Secondary Toxicity Mechanisms of Insecticides and Their Metabolism in Pollinators

杀虫剂是传粉昆虫面临的主要压力之一，传粉昆虫的数量在全球范围内呈下降趋势。很少有研究对其继发性效应进行描述，即不通过主要靶点相互作用介导的反应。酿酒酵母（Baker’s yeast）为描述次生杀虫剂效应提供了一个理想的模型，因为它的基因组缺乏它们的主要分子靶点，同时与其他真核生物共享基本的细胞过程。基因表达分析将揭示酵母对5类12种杀虫剂的介导反应。这些结果将与现有的大黄蜂（b.t arrestris）的类似表达研究相结合，以确定同源的次级反应。全面了解杀虫剂的毒性机制对于评估它们对传粉媒介的风险至关重要。该项目的第二部分将致力于绘制地芽孢杆菌中负责杀虫剂代谢的酶。使用基于酿酒酵母的表达系统，细胞色素p450酶（CYP）驱动的杀虫剂代谢将被评估，并确定单个CYP底物谱。反过来，对代谢重要的CYPs将成为系统发育比较研究的基础，以评估远亲传粉媒介物种的杀虫剂代谢能力。这是预测解毒分析的第一步。

Insecticides are one of the main stressors faced by pollinators, whose numbers are in global decline. Few studies have been undertaken to profile their secondary effects, that is responses not mediated through primary target interactions. S.cerevisiae, Baker's yeast, offers an ideal model for characterising secondary insecticide effects as its genome lacks their main molecular targets, whilst at the same time sharing fundamental cellular processes with other eukaryotes. Gene expression analysis will be conducted to reveal insecticide mediated responses in yeast for twelve insecticides, representing five classes. These results will be combined with existing, analogous expression studies in the bumblebee, B.terrestris, to identify homologous secondary responses. Gaining a holistic understanding of insecticide toxicity mechanisms is crucial for assessing their risk to pollinators. The second part of this project will aim to map the enzymes responsible for insecticide metabolism in B.terrestris. Using S.cerevisiae based expression systems, cytochrome p450 enzyme (CYP) driven insecticide metabolism will be evaluated, with individual CYP substrate profiles determined. In turn, CYPs important to metabolism will become the basis for a phylogenetic comparison study, to assess the capability of insecticide metabolism in distantly related pollinator species. This presents the first step to predictive detoxification profiling.