Balancing the demands of physiological systems: digestion in crustaceans during environemental change

摄食对新陈代谢的一般影响是众所周知的(特定的动态作用，SDA)，这就是为什么它们通常在生理实验中被控制的原因。然而，如果消化和同化的能量成本很高，它们可能会影响其他生理系统。因为动物并不总是在经历环境扰动之前停止进食，所以以前没有考虑消化过程的文章可能不会显示全部情况，甚至可能是错误的。我的初步工作表明，生物体的营养状态会影响其他生理过程。考虑到这一点，本项目将研究三种渗透调节能力不同的十足类甲壳类动物在不同温度/低盐度条件下摄食和消化时的生理反应和消化过程。我们的目标是1)确定动物如何利用心血管机制(心率和局部血流)和呼吸机制(氧气摄取、血气运输和酸碱)来平衡相互竞争的生理过程的需求，以及2)确定特定动态作用的组成部分(机械消化、酶活性、蛋白质合成)如何对总SDA做出贡献，以及它们在温度驯化和低盐暴露期间受到何种程度的调节。这些发现将有助于理解组成SDA的消化阶段的划分和控制，以及生物体如何平衡相互竞争的生理系统的需求。这笔赠款中概述的项目的完成将增加我们对甲壳类动物消化过程的了解，并应对确定水产养殖的最佳养殖条件具有重要意义。近年来，人们对在更自然的环境中甚至在野外研究生物体的反应重新产生了兴趣，这些发现将扩大整个生物体生理学的这一日益增长的领域，并为未来的研究提供一个框架。这笔赠款中概述的项目的完成将增加我们对甲壳类动物消化过程的了解，并对确定水产养殖或渔业资源管理者的最佳养殖条件具有重要意义。

The general effects of feeding on metabolism are well known (specific dynamic action, SDA), which is why they are usually controlled for in physiological experiments. However, if the energetic costs of digestion and assimilation are large they may impact other physiological systems. Because animals do not always stop feeding prior to experiencing an environmental perturbation, previous articles that do not consider digestive processes may not show the whole picture and may even be erroneous. My preliminary work has shown that the nutritional status an organism will affect other physiological processes. With this in mind this project will investigate physiological responses and digestive processes in three species of decapod crustacean of differing osmoregulatory ability when feeding and digest in different temperatures/low salinity regimes. We aim to 1) Determine how animals use cardiovascular (heart rate and regional blood flow) and respiratory mechanisms (oxygen uptake, blood-gas transport and acid-base) to balance the demands of competing physiological processes, and 2) Determine how the components of the specific dynamic action (mechanical digestion, enzyme activity, protein synthesis) contribute to the total SDA and to what degree they are modulated during temperature acclimation and low salinity exposure. These findings will help in understanding the partitioning and control of the phases of digestion that comprise SDA as well as how organisms balance the demands of competing physiological systems. The completion of the projects outlined in this grant will increase our understanding of digestive processes in crustaceans and should be of relevance for determining optimal culture conditions for aquaculture. There has been a renewed interest in recent years in studying the responses of organisms in a more natural setting or even in the field and these findings will extend this growing area of whole organism physiology and provide a framework for future studies. The completion of the projects outlined in this grant will increase our understanding of digestive processes in crustaceans and should be of relevance for determining optimal culture conditions for aquaculture or fisheries resource managers.