Heterogeneous Distribution of G Protein Alpha Subunits in the Main Olfactory and Vomeronasal Systems of Rhinella (Bufo) arenarum Tadpoles

LUCAS D. JUNGBLUT; DANTE A. PAZ; JUAN J. LÓPEZ-COSTA; ANDREA G. POZZI

ZOOLOGICAL SCIENCE

ZOOLOGICAL SOC JAPAN

Año: 2009 vol. 26 p. 722 - 728

0289-0003

We evaluated the presence of G protein subtypes Gáo, Gái2, and Gáolf in the main olfactory system (MOS) and accessory or vomeronasal system (VNS) of Rhinella (Bufo) arenarum tadpoles, and here describe the fine structure of the sensory cells in the olfactory epithelium (OE) and vomeronasal organ (VNO). The OE shows olfactory receptor neurons (ORNs) with cilia in the apical surface, and the vomeronasal receptor neurons (VRNs) of the VNO are covered with microvilli. Immunohistochemistry detected the presence of at least two segregated populations of ORNs throughout the OE, coupled to Gáolf and Gáo. An antiserum against Gái2 was ineffective in staining the ORNs. In the VNO, Gáo neurons stained strongly but lacked immunoreactivity to any other G! subunit in all larval stages analyzed. Western blot analyses and preabsorption experiments confirmed the specificity of the commercial antisera used. The functional significance of the heterogeneous G-protein distribution in R. arenarum tadpoles is not clear, but the study of G- protein distributions in various amphibian species is important, since this vertebrate group played a key role in the evolution of tetrapods. A more complete knowledge of the amphibian MOS and VNS would help to understand the functional organization and evolution of vertebrate chemosensory systems. This work demonstrates, for the first time, the existence of a segregated distribution of G-proteins in the OE of R. arenarum tadpoles.