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Roles of three branchial Na(+)-K(+)-ATPase α-subunit isoforms in freshwater adaptation, seawater acclimation, and active ammonia excretion in Anabas testudineus.
Am J Physiol Regul Integr Comp Physiol. 2012 Jul 01; 303(1):R112-25.AJ

Abstract

Three Na(+)-K(+)-ATPase (nka) α-subunit isoforms, nka α1a, nka α1b, and nka α1c, were identified from gills of the freshwater climbing perch Anabas testudineus. The cDNA sequences of nka α1a and nka α1b consisted of 3,069 bp, coding for 1,023 amino acids, whereas nka α1c was shorter by 22 nucleotides at the 5' end. In freshwater, the quantity of nka α1c mRNA transcripts present in the gills was the highest followed by nka α1a and nka α1b that was almost undetectable. The mRNA expression of nka α1a was downregulated in the gills of fish acclimated to seawater, indicating that it could be involved in branchial Na(+) absorption in a hypoosmotic environment. By contrast, seawater acclimation led to an upregulation of the mRNA expression of nka α1b and to a lesser extent nka α1c, indicating that they could be essential for ion secretion in a hyperosmotic environment. More importantly, ammonia exposure led to a significant upregulation of the mRNA expression of nka α1c, which might be involved in active ammonia excretion. Both seawater acclimation and ammonia exposure led to significant increases in the protein abundance and changes in the kinetic properties of branchial Na(+)-K(+)-ATPase (Nka), but they involved two different types of Nka-immunoreactive cells. Since there was a decrease in the effectiveness of NH(4)(+) to substitute for K(+) to activate branchial Nka from fish exposed to ammonia, Nka probably functioned to remove excess Na(+) and to transport K(+) instead of NH(4)(+) into the cell to maintain intracellular Na(+) and K(+) homeostasis during active ammonia excretion.

Authors+Show Affiliations

Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore. dbsipyk@nus.edu.sgNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

22621969

Citation

Ip, Yuen K., et al. "Roles of Three Branchial Na(+)-K(+)-ATPase Α-subunit Isoforms in Freshwater Adaptation, Seawater Acclimation, and Active Ammonia Excretion in Anabas Testudineus." American Journal of Physiology. Regulatory, Integrative and Comparative Physiology, vol. 303, no. 1, 2012, pp. R112-25.
Ip YK, Loong AM, Kuah JS, et al. Roles of three branchial Na(+)-K(+)-ATPase α-subunit isoforms in freshwater adaptation, seawater acclimation, and active ammonia excretion in Anabas testudineus. Am J Physiol Regul Integr Comp Physiol. 2012;303(1):R112-25.
Ip, Y. K., Loong, A. M., Kuah, J. S., Sim, E. W., Chen, X. L., Wong, W. P., Lam, S. H., Delgado, I. L., Wilson, J. M., & Chew, S. F. (2012). Roles of three branchial Na(+)-K(+)-ATPase α-subunit isoforms in freshwater adaptation, seawater acclimation, and active ammonia excretion in Anabas testudineus. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology, 303(1), R112-25. https://doi.org/10.1152/ajpregu.00618.2011
Ip YK, et al. Roles of Three Branchial Na(+)-K(+)-ATPase Α-subunit Isoforms in Freshwater Adaptation, Seawater Acclimation, and Active Ammonia Excretion in Anabas Testudineus. Am J Physiol Regul Integr Comp Physiol. 2012 Jul 1;303(1):R112-25. PubMed PMID: 22621969.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Roles of three branchial Na(+)-K(+)-ATPase α-subunit isoforms in freshwater adaptation, seawater acclimation, and active ammonia excretion in Anabas testudineus. AU - Ip,Yuen K, AU - Loong,Ai M, AU - Kuah,Jie S, AU - Sim,Eugene W L, AU - Chen,Xiu L, AU - Wong,Wai P, AU - Lam,Siew H, AU - Delgado,Inês L S, AU - Wilson,Jonathan M, AU - Chew,Shit F, Y1 - 2012/05/23/ PY - 2012/5/25/entrez PY - 2012/5/25/pubmed PY - 2012/9/19/medline SP - R112 EP - 25 JF - American journal of physiology. Regulatory, integrative and comparative physiology JO - Am. J. Physiol. Regul. Integr. Comp. Physiol. VL - 303 IS - 1 N2 - Three Na(+)-K(+)-ATPase (nka) α-subunit isoforms, nka α1a, nka α1b, and nka α1c, were identified from gills of the freshwater climbing perch Anabas testudineus. The cDNA sequences of nka α1a and nka α1b consisted of 3,069 bp, coding for 1,023 amino acids, whereas nka α1c was shorter by 22 nucleotides at the 5' end. In freshwater, the quantity of nka α1c mRNA transcripts present in the gills was the highest followed by nka α1a and nka α1b that was almost undetectable. The mRNA expression of nka α1a was downregulated in the gills of fish acclimated to seawater, indicating that it could be involved in branchial Na(+) absorption in a hypoosmotic environment. By contrast, seawater acclimation led to an upregulation of the mRNA expression of nka α1b and to a lesser extent nka α1c, indicating that they could be essential for ion secretion in a hyperosmotic environment. More importantly, ammonia exposure led to a significant upregulation of the mRNA expression of nka α1c, which might be involved in active ammonia excretion. Both seawater acclimation and ammonia exposure led to significant increases in the protein abundance and changes in the kinetic properties of branchial Na(+)-K(+)-ATPase (Nka), but they involved two different types of Nka-immunoreactive cells. Since there was a decrease in the effectiveness of NH(4)(+) to substitute for K(+) to activate branchial Nka from fish exposed to ammonia, Nka probably functioned to remove excess Na(+) and to transport K(+) instead of NH(4)(+) into the cell to maintain intracellular Na(+) and K(+) homeostasis during active ammonia excretion. SN - 1522-1490 UR - https://www.unboundmedicine.com/medline/citation/22621969/Roles_of_three_branchial_Na_+__K_+__ATPase_α_subunit_isoforms_in_freshwater_adaptation_seawater_acclimation_and_active_ammonia_excretion_in_Anabas_testudineus_ L2 - http://journals.physiology.org/doi/full/10.1152/ajpregu.00618.2011?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -