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Esterase amplification is the major organophosphorus (OP) insecticide resistance mechanism in Culex mosquitoes. The amplified Estα2 1\ Estβ2 1 esterases are found in > 90% of resistant populations worldwide, whereas amplified DNAs (amplicons) containing Estβ1s are much rarer. Individuals with the Estβ1 amplicons appear to be at a selective disadvantage in competition with those carrying the Estα2 1 \ Estβ2 1 amplicons. To test the hypothesis that this is because Estβ1 is less able to bind insecticide than the common amplified esterases, Estβ12 was purified from the multi-resistant Habana strain of Culex quinquefasciatus , from Cuba. In its native form Estβ1 is a monomeric enzyme of 66 kDa, with a pI of 4.8. The bimolecular rate constants for interaction of Estβ12 with several OP insecticides were similar to those for the commonly elevated esterases Estα21 and Estβ21 , and much higher than for the electrophoretically identical non-elevated Estβ13 and Estα3. Hence the apparent selective advantage of the Estα2 1 \ Estβ2 1 amplicon is not due to its greater efficiency of insecticide binding, as OP insecticides are significantly better inhibitors of all the amplified esterases than of their non-amplified counterparts and therefore should be equally effective at conferring resistance. 相似文献
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Mosquito carboxylesterases: a review of the molecular biology and biochemistry of a major insecticide resistance mechanism 总被引:5,自引:0,他引:5
The major mechanism of organophosphorus insecticide resistance in Culex mosquitoes involves the elevation of one or more esterases. The general mechanism underlying this resistance is the amplification of the structural genes. This review covers the classification of the mosquito esterases in the context of classical esterase nomenclature. The function of the amplified esterases and the structure of the amplified DNA on which they occur are also described. Implications of information on the esterase amplicons are discussed in relation to the evolution and migration of insecticide resistance in Culex. 相似文献
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