Date

2002

Author

Taşkın, Vatan

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Organophosphate (OP) insecticides (parathion / diazinon) resistance in house fly (Musca domestica L.) is associated with the change in carboxylesterase activity. The product of aE7 gene, which is a member of oc-esterase gene cluster, is probably playing a role in detoxyfication of the xenobiotic esters. In diazinon resistant Lucilia cuprina (blowfly) and diazinon / parathion resistant M.domestica species Gly137 to Asp substitution was found in the active center of the product of aE7. This enhance the ability to hydrolyse the OP in so doing the enzyme compromise its ability to hydrolyse carboxylesters "The mutant ali-esterase hypothesis" (Oppenhorth and Asperen, 1960). In malathion (an OP) resistant L. cuprina strains at the position of Trp251 to Leu substitution was found in the product of aE7, also a high malathion 111carboxylesterase activity (MCE) was reported in these strains (Newcomb et al, 1997). In our research, we have isolated, cloned and sequenced the MdaE7 on four different house fly strains: Ankara, Adana and Ceyhanl, 2 (high doses of malathion were applied in laboratory environment for a long time) and Kirazli strain (no insecticide treatment was performed on this strain in the laboratory). Trp251 to Ser substitutions was found in the product of aE7 in all of these strains. In addition, the MCE, glutathion-S-transferase (GST), acetylcholinesterase (AChE), and general esterase activities were tested in these five strains. In all of these tests WHO was used as a standard sensitive control. A high level MCE and GST activities were observed while lower level of general esterase activities was detected in the tested strains. Moreover, a higher percent remaining activities in AChE than WHO susceptible strain were observed in all malathion resistant strains. In order to understand the allelic diversity of the MdaE7 at a worldwide base, this gene was isolated, cloned and sequenced (from the beginning of exon 2 to the end of exon 6) from eleven house fly strains from different localities (Africa, Asia, America and Middle East). It was found out that diazinon resistant type allele was in high frequency around the world, the malathion type resistant alleles seem to be located at only specific regions.

Subject Keywords

Housefly, Musca, Malathion, Allelomorphism, Organophosphate (OP) resistance, Musca domestica, Malathion, cc- esterase, Ali-esterase, MdaEl, Allelic diversity

URI

https://hdl.handle.net/11511/12843

Collections

Graduate School of Natural and Applied Sciences, Thesis