Center for Chemical Ecology, Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA.
J Insect Physiol. 2012 Mar;58(3):408-12. doi: 10.1016/j.jinsphys.2012.01.003. Epub 2012 Jan 12.
Fatty acid amino acid conjugates (FACs) in the oral secretions of Lepidopteran larvae are responsible for eliciting plant defense responses. FACs are present despite fitness costs which suggests that they are important for larval survival. In previous work, an aminoacylase (L-ACY-1) was identified as the enzyme responsible for hydrolysis of FACs within the larvae gut. This gene is present in three related Heliothine species: Heliothis virescens, Helicoverpa zea, and Heliothis subflexa. Transcript levels in gut tissues are predictive of protein abundance and enzyme activity in the frass. H. zea has the least amount of L-ACY-1 present in gut tissue and frass, while H. virescens has intermediate protein levels and H. subflexa has the highest amount of L-ACY-1 in gut tissue as well as in frass samples. These species differ in their host range and protein intake targets, and recently, it has been shown that FACs, the substrates of L-ACY-1, are involved in nitrogen metabolism. The correlation between protein intake and degree of host range specialization suggests that this aminoacylase may allow specialized larvae to obtain nitrogen requirements despite limitations in diet heterogeneity.
昆虫口腔分泌物中的脂肪酸-氨基酸缀合物（FACs）负责引发植物防御反应。尽管存在适应度代价，但 FACs 仍然存在，这表明它们对幼虫的生存很重要。在之前的工作中，一种氨基酰化酶（L-ACY-1）被鉴定为负责幼虫肠道内 FACs 水解的酶。该基因存在于三种相关的夜蛾物种中：棉铃虫、玉米螟和斜纹夜蛾。肠道组织中的转录水平可预测粪便中蛋白质的丰度和酶活性。H. zea 肠道组织和粪便中 L-ACY-1 的含量最少，而 H. virescens 具有中等水平的蛋白质，H. subflexa 肠道组织和粪便样品中 L-ACY-1 的含量最高。这些物种在宿主范围和蛋白质摄入目标上存在差异，最近的研究表明，L-ACY-1 的底物 FACs 参与氮代谢。蛋白质摄入和宿主范围专门化程度之间的相关性表明，这种氨基酰化酶可能允许专门化的幼虫在饮食异质性有限的情况下获得氮需求。
