Compositional correlates of metabolic depression in the mitochondrial membranes of estivating snails.

The phospholipid and protein compositions of mitochondrial membranes from hepatopancreas of active and estivating terrestrial snails ( Cepaea nemoralis) were compared. Mitochondria from estivating snails contained 82.7% less cardiolipin, and this was associated with an 83.9% reduction in cytochrome- c oxidase activity. Substantial changes also occurred in the proportional amounts of other individual phospholipid classes and their constituent fatty acids, including a 72% loss of total mitochondrial phospholipids, a 37% increase in monoenes, and 49% fewer n-3 fatty acids in membranes of estivating snails. These changes are consistent with those correlated with lowered metabolic rate and lower rates of proton leak in other animal models. Estivating snail hepatopancreas showed no change in total phospholipid content, indicating that the phospholipids lost from mitochondrial membranes may be sequestered elsewhere within the cell. We suggest that estivating snails remodel mitochondrial membranes as part of a coordinated, reversible suppression of mitochondrial membrane-associated processes, which may include a concomitant reduction in rates of proton pumping and leaking.