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

每个细胞被一层膜包围，膜中的脂类可以分解成两个共存的液体相。这一现象具有重要的生物学意义。例如，当酵母细胞变得营养有限时，其液泡(细胞器)的膜就会分离。目前的项目分为五个研究主题，分别是人造膜的生产及其分离过渡的研究。这项研究将测试不对称脂泡(可以模拟细胞膜)是否以完全平坦和紧致的膜(生物学上相关性较小)相分离的相同方式相分离。该项目将在发布新的协议和计算机代码、开发科学教材以及指导下一代经过科学培训的工人方面产生更广泛的影响。发展良好的外联活动包括传播科学成果、培训职业生涯初期的科学家和公众外联。提出了智能价值的评估计划和更广泛的影响。研究集中在膜中的液-液相分离这一主题。该项目解决的一些问题是技术性的。例如，这项研究试图开发一种新的、更容易获得的方法来确定共存的膜相中的脂类比率，并分析由各种方法制成的囊泡的脂类成分。这项研究的其他要素是由理论预测驱动的。例如，拉曼成像将被用来测试脂类跨相分布及其边界的预测，荧光显微镜将被用来测试关于囊泡膜中脂类数量和类型不对称的理论。其他实验将是探索性的。例如，该项目的一个部分是在具有以前未测试的脂质成分的膜中寻找液-液相分离。总而言之，该项目的不同部分提供了一个平衡的投资组合，目标是测试当前的理论，积累评估模拟所需的定量数据，开发能够进行未来定量测量的方法，以及指导和培训拥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优势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.