Comparative Biochemistry and Toxicology
Identifying the properties which contribute to ENM bioactivity will allow industry to design safe nano-enabled products and provide regulators with the necessary data to make informed decisions on novel ENMs. The end goal of this research is to facilitate the responsible development of nanotechnology applications aimed at addressing critical issues in human and environmental health.
We are interested in how changes in a fish's diet and/or environment influence heart and gill function. Aquatic environments are subject to daily and seasonal changes in temperature, oxygen, pH, salinity, etc. and these can influence cardiorespiratory function in fish. We use a variety of methods like electrocardiography and surgically implanted blood pressure and ultrasonic flow probes to measure cardiovascular performance in fish in vivo. Understanding how environmental factors affect fish will allows us to predict how future changes will impact fish populations and behaviors.
Engineered nanomaterials (ENMs) straddle the boundary between the atomic and molecular scale and because of this, they exhibit unique physical, chemical, and electronic properties. Their extremely high surface area to volume ratio in combination with these unique properties, make ENMs desirable in a multitude of applications including environmental remediation, medical imaging, and personal care products. Unfortunately, these same characteristics also make it difficult to predict the toxicity of novel ENMs based on available information for conventional materials. ENMs are now found in thousands of consumer products and there is a growing need to characterize their potential risks to human and environmental health. We examine these questions at multiple scales ranging from purified proteins, to isolated cells, to in vivo studies on organ physiology and energetics. We exploit the tunable nature of ENMs to address how their physicochemical properties (e.g. size, shape, surface charge, chemical composition, etc.) influence their interactions with proteins, membranes, and metabolites in vitro. This data is then applied to higher level studies on the biological and ecological relevance of ‘nanotoxicity’ using fish and aquatic invertebrates as model systems. We specifically focus on the cardiorespiratory system, as the pathology of chronic metabolic and/or physiological stress is often manifested in the form of cardiovascular dysfunction.
Physiological adaptation requires energy and all organisms have a finite level of energy to support life. The difference between an animal's basal and maximal metabolic rate represents the energy available for things like reproduction, foraging, and predator avoidance. The metabolic rate of a fish increases with water temperature, placing demands on energy metabolism and the cardiorespiratory system. Most of what we know about the thermal physiology of fish is based on single, acute heat treatments or chronic, long-term acclimations to high temperature. In many rivers, temperatures fluctuate substantially on a daily basis but it is unclear how these diel cycles impact the animal. Together with Dr. Suzie Currie and Dr. Andrea Morash's labs at Mount Allison, we are studying the influence of short- and long-term diel thermal cycling on the physiology of Atlantic salmon and rainbow trout. We study energy metabolism in vivo using static and swim tunnel respirometry systems with computerized temperature control. We also use biochemical and molecular biology techniques to study cellular stress pathways, energy production and utilization, and the signal transduction pathways that control metabolism. We recently initiated a project examining the metabolic impacts of diel cycling in dissolved oxygen levels as well. This work is supported by funding from the New Brunswick Environmental Trust Fund and the New Brunswick Innovation Foundation.
The physiology and metabolism is relatively poorly studied, as these animals are generally difficult to maintain in the laboratory. Our collaborator Dr. Antonio Sykes has developed robust methods for cuttlefish aquaculture, allowing his team to raise and maintain healthy stocks of animals in the lab. We are studying the complex cardiovascular physiology and metabolism of these animals to gain a better understanding of their capacity to deal with environmental stressors. Pictured to the right is a Sepia officinalis in situ isolated perfused working systemic heart preparation.