Regulation of Energy Balance and Intestinal Function in Ancient Fishes

能量平衡的适当调节对地球上的所有生命都至关重要，在多细胞生物中，通过释放到循环系统的一套激素，部分实现了能量平衡，这些激素的作用是控制营养物质在肠道中的吸收，然后是生物体的分配、储存或使用。胰腺B细胞释放的胰岛素对人体血糖的调节可能是这方面研究最深入的例子。在古代鱼类中，激素如何调节营养物质的摄取、储存和/或使用在很大程度上尚未被探索。作为“活化石”，板鳃类（鲨鱼、鳐鱼和鳐鱼）和鲟鱼是解决我研究项目长期目标的绝佳模型，即了解胰岛素和皮质类固醇等激素的功能是如何在脊椎动物中进化的。有三个主要研究领域的短期目标旨在了解：1)激素释放的控制；2)肠道营养吸收的激素调节；3)肝脏对营养物质处理的激素控制。主要的营养物质是葡萄糖；然而，鲟鱼的代谢组织，特别是板鳃类，表明酮类在整个动物能量平衡中也起着重要作用。提出的目标集中在蓝鳃鱼和鲟鱼胰岛细胞中胰岛素释放的调节，以及胰岛素、胰高血糖素和glp1等血糖调节激素如何影响这些古老鱼类肠道中葡萄糖的摄取。鲟鱼体内的皮质醇和elasmobranch特异性皮质类固醇1 α -羟基皮质酮（1 α - ohb）对两组鱼类肝脏中葡萄糖和酮类加工的作用将进一步加深我们对这些鱼类应激反应的机制基础的理解。具体的研究将检查肠道微生物群落在全身氮平衡中的作用，并测试新的假设，即通过一种互惠关系，组织细菌介导1 α - ohb的合成，1 α - ohb是一种类固醇，在这个古老的鱼类群体中对全身能量和氮平衡至关重要。参与这项研究的HQP将获得整个动物生理学各个层面的技术技能。研究旨在发现在包容性环境中控制复杂生理系统的调节机制的进化，通过社区参与、会议出席、合作和发表来促进所有个体的成功。这项研究将显著影响我们对比较内分泌学中研究最多的激素进化的理解；胰岛素和皮质类固醇。此外，世界上许多种类的鲟鱼和板鳃类正面临灭绝的威胁；所产生的数据将用于改善在全球水族贸易和鲟鱼养护水产养殖中对板鳃类的管理和养护工作。

Appropriate regulation of energy balance is of fundamental importance to all life on earth and is in part achieved in multi-cellular organisms by a suite of hormones released into the circulatory system that act to control uptake of nutrients across the intestine followed by, distribution, storage or use by the organism. Regulation of blood glucose in humans by insulin released from pancreatic B cells is perhaps the most intensively studied example of this. In the ancient fishes how hormones regulate uptake, storage and/or use of nutrients is largely unexplored. As `living fossils' elasmobranchs (sharks, skates and rays) and sturgeons are excellent models to address the long-term goal of my research program that is, to understand how the function of hormones like insulin and corticosteroids have evolved in vertebrates. There are three primary areas of research with short term objectives aiming to understand: 1) control of hormone release; 2) hormonal regulation of nutrient uptake across the gut; and 3) hormonal control of nutrient processing by the liver. The primary nutrient of interest is glucose; however, metabolic organization in sturgeons and in particular, elasmobranchs, indicate ketones also play an important role in whole animal energy balance. Proposed objectives focus on the regulation of insulin release in the pancreatic islet cells of both elasmobranchs and sturgeon and how glucoregulating hormones such as insulin, glucagon and GLP 1 influence uptake of glucose across the gut in these ancient fishes. The action of cortisol in sturgeon and the elasmobranch specific corticosteroid, 1alpha-hydroxycorticosterone (1 alpha-OHB), on processing of glucose and ketones in the liver in both groups of fishes will further our understanding in the mechanistic underpinnings of the stress response in these fishes. Elasmobranch specific research will examine the role the intestine microbial community plays in whole body nitrogen balance and test the novel hypothesis that through a mutualistic relationship tissue bacteria mediate synthesis of 1alpha-OHB, a steroid that is central to whole body energy and nitrogen balance in this ancient group of fishes. HQP involved in this research will gain technical skills at all levels of whole animal physiology. Studies are designed to discover the evolution of regulatory mechanisms controlling complex physiological systems in an inclusive environment that promotes the success of all individuals through community involvement, conference attendance, collaboration and publication. The research will significantly impact our understanding of the evolution of perhaps the most studied hormones in comparative endocrinology; insulin and corticosteroids. Furthermore, many species of sturgeons and elasmobranchs are under threat of extinction around the world; data generated will be applied to improve management and conservation efforts for elasmobranchs in the global aquarium trade and conservation aquaculture of sturgeons.