Figure 1.
Phylogenetic tree of X. tropicalis OR1 and OR2 genes.
Amino acid sequences of all XtOR2 and all XtOR1 class I (OR(I)), four XtOR1 class II ORs (OR(II)γ), and three melanocortin receptors (MCRs), were used for the phylogenetic analysis.
Table 1.
X. tropicalis OR Type 2 genes.
Table 2.
Amino acid sequence identity (%) of X. tropicalis type 2 ORs and class I Ors.
Figure 2.
XtOR2 gene expression in various organs in stage 55 larvae and full-grown adults.
The primer set for class II OR amplified multiple class II OR genes. PCR cycles were adjusted to obtain adequate amounts of the products (35 cycles for OR2 and class I ORs, and 30 cycles for rpL8 and class II ORs).
Figure 3.
OR gene expression in adult olfactory cavities.
A: Schematic illustration of the nasal cavities of the adult frog. The MC is filled in water and the PC is open to air. The air flow goes though the PC to the lung. B: The expression of OR2ηs and some OR1s (class I and II) in adult nasal cavities. Quantitative PCR was done for each OR gene and normalized by using the OMP gene, which is expressed in every mature OSN. Most class I ORs were preferentially expressed in the MC. Class I ORα5 was exceptionally expressed at a significant level in the PC as well as the MC. Bars represent standard deviation (n = 3). Note that the expression level of OBP and class II (mix) OR was much higher than each single OR2η and class I OR gene (different scale). Gene ID: OR1α2: ENSXETG00000024801.1, OR1α4: fgenesh1_pg.C_scaffold_1078000009, OR1α5: e_gw1.2098.6.1, OR1β3: fgenesh1_pg.C_scaffold_976000003, OR1β5: e_gw1.976.19.1, OR1δ2: e_gw1.799.9.1, OR1ε4: e_gw1.799.69.1.
Figure 4.
Whole mounts in situ hybridization for the XtOR2η4 and XtOR2η5 gene in the olfactory cavity of stage 47 tadpoles.
XtOR2η RNA and OMP were detected by Cyanine 3 (red) and fluorescein (green), respectively, and the nucleus was stained with Dapi (blue). A–C: A confocal image of the olfactory cavity. A: XtOR2η5 expression (red). B: Enlargement of dotted square region in panel A. C: XtOR2η4 expression (red). D: A z-stack of all optical planes. XtOR2η4 positive cells (red). OC; olfactory cavity, OE; olfactory epithelium, VNO; veromonasal organ.