Tom Moon - Research
The diversity of aquatic vertebrates and in particular fish is truly amazing! Yet as humans the ‘sink’ for our industrial and personal wastes is ultimately the aquatic environment. Physiologies are extremely sensitive to environmental perturbations and my research examines the apparent paradox in this relationship between the aquatic environment that is constantly changing and the ability of fish to adjust to these changes. Using whole animal, cellular (isolated cells), biochemical (enzymes, metabolites) and molecular (RNA, transfection, transgenes) techniques, my laboratory studies this complex interaction between the fish and the environment. At the moment, research in my laboratory can be grouped into two principal themes: 1) the role of stress as an adaptive mechanism; and 2) the evolution of hormones and hormone function. Our work is continuing to move more towards molecular technologies and toxicology while ensuring that these processes can be traced back to some physiological functions in the animal. We are attempting to take what we see at the level of the cell or tissue and determine whether there will be consequences on the performance of the animal (reproductive, feeding, exercise).
Major Research Interests
The link between diversity and environmental perturbations is a complex suite of biochemical and physiological mechanisms that allow organisms to adjust within limits to changes in their environment. My laboratory uses fish (primarily although not exclusively) to unravel these complex adaptations as fish are in intimate contact with their aquatic environment and can serve as ideal sentinel species for changes to our aquatic resources, and fish represent the largest group of vertebrate species and thus ideal model organisms to track changes in the aquatic environment and to explore evolutionary changes within the vertebrates. We examine all levels of organization from the gene to the whole fish. We use a variety of fish species dependent upon the experimental questions posed. For example, the zebrafish Danio rerio is an excellent model fish species and is the premier developmental model used in research today. However its size precludes 'real' physiological estimates so the rainbow trout (Oncorhynchus mykiss) and goldfish (Carassius auratus) are more appropriate 'physiclogical' models. In addition trout are carnivores and ominivores, respectively and can be effective nutritional models. So as August Krogh clearly stated "For many problems there is an animal on which it can be most conveniently studied", some species are more appropriate models than others, depending upon the experiment. Presently my laboratory is working principally on fish species and two principle themes but multiple components of these themes.
Role of stress as an adaptive mechanism. External and internal factors will displace normal physiology which if not corrected could lead to significant pathology.
1. Pharmaceuticals and personal care products (PPCPs). Many human drugs are found in the aquatic environment and our interest is to understand their impact at environmental levels on fish. Using the lipid lowering drug gemfibrozil we reported that plasma lipid levels decrease, testosterone levels decrease, and the antioxidant system is compromised. We are studying the precise mechanisms responsible for these changes with this and other drugs including statins, selective serotonin-reuptake inhibitors and beta-blockers.
2. Persistent organic pollutants (POPs). POPs such as dioxins and PCBs induce cytochrome P450s which have metabolic consequences. We are studying what these consequences are and how they impact nutrient partitioning in the fish.
3. Nanomaterials. There is potential to apply nanotechnology to nearly every sector of industry, including consumer products, agriculture, health care and transportation, as well as bioremediation and water treatment. While nanotechnology has the potential to produce many societal benefits, we need to better understand the risks posed to aquatic organisms by nanomaterials that ultimately will be released into the environment. We are now examining the role of these nanomaterials (in particular nAg and TiO2) at the cell and whole animal levels.
Evolution of hormones and hormone functions. The phylogeny of hormones and their receptors are important to understand changes in hormone function through vertebrate evolution.
1. Evolution of adrenoceptors (ARs). There are many ARs found in mammals that are critical to pathophysiology. We are examining the evolution of fish ARs and report that significant changes have occurred and that these changes are linked to functional changes in the mechanisms of the adrenergic hormones.
2. Role of carbohydrates in fish. Glucose is poorly used by carnivorous fish but the precise reasons for this remain elusive. We are looking at the hormones involved and the sensitivity of the pancreatic cells that release hormones controlling blood glucose. Of course glucose and fat metabolism are linked and by looking at transcription factors regulating the enzymes of these pathways we may be able to better understand the nutrient processing of these animals.
3. Energy and nutrient sensors. One way of studying nutrients is to understand those agents that direct nutrients towards catabolic vs anabolic paths. A number of molecules are known to act as nutrient sensors (AMPK, SREBP, ChREBP); when changed, these sensors repartition cellular energy flow. We are examining these sensors to determine whether modifying them could modify the ability of a fish to utilize a particular dietary nutrient.