Fig 1.
Proposed biosynthetic pathway for (7Z,10Z)-7,10-hexadecadienal from linoleic acid.
The linoleic acid may be of dietary origin or may be synthesized from stearic acid (dashed arrow).
Table 1.
Methyl esters of fatty acids identified in a methylated chloroform extract of the pheromone gland of Chilecomadia valdiviana.
Fig 2.
After topical application of D11-linoleic acid, a new peak eluting several seconds earlier than the pheromone compound appears.
Gas chromatograms of hexane extracts of (A) a pheromone gland treated with DMSO only and (B) a pheromone gland treated with a solution of D11-linoleic acid in DMSO. Z7,Z10-16:Ald = (7Z,10Z)-7,10-hexadecadienal.
Fig 3.
Mass spectra show the incorporation of the isotope label of topically applied D11-linoleic acid and D3-stearic acid into the pheromone compound.
Mass spectra of (A) natural (7Z,10Z)-7,10-hexadecadienal, (B) D11-(7Z,10Z)-7,10-hexadecadienal from glands treated with D11-linoleic acid, (C) D3-(7Z,10Z)-7,10-hexadecadienal from glands treated with D3-stearic acid.
Table 2.
Titers of unlabeled and labeled Z7,Z10-16:Ald in pheromone glands of Chilecomadia valdiviana females, which were treated with isotope-labeled fatty acids.
Fig 4.
Linoleic acid is chain-shortened to (7Z,10Z)-7,10-hexadecadienoate in the pheromone gland.
Mass spectra of (A) unlabeled methyl (7Z,10Z)-7,10-hexadecadienoate from methylated pheromone gland extracts, (B) methyl D11-(7Z,10Z)-7,10-hexadecadienoate from pheromone glands treated with D11-linoleic acid.
Fig 5.
The isotope label of topically applied D3-stearic acid is incorporated into the pheromone component.
(A) Total ion chromatogram (TIC) of a hexane extract of a pheromone gland treated with D3-stearic acid. Z7,Z10-16:Ald = (7Z,10Z)-7,10-hexadecadienal, Z7-16:Ald = (Z)-7-hexadecenal, Z9-16:Ald = (Z)-9-hexadecenal. (B) Mass chromatograms show the elution of the isotope-labeled pheromone compound (m/z 239, 196, and 182) slightly earlier than the non-labeled compound (m/z 236, 193, and 179).