Similarity of olfactory receptor responses (EOG) of freshwater and marine catfish to amino acids

Abstract

A comparison of olfactory receptor responses of three species of freshwater catfishes (family Ictaluridae) and one species of marine catfish (family Arridae) was performed. With the exception of the reduced response of the sea catfish (Arius felis) to L-glutamine, no distinctive species specific differences in the electro-olfactogram (EOG) responses were noted. The phasic EOG response increased exponentially with a logarithmic increase in amino acid concentration from threshold to 10⁻²M. The relative stimulatory effectiveness of the amino acids tested was similar among the four species. The olfactory receptors were highly responsive to L-cysteine and to amino acids containing five carbon atoms having unbranched and uncharged side chains. From phyletic relationships of the species tested, the present data suggest that the olfactory system of the North American catfishes has remained temporally conservative.