Fig. 2

Dual in situ hybridization with probes to multiple ORs are consistent with OSNs having chosen a single odorant receptor to express by 3 dpf. a Examples of pairs of probes or cocktails of probes used to access OR expression in 3 dpf embryos. The first row of panels demonstrates that probes against individual or111 subfamily members or111–7 and or111–11 are highly specific to the target subfamily member, and further suggest, that individual or111 subfamily members are very rarely, if ever, co-expressed in the same OSN. The second row of panels demonstrates that or111 subfamily members are very rarely co-expressed in OSNs expressing or103, or106, or or128 subfamily members. An exceptional case where or111 and or103 subfamily members were coexpressed is marked with an arrowhead. b Quantification of the numbers of probed OR expressing OSNs per olfactory pit. Cells with overlapping expression are indicated (red). Scale bar: 25 μm