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The impact of nutritional signaling on transmission of endosymbiotic Wolbachia bacteria

营养信号对内共生沃尔巴克氏体细菌传播的影响

基本信息

批准号：
1656811
负责人：
Laura Serbus
金额：
$ 65.06万
依托单位：
Florida International University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-07-01 至 2022-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1656811&HistoricalAwards=false
关键词：
impact nutritional signaling transmission endosymbiotic

项目摘要

Endosymbiosis involves one organism dwelling inside another. One of the most successful endosymbionts is Wolbachia pipientis, a bacterium carried by about half of insect species, including the model insect Drosophila, the fruit fly. Like many other endosymbionts, Wolbachia are transmitted by females to their offspring during egg development. The overall goal of this project is to elucidate the cellular and molecular mechanisms that facilitate Wolbachia maternal transmission. This will include creating a mathematical model of fruit fly egg-cell colonization by Wolbachia, and using the model to test predictions about the factors governing Wolbachia density within developing eggs. Modeling intracellular endosymbiont dynamics is virtually unprecedented, thus this work will provide new insights as well as a valuable analytical tool. In addition, the nutritional signals that regulate host transport and thus Wolbachia distribution within fruit fly eggs will be elucidated. As cellular transport processes are also crucial for establishing the insect body plan, these analyses will inform Wolbachia transmission and insect development as an integrated process. This will link concepts that have been regarded as mechanistically separate. The research will be performed at a majority-minority, Hispanic-serving institution and the nation's largest producer of STEM minority undergraduate degrees. Trainees carrying out this project will also create essays that explain research practices and benefits. These essays will be shared in a web-based outreach forum to enrich public understanding of science.Wolbachia pipientis is among the most widespread of endosymbionts. This maternally transmitted bacterium has a streamlined genome and a facultative intracellular lifestyle. The high prevalence of Wolbachia in insect populations requires robust transmission-enhancing strategies. The overall goal of this project is to apply chemical, genetic and nutritional approaches to define the impacts of host diet and nutrient-responsive signaling on Wolbachia and germline determinant localization in oogenesis. The first aim involves defining how Wolbachia colonize Drosophila maternal germline cells as an integrated physiological process. Though Wolbachia titer in developing oocytes is responsive to host manipulation, the relative contributions of host and symbiont to titer regulation is unknown. To address this issue, Wolbachia life cycle and invasion dynamics, as well as host germline development rates will be assessed cytologically and used to estimate the parameters of a mathematical model. The model will be the first to test for conservation of Wolbachia colonization mechanisms across host-strain combinations, as well as in response to nutrient-sensitive signaling cues. The second aim is to elucidate how strategic Wolbachia localization is regulated during oogenesis. In D. melanogaster, microtubule-based motor proteins concentrate Wolbachia and posterior/germline determinants at the oocyte posterior cortex, thus pre-positioning Wolbachia at the germ cell formation site. The impact of nutritional signaling on this process will be studied using genetic approaches. Taken together, this work will comprehensively inform the cellular basis for transmission of this endosymbiont.

内共生涉及一种生物体居住在另一种生物体内。最成功的内共生菌之一是沃尔巴克氏菌（Wolbachia pipientis），大约一半的昆虫物种都携带这种细菌，包括模型昆虫果蝇（果蝇）。与许多其他内共生体一样，沃尔巴克氏体在卵子发育过程中由雌性传播给后代。该项目的总体目标是阐明促进沃尔巴克氏体母体传播的细胞和分子机制。这将包括创建沃尔巴克氏体在果蝇卵细胞定植的数学模型，并使用该模型来测试有关控制发育中的卵内沃尔巴克氏体密度的因素的预测。模拟细胞内内共生体动力学实际上是前所未有的，因此这项工作将提供新的见解以及有价值的分析工具。此外，还将阐明调节宿主运输以及沃尔巴克氏体在果蝇卵内分布的营养信号。由于细胞运输过程对于建立昆虫身体计划也至关重要，这些分析将为沃尔巴克氏体传播和昆虫发育作为一个综合过程提供信息。这将把那些在机械上被认为是独立的概念联系起来。该研究将在一家以少数族裔为主、为西班牙裔服务的机构中进行，该机构也是美国最大的 STEM 少数族裔本科学位制作机构。执行该项目的学员还将撰写文章来解释研究实践和好处。这些文章将在基于网络的外展论坛上分享，以丰富公众对科学的理解。pipientis 沃尔巴克氏菌是最广泛的内共生体之一。这种母系传播的细菌具有精简的基因组和兼性的细胞内生活方式。沃尔巴克氏体在昆虫种群中的高流行需要强有力的传播增强策略。该项目的总体目标是应用化学、遗传和营养方法来确定宿主饮食和营养响应信号对沃尔巴克氏体和卵子发生中种系决定簇定位的影响。第一个目标涉及定义沃尔巴克氏体如何定殖果蝇母系生殖细胞作为一个完整的生理过程。尽管发育中卵母细胞中的沃尔巴克氏体滴度对宿主操作有反应，但宿主和共生体对滴度调节的相对贡献尚不清楚。为了解决这个问题，将对沃尔巴克氏体生命周期和入侵动力学以及宿主种系发育速率进行细胞学评估，并用于估计数学模型的参数。该模型将是第一个测试宿主菌株组合中沃尔巴克氏体定植机制的保守性以及对营养敏感信号线索的反应的模型。第二个目标是阐明在卵子发生过程中如何调节沃尔巴克氏体的战略定位。在黑腹果蝇中，基于微管的运动蛋白将沃尔巴克氏体和后/种系决定簇集中在卵母细胞后皮质，从而将沃尔巴克氏体预先定位在生殖细胞形成位点。将使用遗传方法研究营养信号对该过程的影响。总而言之，这项工作将全面揭示这种内共生体传播的细胞基础。