Expression analysis of cytochrome P450s in the silkmoth, Bombyx mori

Cytochrome P450 (CYP) is a superfamily of proteins involved in a variety of physiological phenomena. Four cDNAs encoding silkmoth cytochrome P450 proteins, cyp4M5, cyp6AB4, cyp9A20 and cyp9A22, were cloned by reverse transcriptase-polymerase chain reaction. These cDNAs showed identities of 21-24% to each other at the amino acid level. Expression analysis showed that CYP mRNAs were expressed in a tissue-specific manner and that expression was developmentally regulated in the fat body and midgut. We found that various cyps were upregulated in the fat body after exposure to organophosphorus, neonicotinoid and pyrethroid insecticides. Our results suggest that over-expressed CYPs can contribute to insecticide resistance in Lepidopterans.