Trans polyunsaturated fatty acids are produced during heat treatment of oils, such as deodorization and frying. The detailed metabolic pathways of these trans isomers are not fully understood. In the present work, the desaturation and chain elongation of [114 C]linoleic acid, 9 cis ,12 trans -18:2, 9 trans ,12 cis -18:2, a -linolenic acid, 9 cis , 12 cis ,15 trans -18:3 and 9 trans ,12 cis ,15 ...