cVA is a lipid, synthesized mainly in the
male reproductive organs and transferred to the female
with the ejaculate during copulation. cVA is volatile and
hence must be perceived through the olfactory sensory
system. Two major molecular components, a pheromone
binding protein (PBP) and a member of the Or gene
family are thought to transduce this pheromone signal.
Interestingly, a PBP, LUSH, has recently been shown to
mediate the effects of cVA (D Smith, pers comm). Flies
lacking a functional lush gene show a significant decrease
in aggregation. Moreover, it was shown in electrophysiological
recordings of lush– flies that neurons in the subset
of trichoid sensilla normally expressing LUSH fail to be
stimulated when cVA is applied. Significantly, infusing
recombinant LUSH into trichoid sensilla of such animals
can completely restore the cVA mediated electrical
responses. This indicates that this protein is necessary
for neuronal activation of OSNs expressing a specific
receptor for a cVA/LUSH complex. Identification of this
receptor — probably an OR — is now feasible, because
expression of many ORs has been mapped to specific
olfactory sensilla [28,42,