Applying bacterial growth theory to understand the evolution of thermal performance

温度影响生物的各个层面，从单个分子到整个生物体。然而，温度对包括蛋白质合成和营养吸收在内的重要细胞过程的影响仍然知之甚少。解决这一长期和激烈争论的难题对于更好地理解生物如何对环境温度的长期变化做出反应至关重要。在这里，研究人员将针对两组独立适应高温的极端环境中的细菌来解决这个问题。该方法将结合最近发展的理论的扩展和监测蛋白质合成的新技术的新应用。这项研究将提供一个通用的预测框架，有可能改变我们对热生理进化的理解。调查人员还将通过在K-12和大学层面上的指导和推广，将研究和教育结合起来。研究生将接受培训，与公众交流他们的研究成果，增加对社区的外展努力。将开发关于温度对生物系统的影响的模块，并在不同的地点展示，以接触到广泛的K-12学生。最后，代表不足的学生将参与这项研究的所有方面。理解温度、新陈代谢和健康之间的联系仍然是进化生理学的一个基本挑战。长期以来，关于热力学效应对生理速率的相对重要性与生物化学适应对生物体表现的温度依赖性的相对重要性的争论尤其有争议。为了更好地区分可能有助于热性能进化的替代机制，PI建议扩展最近发展的关于微生物生长速度和基因表达相互依赖的理论，以研究温度如何通过对代谢率的热力学影响以及蛋白质合成和营养代谢之间的细胞分配权衡而产生对适应性的影响。生长理论模型将确定沿地温梯度会聚辐射的两个嗜热蓝藻分支的生态分歧成员在不同温度下的生长速度和资源分配之间的关系。此外，用下一代测序方法表征核糖体活性将把这些模型所描述的生物体水平的现象与它们潜在的基因表达的分子机制联系起来。实验设计将能够确定温度效应对生理速率的相对贡献与温度补偿、热性能演变的适应机制。它将同时考虑温度对代谢率的影响和有限细胞资源对生长的限制，从而改进现有理论，从而能够改进对基因表达、新陈代谢和适应能力如何沿着生物体的热生态位变化的预测。总而言之，这项研究将为推动利基分化和热专业化的机制提供一个新的视角。这些研究的教育影响还将包括对从博士后到K-12的学生的培训和指导，包括来自代表性不足的人群的学生。该项目由综合组织系统部门的综合生态生理学计划和促进竞争性研究的实验计划共同资助。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。

Temperature affects biology at all levels, from single molecules to whole organisms. However, the effects of temperature on important cellular processes including protein synthesis and nutrient uptake remain poorly understood. Resolution of this longstanding and hotly debated puzzle is essential for developing a better understanding of how organisms respond to long-term changes in environmental temperature. Here, the investigators will address this issue for two groups of bacteria from extreme environments that have independently adapted to high temperatures. The approach will combine the extension of recently developed theory with the novel application of new technologies for monitoring protein synthesis. This research will provide a general predictive framework with the potential to transform our understanding of the evolution of thermal physiology. The investigators will also integrate research and education through mentoring and outreach at both K-12 and university levels. Graduate students will be trained to communicate their research to the general public, increasing the outreach efforts to the community. Modules on effect of temperature on biological systems will be developed and presented at different venues to reach a broad spectrum of K-12 students. Finally, underrepresented students will be involved in all aspects of this research.Understanding the links between temperature, metabolism and fitness remains a fundamental challenge in evolutionary physiology. The longstanding debate over the relative importance of thermodynamic effects on physiological rates versus biochemical adaptation for the temperature dependence of organism performance has been particularly contentious. To better distinguish among alternative mechanisms that may contribute to the evolution of thermal performance, the PI proposes to extend recently developed theory on the interdependence of microbial growth rate and gene expression to investigate how temperature effects on fitness arise from both thermodynamic effects on metabolic rates and cell allocation trade-offs between protein synthesis and nutrient metabolism. Growth theory models will determine the relationship between growth rate and resource allocation at different temperatures for ecologically divergent members of two clades of thermophilic cyanobacteria that have convergently radiated along geothermal gradients. Further, characterization of ribosome activity with a next-generation sequencing approach will connect the organism-level phenomena described by the models with their underlying molecular mechanisms of gene expression. The experimental design will enable the determination of the relative contributions of temperature effects on physiological rates versus temperature-compensating, adaptive mechanisms for the evolution of thermal performance. It will improve on existing theory by simultaneously accounting for both the temperature effects on metabolic rates and the constraints imposed on growth by finite cellular resources, thereby enabling improved predictions for how gene expression, metabolism and fitness change along an organism's thermal niche. Together, the research will provide a fresh perspective on the mechanisms that drive niche differentiation and thermal specialization. The educational impacts of these research will also involve training and mentoring of students from the postdoctoral level to K-12 and include students from underrepresented populations.This project is co-funded by the Integrative Ecological Physiology Program in the Division of Integrative Organismal Systems and by the Experimental Program to Stimulate Competitive Research.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.