Exploiting an extraordinary case of intrasexual cuticular hydrocarbon profile dimorphism in a mason wasp, Odynerus spinipes, to shed new light on cuticular hydrocarbon genetics and evolution

昆虫的角质层覆盖着一层角质碳氢化合物(CHC)。六氯环己烷是一种重要的干燥屏障，对昆虫之间的交流具有额外的基本重要性。例如，在许多物种中，CHC充当物种和性别识别的线索和信号。然而，人们对参与CHC生物合成的基因知之甚少。特别是在物种丰富的昆虫目膜翅目中，包括蚂蚁、蜜蜂和黄蜂在内的这些基因就是如此。在DGF资助的一个研究项目的背景下，我们最近发现了一个独特的两性内CHC二型性：石蜂Odynerus spinipe的雌性能够表达两种非常不同的CHC化学型。这两种化学类型在70多种物质上存在质的差异。在同一时间和采样点发现不同化学类型的棘豆雌体在任何非CHC相关性状上都没有差异，这使该物种成为了解更多CHC生物合成相关基因的合格和有前途的模型。因此，我们的研究项目旨在确定那些与脊椎动物惊人的CHC二型性表现有关的基因。为了确定与化学型相关的活性/表达差异的基因，我们将对转录本进行测序，并评估转录本的丰度，以衡量相应基因的活性，即每种化学型的雌性棘豆成虫的所有蛋白质编码基因的活性。为了证明这些基因的表达与CHC的生物合成之间的因果联系，我们打算在实验中操纵10个选定的基因的表达，这些基因的表达在不同化学型的雌性之间存在显著差异。我们将通过一种名为RNA干扰(RNAi)的分子技术来操纵上述基因的表达。我们计划的实验是可行的，因为我们能够在实验控制的条件下饲养棘豆，并对棘豆基因组进行了深度测序。我们将把这些候选基因的核苷酸和氨基酸序列与我们在国际1KITE计划(http://www.1kite.org).)中测序的另外21只水泡蜂的相应序列进行比较，这些候选基因参与了CHC的生物合成这将使我们能够阐明这些基因的进化史，以及作用于它们的选择性力量。随之而来的实验室和野外实验将解决成年棘豆雌性是否有能力改变它们的化学型的问题。因此，我们项目的结果将引起众多生物学学科的研究人员的重大和根本兴趣，从化学生态学和进化基因组学到物种形成遗传学和行为生物学。

The cuticle of insects is covered by a layer of cuticular hydrocarbons (CHCs). CHCs serve as an important desiccation barrier and have gained additional fundamental importance for communication among insects. For example, in many species, CHCs act as cues and signals for species and sex recognition. However, little is known about the genes involved in the biosynthesis of CHCs. In particular this is the case for these genes in the species-rich insect order Hymenoptera, which includes ants, bees, and wasps. In context of a DGF-funded research project, we recently discovered an extraordinary case of distinct intrasexual CHC dimorphism: females of the mason wasp Odynerus spinipes are capable of expressing two very different CHC chemotypes. These two chemotypes differ qualitatively from each other in over 70 substances. O. spinipes females with different chemotypes found at the same time and at the sample place do not differ in any non CHC-related trait, making this species an eligible and promising model for learning more about the genes involved in CHC biosynthesis. Our research project accordingly aims to identify those genes that are involved in the manifestation of the astounding CHC dimorphism in O. spinipes. To identify genes with chemotype-associated activity/expression differences, we will sequence the transcripts, and assess the transcripts' abundance as a measure of the activity of the corresponding genes, of all protein-coding genes of adult O. spinipes females of each chemotype. To demonstrate a causal link between the expression of these genes and the biosynthesis of CHCs, we intend to experimentally manipulate the expression of ten selected genes, whose expression significantly differs between females with different chemotype. We will manipulate the expression of the above genes by means of a molecular technique called RNA interference (RNAi). Our intended experiments are feasible, since we are able to raise O. spinipes under experimentally controlled conditions and have deeply sequenced the O. spinipes genome. We will compare the nucleotide and amino acid sequences of those candidate genes, whose involvement in CHC biosynthesis we were able to experimentally prove, with corresponding sequences from 21 additional vespid wasps, whose transcripts we sequenced in the international 1KITE project (http://www.1kite.org). This will allow us to also shed light on the evolutionary history of these genes and on the selective forces that have acted on them. Accompanying laboratory and field experiments will address the question of whether or not adult O. spinipes females are capable of changing their chemotype. The results from our project will consequently be of major and fundamental interest to researchers in numerous biological disciplines, ranging from chemical ecology and evolutionary genomics to speciation genetics and behavioral biology.