Fatty acid desaturase specificity of Tetrahymena.

The ciliate, Tetrahymena, was provided a supplement of the fatty acid [1-14 C]18:2 delta 6.9. After a period of growth the cells were claimed, the lipids extracted, the polar lipids recovered and the mild alkali-labile fatty acid methyl esters generated. The fatty acids were resolved by high pressure liquid chromatography (HPLC), the 18:3 delta 6.9,12(gamma-linolenic acid) was recovered and its identity verified by high pressure liquid chromatography (HPLC), gas liquid chromatography (GLC), hydrogenation and oxidation. Fifty-three percent of the cell-associated label was found in gamma-linolenic acid; thus, a delta 12 fatty acid desaturase converts the 6,9 octadecadienoic acid to the 6,9,12 derivative. No carboxyl or methyl terminus restriction appears on delta 9 monoenoic or dienoic fatty acid desaturation in this cell as is found in higher plants and animals.