QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online April 18, 2006
Journal of Experimental Biology 209, 1696-1708 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02198

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Choe, K. P. Articles by Evans, D. H. Search for Related Content PubMed PubMed Citation Articles by Choe, K. P. Articles by Evans, D. H. Social Bookmarking                         What's this?

COX2 in a euryhaline teleost, Fundulus heteroclitus: primary sequence, distribution, localization, and potential function in gills during salinity acclimation

Keith P. Choe^1,2,*, Justin Havird^1,2, Rachel Rose^1,2, Kelly Hyndman^1,2, Peter Piermarini³ and David H. Evans^1,2

¹ Department of Zoology, University of Florida, Gainesville, FL 32611, USA
² Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04672, USA
³ Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520, USA

^* Author for correspondence at present address: T-4202 Medical Center North, 1161 21st Ave South, Anesthesiology Research, Vanderbilt Medical Center, Nashville, TN 37232-2520, USA (e-mail: keith.p.choe{at}vanderbilt.edu)

Accepted 7 March 2006

In the kidneys of mammals, cyclooxygenase type 2 (COX2) is expressed in medullary interstitial cells, the macula densa and epithelial cells of the cortical thick ascending limb where it generates prostaglandins that regulate hormone secretion, inhibit ion transport, and support cell survival during salt loading and dehydration. In teleosts, the gills are in direct contact with an aquatic environment and are the dominant site of osmoregulation. During transfers between salinities, specialized cells in the gills (chloride cells) rapidly regulate NaCl secretion for systemic osmoregulation while they simultaneously are exposed to acute osmotic shock. This study was conducted to determine if COX2 is expressed in the gills, and if so, to evaluate its function in cellular and systemic osmoregulation. Degenerate primers, reverse transcription–PCR and rapid amplification of cDNA ends were used to deduce the complete cDNA sequence of a putative COX2 enzyme from the gills of the euryhaline killifish (Fundulus heteroclitus). The 2738 base pair cDNA includes a coding region for a 610 amino acid protein that is over 70% identical to mammalian COX2. A purified antibody generated against a conserved region of mouse COX2 labeled chloride cells, suggesting that the enzyme may control NaCl secretion as an autocrine agent. Real-time PCR was then used to demonstrate that mRNA expression of the COX2 homologue was threefold greater in gills from chronic seawater killifish than in gills from chronic freshwater killifish. Expression of Na⁺/K⁺/2Cl^– cotransporter and the cystic fibrosis transmembrane conductance regulator were also greater in seawater, suggesting that chronic COX2 expression in the gills is regulated in parallel to the key ion transporters that mediate NaCl secretion. Real-time PCR was also used to demonstrate that acute transfer from seawater to freshwater and from freshwater to seawater led to rapid, transient inductions of COX2 expression. Together with previous physiological evidence, the present molecular and immunological data suggest that constitutive branchial COX2 expression is enhanced in seawater, where prostaglandins can regulate NaCl secretion in chloride cells. Our data also suggest that branchial COX2 expression may play a role in cell survival during acute osmotic shock.

Key words: osmoregulation, prostaglandin, chloride cell, mitochondrion-rich cell, killifish, Fundulus heteroclitus

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				J. C. Havird, M. M. Miyamoto, K. P. Choe, and D. H. Evans Gene Duplications and Losses within the Cyclooxygenase Family of Teleosts and Other Chordates Mol. Biol. Evol., November 1, 2008; 25(11): 2349 - 2359. [Abstract] [Full Text] [PDF]

				G. R. Scott, D. W. Baker, P. M. Schulte, and C. M. Wood Physiological and molecular mechanisms of osmoregulatory plasticity in killifish after seawater transfer J. Exp. Biol., August 1, 2008; 211(15): 2450 - 2459. [Abstract] [Full Text] [PDF]

				D. H. Evans Teleost fish osmoregulation: what have we learned since August Krogh, Homer Smith, and Ancel Keys Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2008; 295(2): R704 - R713. [Abstract] [Full Text] [PDF]

				K. A. Hyndman and D. H. Evans Endothelin and endothelin converting enzyme-1 in the fish gill: evolutionary and physiological perspectives J. Exp. Biol., December 15, 2007; 210(24): 4286 - 4297. [Abstract] [Full Text] [PDF]