The evolution of parasitic sex ratio distortion

寄生性别比例畸变的演变

基本信息

批准号：
NE/D012937/1
负责人：
Alison Dunn
金额：
$ 38.79万
依托单位：
Bangor University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FD012937%2F1
关键词：
evolution parasitic sex ratio distortion

项目摘要

Host-parasite interactions are pervasive throughout the natural world, forming a critical component of plant and animal communities. Among them, parasites that distort host sex ratios are widespread in invertebrates. The effect of sex ratio distorters can have a powerful effect on biodiversity; they can cause populations to become extinct and change the composition of animals in the community. Additionally as they can affect harmful as well as beneficial hosts, there is currently a great deal of interest in the use of such parasites for biological control. Sex ratio distortion has evolved in diverse parasites (eukaryotes and bacteria) and affects diverse hosts. Why distort sex ratio? These parasites are passed from mother to offspring in the eggs and are only transmitted by females. These parasites have evolved a number of strategies to increase the relative frequency of female hosts (so increasing the spread of the parasite). Feminisation is induced by the bacterium Wolbachia and by microsporidia (eukaryotic parasites) in Crustacea. In contrast Wolbachia causes male killing in insects. Discovering the mechanisms of male killing and feminisation is key to understanding host-parasite coevolution. We propose that these intracellular parasites are most likely to act by secreting molecules into the host cell which will then influence host molecular pathways, they may modify the response to external hormonal signals or even induce programmed cell death (apoptosis). Such changes could disrupt patterns of sexual development or lead to sex-specific embryo mortality. AIMS: We will investigate the evolution of sex ratio distortion in distantly related parasites by testing the hypotheses that - Similar mechanisms lead to contrasting strategies of sexual manipulation by Wolbachia (male killing in insect hosts, feminisation in crustacean hosts) - Parallel mechanisms of feminisation have evolved in distantly related parasites (Wolbachia and microsporidia) OBJECTIVES I. WE WILL INVESTIGATE THE MOLECULAR BASIS OF WOLBACHIA INDUCED MALE KILLING AND FEMINISATION. We will use state of the art techniques (proteomics) to identify molecules secreted into the host cytoplasm that cause feminisation or male killing, and to follow the changes they induce in the host. We will study this initially in the Drosophila (fruit fly)/Wolbachia male killing system. The genome of both these organisms is known and will help us to identify proteins and their function. We will then go on to study feminising Wolbachia in the crustacean Armadillidium vulgare (woodlouse). II. WE WILL INVESTIGATE THE CELLULAR BASIS OF WOLBACHIA AND MICROSPORIDIA INDUCED FEMINISATION BY TESTING FOR MANIPULATION OF THE PATTERN OF CELL DEATH IN THE DEVELOPING HOST Parasites cause feminisation in Crustacea by inhibiting development of the androgenic gland (the gland that controls male sexual differentiation). To pinpoint the site of action, we will map the distribution of feminising microsporidia and Wolbachia during sexual differentiation of their crustacean hosts. We have recently observed an association between male killing in Drosophila bifasciata by Wolbachia and apoptosis (programmed cell death). We will test whether feminising parasites also induce apoptosis in the androgenic gland in order to feminise the host.

宿主 - 寄生虫相互作用在整个自然世界中普遍存在，构成了动植物社区的关键组成部分。其中，扭曲宿主性别比例的寄生虫在无脊椎动物中普遍存在。性别比扭曲者的影响对生物多样性产生强大的影响。它们可能导致人口灭绝并改变社区中动物的组成。此外，由于它们会影响有害和有益的宿主，因此目前对使用此类寄生虫进行生物控制有很大的兴趣。性别比扭曲已经在多种寄生虫（真核生物和细菌）中演变，并影响了多种宿主。为什么会扭曲性别比？这些寄生虫在卵中从母亲传给后代，只有女性传播。这些寄生虫已经发展了许多策略，以增加雌性宿主的相对频率（因此增加了寄生虫的传播）。女性化是由wolbachia细菌和甲壳酸酯中的微孢子虫（真核生物寄生虫）诱导的。相比之下，沃尔巴基亚会导致昆虫中的雄性杀害。发现男性杀戮和女性化的机制是理解宿主 - 寄生虫进化的关键。我们建议这些细胞内寄生虫最有可能通过将分子分泌到宿主细胞中，从而影响宿主分子途径，它们可能会改变对外部激素信号的反应，甚至会诱导程序性细胞死亡（细胞凋亡）。这种变化可能会破坏性发展的模式或导致特定性别的胚胎死亡。目的：我们将通过测试假设的假设来调查性别比率扭曲的演变 - 相似机制导致沃尔巴基亚（Wolbachia在远距离相关的寄生虫（Wolbachia和Microsporidia）目标中进化。我们将研究沃尔巴奇诱导的男性杀戮和女性化的分子基础。我们将使用最先进的技术（蛋白质组学）来识别分泌到宿主细胞质中的分子，导致女性化或雄性杀害，并遵循它们在宿主中诱导的变化。我们最初将在果蝇（果蝇）/沃尔巴基亚男性杀戮系统中进行研究。这两种生物的基因组都是已知的，它将帮助我们鉴定蛋白质及其功能。然后，我们将继续学习在甲壳动物Armadillidium vulgare（木叶）的女性化的Wolbachia。 ii。我们将通过测试正在发育中的宿主寄生虫中细胞死亡模式的操纵来研究沃尔巴氏菌和微孢子虫诱导女性化的细胞基础，通过抑制雄激素（控制男性性别分化的腺体的发展），从而导致甲壳甲酸的女性化导致女性化。为了查明作用部位，我们将在其甲壳类宿主的性别分化过程中绘制女性化的微孢子虫和沃尔巴基亚的分布。最近，我们观察到沃尔巴奇果蝇（Drosophila Bifasciata）在果蝇中杀死男性与凋亡（程序性细胞死亡）之间的关联。我们将测试女性化的寄生虫是否还会诱导雄激素中的凋亡，以使宿主女性化。