Specificity and sensitivity of the olfactory organ of the zebrafish, Danio rerio.

1. The specificity and sensitivity of the olfactory organ of adult zebrafish, Danio rerio, to selected amino acid, bile acid, and steroid odorants were characterized using the electro-olfactogram recording technique. The olfactory organ was responsive to 28 of the 29 odorants tested. 2. All of the 100 microM amino acid and bile acid stimulants elicited a negative-going response that was significantly greater than the response to the artificial fresh-water control. The general pattern of relative stimulatory effectiveness established for the amino acid stimuli was neutral amino acids > basic amino acids > acidic amino acids > imino acids. The general pattern of relative stimulatory effectiveness of 100 microM bile acid stimuli was taurine-conjugated bile acids > glycine-conjugated bile acids approximately non-conjugated bile acids. The responses to the most stimulatory bile acid odorants were up to 40% larger than the responses to the most stimulatory amino acid odorants. 3. The response threshold for cysteine and taurocholic acid, the most stimulatory of the amino acid and bile acid stimuli tested, was approximately 10(-8) M. Females are significantly more sensitive to these odorants than males.