Sensilla classes

The differential expression of OBPs within specific classes of sensilla, along with the demonstrated ability of OBPs to bind pheromone and non-pheromone... 

A detailed analysis of coding properties of ORNs in B sensilla of palps and antennae has revealed 22 functional types of sensilla, most with two ORNs and one with four (de Bruyne et al, 1999,2001). Hierarchical cluster analysis indicates that populations of ORNs can be categorized in distinct classes, with differences between classes larger than within (de Bruyne et al, 1999). The physiological classification of this large set of neurons, representing more than half of all... 

A tungsten electrode inserted at the sensillum base records action potentials fired by two neurons, which can be reliably separated based on amplitude and shape of spikes. Neuron A fires the large spike and responds to stimulation with ethyl acetate. Neuron B (small spikes labeled with dots) does not respond to this odorant. For odor stimulation, air was expelled from a 5 ml syringe laden with 20 pi of odorant, diluted 10-2 in paraffin oil. B The palp carries six classes of ORN with different response spectra. They are consistently housed together as stereotypical pairs in three functional types of sensilla. 

Moreover, the pbl A neuron on the maxillary palps also responds to these levels of Zll-18Ac, but is clearly much more sensitive to other esters (Figure 23.2B). Stocker and Gendre (1989) did demonstrate a role for palpal sensilla in male courtship inhibition, so if Zll-18Ac plays a pheromonal role, at least two ORN classes encode it. This compound has also been suggested to function as an aggregation pheromone (Bartelt el al., 1985). 

In insects, odor molecules are thought to be transported to ORs by OBPs and subsequently degraded by ODEs, though there is considerable uncertainty about the nature of the interactions between these three protein classes. OBPs and ORs comprise multigene families and there are multiple ODEs. The distinct odor sensitive phenotypes of different sensilla are presumed to be based on the differential expression of specific combinations of ORs, OBPs and ODEs which have ligand... 

The antennae of male cabbage looper moth Trichoplusia ni have two classes of pheromone-sensitive sensilla. The sensilla from each class contain two receptor neurons, one producing the larger impulse and the other producing the smaller. The first of these is excited by low doses of Z-7-dodecenyl acetate (1), whereas the other is excited by low doses of the corresponding alcohol (51) 244),... 

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