta

Manduca sexta larvae respond to bacterial challenge by synthesizing a set of antibacterial hemolymph proteins. We have purified and sequenced three members of a family of cecropin D-like bactericidal peptides and isolated a cDNA clone complementary to a closely related bactericidin. Results obtained by Northern hybridization and RNase protection analysis showed that the increased synthesis of bactericidins is due to induction of their mRNA levels and that the synthesis of these peptides is not strictly tissue-specific, in contrast to previous beliefs. Although fat body was a richer source, the relative amounts of bactericidin mRNA were significant in seven other tissues examined.