Abstract
The house fly cytochrome P450 monooxygenase gene cyp6d1 played an important role in metabolizing pyrethroid insecticides and other xenobiotics. The house fly permethrin resistant strain LPR gained increased cyp6d1 expression (nine-fold higher expression level relative to susceptible strains), which in turn increased detoxification and conferred the resistance. However, the cyp6d1 over expression in LPR strain induced by Phenobarbital was not increasing as dramatically as that in susceptible strains. These implied there were probably various pathways involved in the regulation of cyp6d1 expression, and resistant and susceptible strains probably adopt not completely similar pathways. We had got the promoter region nucleotide sequences from LPR resistant strain and other susceptible strains. Sequence comparison indicated a 15 bp insert observed in LPR strain interrupts a putative GFI-1 protein recognition site in the promoter region but not observed in susceptible strains. This probably suggested GFI-1 protein may play a role in regulating cyp6d1 expression. In order to understand the mechanism conferring the resistance, identifying cis-elements and trans acting factors involved in the regulation of cyp6d1 is essential. By serial deletion analysis in the promoter region of house fly cyp6d1, we try to identify cis-elements in cyp6d1 promoter region which effect the transcription of cyp6d1. Furthermore, the identified cis-elements will benefit us to identify and purify the possible trans acting factors which regulate the expression of cyp6d1. In addition, we will also focus on the interaction between GFI-1 protein and cyp6d1 promoter region. These works will offer a whole picture of the machinery of the gene regulation in house fly cyp6d1 expression and manifest the reason for the resistance to permethrin in house fly LPR strain.
