Carbon dioxide, pH and bicarbonate sensing in sharks

所有生物体都必须能够感知和调节其内部液体的酸度（低pH值）和碱度（高pH值）。然而，生物体感知酸碱度的机制还不清楚。鲨鱼的血液pH值作为其正常生理学的一部分会发生明显的变化，因此是研究pH传感和调节机制的绝佳模型。该项目将使用生物化学，分子，细胞生物学和生理学工具来确定鲨鱼如何感知pH值的变化，并描述下游调控过程。这些信息将帮助我们了解和预测生物体如何应对环境和代谢压力。由于该项目将重点关注与其他生物体共享的细胞途径，因此其结果也将适用于广泛的其他学科领域。 此外，一些信息将被纳入UCSD教授的本科生和研究生生理学课程。本项目将培养一名博士后研究员和一名少数民族生物学研究生，以及若干名本科生。为了让公众了解鲨鱼，该项目将与斯克里普斯的伯奇水族馆建立合作伙伴关系，通过为高中生提供的创新性解释性实习计划，建立对鲨鱼生物学、生态学和保护问题的认识。该项目将重点关注碳酸氢盐敏感酶可溶性腺苷酸环化酶（sAC）和与跨膜腺苷酸环化酶相关的假定pH敏感G蛋白偶联受体（GPCR/tmAC）。利用从分子到细胞再到活鲨鱼的整个复杂光谱的实验技术组合，拟议的研究将：1）确定对sAC和tmAC有选择性的药理学抑制剂，供本项目以及其他研究人员在细胞和整个生物体实验中使用; 2）研究鲨鱼细胞对内外CO2、pH和碳酸氢盐刺激的sAC和GPCR/tmAC刺激机制;和3）探索sAC在细胞核中的存在及其在调节基因表达中的作用，使用分离的细胞核、细胞和器官的实验以及对来自饥饿的组织样品的转录组学和蛋白质组学分析的组合。 该项目将表征试剂并为未来的生理学和跨学科研究产生可验证的假设。研究结果将通过期刊、会议和公共数据库（如NCBI）进行传播。

All organisms must be able to sense and regulate the levels of acidity (low pH) and alkalinity (high pH) in their internal fluids. However, the mechanisms by which organisms sense acidity and alkalinity are not well understood. Sharks undergo pronounced variations in blood pH as part of their normal physiology, and therefore are excellent models to study mechanisms for pH sensing and regulation. This project will use biochemical, molecular, cell biology, and physiological tools to determine how sharks sense changes in pH and to characterize downstream regulatory processes. This information will help us understand and predict how organisms respond to environmental and metabolic stress. Because this project will focus on cellular pathways that are shared with other organisms, the results will also be applicable to a broad array of additional subject areas. Additionally, some of the information will be incorporated into undergraduate and graduate physiology courses taught at UCSD. This project will train one postdoctoral researcher and one minority graduate student in biological research, as well as several undergraduate students. To reach the general public, this project will establish a partnership with Birch Aquarium at Scripps to build awareness of shark biology, ecology and conservation issues through an innovative interpretive internship program for high school students.This project will focus in the bicarbonate-sensing enzyme soluble adenylyl cyclase (sAC), and in putative pH-sensing G-protein coupled receptors associated with transmembrane adenylyl cyclases (GPCR/tmAC). Using a combination of experimental techniques over the entire complexity spectrum from molecules to cells to live sharks, the proposed research will: 1) identify pharmacological inhibitors selective for sAC and tmACs, for their use in cell and whole-organism experiments in this project as well as by other researchers; 2) characterize the mechanisms of sAC and GPCR/tmAC stimulation in shark cells in response to internal and external carbon dioxide, pH and bicarbonate stimuli; and 3) explore the presence of sAC in the cell nucleus and its role in regulating gene expression, using a combination of experiments with isolated nuclei, cells and organs, and transcriptomic and proteomic analyses on tissue samples from starved. This project will characterize reagents and generate testable hypothesis for future physiological and interdisciplinary studies. Results will be disseminated through journals, conferences, and public databases such as NCBI.