An integrated approach to stress in fish: behaviour, molecular biology and physiology

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The long-term objectives of my research program focus on integrating physiology and behaviour in fish, and on understanding piscine strategies for gas transfer and acid-base regulation.  While these two objectives appear superficially to be quite disparate, they are in fact linked by such unifying themes as stress responses, cortisol, acid-base and ionic regulation, the enzyme carbonic anhydrase (CA), and CO2 excretion.      In terms of integrating physiology and behaviour, we use social hierarchies in rainbow trout to examine the physiological causes and consequences of social status.  Building on recent progress in this area, in which we have focused on the immediate physiological costs of low social status, including growth depression, reduced tolerance of low O2 and the impact of chronic social stress on acute stress responses, I now propose to identify the physiological mechanisms underlying socially-induced growth depression and investigate the impact of low social status on ionic regulation and acid-base balance.  The aim of this work is to improve our understanding of the physiological mechanisms underpinning behaviour, but the information gained can also be important in an applied setting, for example in predicting the impact of pollutants on fish populations, or in designing effective animal husbandry practices for aquaculture.    With respect to the long-term goal of understanding strategies for gas transfer and acid-base regulation in fish, I aim to build on our recent progress in identifying the molecular structure and function of fish CAs.  CA is a near-ubiquitous enzyme that catalyzes CO2 reactions and hence contributes to physiological processes ranging from CO2 excretion and acid-base balance to metabolism.  I propose to explore the physiological roles of a group of CA isoforms that we cloned from lungfish, to examine the regulation of CA expression during acid-base disturbances, and to identify hypoxia-inducible CA isoforms in zebrafish.  By generating new information on CA isoforms in fish and their functions, this work will increase our understanding both of gas transfer and acid-base regulation in fish, and of the evolution of the CA gene family in vertebrates.