Bacteriophages in Endosymbiotic Bacteria

Seth BordensteinIOS-0749783噬菌体是细菌的病毒，是地球上最丰富的生物实体。通过交换基因并将自身插入细菌基因组，噬菌体深刻地影响了开放环境中细菌群落的生态和进化。噬菌体与共生细菌细胞内群落的相关性较少被考虑，但基于在只在宿主细胞内复制的细菌中发现越来越多的噬菌体，可能具有重要意义。然而，宿主细胞的环境是否限制了噬菌体基因组的进化和功能，目前还知之甚少。这项研究是首次对细胞内模式细菌Wolbachia limientis中噬菌体的基因组序列和功能进行全面研究。这些母系遗传的细菌只在至少20%的节肢动物物种的细胞内复制，使它们成为地球上最常见的细胞内感染之一。这项研究将测试是否通过与其他噬菌体交换不相关的DNA块的经典方式，或者通过共同感染相同宿主细胞和组织的不同品系之间的新型噬菌体基因转移，来进化嗜水杆菌噬菌体染色体。除了噬菌体的基因组学和传播性外，这项研究还将测试噬菌体是否直接有助于杀死细胞内的细菌，从而导致依赖于滴度的细菌功能的变化。更广泛的影响包括通过应用共生战略将这项研究应用于人类健康和农业，将这项研究扩展到K-12课程开发和社区推广，以及更好地了解生命的三个不同实体--噬菌体、细菌和真核生物之间的共生关系。

Seth BordensteinIOS-0749783Bacteriophages, viruses of bacteria, are the most abundant biological entity on the planet. By exchanging genes and inserting themselves into the genomes of bacteria, bacteriophages profoundly influence the ecology and evolution of bacterial communities in open environments. The relevance of bacteriophages to intracellular communities of symbiotic bacteria is less considered, but potentially important based on increasing discoveries of bacteriophages in bacteria that only replicate inside host cells. However, little is known about whether the environment of a host cell constrains phage genome evolution and function. This research is the first comprehensive study of the genome sequences and functions of bacteriophage in the model intracellular bacterium Wolbachia pipientis. These maternally-inherited bacteria replicate exclusively inside the cells of at least 20% of all arthropod species, making them one of the most common intracellular infections on the planet. This study will test if W. pipientis bacteriophage chromosomes evolve by the classic exchange of blocks of unrelated DNA with other bacteriophages or by new kinds of bacteriophage gene transfer between divergent strains of W. pipientis that coinfect the same host cells and tissues. In addition to the genomics and transmissibility of phages, this study will test if bacteriophages contribute directly to killing intracellular bacteria and thereby cause changes in bacterial functions dependent on titers. Broader impacts include applications to human health and agriculture through applied symbiosis strategies, extensions of this research to K-12 curriculum development and community outreach, and a greater understanding of the symbiotic associations between three different entities of Life - bacteriophages, bacteria, and eukaryotes.