SUBCELLULAR ORGANIZATION OF INTERMEDIARY METABOLISM IN THE HEPATOPANCREAS OF THE TERRESTRIAL SNAIL, CEPAEA-NEMORALIS - A CYTOSOLIC BETA-HYDROXYBUTYRATE DEHYDROGENASE
Ja. Stuart et Js. Ballantyne, SUBCELLULAR ORGANIZATION OF INTERMEDIARY METABOLISM IN THE HEPATOPANCREAS OF THE TERRESTRIAL SNAIL, CEPAEA-NEMORALIS - A CYTOSOLIC BETA-HYDROXYBUTYRATE DEHYDROGENASE, The Journal of experimental zoology, 274(5), 1996, pp. 291-299
The subcellular distributions of key enzymes of the tricarboxylic acid
cycle, electron transport chain, ketone body, amino acid, and carbohy
drate metabolism were studied in the hepatopancreas of the terrestrial
snail Cepaea nemoralis. The presence of mitochondrial carnitine octan
oyl transferase, carnitine palmitoyl transferase, and 3-hydroxyacyl-Co
A dehydrogenase indicate an active lipid catabolic pathway in this tis
sue. Activities of enzymes of ketone body metabolism are similar in ma
gnitude to those of carbohydrate metabolism, suggesting an important m
etabolic role for ketone bodies in C. nemoralis. Two enzymes that, in
mammals, catalyze the synthesis of ketone bodies, hydroxymethylglutary
l-CoA synthase and hydroxymethylglutaryl-CoA lyase, are not detectable
in Cepaea hepatopancreas. The activity of 3-oxoacid-CoA transferase a
nd a portion of acetoacetyl-CoA thiolase activity are found in the mit
ochondria. beta-hydroxybutyrate dehydrogenase is a cytosolic enzyme in
this tissue, and preferentially oxidizes the L-isomer of beta-hydroxy
butyrate. A portion of glutamate dehydrogenase activity is also cytoso
lic. The subcellular organization distribution of enzymes of intermedi
ary metabolism in Cepaea hepatopancreas suggests adaptation to periodi
c anoxia. (C) 1996 Wiley-Liss, Inc.