Cytosolic carbonic anhydrase in the Gulf toadfish is important for tolerance to hypersalinity

G. Sattin, E. M. Mager, M. Beltramini, M. Grosell

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


Carbonic anhydrase (CA) is a ubiquitous enzyme involved in acid-base regulation and osmoregulation. Many studies have demonstrated a role for this enzyme in fish osmoregulation in seawater as well as freshwater. However, to date CA responses of marine fish exposed to salinities exceeding seawater (∼ 35 ppt) have not been examined. Consequently, the aim of the present study was to examine CA expression and activity in osmoregulatory tissues of the Gulf Toadfish, Opsanus beta, following transfer to 60 ppt. A gene coding, for CAc of 1827 bp with an open reading frame of 260 amino acids was cloned and showed high expression in all intestinal segments and gills. CAc showed higher expression in posterior intestine and rectum than in anterior and mid intestine and in gills of fish exposed to 60 ppt for up to 4 days. The enzymatic activity, in contrast, was higher in all examined tissues two weeks following transfer to 60 ppt. Comparing early expression and later activity levels of acclimated fish reveals a very different response to hypersalinity among tissues. Results highlight a key role of CAc in osmoregulation especially in distal regions of the intestine; moreover, CAc play a role in the gill in hypersaline environments possibly supporting elevated branchial acid extrusion seen under such conditions.

Original languageEnglish (US)
Pages (from-to)169-175
Number of pages7
JournalComparative Biochemistry and Physiology - A Molecular and Integrative Physiology
Issue number2
StatePublished - Jun 2010


  • Carbonic anhydrase
  • Gills
  • Intestine
  • Marine fish
  • Osmoregulation

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Physiology


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