title: Amino acid specificity of fibers of the facial/trigeminal complex innervating the maxillary barbel in the Japanese sea catfish, Plotosus japonicus.
abstract: The Japanese sea catfish, Plotosus japonicus, possesses taste and solitary chemoreceptor cells (SCCs) located on the external body surface that detect specific water-soluble substances. Here, we identify two major fiber types of the facial/trigeminal complex that transmit amino acid information to the medulla. Both single and few fiber preparations respond to amino acid stimulation in the 0.1 μM to mM range. One fiber type responds best to glycine and l-alanine (i.e. Gly/Ala fibers) whereas the other fiber type is best stimulated by l-proline and glycine betaine (hereafter referred to only as betaine) (i.e. Pro/Bet fibers). We demonstrate that betaine, which does not alter the pH of the seawater and therefore does not activate the animals' highly sensitive pH sensors (Caprio et al., Science 344:1154-1156, 2014), is sufficient to elicit appetitive food search behavior. We further show that the amino acid specificity of fibers of the facial/trigeminal complex in P. japonicus is different from that in Ariopsis felis (Michel and Caprio, J. Neurophysiol. 66:247-260, 1991; Michel et al., J. Comp. Physiol. A. 172:129-138, 1993), a representative member of the only other family (Ariidae) of extant marine catfishes.
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA. Electronic address: jcap@lsu.edu.
authors.forename: John
authors.initials: J
authors.lastname: Caprio
authors.affiliation: Graduate School of Science and Engineering, Department of Chemistry and BioScience, Kagoshima University, Kagoshima 890-8580, Japan.
authors.forename: Mami
authors.initials: M
authors.lastname: Shimohara
authors.affiliation: 409 Koyocho, Sukagawa, Fukushima 962-0401, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Marui
authors.affiliation: Laboratory of Fish Physiology, Faculty of Bioresources, Mie University, Mie 514-8507, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Kohbara
authors.affiliation: Department of Oral Physiology, Kagoshima University, Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan.
authors.forename: Shuitsu
authors.initials: S
authors.lastname: Harada
authors.affiliation: Graduate School of Science and Engineering, Department of Chemistry and BioScience, Kagoshima University, Kagoshima 890-8580, Japan.
authors.forename: Sadao
authors.initials: S
authors.lastname: Kiyohara
mesh_terms: D000200:Action Potentials; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001070:Appetitive Behavior / Q000502:physiology; D002397:Catfishes / Q000033:anatomy & histology / Q000502:physiology*; D002628:Chemoreceptor Cells / Q000166:cytology / Q000502:physiology*; D005154:Facial Nerve / Q000166:cytology / Q000502:physiology*; D005247:Feeding Behavior / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D009915:Orbit; D010812:Physical Stimulation; D012623:Seawater / Q000737:chemistry; D013045:Species Specificity; D013649:Taste / Q000502:physiology*
chemical_list: D000596:Amino Acids
keywords: Amino acids; Behavior; Facial/trigeminal complex; Fish; Physiology