title: Expression of Na(+) / H(+) exchanger mRNA in the gills of the Atlantic hagfish (Myxine glutinosa) in response to metabolic acidosis.
abstract: Sodium/proton exchangers (NHE) are transmembrane proteins that facilitate the exchange of a Na(+) ion for a H(+) ion across cellular membranes. The NHE are present in the gills of fishes and are believed to function in acid-base regulation by driving the extrusion of protons across the branchial epithelium in exchange for Na(+) in the water. In this study, we have used reverse transcriptase-polymerase chain reaction (RT-PCR) to detect the presence of a branchial NHE in the gills of the Atlantic hagfish, Myxine glutinosa. The subsequent partial cDNA sequence shares homology with other vertebrate and invertebrate NHE isoforms. In addition, using semi-quantitative, multiplex RT-PCR we demonstrate that mRNA expression of hagfish gill NHE is upregulated following an induced metabolic acidosis. Expression was increased to 4.4 times basal levels at 2-h post-infusion and had decreased to 1.6 times basal by 6 h. Expression had returned to basal levels by 24-h post-infusion. The inference from this study is that a gill NHE which is potentially important in acid-base regulation has been present in the vertebrate lineage since before the divergence of the hagfishes from the main vertebrate line.
authors.affiliation: Department of Biology, Georgia Southern University, Statesboro, GA 30460, USA. sledward@gasou.edu
authors.forename: S L
authors.initials: SL
authors.lastname: Edwards
authors.forename: J B
authors.initials: JB
authors.lastname: Claiborne
authors.forename: A I
authors.initials: AI
authors.lastname: Morrison-Shetlar
authors.forename: T
authors.initials: T
authors.lastname: Toop
mesh_terms: D000136:Acid-Base Equilibrium / Q000502:physiology; D000138:Acidosis / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary / Q000302:isolation & purification; D004847:Epithelial Cells / Q000378:metabolism; D019143:Evolution, Molecular; D015870:Gene Expression / Q000502:physiology; D005880:Gills / Q000166:cytology / Q000502:physiology*; D006196:Hagfishes / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D011522:Protons; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012964:Sodium / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D011522:Protons; D012333:RNA, Messenger; D017923:Sodium-Hydrogen Exchangers; D012964:Sodium