Distribution patterns of palatal taste buds and their responses to amino acids in salmonids

• Published in: Journal of Fish Biology
• Main Authors: Hara, Toshiaki J., Kitada, Yasuyuki, Evans, Robert E.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1994
• Subjects: Arctic; Arctic grayling; Atlantic salmon; Salmo salar; Thymallus arcticus
• Online Access: http://dx.doi.org/10.1111/j.1095-8649.1994.tb01328.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1095-8649.1994.tb01328.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1095-8649.1994.tb01328.x

The distribution pattern of the palatal taste buds and their electrical response characteristics to amino acids were studied in five salmonid species: Arctic grayling ( Thymallus arcticus ), lake whitefish ( Coregonus clupeaformis ), Atlantic salmon ( Salmo salar ), brown trout ( Salmo trutta ), and kokanee ( Oncorhynchus nerka ). In these fish the most dense taste bud populations were found on ridges in tine area around the palatine teeth. With the exception of lake whitefish, the ridges adjacent to the teeth on the head and shaft of the prevomer were also dense in taste buds, which appear to be largely responsible for amino acid detection. All species, except for lake whitefish, responded well to l ‐proline ( l ‐Pro) and l ‐α‐amino‐ β ‐guanidinopropionic acid ( l ‐AGPA), with thresholds at 10 −8 ‐10 −7 and 10 −5 ‐10 −4 M, respectively. These species also responded to varying degrees to hydroxy‐ l ‐proline ( l ‐Hpr) and l ‐alanine ( l ‐Ala), believed to be agonists for l ‐Pro receptors. In addition, kokanee detected l ‐phenylalanine, l ‐leucine and betaine. Of six lake whitefish examined, only one specimen responded to l ‐Pro, l ‐AGPA and l ‐arginine. We concluded that in these five salmonid species l ‐Pro and l ‐AGPA receptors play a major role in amino acid gustation, and further proposed a hypothesis that salmonids may have initially evolved these two gustatory receptors. With phylogenetic advancement, they gained greater response capabilities by (1) acquiring new receptor types, and (2) by losing the specificity of existing receptors.