Co-expression of Gr21a^Scer\UAS.cKa and Gr63a^Scer\UAS.cKa under the control of Scer\GAL4^Or22a.8010 in the "empty neuron" system ("Δhalo" embryos - Dp(2;2)dpp^d21 + Df(2L)dp-79b - in which Or22a and Or22b are deleted) confers a modest response to CO[[2]] in the ab3A olfactory receptor neuron (ORN). Additional co-expression of Gα49B^Scer\UAS.cRa dramatically increases the response of the ab3A ORN to CO[[2]], to a level comparable to that of the endogenous CO[[2]] responsive neuron (ab1C), while additional co-expression of G-sα60A^Scer\UAS.cCa does not increase the response of the ab3A ORN to CO[[2]].

Co-expression of Gr21a^Scer\UAS.cKa and Gr63a^Scer\UAS.cKa under the control of Scer\GAL4^Or22a.8010 in the "empty neuron" system (Dp(2;2)dpp^d21 + Df(2L)dp-79b - in which Or22a and Or22b are deleted) confers a response to CO[[2]] in the ab3A olfactory receptor neuron, with the magnitude of the response depending on the dosage of the Gr21a and Gr63a genes.

The level of spontaneous activity of the ab3A olfactory receptor neuron is increased in animals co-expressing Gr21a^Scer\UAS.cKa and Gr63a^Scer\UAS.cKa under the control of Scer\GAL4^Or22a.8010 in the "empty neuron" system.