MAXIMAL ACTIVITIES OF ENZYMES OF INTERMEDIARY METABOLISM IN THE ESTIVATING TERRESTRIAL SNAIL CEPAEA-NEMORALIS

The effects of estivation on maximal activities of key enzymes of aero bic, carbohydrate, lipid, ketone body and amino acid metabolism were s tudied in tissues of the terrestrial snail Cepaea nemoralis. With the exception of a 40% decrease in citrate synthase activity in hepatopanc reas, enzyme activities were unaltered in all tissues following 6 week s of estivation. Activities of enzymes of lipid, ketone body and carbo hydrate metabolism were reduced in the kidney, when expressed on a per g wet tissue weight basis. However, estivation resulted in a near-dou bling of kidney weight, though protein concentration of this tissue wa s decreased by 27%. When enzyme activities were expressed as units per mg(-1) protein, no changes were observed with estivation in kidney. I t was suggested that the changes in kidney weight are due to the stora ge of metabolic by-products, perhaps uric acid. No change in weight or protein content of heart or hepatopancreas were observed. These resul ts suggest that no universal down-regulation of enzyme activities occu rs during long-term estivation. (C) 1998 Elsevier Science Inc. All rig hts reserved.