Project description:The effect of xenobiotics (phenobarbital and atrazine) on the expression of Drosophila melanogaster CYP genes encoding cytochromes P450, a gene family generally associated with detoxification, was analyzed by DNA microarray hybridization and verified by real time RT-PCR in adults of both sexes. Only a small subset of the 86 CYP genes was significantly induced by the xenobiotics. Eleven CYP genes and three GST genes were significantly induced by phenobarbital, seven CYP and one GST gene were induced by atrazine. Cyp6d5, Cyp6w1, Cyp12d1 and the ecdysone-inducible Cyp6a2 were induced by both chemicals. The constitutive expression of several of the inducible genes (Cyp6a2, Cyp6a8, Cyp6d5, Cyp12d1) was higher in males than in females, and the induced level similar in both sexes. Thus, the level of induction was consistently higher in females than in males. The female-specific and hormonally-regulated yolk protein genes were significantly induced by phenobarbital in males and repressed by atrazine in females. Our results suggest that the numerous CYP genes of Drosophila respond selectively to xenobiotics, providing the fly with an adaptive response to chemically adverse environments. The xenobiotic-inducibility of some CYP genes previously associated with insecticide resistance in laboratory-selected strains (Cyp6a2, Cyp6a8, Cyp12d1) suggests that deregulation of P450 gene expression may be a facile way to achieve resistance. Our study also suggests that xenobiotic-induced changes in P450 levels can affect insect fitness by interfering with hormonally-regulated networks. Keywords: induction by phenobarbital and atrazine in adults drosophila melanogaster of both sex.
Project description:Piperonyl butoxide (PBO) is an insecticide synergist known to inhibit the activity of cytochrome P450 enzymes. PBO is currently used in many insecticide formulations, and has also been suggested as a pre-treatment in some pesticide applications. Little is known about how insects respond to PBO exposure at the gene transcription level. We have characterised the transcriptional response of the Drosophila melanogaster genome after PBO treatment, using both a custom designed “detox” microarray containing cytochrome P450 (P450), glutathione S-transferase (GST) and esterase genes, and a full genome microarray. We identify a subset of P450 and GST genes, along with additional metabolic genes, that are highly induced by PBO. The gene set is an extremely similar gene set to that induced by phenobarbital, a compound for which pre-treatment is known to confer tolerance to a range of insecticide compounds. The implications of the induction of gene families known to metabolise insecticides and the use of PBO in pest management programs are discussed. Keywords: Induction response after treatment by PBO