Integrative control of cardiorespiratory energetics during stress

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A plethora of regulatory processes are involved in the maintenance of energy balance and cardiorespiratory function in aquatic animals and each can be uniquely affected by environmental stressors. The long-term goal of my research program is to understand how these processes are controlled and how they allow animals to thrive in stressful environments. In the short term, I will focus on understanding the signalling mechanisms controlling cardiac and metabolic depression in 3 research themes: ***Theme 1) The regulation of cardiac function and metabolism by taurine. Taurine is present in significant quantities in the cardiac muscle of most animals. It is known to protect mammalian hearts from stress-associated damage, influence contractile function, and regulate energy metabolism but these functions have received little attention in stress-tolerant aquatic animals. Experiments in this theme will address taurine's regulatory functions in fish and cephalopods to determine how it influences heart function and metabolism to promote stress tolerance. ***Theme 2) Mechanisms underlying hardening in response to cyclic environmental stressors. Fluctuations in temperature and oxygen availability are common in aquatic environments but our understanding of how aquatic animals deal with such stresses are based largely on studies examining single acute stress exposures. Our initial work showed that fish respond differently to cyclic stressors and may activate novel energy conserving mechanisms to promote survival. This theme will examine potential cellular and metabolic processes underlying these responses and their impacts on cardiorespiratory function to determine how fish thrive under such conditions. ***Theme 3) Unifying mechanisms of engineered nanomaterial (ENM) toxicity. The proliferation of ENMs has increased concerns over their toxicity. In fish, a variety of ENMs trigger metabolic depression and cardiorespiratory dysfunction reminiscent of a response to oxygen deprivation but the underlying mechanisms have not been investigated. ENMs also cause inflammation, which can activate cellular pathways involved in the metabolic and cardiorespiratory responses to hypoxia. This theme will examine regulatory signaling pathway activation in fish exposed to a variety of ENMs to determine if they act through a common receptor or set of receptors. Pharmacological techniques will then be applied to confirm that blocking receptor activation prevents the cardiorespiratory and metabolic impacts of ENM exposure. ***Significance: My research program aims to improve our understanding of the mechanisms used by animals to respond to and thrive in stressful environments. Understanding these mechanisms and their physiological consequences will allow us to better predict the impacts of environmental change and anthropogenic activity on aquatic animals.