Deduced amino acid sequence and expression of zebrafish Omp. A, Alignment of the amino acid sequences of zebrafish, Xenopus, mouse, and human olfactory marker proteins. Amino acid residues identical in three or more sequences areshaded. Dashes represent gaps in the alignment.B, C, Dorsal views of the head of 28 hpf embryos stained by in situ hybridization with DIG-labeled sense (B) and antisense (C) probes of the zebrafish omp mRNA. Scale bar, 100 μm.D, A paraffin section of the olfactory placode stained by in situ hybridization with the antisense probe of the zebrafish omp mRNA. The section was counterstained with methyl green. D corresponds to the insetin C. OB, Olfactory bulb;OP, olfactory placode; EYE, eye. Thearrowhead in D points to the nasal pit.