MPS-BIO: Collaborative Research: Physical Mechanisms Regulating Sperm Chemotaxis

尽管经过了一个世纪的密集研究，受精仍然是最不被了解的基本生物学过程之一。配子之间的化学信号通过流体传播的线索发生在不同的类群中，具有高度不同的生殖策略，被认为在生殖中发挥着基础作用。尽管如此，在自然条件下配子之间的化学交流是如何发生的还不清楚。化学线索的有效性及其对雄配子运动的影响的一个关键决定因素是环境流体运动。流体运动可以通过将配子聚集在一起来促进细胞间的相互作用，或者交替地抑制黏附和结合，但对流动对雄配子的运动和趋化的影响知之甚少。现有的方法研究物理和化学在调节配子行为和受精中的作用的能力有限。在微观尺度上精确控制流体运动和化学线索是非常困难的。在这个项目中，最先进的微流体方法将使人们能够对配子自然栖息的微环境进行前所未有的控制。这项研究将采取综合的方法和应用微流体学来确定物理和化学在配子相互作用中所起的作用。因此，这项拟议的研究将在华盛顿大学PIS杰夫·里菲尔、麻省理工学院罗曼·斯托克和加州大学洛杉矶分校理查德·齐默的指导下进行，因此围绕两个主要目标展开：(I)确定化学线索对雄配子运动和受精成功的影响；(Ii)建立流体运动对雄配子运动的影响及其对化学线索的反应。这三个PI之间的专业知识的协同和互补将使人们能够深入描述雄配子游泳的生物力学和生殖细胞之间的化学交流。这项研究的综合性和跨学科方法将对科学和社会产生广泛和不同的影响。微流控技术的使用将有助于更好地理解雄配子趋化性，并为生殖和保护生物学提供新的知识。同时，这项研究在实现微观尺度上的流体流动和化学线索控制方面的进展将为生物学的不同领域提供一个广泛的方法学框架。这项研究中物理、生物和化学的紧密结合将为高中、本科生和研究生水平的学生提供充足的培训机会，强调在科学方面代表性不足的群体，通过以下方式：(1)与华盛顿大学生命科学夏季研究所(SILS)合作，这是一个为期4周的实践暑期研究所，为4-8年级的教师提供研究经验；(2)通过麻省理工学院的埃杰顿中心外联计划，为高中生提供3小时的科学体验，以促进学生的科学实践经验；(3)在加州大学洛杉矶分校设立一个新的课程模块，每个季度有3-4名加州大学洛杉矶分校的本科生参与研究；这些本科生将通过加州大学洛杉矶分校的CARE(卓越学术与研究中心)和UC Leads(卓越领导力到高级学位)计划从代表性不足的群体中挑选出来；以及(4)细胞生物学和微流体学方面的研究生和博士后培训。总之，这些计划将在多个教育级别促进外展和科学教育。按照所有三个私营部门主管的传统，在技术和通俗文献中广泛传播成果将补充这一外联计划。

Despite a century of intensive research, fertilization is one of the least understood fundamental biological processes. Chemical signaling between gametes through fluid-borne cues occurs in diverse taxa with highly divergent reproductive strategies and is thought to play a fundamental role in reproduction. Still, it is unclear how chemical communication between gametes occurs under natural conditions. A critical determinant of the effectiveness of chemical cues and their influence on the motility of male gametes is ambient fluid motion. Fluid motion may promote cell interactions by bringing gametes together or alternately may inhibit adhesion and binding, yet very little is known about the effects of flow on the motility and chemotaxis of male gametes. Existing methods have limited ability to study the role of physics and chemistry in mediating gamete behavior and fertilization. It is very difficult to accurately control fluid motion and chemical cues at microscopic scales. In this project, state-of-the-art microfluidic approaches will enable unprecedented control over microenvironments naturally inhabited by gametes. This study will take a comprehensive approach and apply microfluidics to determine the roles played by physics and chemistry in gamete interactions. The proposed research, to be carried out under the guidance of PIs Jeff Riffell (U. Washington), Roman Stocker (MIT) and Richard Zimmer (UCLA), is thus structured around two principal aims: (i) determine the impact of chemical cues on male gamete motility and on fertilization success; (ii) establish the effects of fluid motion on the motility of male gametes and their response to chemical cues. The synergy and complementarity of expertise between the three PIs will enable an in-depth characterization of the biomechanics of male gamete swimming and of chemical communication between germ cells. The comprehensive and interdisciplinary approach of this study will have broad and diverse impacts on science and society. A better understanding of male gamete chemotaxis will arise from the use of microfluidic technology and provide new knowledge on reproduction and conservation biology. At the same time, the advances fostered by this study in attaining control of fluid flow and chemical cues at the microscale will provide a broad methodological framework for diverse areas of biology. The intimate combination of physics, biology and chemistry in this study will provide ample training opportunities for students at high school, undergraduate and graduate levels, emphasizing under-represented groups in science, through (1) a collaboration with the Summer Institute for Life Science (SILS) at the University of Washington, a 4-week hands-on summer institute that provides grade 4-8 teachers with research experience; (2) the development of a 3-hour science experience to be offered through MIT's Edgerton Center Outreach Program, designed for high-school students to promote hands-on experience in science; (3) the creation of a new course module at UCLA and the involvement of 3-4 UCLA undergraduates in research, each quarter; these undergraduates will be drawn from underrepresented groups through the UCLA CARE (Center for Academic and Research Excellence) and the UC LEADS (Leadership Excellence through Advanced DegreeS) Programs; and (4) the training of graduate students and postdoctorates in cell biology and microfluidics. Together, these programs will foster outreach and science education at multiple educational levels. Broad dissemination of results in technical and popular literature, in the tradition of all three PIs, will complement this outreach plan.