Uncovering the molecular mechanisms underlying honest signalling in a lower termite

揭示低等白蚁诚实信号背后的分子机制

• 批准号: 364672270
• 负责人: Professorin Dr. Judith Korb
• 金额: --
• 依托单位: Abteilung Evolutionsbiologie und Ökologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/364672270?language=en
• 关键词: Uncovering; molecular; mechanisms; underlying; honest

Cooperatively breeding vertebrates and social insects are characterized by reproductive division of labour in which reproductives hinder offspring from reproducing often via chemical means. In ants and termites, cuticular hydrocarbons (CHCs) are supposed to function as honest signals that inform the workers about the queens fertility. There are two principle proximate mechanisms for the maintenance of honest signalling. A signal can be a handicap that is costly to produce, or it can be an index that cannot be faked, because it is causally linked to the property it is providing information about. We will test the hypothesis that queen-CHCs are an index, i.e., that the production of queen-CHCs (fertility signalling) is directly linked to molecular reproductive pathways (fertility).In the lower termite Cryptotermes secundus we recently identified a gene (Neofem4) which is essential for production of the queens CHCs. This allows unravelling the molecular pathways underlying fertility signalling in social insects for the first time. We hypothesize that Neofem4 expression is directly linked to the fertility of an individual via conserved molecular pathways (namely, the insulin-like signalling (IIS) - juvenile hormone (JH) - vitellogenin (Vg) circuit). In a combination of endocrine experiments and genetic studies we will manipulate (a) juvenile hormone titres which directly effect fertility as gonadotropic hormones, and (b) Neofem4 expression via RNA interference. By testing the effects of these manipulations on the behaviour, chemical communication and gene expression (transcriptome analyses and quantitative realtime PCR) of caste members we will uncover (a) links between fertility and Neofem4 expression and (b) pathways downstream of Neofem4 as well as potential feedback loops to fertility.This study extends the index-hypothesis of honest signalling to the molecular level and for the first time it will also be possible to test the index-hypothesis. Additionally, our work will contribute to improve our understanding how reproductive division of labour is maintained in social insects, the textbook examples for social evolution.

脊椎动物和社会性昆虫的合作繁殖以生殖分工为特征，其中生殖动物通常通过化学手段阻碍后代的生殖。在蚂蚁和白蚁中，表皮碳氢化合物（CHCs）被认为是告知蚁后生育能力的诚实信号。有两个原则性的接近机制来维持诚实的信号。信号可以是一个制作成本高昂的障碍，也可以是一个无法伪造的指数，因为它与它提供信息的财产有因果关系。我们将检验queen-CHC是指数的假设，即，在低等白蚁Cryptotermes secundus中，我们最近鉴定了一个基因（Neofem 4），该基因对蚁后CHC的产生至关重要。这使得解开社会昆虫生育信号的分子途径第一次。我们假设Neofem 4表达通过保守的分子途径（即胰岛素样信号传导（IIS）-保幼激素（JH）-卵黄蛋白原（Vg）回路）与个体的生育力直接相关。在内分泌实验和遗传研究的组合中，我们将操纵（a）作为促性腺激素直接影响生育力的保幼激素滴度，和（B）通过RNA干扰的Neofem 4表达。通过测试这些操作对行为的影响，化学通讯和基因表达（转录组分析和定量实时PCR），我们将揭示（a）生育力和Neofem 4表达之间的联系和（B）Neofem 4下游的途径以及生育力的潜在反馈回路。这将是诚实信号传导到分子水平的假设，并且第一次也将有可能测试指数假设。此外，我们的工作将有助于提高我们的理解如何生殖分工维持社会昆虫，社会进化的教科书的例子。