Heterogenic distribution of G proteins alpha subunit in the main olfactory and vomeronasal system of Rhinella (Buffo) arenarum tadpoles.

JUNGBLUT LD.; PAZ DA.; LÓPEZ-COSTA JJ.; POZZI AG.

ZOOLOGICAL SCIENCE

ZOOLOGICAL SOC JAPAN

Lugar: Japón; Año: 2009 vol. 26 p. 722 - 728

0289-0003

We evaluated the presence of G protein subtypes Galfao, Galfai2, Galfaolf in the main olfactory system (MOS) and accesory 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) are covered with microvilli. Immunohistochemistry detected the presence of at least two segregated populations of ORNs throughout the OE, coupled to Galfa-olf and Galfa-o. An antiserum against Galfa-i2 was inefective in staining the ORNs. In the VNO, Galfa-o neurons stained strongly but lacked immunoreactivity to any other Galfa 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 heterogeneuous 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.