Fig. 5.
G-protein immunohistochemistry in the main olfactory epithelium and the main olfactory bulb. Antibodies against Gαi (a) and Gαo (d) preferentially labeled apical structures of ORNs located in the lateral and intermediate part of the MOE (middle row) and axon bundles of the olfactory nerve and glomeruli of the lateral and intermediate glomerular clusters of the MOB, as well as glomeruli in the AOB (lower row). Dotted lines indicate the approximate borders and subdivisions of MOE and olfactory bulb. Gαi and Gαo immunoreactivity was localized in apical endings of phalloidin-positive (arrows) and tubulin-negative microvillous olfactory receptor neurons (upper row). Gαolf/s (g) immunoreactivity showed a complementary distribution, preferentially localized in ORNs and glomeruli of the medial and intermediate regions of MOE and MOB (middle and lower row, respectively). Gαolf/s in apical endings of ORNs co-localized with the ciliary marker tubulin, but not with f-actin (upper row, arrows). Western-blot analysis of Gαi (b), Gαo (e) and Gαolf/s (h) antibodies using tissue samples of olfactory organ and olfactory bulb of larval Xenopus laevis (a stages 43–45, b 52–54, and c 64–66, respectively). Arrows indicate bands corresponding to the predicted molecular weights of Gαi and Gαo (~40 kDa) and Gαolf/s (~44 kDa). The Gαi antibody is highly specific, whereas Gαo and Gαolf/s antibodies show minor crossreactivity to other proteins. Quantification of fluorescence intensity of G protein labeling for Gαi (c n = 9 MOEs), Gαo (f n = 7 MOEs) and Gαolf/s (i n = 5 MOEs). Gαi and Gαo are enriched laterally, whereas Gαolf/s shows clear depletion in the lateral segment. Significance was evaluated by t test (*p < 0.05, **p < 0.01; error bars show SEM). A anterior, P posterior, L lateral, M medial, OO olfactory organ, OB olfactory bulb