|
|
|
|||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
First published online June 15, 2007
Journal of Experimental Biology 210, 2320-2332 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.005041
Salinity-stimulated changes in expression and activity of two carbonic anhydrase isoforms in the blue crab Callinectes sapidus
Department of Biological Sciences, 101 Life Science Building, Auburn University, Auburn, AL 36849, USA
* Author for correspondence (e-mail: henryrp{at}auburn.edu)
Accepted 16 April 2007
Two isoforms of the enzyme carbonic anhydrase (CA) in the blue crab gill,
CasCAg and CasCAc, were identified, sequenced, and found to match the
membrane-associated and cytoplasmic isoforms, respectively. The
membrane-associated isoform is present in much higher levels of mRNA
expression in both anterior and posterior gills in crabs acclimated to high
salinity (35 p.p.t.), but expression of the cytoplasmic isoform in the
posterior gill undergoes a significantly greater degree of up-regulation after
exposure to low salinity (15 p.p.t.). CasCAc has the largest scope of
induction (100-fold) reported for any transport-related protein in the gill,
and this may be necessary to overcome diffusion limitations between gill
cytoplasm and the apical boundary layer. Furthermore, the timing of the
changes in expression of CasCAc corresponds to the timing of the induction of
protein-specific CA activity and CA protein concentration. No changes in CA
mRNA expression or activity occur in the anterior gills. The pattern of
up-regulation of expression of mRNA of the
-subunit of the
Na+/K+-ATPase is similar to that for CasCAc, and both
precede the establishment of the new acclimated physiological state of the
crab in low salinity. A putative `housekeeping' gene, arginine kinase, also
showed about a threefold increase in expression in response to low salinity,
but only in the posterior gills. These results suggest that for studies of
expression in crustacean gill tissue, a control tissue, such as the anterior
gill, be used until an adequate control gene is identified.
Key words: carbonic anhydrase, ion regulation, crustacean, Callinectes sapidus
![]()
CiteULike
Complore
Connotea
Del.icio.us
Digg
Reddit
Technorati
Twitter What's this?
This article has been cited by other articles:
![]() |
C. M. Nawata and C. M. Wood The effects of CO2 and external buffering on ammonia excretion and Rhesus glycoprotein mRNA expression in rainbow trout J. Exp. Biol., October 15, 2008; 211(20): 3226 - 3236. [Abstract] [Full Text] [PDF] |
||||