First published online February 13, 2009
Journal of Experimental Biology 212, 704-712 (2009)
Published by The Company of Biologists 2009
doi: 10.1242/jeb.015875
Urea transporter and glutamine synthetase regulation and localization in gulf toadfish gill
M. Danielle McDonald1,*,
Branka Vulesevic2,
Steve F. Perry2 and
Patrick J. Walsh2
1 Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600
Rickenbacker Causeway, Miami, FL 33149 USA
2 Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N
6N5
View larger version (16K):
[in this window]
[in a new window]
|
Fig. 1. (A) Plasma cortisol concentrations and (B) plasma urea concentrations in
toadfish that were relatively unstressed (uncrowded) compared with those under
different experimental treatments. Values are means + 1 s.e.m. Different
letters depicted significant difference, P<0.05.
|
|
View larger version (23K):
[in this window]
[in a new window]
|
Fig. 2. (A) Total glutamine synthetase (GS) activity, (B) relative mRNA expression
of the gill-specific GS isoform (GGS) and (C) relative mRNA expression of the
ubiquitous isoform (LGS). Notably, treatments that resulted in changes in
enzyme activity do not correspond to mRNA expression changes in either GS
isoform. Values are means + 1 s.e.m. Different letters depict significant
difference, P<0.05.
|
|
View larger version (8K):
[in this window]
[in a new window]
|
Fig. 3. Relative tUT mRNA expression in gill of toadfish that are unstressed
(uncrowded) compared to those under different experimental treatments. In
addition to elevations in tUT mRNA expression observed in cortisol-infused
fish, the greatest elevation in expression was measured in fish that were
infused with urea. Values are means + 1 s.e.m. Different letters depicted
significant difference, P<0.05.
|
|
View larger version (12K):
[in this window]
[in a new window]
|
Fig. 4. (A) Daily excretion of urea in toadfish that were saline infused for an
initial 48 h control period and were then switched to being infused either
with saline or with cortisol for a subsequent 48 h. A significant decrease in
excretion was measured in cortisol-treated fish compared with their urea
excretion values measured during the control period and compared with
saline-infused fish at the same time point. (B) Daily excretion of urea in
toadfish that were saline infused for an initial 48 h control period and were
then switched to being infused with either urea alone or urea+RU486. Both
groups showed a significant elevation in urea excretion compared with the
initial saline control period; however, the treatments were not significantly
different from one another. Values are means ± 1 s.e.m.;
*P<0.05, significantly different from corresponding
treatment group;  P<0.05, significantly
different from control infusion period.
|
|
View larger version (101K):
[in this window]
[in a new window]
|
Fig. 5. The pattern of Na+/K+-ATPase (A,B), GGS (C) and tUT
(D) localization in the toadfish gill whether by in situ
hybridization (A,C,D) or immunocytochemistry (B), demonstrating
Na+/K+-ATPase-positive mitochondria-rich cells (MRCs)
scattered along the lamellae (A,B). The insets in A and B represent a no-probe
negative control and a negative control in which primary antibody was omitted,
respectively. GGS (C) and tUT mRNA (D) showed a similar pattern of staining to
Na+/K+-ATPase, scattered along the lamellae and within
the interlamellar regions. The scale bars indicate 50 µm.
|
|
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati 
Twitter What's this?
© The Company of Biologists Ltd 2009
