Modulation of membrane fluidity in a fatty acid auxotrophe of Tetrahymena thermophila.

A mutant of Tetrahymena thermophila has been isolated which requires an unsaturated fatty acid for growth. Pellicles isolated from cultures supplemented with palmitoleic, elaidic, oleic, linoleic and gamma-linolenic acids show widely differing membrane fluidities, as measured by the polarisation of fluorescence technique. In contrast to the behaviour of the wild type organism, the changes in fluidity of the membrane, once induced by supplementation, are permanent. This mutant should prove extremely useful for studying structure-function relationships in the various membrane systems of Tetrahymena.