• Environmental Physiology

    Environmental Physiology

Research in environmental physiology explores how cells and physiological systems respond to changes in their environment. The environmental physiologists in the Department of Biology study a broad range of topics in a variety of vertebrate (mammals, fish, birds) and invertebrate (insects, crustaceans, worms) animals. Our studies take advantage of a diverse array of cutting-edge techniques, such as in vivo physiological recording, patch-clamp analysis, scanning ion-selective microelectrode technique (SIET), cell and tissue culture, confocal immunofluorescence analysis, transcriptomics, and proteomics. Work in the laboratory is complemented by field research in a diversity of locations, including the Queens University Biological Station in Ontario, the Bamfield Marine Station in British Columbia, Mongolia, China, the Andean Mountains of Peru, the Rift Valley of Africa, and the Brazilian Amazon. Motivated students and post-doctoral fellows can expect an exciting, highly interactive, and intellectually stimulating environment for research.

Michael O'Donnell
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LSB 530
(905) 525-9140 ext. 23103

Membrane Physiology of Ion transport and Excretion The primary goal of my research program is to elucidate the cellular and molecular mechanisms of excretion and ion transport, particularly by insect epithelia. We study how such processes are controlled by hormones and intracellular second messengers, and how mechanisms for excretion and ion transport are altered in response to changing environmental conditions. Blood feeding insects such as mosquitoes are of enormous importance as vectors of diseases such as malaria, and our studies of physiological mechanisms of ionoregulation and excretion provide insights that we hope will aid development of novel, environmentally-benign insecticides for pest species. Recently we have become fascinated by the ability of insects to rid themselves of toxins. Co-evolution of insects with flowering plants means that many insects are extraordinarily effective at detoxifying synthetic or natural pesticides, and the excretory system plays an important role in elimination of toxins or their metabolites. My research makes extensive use of electrophysiological methods, including intracellular recording, ion-selective microelectrodes and patch clamping. My students and I develop or adapt specialized micro-techniques for measuring pH or ion concentrations inside or adjacent to epithelial cells, or in nanoliter samples of biological fluids. We have recently developed a method of measuring transport of fluorescent substrates of ion transporters by means of confocal laser scanning microscopy of nanoliter droplets of secreted fluids, and we have used this technique to assess the roles of transporters related to p-glycoproteins and multidrug resistant proteins (MRP) in insect Malpighian (renal) tubules. We are also one of the few labs in Canada to make use of the Automated Scanning Electrode Technique (ASET). Transport of ions into or out of cells perturbs the concentration of ions in the unstirred layer (USL) near the surface of the cell. ASET uses computer-controlled stepper motors to position ion-selective microelectrodes near cells and measure tiny changes ( <0.04% ) in ion concentration between two positions within the USL. The difference in ion concentration is then used to calculate the rate of ion transport using the Fick equation.

Environmental Physiology

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McMaster University - Faculty of Science | Biology