A Striking Parallel Between Cardiolipin Fatty Acid Composition and Phylogenetic Belonging in Marine Bivalves: A Possible Adaptative Evolution?

摘要

Thirty-five species of marine mollusk bivalves were analyzed for their fatty acid (FA) composition of cardiolipin (Ptd₂Gro). All species showed a Ptd₂Gro with strong selectivity for only a few polyunsaturated fatty acids, but three characteristic FA profiles emerged, with clear parallels to bivalve phylogeny. A first group of 12 species belonging to the Eupteriomorphia subgroup (Filibranchia) was characterized by a Ptd₂Gro almost exclusively composed of 22:6n-3, whereas in the four Filibranchia Pteriomorph species analyzed, this FA was combined with substantial proportions of 18:2n-6 and 18:3n-3. Finally, a third group of 20 species, all belonging to the Heterodonta subclass, possessed Ptd₂Gro containing predominantly both 22:6n-3 and 20:5n-3. Polyunsaturated FA moieties and arrangements in the Ptd₂Gro of some marine species investigated in other classes of the mollusk phylum (Gastropoda, Polyplacophora) were found to be different. The present results suggest that the specific Ptd₂Gro FA compositions in bivalves are likely to be controlled and conserved in species of the same phylogenetic group. Functional significances of the evolution of this mitochondrial lipid structure in bivalves are discussed.