Currently, we are determining the fiber-type profiles of the locomotor muscles of three species of Arctic seals: bearded, ringed, and spotted. With this information, we hope to understand how the feeding of these animals will be impacted by global climate change, as all three species rely on sea ice as a platform for their dives. We are also studying the construction of the diaphragm and scalenus muscles in cetaceans (whales, dolphins, and porpoises) to determine how these muscles power the explosive breathing of these animals and also allow them to breath-hold dive. The other studies in the lab are investigations of guinea pig breathing muscle development and the effects of prenatal steroids on this process. Characteristics that we are investigating include: fiber-type profiles (percent slow- and fast-twitch fibers), fiber diameters, oxidative enzyme activities, myoglobin concentrations, and myosin heavy and light chain protein expression.