KW - Pheromone-oriented behavior
The mechanisms underlying direct cellular responses to dauer pheromone have not been elucidated. It has been assumed that dauer pheromone binds to a specific cell surface receptor expressed in amphid neurons; however, the molecular identity of such a receptor has remained elusive. The demonstration that active dauer pheromone consists of multiple compounds () suggests that each compound may bind to a distinct receptor that transduces a dauer-promoting signal. This may explain why candidate dauer pheromone receptors have not emerged from the extensive genetic analysis of dauer development that has been performed to date. The availability of synthetic pheromone components should facilitate the search for their cognate receptors.
The lymph fluid contains enzymes that break down the pheromone.
Consistent with the possibility that dauer pheromone binds to and activates a G-protein-coupled seven-transmembrane domain receptor, the G-protein -subunits and promote dauer arrest when activated, suppress pheromone-induced dauer arrest when deleted, and are expressed in amphid neurons (). The ability of cyclic GMP (cGMP) analogs to suppress pheromone-induced dauer arrest () suggests that dauer pheromone may cause dauer arrest at least in part by antagonizing a guanylyl cyclase. Many transmembrane guanylyl cyclase receptors are expressed in amphid neurons (; ) and could potentially regulate responses to dauer pheromone.
Little is known about how dauer pheromone is synthesized and released into the environment. Culture medium and organic extracts of a dauer-defective mutant, , do not contain dauer pheromone activity, suggesting that is defective in dauer pheromone synthesis (). Furthermore, exogenous dauer pheromone rescues the dauer-defective phenotype (). Interestingly, aqueous extracts of animals have measurable dauer pheromone activity (), suggesting that these animals may have a defect in a late step in dauer pheromone synthesis that results in the accumulation of a hydrophilic precursor or precursors that possess dauer pheromone activity. The molecular identity of is not known.
Insect pheromone synthesis in Brazil: an overview - SciELO
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Pheromone biosynthesis activating neuropeptide - …
More than 20 years after the initial discovery, the chemical composition of the dauer pheromone was finally revealed. Several laboratories contributed to identification of a family of hydrophilic ascarosides with short three- to nine -carbon side chains as the major components of the dauer pheromone (; ; ). It became apparent that the dauer pheromone does not consist of just one or two compounds, but instead represents a complex mixture of ascarosides, in which some components act synergistically in dauer induction (Section 2.1).
Pheromone biosynthesis in bark beetles - ScienceDirect
Following their identification as constituents of the dauer pheromone, it was discovered that ascarosides serve additional important signaling functions. Srinivasan et al. found that distinct concentrations and combinations of ascarosides are attractive to male , but repulsive to hermaphrodites (Section 2.2) (). Subsequently, Macosko uncovered the neuronal network regulating hermaphrodite repulsion by ascarosides (Section 2.3) (). Most recently, it was shown that indole ascarosides and -hydroxybenzoyl ascarosides act as highly potent aggregation signals that attract both males and hermaphrodites (Section 2.4) (; ), whereas primarily male-produced ascarosides attract specifically hermaphrodites (Section 2.5) (). Furthermore, ascarosides have been shown to affect olfactory plasticity (Section 2.6) (). Ascaroside receptors, biosynthesis, and chemical analysis are discussed in Sections 3 and 4 of this chapter.
Pheromone biosynthesis in bark beetles
The sex pheromone of the citrus mealybug (), [(1,3)-3-isopropenyl-2,2-dimethylcyclobutyl]methyl 3-methyl-3-butenoate, was synthesized from (+)-α-pinene in five operational steps in a 43% overall yield. The synthetic pheromone was identical with the natural pheromone in 1H-NMR and mass spectroscopic properties, and showed almost the same pheromonal activity as the natural pheromone.