Højland Dorte H, Jensen Karl-Martin Vagn, Kristensen Michael
Department of Agroecology, Aarhus University, Aarhus, Denmark.
PLoS One. 2014 Jan 28;9(1):e85965. doi: 10.1371/journal.pone.0085965. eCollection 2014.
The housefly, Musca domestica, has developed resistance to most insecticides applied for its control. Expression of genes coding for detoxification enzymes play a role in the response of the housefly when encountered by a xenobiotic. The highest level of constitutive gene expression of nine P450 genes was previously found in a newly-collected susceptible field population in comparison to three insecticide-resistant laboratory strains and a laboratory reference strain.
We compared gene expression of five P450s by qPCR as well as global gene expression by RNAseq in the newly-acquired field population (845b) in generation F1, F13 and F29 to test how gene expression changes following laboratory adaption. Four (CYP6A1, CYP6A36, CYP6D3, CYP6G4) of five investigated P450 genes adapted to breeding by decreasing expression. CYP6D1 showed higher female expression in F29 than in F1. For males, about half of the genes accessed in the global gene expression were up-regulated in F13 and F29 in comparison with the F1 population. In females, 60% of the genes were up-regulated in F13 in comparison with F1, while 33% were up-regulated in F29. Forty potential P450 genes were identified. In most cases, P450 gene expression was decreased in F13 flies in comparison with F1. Gene expression then increased from F13 to F29 in males and decreased further in females.
The global gene expression changes massively during adaptation to laboratory breeding. In general, global expression decreased as a result of laboratory adaption in males, while female expression was not unidirectional. Expression of P450 genes was in general down-regulated as a result of laboratory adaption. Expression of hexamerin, coding for a storage protein was increased, while gene expression of genes coding for amylases decreased. This suggests a major impact of the surrounding environment on gene response to xenobiotics and genetic composition of housefly strains.
家蝇（Musca domestica）已对大多数用于控制其数量的杀虫剂产生抗性。编码解毒酶的基因表达在家蝇接触外源化合物时的反应中起作用。与三种抗杀虫剂的实验室品系和一个实验室参考品系相比，先前在一个新采集的敏感田间种群中发现了九个P450基因的最高组成型基因表达水平。
我们通过qPCR比较了五个P450基因的表达，并通过RNAseq比较了新获得的田间种群（845b）在F1、F13和F29代的全局基因表达，以测试实验室适应后基因表达如何变化。五个被研究的P450基因中有四个（CYP6A1、CYP6A36、CYP6D3、CYP6G4）通过降低表达来适应繁殖。CYP6D1在F29代的雌性中表达高于F1代。对于雄性，与F1种群相比，全局基因表达中约一半的基因在F13和F29代上调。对于雌性，与F1代相比，60%的基因在F13代上调，而33%的基因在F29代上调。鉴定出40个潜在的P450基因。在大多数情况下，与F1代相比，F13代家蝇的P450基因表达降低。然后，基因表达在雄性中从F13代增加到F29代，在雌性中进一步降低。
在适应实验室繁殖的过程中，全局基因表达发生了巨大变化。总体而言，由于实验室适应，雄性的全局表达下降，而雌性的表达并非单向变化。由于实验室适应，P450基因的表达总体上被下调。编码储存蛋白的六聚蛋白的表达增加，而编码淀粉酶的基因的基因表达降低。这表明周围环境对家蝇品系对外源化合物的基因反应和遗传组成有重大影响。
