Partner association and adaptation in the Dictyostelium-Burkholderia proto-farming symbiosis

不同物种的成员有时会相互联系和适应。有时，这种联系是互惠互利的，就像许多与人类肠道相关的细菌一样。在这项工作中，研究人员将探索一个简单得多的系统中最有益的相互作用，在这个系统中，几种细菌物种在变形虫的肠道中携带。细菌通过在阿米巴孢子中被运输到新的地点而获得收益，而阿米巴通过能够在新的地区播种出食物细菌种群而获得收益。其结果是一种原始的农业。研究人员将首先探索选择如何在这个系统上发挥作用，通过实验来测试新的理论，这些理论也可以应用于更复杂的系统。其次，他们将探索伙伴关系是如何形成的。伴侣之间是否相互吸引，特别好的食用菌是否受到青睐？最后，研究人员将利用双方都可以被基因操纵的事实，确定控制这种相互作用的许多阿米巴和细菌基因。参与该项目的学生和博士后将在基因组学等重要领域获得宝贵的培训。调查人员还将通过校园研讨会影响高中生，通过关于成为一名学者的博客影响本科生和毕业生，通过弗格森农贸市场的创新科学摊位影响当地社区。社会变形虫Dictyostelidiscoideum和两个Burkholderia细菌分支进行了惊人的微生物群状共生。伯克霍尔德氏菌在变形虫孢子内扩散，并诱导携带食用菌，这些细菌在孢子扩散后释放出来，为变形虫播种新的粮食作物。这种共生模式系统利用了短寿命、小基因组、遗传可操纵性和其他优势。绩效指标将使用一种新的理论框架来估计双方伙伴的选择内容(目标1)。这一框架借鉴了亲属选择理论的类比，并有望同样有用。其次，他们将探索伴侣关联，测试伯克霍尔德氏菌和网柄金线菌是如何找到对方的，它们是否成功地选择了有益的伴侣，以及是否与有益的食物细菌有优先的关联。最后，他们将发现许多参与共生的基因以及它们是如何进化的(目标3)。双方的插入突变文库将被构建，经过各种选择机制，并进行测序，以确定将识别相关基因的频率变化。

Members of different species sometimes associate and adapt to each other. Sometimes the associations are mutually beneficial, as in many of the bacteria associated with the human gut. In this work, the investigators will explore the mostly beneficial interactions in a much simpler system where several bacterial species are carried in the gut of an amoeba. The bacteria gain by being transported to new localities in amoeba spores while the amoeba gains by being able to seed out populations of food bacteria in new areas. The result is a sort of primitive farming. The investigators will first explore how selection works on this system using experiments to test new theory that could also be applied to more complex systems. Second, they will explore how the partnerships are formed. Are the partners attracted to each other and are particularly good food bacteria favored? Finally, the investigators will determine many of the amoeba and bacterial genes that control this interaction, exploiting the fact that both partners can be genetically manipulated. The students and post-doctoral individuals in this project will gain valuable training in important areas like genomics. The investigators will also impact high school students through on-campus workshops, undergrads and grads via a blog on being an academic, and the local community via an innovative science booth at the Ferguson farmer's market.The social amoeba Dictyostelium discoideum and two clades of Burkholderia bacteria engage in a remarkable microbiome-like symbiosis. The Burkholderia gain dispersal inside amoeba spores and also induce carriage of food bacteria that are released after spore dispersal to seed new food crops for the amoebas. This model system for symbiosis exploits short lifespans, small genomes, genetically manipulability, and other advantages. The PIs will use a new theoretical framework to estimate components of selection for both partners (Aim 1). This framework draws on analogies with kin selection theory and promises to be similarly useful. Second, they will explore partner association, testing how Burkholderia and Dictyostelium find each other, whether they succeed at choosing beneficial partners, and whether there is preferential association with beneficial food bacteria. Finally, they will discover many of the genes involved in the symbiosis and how they have evolved (Aim 3). Insertional mutant libraries of both partners will be constructed, put through various selection regimes, and sequenced to determine frequency changes that will identify relevant genes.