Brown Elizabeth B, Layne John E, Elchert Alexandra R, Rollmann Stephanie M
Department of Biological Sciences, University of Cincinnati, OH 45221.
Department of Biological Sciences, University of Cincinnati, OH 45221
G3 (Bethesda). 2020 Apr 9;10(4):1283-1296. doi: 10.1534/g3.120.401117.
The detection, discrimination, and behavioral responses to chemical cues in the environment can have marked effects on organismal survival and reproduction, eliciting attractive or aversive behavior. To gain insight into mechanisms mediating this hedonic valence, we applied thirty generations of divergent artificial selection for olfactory behavior. We independently selected for positive and negative behavioral responses to two ecologically relevant chemical compounds: 2,3-butanedione and cyclohexanone. We also tested the correlated responses to selection by testing behavioral responses to other odorants and life history traits. Measurements of behavioral responses of the selected lines and unselected controls to additional odorants showed that the mechanisms underlying responses to these odorants are, in some cases, differentially affected by selection regime and generalization of the response to other odorants was only detected in the 2,3-butanedione selection lines. Food consumption and lifespan varied with selection regime and, at times, sex. An analysis of gene expression of both selection regimes identified multiple differentially expressed genes. New genes and genes previously identified in mediating olfactory behavior were identified. In particular, we found functional enrichment of several gene ontology terms, including cell-cell adhesion and sulfur compound metabolic process, the latter including genes belonging to the glutathione S-transferase family. These findings highlight a potential role for glutathione S-transferases in the evolution of hedonic valence to ecologically relevant volatile compounds and set the stage for a detailed investigation into mechanisms by which these genes mediate attraction and aversion.
对环境中化学信号的检测、辨别及行为反应，会对生物体的生存和繁殖产生显著影响，引发吸引或厌恶行为。为深入了解介导这种享乐效价的机制，我们针对嗅觉行为进行了三十代的定向人工选择。我们分别针对对两种具有生态相关性的化合物——2,3 - 丁二酮和环己酮的正向和负向行为反应进行选择。我们还通过测试对其他气味剂的行为反应和生活史特征，来检测选择的相关反应。对所选品系和未选对照组对其他气味剂的行为反应测量表明，在某些情况下，对这些气味剂的反应机制受选择方式的影响不同，且仅在2,3 - 丁二酮选择品系中检测到对其他气味剂反应的泛化。食物消耗和寿命随选择方式以及有时随性别而变化。对两种选择方式的基因表达分析鉴定出多个差异表达基因。鉴定出了新基因以及先前在介导嗅觉行为中鉴定出的基因。特别是，我们发现了几个基因本体术语的功能富集，包括细胞 - 细胞粘附和硫化合物代谢过程，后者包括属于谷胱甘肽S - 转移酶家族的基因。这些发现凸显了谷胱甘肽S - 转移酶在对具有生态相关性的挥发性化合物的享乐效价进化中的潜在作用，并为详细研究这些基因介导吸引和厌恶的机制奠定了基础。
