Institute of Organismic and Molecular Evolution, Faculty of Biology, Johannes-Gutenberg-University Mainz, 55128 Mainz, Germany.
Department of Animal Ecology and Tropical Biology, University of Würzburg, 97074 Würzburg, Germany.
G3 (Bethesda). 2021 May 7;11(5). doi: 10.1093/g3journal/jkab078.
Insect cuticular hydrocarbons (CHCs) are highly diverse and have multiple functions, including communication and waterproofing. CHC profiles form species-specific, complex blends of up to 150 compounds. Especially in ants, even closely related species can have largely different profiles, raising the question how CHC differences are mirrored in the regulation of biosynthetic pathways. The neotropical ants Crematogaster levior and Camponotus femoratus both consist of two cryptic species each that are morphologically similar, but express strongly different CHC profiles. This is ideal to study the molecular basis of CHC differences. We thus investigated gene expression differences in fat-body transcriptomes of these ants. Despite common garden conditions, we found several thousand differentially expressed transcripts within each cryptic species pair. Many of these were related to metabolic processes, probably accounting for physiological differences. Moreover, we identified candidate genes from five gene families involved in CHC biosynthesis. By assigning candidate transcripts to orthologs in Drosophila, we inferred which CHCs might be influenced by differential gene expression. Expression of these candidate genes was often mirrored in the CHC profiles. For example, Cr. levior A, which has longer CHCs than its cryptic sister species, had a higher expression of elongases and a lower expression of fatty acyl- CoA reductases. This study is one of the first to identify CHC candidate genes in ants and will provide a basis for further research on the genetic basis of CHC biosynthesis.
昆虫表皮碳氢化合物 (CHC) 具有高度的多样性和多种功能，包括通讯和防水。CHC 谱形成物种特异性的、多达 150 种化合物的复杂混合物。特别是在蚂蚁中，即使是密切相关的物种也可能有很大不同的图谱，这就提出了一个问题，即 CHC 差异如何反映在生物合成途径的调节中。新热带蚂蚁 Crematogaster levior 和 Camponotus femoratus 都由两个隐性物种组成，每个物种在形态上都相似，但表达的 CHC 图谱却大不相同。这是研究 CHC 差异的分子基础的理想选择。因此，我们研究了这些蚂蚁的脂肪体转录组中的基因表达差异。尽管有共同的花园条件，但我们在每个隐种对中发现了几千个差异表达的转录本。其中许多与代谢过程有关，可能解释了生理差异。此外，我们从参与 CHC 生物合成的五个基因家族中鉴定了候选基因。通过将候选转录物分配给果蝇的同源物，我们推断出哪些 CHC 可能受到差异基因表达的影响。这些候选基因的表达在 CHC 图谱中经常得到反映。例如，Cr. levior A 的 CHC 比其隐性姐妹种更长，其延长酶的表达更高，而脂肪酸酰基辅酶 A 还原酶的表达更低。这项研究是首次在蚂蚁中鉴定 CHC 候选基因的研究之一，将为进一步研究 CHC 生物合成的遗传基础提供基础。
