Biochemical studies of olfaction: isolation, characterization, and odorant binding activity of cilia from rainbow trout olfactory rosettes.

Abstract

Cilia from the intact olfactory rosettes of the rainbow trout, S. gairdneri, were isolated, characterized biochemically, and examined by EM. Markers associated with cilia in other organisms were studied. Dynein arms contain Mg2+-ATPase; this enzyme was enriched in the isolated cilia preparation. Guanine nucleotides are associated with the outer microtubule doublets of cilia but adenine nucleotides are not; a substantial enrichment in guanine, relative to adenine, was found in the cilia preparation. Tubulin, the structural protein component of microtubules, occur in large amounts in cilia. Disc gel electrophoresis indicated tubulin in the cilia preparation. EM confirmed the presence of cilia in the isolated preparation. Rainbow trout have an acute sense of smell and many amino acids are odorants to this species. Functional activity of the cilia preparation relevant to odorant recognition was assessed by using binding of radioactively labeled odorant amino acids. L-Alanine, L-serine, L-threonine, L-lysine and D-alanine bound to the cilia preparation. Olfactory cilia apparently bind odorant molecules and odorant recognition sites are integral parts of the cilia.