Reaction-diffusion analysis of chemical energetics in marine organisms

This project, which is funded by NSF, is an examination of the effects of diffusive constraints on the energy metabolism in muscle of marine organisms. To do this, we take advantage of the fact that muscle fibers in many marine organisms, such as crustaceans and fishes, have extreme sizes, meaning that metabolic processes that require intracellular diffusion are constrained by the rates of diffusive flux and the intracellular barriers that hinder diffusion. Importantly, the muscle fibers in these organisms span a large range of dimensions during development, such that fibers from juvenile animals have "normal" dimensions while fibers from adults are "giant". We therefore use microscopic and chemical methods to examine how muscle metabolic design is modified in response to changing cell size. To determine the consequences of increasing cell size, we combine non-invasive NMR methods with microscopic and wet-chemical techniques to measure diffusive and metabolic processes, and we use mathematical modeling methods to interpret our results. By using extreme examples from the marine environment, we hope to better understand cellular energetics in other model systems.

Salinity effects on juvenile blue crabs

Our lab also is part of a collaborative project that is funded by NSF to examine the impact of low salinity environments on juvenile blue crab energetics and ecology. Juvenile blue crabs are found in abundance in the Cape Fear River at salinities that approach freshwater. However, it is generally thought that juvenile blue crabs are less capable osmoregulators than adult crabs, so we have been investigating the energetic costs and physiological/biochemical consequences associated with changing environmental salinities.