Extended Data Fig. 8: Odour-tuning properties of drosophilid Or85c/b and Or22a/b neurons, and genomic modifications of the Or22a/b loci.
From: Olfactory receptor and circuit evolution promote host specialization

a, Left, dose-dependent electrophysiological responses of Or85c/b neurons (ab3B) in Dsec.07 to 2-heptanone and 1-hexanol. Mean ± s.e.m. and individual data points; n = 11–20, female flies. Right, dose-dependent electrophysiological responses of Or22a neurons (ab3A) in Dsec.07 to methyl butanoate, methyl hexanoate and methyl octanoate. Mean ± s.e.m. and individual data points; n = 11–20, female flies. The dose–response curves for 2-heptanone and methyl hexanoate are replotted from Fig. 3a. b, Schematics depicting the arrangement of wild-type, mutant and rescue allele versions of DsecOr22a (top) and DmelOr22a/b (bottom). Asterisk, stop codon that prevents read-through from the endogenous Or22a ORF. c, Schematics depicting the arrangement of wild-type and mutant alleles of DsimOr22a and DsimOr22b. d, RNA FISH for Or22a on whole-mount antennae from wild-type D. simulans (DSSC 14021-0251.195 (Dsim.195)), DsimOr22aRFP and DsimOr22a/bRFP mutant flies. As Or22a shares 85% sequence similarity with Or22b, the Or22a probe hybridizes with transcripts from both genes. Arrowheads indicate Or22b-expressing cells in DsimOr22aRFP. Scale bar, 25 μm (main panels), 5 μm (insets). e, Electrophysiological responses of Or22a/b neurons to different esters in wild-type D. simulans and olfactory-receptor mutants (DsimOr22aRFP and DsimOr22a/bRFP). n = 6–10, female flies. Representative response traces to methyl hexanoate (10−6 dilution) and ethyl butanoate (10−2 dilution) are shown to the left. f, Heat maps of the data shown in e, together with the data of the DsimOr22aWT response profile when expressed in DsecOr22aRFP (replotted from Fig. 3c). The receptors expressed in the analysed neurons are listed to the right. Significant differences to responses of wild-type D. simulans are shown. Pairwise Wilcoxon rank-sum test and P values adjusted for multiple comparisons using the Benjamini and Hochberg method. The equivalent responses to ethyl butanoate of wild-type D. simulans and Or22a-mutant neurons (but complete loss in Or22a/b-mutant neurons) suggests that this odour is detected principally by Or22b. g, Box plots with individual data points of the electrophysiological data presented in Fig. 3b. h, Box plots with individual data points of the electrophysiological data presented in Fig. 3c. i, Box plots with individual data points of the electrophysiological data presented in Fig. 3e. NS, not significant (P > 0.05); *P < 0.05; **P < 0.01; ***P < 0.001.