spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

First published online May 15, 2009
Journal of Experimental Biology 212, 1647-1661 (2009)
Published by The Company of Biologists 2009
doi: 10.1242/jeb.029181
This Article
Right arrow Summary Freely available
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Related articles in JEB
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Google Scholar
Right arrow Articles by Gilmour, K. M.
Right arrow Articles by Perry, S. F.
PubMed
Right arrow Articles by Gilmour, K. M.
Right arrow Articles by Perry, S. F.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati   Add to Twitter  
What's this?

Carbonic anhydrase and acid–base regulation in fish

K. M. Gilmour* and S. F. Perry

Department of Biology and Centre for Advanced Research in Environmental Genomics, University of Ottawa, Ottawa, ON, Canada


Figure 1
View larger version (14K):
[in this window]
[in a new window]

  		Fig. 1. A summary of the phylogenetic relationships among mammalian carbonic anhydrase (CA) isoforms illustrating their grouping into extracellular, intracellular and CA-related proteins (CA-RP). In addition, the sensitivity of the various isoforms to inhibition by the sulphonamide acetazolamide is depicted together with the domain structure of the associated genes. The phylogenetic relationships are for mouse (Mus musculus) CA isoforms and were taken from Hilvo et al. (Hilvo et al., 2005Go) (please see Hilvo et al. for details of the phylogenetic tree). Sensitivity to inhibition by acetazolamide was obtained from Hilvo et al. (Hilvo et al., 2008Go), and larger font indicates greater sensitivity (i.e. lower inhibition constant or Ki value). Domain structures for the various CA genes are according to Purkerson and Schwartz (Purkerson and Schwartz, 2007Go) with leader sequences indicated by arrows or lines, catalytic activity indicated by CA domain colour [high=green, moderate=blue and low=red (Hilvo et al., 2008Go)], and membrane linkage indicated as transmembrane (TM) or glycosylphosphatidylinositol (GPI).

 

Figure 2
View larger version (39K):
[in this window]
[in a new window]

  		Fig. 2. A summary of the phylogenetic relationships among mammalian (mouse, Mus musculus; m) and fish (medaka Oryzias latipes; pufferfish Tetraodon nigroviridis; rainbow trout Oncorhynchus mykiss; zebrafish Danio rerio) CA isoforms. The original consensus tree was created by Lin et al. (Lin et al., 2008Go), which should be consulted for details of tree construction and bootstrap values. The original tree has been modified for this figure to emphasize the relationships between mammalian (represented by mouse) and fish isoforms and to emphasize clusters of isoforms that form groups (varying font colours have been used to highlight the members of a group). Mouse CA XI is highlighted because a fish equivalent has not been identified. CA-RP, carbonic anhydrase-related protein.

 

Figure 3
View larger version (16K):
[in this window]
[in a new window]

  		Fig. 3. A summary of the phylogenetic relationships among mammalian (human Homo sapiens; mouse Mus musculus; rat Rattus norvegicus) and fish (carp Cyprinus carpio; dogfish Squalus acanthias; gar Lepisosteus osseus; lamprey Petromyzon marinus; Osorezan dace Tribolodon hakonensis; rainbow trout Oncorhynchus mykiss; salmon Salmo salar; tilapia Oreochromis mossambicus; zebrafish Danio rerio) cytosolic CA isoforms. Redrawn from Gilmour et al. (Gilmour et al., 2007aGo), which should be consulted for details of tree construction and bootstrap values.

 

Figure 4
View larger version (23K):
[in this window]
[in a new window]

  		Fig. 4. Schematic representations of cell types in the (A) trout and (B) zebrafish branchial epithelium that are thought to be responsible for the excretion of acid–base equivalents (see Perry and Gilmour, 2006Go; Hwang and Lee, 2007Go) [see also Ivanis et al. (Ivanis et al., 2008bGo) for data that necessitate a re-evaluation of the trout model]. Electroneutral exchangers are drawn as open circles while ATPases are drawn as filled circles. The extensive basolateral tubular network of the trout PNA+ MR cell is indicated by the irregular basolateral membrane; the basolateral membranes of the trout PNA– MR cell and zebrafish HR cell probably possess some infoldings but not to the extent observed in the trout PNA+ MR cell. The zebrafish HR cell is less enriched in Na+,K+-ATPase than is another ionocyte in the branchial epithelium and this difference is indicated by the greying of the basolateral Na+,K+-ATPase (see text). PNA, peanut lectin agglutinin; MR, mitochondrion rich; HR, V-type H+-ATPase-rich; NHE, Na+/H+ exchanger; NBC, Na+/HCO3– cotransporter; CAc, trout general cytosolic carbonic anhydrase isoform; CA II-like a, zebrafish general cytosolic carbonic anhydrase isoform; CA 15a, zebrafish CA IV-like isoform a.

 

Figure 5
View larger version (14K):
[in this window]
[in a new window]

  		Fig. 5. A schematic representation of the cell types in the dogfish branchial epithelium that are thought to be responsible for the excretion of acid–base equivalents (see Piermarini and Evans, 2001Go; Tresguerres et al., 2006cGo), as well as the underlying pillar cells that express CA IV (see Gilmour et al., 2007aGo). Electroneutral exchangers are drawn as open circles while ATPases are drawn as filled circles. The basolateral membranes of the acid- and base-secreting cells are depicted as smooth but probably possess moderate infoldings (Evans et al., 2005Go). In the base-secreting cell, V-type H+-ATPase is trafficked to the basolateral membrane from cytoplasmic vesicles in response to systemic alkalosis (Tresguerres et al., 2006cGo); this process is indicated by the greyed vesicle and arrow. NHE, Na+/H+ exchanger; P, pendrin; CAc, cytosolic carbonic anhydrase; CA IV, dogfish carbonic anhydrase IV.

 

Figure 6
View larger version (47K):
[in this window]
[in a new window]

  		Fig. 6. Immunolocalization of (A) cytosolic carbonic anhydrase (CAc) and (C) CA IV in renal proximal tubules of rainbow trout (Oncorhynchus mykiss); in each micrograph CA is depicted by green fluorescence, Na+,K+-ATPase by red fluorescence and nuclei by blue fluorescence. Inhibition of (B) total CA activity with acetazolamide or (D) only extracellular CA activity with F3500 significantly reduced net urinary acid excretion (negative values indicate net base loss; asterisks indicate statistically significant differences between control and treatment values). Data were obtained from Georgalis et al. (Georgalis et al., 2006aGo).

 

Figure 7
View larger version (6K):
[in this window]
[in a new window]

  		Fig. 7. A schematic representation of HCO3– reabsorption by the teleost kidney proximal tubule. Luminal CA isoform IV (and/or another membrane-associated isoform) catalyses the combination of filtered HCO3– with H+ provided by Na+/H+ exchange (NHE) or H+-ATPase (ATPases are drawn as filled circles). The CO2 formed by the dehydration reaction diffuses into the cytosol where cytoplasmic CA (CAc) catalyses its hydration to HCO3– and H+. The HCO3– exits across the serosal membrane via the Na+/HCO3– cotransporter isoform 1 (NBC1) and the H+ refuels the NHE or H+-ATPase.

 

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



© The Company of Biologists Ltd 2009