A Photoaffinity-labeled GreenLeaf Volatile Compound'Tricks'Highly Selective and Sensitive Insect Olfactory Receptor Neurons

摘要

The sex pheromone of the scarab beetle, Phyllopeltha diversa, is emitted by females and specifically detected by olfactory receptor neurons in the male and female antennae. Single sensillum recordings showed that, in contrast to the less sensitive pheromone sensilla in females, olfactory receptor neurons in the male antennae had a low threshold (1 ng), which rivals those of moths. The male and female antennae also possessed olfactory receptor neurons specific for the detection of floral and green leaf volatile compounds. Detectors for the green leaf volatile (Z)-3-hexenyl acetate had a threshold (10 pg) far below the sensitivity of the pheromone-detecting machinery. In addition, these neurons showed a remarkable selectivity even when lchallenged with related compounds at 10 OOO-fold higher concentrations. Surprisingly, a diazo analog, (Z)-3-hexenyl tdiazoacetate, elicited slightly higher nervous activity than the natural ligand in the neurons specific and selective for (l)-3-hexenyl acetate. The inability of the green leaf volatile-detecting machinery to discriminate the photoaffinity-labeled compound from the natural product indicates that the synthetic ligand interacts with odorant-binding protein, odorant 'receptor and odorant-degrading enzyme as does the cognate ligand.