NSF Postdoctoral Fellowship in Biology FY 2020:Consequences of reductive evolution on cell wall metabolism in the obligate intracellular bacterium Rickettsia parkeri

这一行动资助了2020财年NSF生物学博士后研究奖学金，扩大了生物学领域代表性不足群体的参与。该奖学金支持一项针对该研究员的研究和培训计划，该计划将增加生物学中代表性不足的群体的参与。细菌是一种单细胞微生物，已经进化成在包括土壤、湖泊甚至海洋深处在内的各种自然环境中定居。一些细菌已经进化成依赖宿主，形成有益的(内共生)或有害的(致病)联系。立克次体是一种只生长在宿主细胞内的细菌，可以通过扁虱和其他节肢动物传播给哺乳动物。在进化过程中，立克次体失去了许多支持基本活动的基因，导致它们的生长严格依赖宿主。虽然对允许自由生活有机体生长的过程的了解已经很成熟，但由于缺乏工具，对生活在宿主细胞内的细菌的这些过程的了解有限。通过这个奖项，这位研究员将转化可用于自由生活的有机体的技术，以了解寄主细胞内的细菌是如何生长和复制的，重点是立克次体的一种成员。该项目有可能影响昆虫生物学，并为下一代抗菌药物提供新的细菌或宿主靶标。此外，该项目还将开发一个研究生和博士后实习生指导计划，名为Bridge，通过最大限度地提高研究生的升迁和留存来增强多样性。利用帕氏立克次体作为立克次体的代表性成员，本项目的目标是(1)实施活的和固定的显微镜方法，以定量评估宿主细胞内单个细菌细胞的生长；(2)表征帕氏立克次体缓慢生长的突变体。为了达到这些目标，该研究员将开发实时延时和固定显微镜，并结合定量图像分析工具来探测活跃的细胞壁合成。这种方法将建立量化细胞内细菌生长参数的方法。其次，该研究员将表征细胞壁循环途径因子AMPG中生长缓慢的突变体的细胞内生长和细胞壁新陈代谢。在执行该项目期间，研究员将接受赞助科学家和博士后咨询委员会的培训，并将利用约翰·霍普金斯大学专业发展和职业办公室现有的资源。最后，这位研究员将通过创建一个名为Bridge的指导计划来扩大代表不足的团体的参与。该计划的核心是将URM博士后作为导师匹配来自约翰·霍普金斯大学多元化和包容性组织的研究生，以帮助研究生发展和实现他们的个人发展计划目标，同时推进博士后培训。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2020, Broadening Participation of Groups Under-represented in Biology. The fellowship supports a research and training plan for the Fellow that will increase the participation of groups underrepresented in biology. Bacteria are single-celled microbes that have evolved to colonize a wide variety of natural environments including soil, lakes, and even the depths of the ocean. Some bacteria have evolved to become dependent on hosts, forming beneficial (endosymbiotic) or detrimental (pathogenic) associations. The Rickettsiales are bacteria that grow exclusively inside a host cell and may be transmitted to mammals by ticks and other arthropods. Through evolution, the Rickettsiales have lost many genes that support essential activities, leading to their strict dependence on the host for growth. While the understanding of processes that allow growth of free-living organisms is well-developed, knowledge of these processes in bacteria that live within host cells is limited due to a lack of tools. Through this award, the fellow will translate technologies available for free-living organisms to understand how bacteria residing inside host cells grow and replicate, focusing on a member of the Rickettsiales. The project has the potential to impact insect biology and to provide novel bacterial or host targets for the next generation of antimicrobial drugs. In addition, the project will develop a graduate student and postdoctoral trainee mentoring program, called BRIDGE, to enhance diversity by maximizing graduate student advancement and retention. Using Rickettsia parkeri as a representative member of the Rickettsiales, the objectives of this project are (1) to implement live and fixed microscopy methods for quantitatively evaluating growth of single bacterial cells within the host cell and (2) to characterize R. parkeri slow-growing mutants. To address these objectives, the fellow will develop live time-lapse and fixed microscopy with probes for active cell wall synthesis coupled to quantitative image analysis tools. This approach will establish methods for quantifying parameters of growth in intracellular bacteria. Second, the fellow will characterize intracellular growth and cell wall metabolism of slow-growing mutants in the cell wall recycling pathway factor AmpG. During execution of this project, the fellow will receive training by the sponsor scientist and a postdoctoral advisory committee, and will leverage resources available at the Professional Development and Career Office at Johns Hopkins University. Finally, the fellow will broaden the participation of underrepresented groups by creating a mentoring program called BRIDGE. The core of the program involves matching URM postdocs as mentors to graduate students from diversity and inclusion-oriented organizations at Johns Hopkins University to help graduate students develop and meet their individual development plan goals while advancing postdoctoral training.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.