Figure 1.

Gr genes expressed in proboscis taste sensilla (after Weiss et al., 2011). (A) Cellular composition of the different type of sensilla located on the external side of the proboscis. L-type sensilla house four neurons, one of which is sensitive to sugars (S). S-type sensilla house four neurons, including one sugar-sensitive neuron (S) and one sensitive to bitter (B); I-type sensilla house only two taste neurons (B and S). Each of these sensilla also include one mechanoreceptor neuron not represented here. (B) Table showing a map of the expression of the gustatory genes within the different types of sensilla and bitter-sensitive (bitter row) and sugar-sensitive (sweet row) neurons. This map was obtained by establishing GAL4 lines with the promoter of each of these gustatory genes to map the neurons which express these gustatory genes.