Functional transitions in an insect-bacteria symbiosis

昆虫是研究动物与微生物之间关系的理想模型系统，因为它们之间形成的相互作用具有多样性。这些相互作用，或共生，跨越了广泛的连续类型，从那些致病的和短暂的到那些有益的和在极长时间内稳定的。特别是以汁液为食的昆虫，已被证明与只生活在昆虫细胞内的细菌形成亲密而稳定的共生关系。这种严格的细胞内生活方式对共生细菌产生了深远的影响，这种影响在它们高度减少的基因组中显着表现出来。这个项目将研究一种共生关系，涉及生活在美国西南部的蝉和它的双重细菌共生。其中一种共生体叫做霍奇金虫，它的基因组非常小，编码的基因比人们认为的一个自主有机体可能编码的基因要少得多。研究人员将使用遗传和分子技术来揭示导致霍奇金尼亚极端基因组减少的机制变化。预计在宿主昆虫和共生体中都将发现使如此戏剧性的基因丢失的适应性。这项工作对我们理解细菌基因组减少的方式，在亲密共生的背景下生物体的整合以及线粒体等细胞器的形成具有广泛的影响。该项目的更广泛影响将涉及通过与米苏拉县公立学校和蒙大拿大学教育与人文科学学院合作，培训几名本科生、一名研究生、一名博士后和几名K-12教师和学生。

Insects are ideal model systems for studying associations between animals and microorganisms because of the diversity of interactions formed between them. These interactions, or symbioses, span a wide continuum of types, from those that are pathogenic and short-lived to those that are beneficial and stable over extremely long periods of time. Sap-feeding insects in particular have been shown to form intimate and stable symbioses with bacteria that live exclusively within insect cells. This strict intracellular lifestyle has profound effects on the symbiotic bacteria, effects that are dramatically manifest in their highly reduced genomes. This project will investigate a symbiosis involving a cicada that lives in the southwestern United States and its dual bacterial symbionts. One of these symbionts, named Hodgkinia, has a remarkably small genome encoding many fewer genes than was thought possible for an autonomous organism. The investigators will use both genetic and molecular techniques to uncover the mechanistic changes that have allowed Hodgkinia's extreme genome reduction. It is expected that adaptations in both the host insect and symbiont will be found that enable such dramatic gene loss. This work has broad-reaching consequences for the way we understand genome reduction in bacteria, the integration of organisms in the context of intimate symbioses, and the formation of cellular organelles such as mitochondria. The broader impacts of this project will involve the training of several undergraduate students, one graduate student, one postdoctoral fellow, and several K-12 teachers and students through collaboration with the Missoula County Public Schools and College of Education and Human Sciences at the University of Montana.