Ammonia exposure affects the mRNA and protein expression levels of certain Rhesus glycoproteins in the gills of climbing perch.

Autor: Chen XL; Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore., Zhang B; Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore., Chng YR; Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore., Ong JLY; Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore., Chew SF; Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616, Republic of Singapore., Wong WP; Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore., Lam SH; Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore.; NUS Environmental Research Institute, National University of Singapore, Kent Ridge, Singapore 117411, Republic of Singapore., Nakada T; Department of Molecular Pharmacology, Shinshu University School of Medicine, Matsumoto, Nagano 390-8621, Japan., Ip YK; Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 117543, Republic of Singapore dbsipyk@nus.edu.sg.
Jazyk: angličtina
Zdroj: The Journal of experimental biology [J Exp Biol] 2017 Aug 15; Vol. 220 (Pt 16), pp. 2916-2931. Date of Electronic Publication: 2017 Jun 02.
DOI: 10.1242/jeb.157123
Abstrakt: The freshwater climbing perch, Anabas testudineus , is an obligate air-breathing and euryhaline teleost capable of active ammonia excretion and tolerant of high concentrations of environmental ammonia. As Rhesus glycoproteins (RhGP/Rhgp) are known to transport ammonia, this study aimed to obtain the complete cDNA coding sequences of various rhgp isoforms from the gills of A. testudineus , and to determine their mRNA and protein expression levels during 6 days of exposure to 100 mmol l -1 NH 4 Cl. The subcellular localization of Rhgp isoforms in the branchial epithelium was also examined in order to elucidate the type of ionocyte involved in active ammonia excretion. Four rhgp ( rhag , rhbg , rhcg1 and rhcg2 ) had been identified from the gills of A. testudineus They had conserved amino acid residues for NH 4 + binding, NH 4 + deprotonation, channel gating and lining of the vestibules. Despite inwardly directed NH 3 and NH 4 + gradients, there were significant increases in the mRNA expression levels of the four branchial rhgp in A. testudineus at certain time points during 6 days of ammonia exposure, with significant increases in the protein abundances of Rhag and Rhcg2 on day 6. Immunofluorescence microscopy revealed a type of ammonia-inducible Na + /K + -ATPase α1c-immunoreactive ionocyte with apical Rhag and basolateral Rhcg2 in the gills of fish exposed to ammonia for 6 days. Hence, active ammonia excretion may involve NH 4 + entering the ionocyte through the basolateral Rhcg2 and being excreted through the apical Rhag, driven by a transapical membrane electrical potential generated by the apical cystic fibrosis transmembrane conductance regulator Cl - channel, as suggested previously.
Competing Interests: Competing interestsThe authors declare no competing or financial interests.
(© 2017. Published by The Company of Biologists Ltd.)
Databáze: MEDLINE
Externí odkaz: