Meeting Abstract
Minimizing maintenance costs is a strategy employed by many organisms to conserve energy and thus allocate it towards survival, reproduction, and growth. It has been demonstrated that skeletal muscle fibers grow to the verge of oxygen diffusion limitation to minimize costs of maintaining sarcolemmal membrane potential in many organisms. However, the sarcolemmal/plasma membrane in cells is but one of many membrane bound compartments across which gradients must be maintained. Some of the variation in metabolic rate therefore may be explained by the costs associated with maintaining gradients across these cellular and intracellular compartments. This research tested the hypothesis that the density of membrane associated lipids was positively related to mass specific standard metabolic rate in a range of marine invertebrate species. Standard metabolic rate was assessed by measuring the oxygen consumption rate. The lipid content of each whole individual was determined using thin-layer chromatography. Non-membrane associated lipids including sterol esters, triacylglycerols, and fatty acids as well as membrane associated lipids including phospholipids and cholesterol were identified. Overall, oxygen consumption rate was significantly elevated in small individuals compared to large individuals. Membrane associated lipids were positively correlated with standard metabolic rate, while non-membrane associated lipids were not, as expected. These results indicate that the extent of metabolic compartmentalization may contribute to the variation in standard metabolic rates of marine invertebrates.
