Collaborative Research: Development, Structure, and Function of the Bacterial Symbiont Colonization Site in Steinernematid Nematodes

大多数孩子被教导细菌（微生物）会使他们生病，事实上，有些人可以。然而，动物和微生物之间更常见的自然关系是互利的（互惠），因为微生物对正常的动物发育，营养和免疫力是绝对必要的。在这些关联中，微生物通常在动物身上或动物体内的离散位置定殖。关于这种殖民地的独特物理性质，或者如何形成和维持有益的动物-微生物协会，目前还知之甚少。众所周知，这些过程依赖于动物-微生物通信，其中可能涉及从远处交换的化学信号，以及通过直接物理接触发出的信号。仍然缺乏的是对信号身份的基本理解，它们是如何产生的，在哪里产生的，它们是如何被识别的，以及它们在每个伴侣中的作用。为了开始解决这些问题，拟议的研究集中在一个新兴的动物-微生物互利共生模型之间的一个小的，土壤中居住的线虫（蛔虫）和有益的细菌（共生体），它与。细菌共生体生活在线虫肠道内的特定囊泡（容器）中，是唯一能够驻留在此位置并与线虫建立关系的微生物;换句话说，它是唯一能够与线虫正确沟通以实现互利关系的微生物。在这项研究中，线虫肠囊泡的形态和发育特征进行了分析，以更好地了解定殖过程。拟议的研究还将探索关于线虫和共生体之间发生的化学信号和物理相互作用的新假设，以及这些相互作用如何影响每种生物的生理学。此外，拟议中的研究将解决这样的亲密的动物-微生物协会如何演变的问题。本提案的具体目标是，使用显微镜，生物化学和微生物遗传学，线虫和共生体之间的相互作用的结构和发展的特点，以及每个伙伴如何有助于这种关系。所研究的模型系统很容易在实验室中进行研究。参与这项合作研究的三个实验室都为拟议研究提供了所需的独特专业知识。这些实验室将一起：1）使用显微镜和生物化学分析与微生物共生体相互作用的线虫肠道区域的物理方面;2）比较不同线虫的肠道结构，以了解与共生体特异性相互作用的能力如何进化;3）研究与共生体相互作用的肠道区域如何发展，以及共生体如何影响这种发展; 4）利用生物化学和遗传学的方法，描述线虫和共生体之间交换的化学信号。这个模型系统非常适合教育，因为它与农业，医学和基础研究以及多学科观点具有广泛的相关性。一个代表性不足的少数民族本科生为初步研究做出了贡献，每个实验室将继续培训和教育来自不同背景的学生。将举办一个讲习班，其中包括通过这项研究开发的数据和技术。最后，这项研究将加强K-12教学工具开发的NSF资助的K通过无限程序在威斯康星大学麦迪逊分校的一部分。

Most children are taught that germs (microbes) will make them sick, and indeed, some can. However, the more common natural relationship between animals and microbes is mutually beneficial (mutualistic) since microbes are absolutely necessary for normal animal development, nutrition, and immunity. In these associations microbes typically colonize discrete locations on or within the animal. Little is as yet understood regarding the distinct physical nature of such colonization sites, or how beneficial animal-microbe associations are formed and maintained. It is known that these processes rely on animal-microbe communication that can involve chemical signals exchanged from a distance, as well as signaling through direct physical contact. Still lacking is a fundamental understanding of the identities of signals, how and where they are produced, how they are recognized, and the effects they mediate in each partner. To begin to address these questions, the proposed research focuses on an emerging model of animal-microbe mutualism between a small, soil-dwelling nematode (roundworm) and the beneficial bacterium (symbiont) with which it associates. The bacterial symbiont lives in a specific vesicle (receptacle) within the intestine of the nematode, and is the only microbe capable of residing at this location and establishing a relationship with the nematode; in other words, it is the only microbe that can correctly communicate with the nematode to achieve a mutually beneficial relationship. In this study the morphological and developmental features of the nematode intestinal vesicle will be analyzed to better understand the colonization process. The proposed research will also explore new hypotheses regarding the chemical signals and the physical interactions that occur between the nematode and the symbiont and how these interactions might affect the physiology of each organism. Furthermore, the proposed research will address questions of how such intimate animal-microbe associations evolve.The specific goal of this proposal is to characterize, using microscopy, biochemistry, and microbial genetics, the structure and development of the interaction between the nematode and the symbiont and how each partner contributes to this relationship. The model system being studied is easily studied in the laboratory. The three labs involved in this collaborative research are each contributing distinct expertise required for the proposed studies. Together these labs will:1) Analyze, using microscopy and biochemistry, the physical aspects of the nematode intestinal region that interacts with the microbial symbiont;2) Compare the intestinal structures of different nematodes to understand how the ability to specifically interact with the symbiont evolved;3) Study how the intestinal region that interacts with the symbiont develops, and how the symbiont affects this development; and4) Characterize, using biochemistry and genetics, the chemical signals exchanged between the nematode and the symbiont.This model system is well suited for education because of its broad relevance to agricultural, medical, and basic research and multiple disciplinary perspectives. An underrepresented minority undergraduate has contributed to preliminary research, and each lab will continue to train and educate students from diverse backgrounds. A workshop will be held that includes data and techniques developed through this research. Finally, this study will enhance a K-12 teaching tool developed as part of the NSF-funded K through Infinity program at UW-Madison.