Hick C A, Field L M, Devonshire A L
IACR-Rothamsted, Harpenden, Hertfordshire, U.K.
Insect Biochem Mol Biol. 1996 Jan;26(1):41-7. doi: 10.1016/0965-1748(95)00059-3.
Insecticide resistance in peach-potato aphids, Myzus persicae, results from the amplification of genes encoding an esterase that hydrolyses and sequesters insecticides. Resistance is normally stable, but highly resistant aphid clones sometimes lose resistance when insecticidal selection pressure is removed. This loss of resistance, termed reversion, arises from a loss of elevated esterase enzyme through transcriptional control, i.e. without loss of the amplified esterase DNA sequences. We have shown that loss of the elevated enzyme occurred simultaneously with loss of methylation at CCGG sites in the amplified DNA sequences. During reselection of resistance in these revertant clones, enzyme levels increased, but there was no corresponding return of methylation to DNA sequences. Thus, although DNA methylation is closely correlated with expression of the amplified esterase genes during reversion, it may not be a factor in the reverse process.
桃蚜（Myzus persicae）对杀虫剂产生抗性是由于编码一种酯酶的基因发生扩增，该酯酶可水解并隔离杀虫剂。抗性通常是稳定的，但当去除杀虫选择压力时，高抗性蚜虫克隆有时会失去抗性。这种抗性丧失，称为回复突变，是通过转录控制导致酯酶水平升高的丧失而产生的，即扩增的酯酶DNA序列没有丢失。我们已经表明，酶水平升高的丧失与扩增DNA序列中CCGG位点甲基化的丧失同时发生。在这些回复突变克隆中重新选择抗性的过程中，酶水平增加，但DNA序列的甲基化没有相应恢复。因此，尽管在回复突变过程中DNA甲基化与扩增酯酶基因的表达密切相关，但它可能不是反向过程中的一个因素。
