Research directions and questions of interest in my laboratory include
1. Allometric scaling of and upper limits to mass specific metabolic rates
Small vertebrate homeotherms display higher maximum mass-specific rates of aerobic metabolism than larger ones. The anatomical and physiological correlates of these differences have been well studied, but the biochemical basis for them is poorly understood. It is possible that upper limits to mass-specific metabolic rates are involved (along with other factors) in establishing lower limits to vertebrate homeotherm size. I am very interested in how morphology, physiology, and biochemistry together might constrain animal size and maximum rates of metabolism.
Video on the left shows, in Quick Time Movie format, a rufous hummingbird taking a drink of sugar water from a feeder. While doing so, it breathes in a plastic flower modified to function as mask for flow-through respirometry
2. Ecological implications of metabolic biochemistry
Metabolic biochemists seldom think about how and in what types of environments animals actually live, as well as how metabolism may influence or constrain behavior. Ecologists seldom think about metabolism and how behavior and the environment influence metabolism. If an organism's energetic goal is to maximize net energy gain, what are the relationships between strategies and mechanisms of metabolic fuel selection and behavioral choices made in changing environments? Can behavior optimize metabolism and increase net energy gain? Has metabolism influenced the evolution of behavior?
3. Evolutionary design of pathways of energy metabolism in muscles
What are the relationships between biochemical capacities and maximum physiological requirements? A subject of much controversy is the idea that animals are designed economically, such that structures and functional capacities simply match, but do not exceed maximum physiological requirements or loads (the concept of "symmorphosis"). Do muscles possess enough or too much enzyme? Do muscles have just enough mitochondria, such that these operate at their maximal capacities during maximum aerobic exercise? I am very interested in deciphering the rules that govern the evolutionary design of functional capacities at the biochemical level.
4. Energetics of flight in hummingbirds and insects
Because of their small size and ability to fly, these animals achieve the highest mass-specific metabolic rates in the animal kingdom. How do morphology, physiology, and biochemistry all "fit together" to allow these animals to achieve such high rates of metabolism? How do enzymes, pathways, and mitochondria really work in vivo? The smallest and presumably, most metabolically active, vertebrate homeotherms are 2 gram Thai bumblebee bats, Cuban bee hummingbirds, and Etruscan shrews. How can smaller flying insects achieve even higher mass-specific rates of metabolism than the smallest vertebrate homeotherms?
5. Control of muscle energy metabolism
When muscles work at their maximum power outputs, metabolic rates increase by up to several hundred-fold. How this actually happens remains a mystery, despite the fact that Meyerhof and others worked on glycolysis, Hans Krebs and others worked on the citric acid cycle, and Warburg and others worked on mitochondrial respiration early in this century. A fruitful direction will be the application of metabolic control analysis.