Metabolism of odd‐numbered fatty acids inOchromonas danica

The lipids of the protozoon,Ochromonas danica, contain very small amounts of odd‐numbered fatty acids. Nevertheless the organism incorporates into its lipids odd‐ as well as evenumbered acids from the media. Unsaturated odd acids such as 9–17∶1 or 6,9,12–17∶3 were efficient substrates for elongation and desaturation in the proximal and the former acid also in the distal part of the chain. In contrast none of these conversions was observed with 7–17∶1, 10–17∶1 and 10,13–19∶2 acids, although these substrates were taken up by the organism. Elongation and desaturation of the proximal part of already unsaturated fatty acid chains appear to be subject to the same structural requirements inO. danica as in the rat, and the same effects apply to desaturation in the distal part of the chain.