Evidence for two‐step regulation of pheromone biosynthesis by the pheromone biosynthesis‐activating neuropeptide in the moth Heliothis virescens

Abstract

The control of pheromone biosynthesis by the neuropeptide PBAN was investigated in the moth Heliothis virescens. When decapitated females were injected with [2-(14)C] acetate, females co-injected with PBAN produced significantly greater quantities of radiolabeled fatty acids in their pheromone gland than females co-injected with saline. This indicates that PBAN controls an enzyme involved in the synthesis of fatty acids, probably acetyl CoA carboxylase. Decapitated females injected with PBAN showed a rapid increase in native pheromone, and a slower increase in the pheromone precursor, (Z)-11-hexadecenoate. Total native palmitate and stearate (both pheromone intermediates) showed a significant decrease after PBAN injection, before their titers were later restored to initial levels. In contrast, the acyl-CoA thioesters of these two saturated fatty acids increased during the period when their total titers decreased. When a mixture of labeled palmitic and heptadecanoic (an acid that cannot be converted to pheromone) acids was applied to the gland, PBAN-injected females produced greater quantities of labeled pheromone and precursor than did saline-injected ones. The two acids showed similar time-course patterns, with no difference in total titers of each of the respective acids between saline- and PBAN-injected females. When labeled heptadecanoic acid was applied to the gland alone, there was no difference in titers of either total heptadecanoate or of heptadecanoyl-CoA between PBAN- and saline-injected females, suggesting that PBAN does not directly control the storage or liberation of fatty acids in the gland, at least for this fatty acid. Overall, these data indicate that PBAN also controls a later step involved in pheromone biosynthesis, perhaps the reduction of acyl-CoA moieties. The control by PBAN of two enzymes, near the beginning and end of the pheromone biosynthetic process, would seem to allow for more efficient utilization of fatty acids and pheromone than control of only one enzyme.

Sugar feedingviatrehalose haemolymph concentration affects sex pheromone production in matedHeliothis virescensmoths

“…These females were left for 6 h [when pheromone titre had declined to a very low level, <0.5 ng (Eltahlawy et al, 2007) ; adjusted to pH=6.8). After 1.5 h, pheromone glands were dissected and analysed for pheromone.…”

Pheromone biosynthetic pathways: PBAN-regulated rate-limiting steps and differential expression of desaturase genes in moth species

“…Recent studies utilizing Heliothis virescens and timecourse experiments (Eltahlawy et al, 2007) demonstrated a rapid decrease ( ¼ ''pull'') in total 16:Acid and stearic acid following treatment with PBAN with a concomitant increase in pheromone from fatty acid stores. If this rapid production of pheromone were caused solely by de novo production of fatty acids, then total saturated fatty acid titers should not decrease initially.…”

“…1 Mevastatin was only shown to be active in B. mori(Osawa et al, 1995). 2 ''Push and pull'' theory demonstrated in Heliothis virescens(Eltahlawy et al, 2007).…”

Sex Pheromone Production in the Silkworm,Bombyx mori, Is Mediated by Store-Operated Ca2+Channels

“…6,12) In heliothine moths, however, PBAN regulates a step (most likely acetyl-CoA carboxylase) in fatty acid biosynthesis. [13][14][15] (iii) In B. mori, the cyclic nucleotide second messenger, cyclic adenosine-3 0 ,5 0 -monophosphate (cAMP), is not involved in the PBAN signal transduction cascade, 16) whereas in heliothine species, the second messenger is a crucial component in PBAN signaling. 4,8) Because numerous biological processes are mediated by fluctuations in the intracellular levels of Ca 2þ , the entry of Ca 2þ into the cell is tightly regulated.…”