REMODELING OF PHOSPHOLIPID FATTY-ACIDS IN MITOCHONDRIAL-MEMBRANES OF ESTIVATING SNAILS

The effects of estivation on the phospholipid-specific fatty acid comp osition of mitochondrial membranes in the hepatopancreas of the terres trial snail Cepaea nemoralis were investigated. The fatty acid composi tion of all phospholipids was significantly altered in snails estivati ng for 6 wk, indicating that substantial remodeling occurs. The most p rofound changes occurred in cardiolipin (CL). CL of estivating snails was 13-fold more saturated, contained 9-fold more monoenes, and had 45 % fewer polyenes than in active snails. These differences were due, in part, to a reduction in linoleic acid (18:2n-6) content of CL from es tivators. As in mammals, CL of active snails appears to preferentially incorporate 18:2n-6, which accounts for 60% of the acyl chains in thi s phospholipid. This proportion was reduced by 50% in estivators. Chan ges in the fatty acyl content of other phospholipids of estivating sna ils included increased monoenes in phosphatidylethanolamine (PE) and p hosphatidylinositol, reduced ratios of n-3/n-6 polyenes in PE and phos phatidylcholine (PC), and an increased n-3/n-6 ratio in phosphatidylse rine (PS). Arachidonic acid (20:4n-6) levels were reduced in PS but in creased in CL and PC. Taken together, these alterations to fatty acid composition are consistent with decreased biological activity of membr ane-related processes which occur in conjunction with the reduction of mitochondrial aerobic metabolism observed during estivation.