Karunaratne S H, Vaughan A, Paton M G, Hemingway J
School of Pure and Applied Biology, University of Wales Cardiff, UK.
Insect Mol Biol. 1998 Nov;7(4):307-15. doi: 10.1046/j.1365-2583.1998.740307.x.
Culex tritaeniorhynchus, the major vector of Japanese encephalitis in Sri Lanka, is resistant to organophosphorus insecticides, with a 10-fold resistance ratio at the LC50 for chlorpyrifos, and a high heterogenelty factor in the insect field population. The major mechanism of resistance in this species, as in the mosquito C. quinquefasciatus, is elevation of esterase activity. Basic biochemical, immunological and molecular analysis suggests that the C. tritaeniorhynchus CtrEstbeta1 gene is orthologous to the C. quinquefasciatus amplified Estbetas. The Estbeta2(1) antiserum cross-reacts strongly with CtrEstbeta1(1). Its corresponding cDNA, over the 545 base pairs sequenced, has approximately 84% identity with the various C. quinquefasciatus Estbetas. The gene is amplified in C. tritaeniorhynchus. Amplification of the same esterase in two independent species, along with multiple amplification events involving this esterase gene in C. quinquefasciatus suggests that the location of this gene within the genome predisposes it to amplification.
三带喙库蚊是斯里兰卡日本脑炎的主要传播媒介，对有机磷杀虫剂具有抗性，对毒死蜱的半数致死浓度（LC50）抗性比为10倍，且昆虫野外种群的异质性因子较高。与致倦库蚊一样，该物种抗性的主要机制是酯酶活性升高。基础生化、免疫和分子分析表明，三带喙库蚊的CtrEstbeta1基因与致倦库蚊扩增的Estbetas基因直系同源。Estbeta2(1)抗血清与CtrEstbeta1(1)强烈交叉反应。在测序的545个碱基对中，其相应的cDNA与各种致倦库蚊Estbetas基因约有84%的同一性。该基因在三带喙库蚊中被扩增。同一酯酶基因在两个独立物种中的扩增，以及致倦库蚊中涉及该酯酶基因的多次扩增事件，表明该基因在基因组中的位置使其易于扩增。
