Michael J O'donnell
Professor Emeritus, Biology

Insects are the most successful and diverse group of terrestrial animals, but we still know little about the mechanisms of some of their most important physiological processes. The goals of my research program are to elucidate the cellular and molecular mechanisms of excretion and ionoregulation by epithelial cells in insects and other invertebrates and to explain how such processes are modulated by hormones and by exposure to environmental stressors, feeding or dietary toxins. Our studies help us to understand how excretory processes contribute to insecticide resistance in agricultural pests and disease vectors. Our findings also underpin the development of novel control measures based on agents which mimic diuretic or other hormones which modulate renal or gut function. We make extensive use of sophisticated electrophysiological methods, including ion-selective microelectrodes (ISMEs), to measure transepithelial ion transport both in pest insects (mosquitoes, beetles, caterpillars) and in genetically tractable model organisms such as Drosophila and C. elegans. Use of model organisms greatly facilitates analysis of transport mechanisms through measurement of transporter gene expression in specific tissues using qRT-PCR and through use of mutants or RNAi knock-down of genes for specific organic or inorganic ion transporters. Our pairing of electrophysiological techniques with use of mutants, RNAi knock-down techniques and shotgun sequencing (RNAseq) gives us the capability to precisley characterize specific transporters and signaling pathways in identified cells.