HAIR, N. L. *; MORRISON-SHETLAR, A. I.; CLAIBORNE, J. B.: Detection of Na⁺/H⁺ Antiporter in the Gills of Elasmobranchs: Little Skate (Raja erinacea) and Dogfish Shark (Squalus acanthias)

The Na⁺/H⁺exchanger (NHE) is a transport protein hypothesized to be involved in acid-base regulation across fish gill epithelia. Recent studies have shown the presence of NHE in the gill tissue of two marine teleosts, the long-horned sculpin, Myoxocephalus octodecimspinosus, and the killifish, Fundulus heteroclitus. Preliminary results suggest the presence of this protein in the gills of two elasmobranchs, the little skate (Raja erinacea) and the dogfish shark (Squalus acanthias). The aim of this study was to detect the protein and use the detected fragmet obtained from these two elasmobranchs to determine the further cDNA sequence for the NHE gill from Raja erinacea. The initial fragment was 470 bp in length and found to have 85% amino acid homology (71% identity) to the NHE2 human isoform and close identity to the dogfish shark. Rapid amplification of cDNA ends (3’/5′ RACE) was attempted using an NHE specific primer, previously developed from the known elasmobranch sequence, and a universal primer to amplify the skate DNA sequence. We hope to determine if the near identity of the partial fragment observed in the skate and the dogfish will be confirmed in the full length sequence. This research was funded by NSF IBM-9808141 to J.B.C. and A.I.M.S. and by GSU Academic Excellence and Competitive Grant to N.L.H.