GC/MS analyses of lipid extracts from ole1 elo1 yeast transformed with the Lca -Z11-KPVQ desaturase gene. (A) DMDS derivatives from a methanolyzed lipid extract from yeast transformed with pYEX-Lca-Z11-KPVQ and grown in presence of 1 mM CuSO4. The chromatogram trace corresponds to the ion current obtained by extraction of the characteristic Δ11 DMDS fragments at m/z 245. Peaks labelled as Z11–14:DMDS, Z11–16:DMDS, Z11–18:DMDS and Z11–20:DMDS correspond respectively to the dimethyldisulfide adducts of methyl (Z)-11-tetradecenoate, of methyl (Z)-11-hexadecenoate, of methyl (Z)-11-octadecenoate and of methyl (Z)-11-eicosenoate. (B) Analysis of MTAD derivatives of methyl dienoates from yeast transformed with pYEX-Lca-Z11-KPVQ and grown in presence of 1 mM CuSO4 and 0.5 mM Z9–14:Me. The top panel represents the total ion current (TIC) chromatogram. Peaks labelled as cis and trans adducts are produced upon MTAD reaction with methyl (Z,Z)-9,11–14-tetradecadienoate and methyl (Z,Δ)-9,11-tetradecadienoates, respectively. The delta symbol (Δ) refers to both Z or E geometrical configurations. The chromatogram traces in the lower panel are obtained by extraction of the characteristic ions at m/z 194, 322 and 351, respectively. (C) Mass spectrum of MTAD adducts of methyl (Z,Z)-9,11-tetradecadienoate (Z9,Z11–14:MTAD) and methyl (Z,Δ)-9,11-tetradecadienoates (Z9,Δ11–14:MTAD) confirming the double-bond positions. MTAD-adducts of synthetic dienes have the same retention time and mass spectra than the natural compounds. Experiments were performed as described in the experimental section.