Fundamental measurements of liquid-liquid phase separation in lipid membranes and development of methods to assay domain compositions

每个细胞都被膜包围，膜中的脂质可以分层混合成两个共存的液相。这种现象具有重要的生物学意义。例如，当酵母细胞的营养受到限制时，其液泡（细胞器）的膜就会分层。 当前的项目分为五个研究主题，涉及人造膜的生产及其分层转变的研究。该研究将测试不对称脂质囊泡（可以模仿细胞膜）的相分离是否与完全平坦且拉紧的膜（生物学相关性较低）相分离相同。该项目将在发布新协议和计算机代码、开发科学教材以及指导下一代受过科学训练的工人方面产生更广泛的影响。完善的外展活动包括传播科学成果、培训早期职业科学家和公共外展。提出了智力价值和更广泛影响的评估计划。该研究的主题是膜中的液-液相分离。该项目解决的一些问题是技术性的。例如，该研究试图开发一种新的、更容易实现的方法来确定共存膜相中脂质的比例，并分析通过各种方法制成的囊泡的脂质成分。研究的其他要素是由理论预测驱动的。例如，拉曼成像将用于测试脂质跨相及其边界分布的预测，荧光显微镜将用于测试有关囊泡膜中脂质数量和类型不对称的理论。其他实验将是探索性的。例如，该项目的一部分是寻找具有先前未经测试的脂质成分的膜中的液-液相分离。该项目的不同部分共同呈现出一个平衡的组合，其目标是测试当前理论、收集评估模拟所需的定量数据、开发实现未来定量测量的方法，以及指导和培训具有强大科学和技术技能的未来劳动力。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Each cell is surrounded by a membrane, and lipids in this membrane can demix into two coexisting liquid phases. This phenomenon is biologically important. For instance, when a yeast cell becomes nutrient limited, the membrane of its vacuole (an organelle) demixes. The current project is organized into five research themes on the production of artificial membranes and the study of their demixing transitions. The research will test if asymmetric lipid vesicles (which can mimic cell membranes) phase separate in the same way that entirely flat and taut membranes (which are less biologically relevant) phase separate. The project will have broader impacts of publishing new protocols and computer code, developing scientific teaching materials, and mentoring the next generation of scientifically-trained workers. Well-developed outreach activities include dissemination of scientific results, training of early-career scientists, and public outreach. Assessment plans for the Intellectual Merit and the Broader Impacts are presented.The research centers on the topic of liquid-liquid phase separation in membranes. Some of the problems the project addresses are technical. For example, the research seeks to develop a new, more accessible method of determining ratios of lipids in coexisting membrane phases and to analyze lipid compositions of vesicles made by a variety of methods. Other elements of the research are driven by theoretical predictions. For example, Raman imaging will be used to test predictions of the distributions of lipids across phases and their boundaries, and fluorescence microscopy will be used to test theories about asymmetry in the number and type of lipids in vesicle membranes. Other experiments will be exploratory. For example, one part of the project is to search for liquid-liquid phase separation in membranes with previously untested lipid compositions. Together, the different parts of the project present a balanced portfolio with goals of testing current theory, amassing quantitative data needed to evaluate simulations, developing methods that enable future quantitative measurements, and mentoring and training a future workforce that has strong scientific and technical skills.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.