[The possible role of fatty acids and their conformation in the realization of the respiratory function and in the adaptations of fish gill membranes and of mammalian lungs].

Fatty acid composition of major phospholipids has been studied in 12 fish and 7 mammalian species. Projections of the fatty acid pairs of these molecules on the plane parallel to the membrane surface have been computed. The projection area of two saturated acids was shown to look like the projection area of its "head", while substitution of one or two saturated acids to unsaturated ones increases the projection area 25%.