Sterol Limitation of Zooplankton Growth: Roles in Nutrition and Membrane Biology

这项研究将首次提供胆固醇作为浮游动物的限制性营养物质和质膜成分的研究。将确定膳食甾醇成为限制的物理和生物条件，并定义膳食和膜特异性对甾醇的需求之间的耦合。拟验证的中心假设包括：1)外源固醇是桡足动物生长的限制因素。2)饲粮中添加胆固醇影响生长速率，但不影响质膜中胆固醇含量（即，尽管饲粮变化，但仍能维持最佳胆固醇水平）。3)生长温度对膜胆固醇含量和饲粮胆固醇限量有影响。拟议研究的重点将包括从有机体到生物组织的一系列水平。到生物化学过程。浮游动物（包括eurythermal和其他具有重要生态意义的物种）将在饮食中使用不同的a)藻类和b)补充胆固醇水平来饲养。产蛋率、蛋孵化率和/或生长率将在不同的生物和物理条件下决定。胆固醇将递送明胶-金合欢微胶囊和摄取率监测粒子计数器。质膜将用密度梯度离心制备，并分析胆固醇含量。提出的许多研究特别适合本科生参与。学生将获得浮游动物和温度生物学的概念和具体知识，以及生理学/生物化学的基本机制。此外，学生将从各种方法的实践经验中学习宝贵的实验室技术。与海洋实验室研究人员的互动将进一步丰富这些经验。

This study will provide a first look at cholesterol as a limiting nutrient and plasma membrane constituent for zooplankton. Physical and biotic conditions for which dietary sterols become limiting will be identified, and the coupling between dietary and membrane-specific requirements for sterol will be defined. The central hypotheses to be tested include: 1) Exogenous sterols are limiting factors for copepod growth. 2) Cholesterol supplementation of the diet affects growth rates but not cholesterol contents in plasma membranes (i.e., an optimal level of cholesterol is maintained despite variability in diet). 3) Cholesterol contents of membranes and dietary limitation of cholesterol are affected by growth temperature. The foci of the proposed research will encompass a range of levels of biological organization from organismal. to biochemical processes. Zooplankton (including eurythermal and other, ecologically important, species) will be raised on diets using different a) algal species and b) levels of supplemented cholesterol. Egg production rates, egg hatch rates, and/or growth rates will be determined under different biotic and physical conditions. Cholesterol will be delivered in gelatin-acacia microcapsules and ingestion rates monitored by particle counter. Plasma membranes will be prepared using density-gradient centrifugation and cholesterol contents analyzed. Much of the research proposed is especially well-suited for undergraduate student involvement. Students will gain conceptual and specific knowledge of zooplankton and temperature biology as well as fundamental mechanisms in physiology/biochemistry. In addition, students will learn valuable laboratory techniques from hands-on experience with a variety of methodologies. These experiences will be further enriched by interactions with researchers at a marine laboratory.