Nb. Fang et al., BIOSYNTHESIS OF CONJUGATED OLEFINIC SYSTEMS IN THE SEX-PHEROMONE GLAND OF FEMALE TOBACCO HORNWORM MOTHS, MANDUCA-SEXTA (L), Insect biochemistry and molecular biology, 25(1), 1995, pp. 39-48
Deuterium-labelled fatty acid putative precursors of the 16-carbon ald
ehydic sex pheromones of Manduca sexta (L.) were applied to the sex ph
eromone glands of females. After 24 h in vivo incubation, and injectio
n of pheromone biosynthesis activating neuropeptide into the abdomens
of treated females, glands were excised, extracted, and the extracts a
nalyzed by gas chromatography-mass spectrometry. Incubation of glands
with [16, 16, 16-H-2(3)] hexadecanoic acid resulted in the label being
incorporated into seven of the eight 16-carbon aldehydes found in the
gland, including monoenes, dienes, and trienes. Similarly, incubation
with [16, 16, 16-H-2(3)] (Z)-11-hexadecenoic acid led to incorporatio
n of the label into (Z)-11-hexadecenal and both conjugated diene and t
riene aldehydes. However, incubation with [13, 13, 14, 14, 15, 15, 16,
16, 16-H-2(9)] (Z)-11-hexadecenoic acid resulted in incorporation of
the label into only (Z)-11-hexadecenal, (E, Z)- and (E, E)-10, 12-hexa
decadienal, indicating interference of the deuterium isotope in the de
saturation process leading to the conjugated triene system, Incubation
with the similarly labelled (E)-11-hexadecenoic acids gave labelled (
E)-11-hexadecenal in both cases, but none of the other unsaturated phe
romone aldehydes. The results indicate that fatty acids are the precur
sors of the aldehydic pheromones in this species and that hexadecanoat
e is the precursor of the 16-carbon monoenes, dienes, and trienes. The
conjugated dienes and trienes are formed via desaturation/isomerizati
on of (Z)-11-hexadecenoate.