First published online February 4, 2005
Journal of Experimental Biology 208, 603-610 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01422
Analysis of Na+, Cl-, K+, H+ and NH4+ concentration gradients adjacent to the surface of anal papillae of the mosquito Aedes aegypti: application of self-referencing ion-selective microelectrodes
Andrew Donini* and
Michael J. O'Donnell
Department of Biology, McMaster University, Life Sciences Building,
1280 Main Street West, Hamilton, Ontario, Canada, L8S 4K1

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Fig. 1. Representative example of SeRIS microelectrode measurements showing
calculated ion fluxes along the surface of the anal papillae in vivo.
The length of the arrows and the arrowheads indicate the magnitude and
direction of flux, respectively. The papillae were arbitrarily divided into
quarters such that regions 1 and 2 comprised the proximal half of the papillae
and regions 3 and 4 the distal portion of the papillae. (A) H+
flux. H+ is released by the papillae into the bathing medium. Note
that H+ flux is higher in the proximal regions of the papillae.
Vertical scale bar, 6.5 pmol cm-2 s-1; horizontal scale
bar, 90 µm. (B) Cl- flux. Cl- is taken up by the
papillae from the bathing medium. The papillae that measurements were taken
from was positioned approximately 500 µm below the other papilla that is
seen in the field of view. Vertical scale bar, 42 pmol cm-2
s-1, horizontal scale bar, 54 µm.
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Fig. 2. Summary of ion fluxes in the four regions of the anal papilla in
vivo. Negative values denote influx of ions from the bathing medium into
papilla, and positive values denote efflux of ions from the papilla into the
bathing medium. H+ and K+ fluxes were significantly
higher in region 1 (asterisks; K+ flux: ANOVA P<0.01;
Tukey-Kramer P<0.05; H+ flux: ANOVA P<0.05;
Dunn's test P<0.05). There were no regional differences in
Na+, Cl- and NH4+ fluxes. Values
are mean + S.E.M. (Na+, N=5; Cl-,
N=7; H+, N=6; K+, N=5;
NH4+, N=7).
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Fig. 3. H+ flux along the length of a papilla in vitro. The
papilla was removed from the larva and sealed at the open end with Vaseline.
Note that in comparison with Fig.
2A there were no regional differences in H+ flux.
Vertical scale bar, 7 pmol cm-2 s-1; horizontal scale
bar, 115 µm.
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Fig. 4. Summary of ion fluxes in the four regions of the anal papilla in
vitro. There were no regional differences in ion fluxes. Values are mean
+ S.E.M. (Na+, N=6; Cl-,
N=7; H+, N=9; K+, N=9).
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© The Company of Biologists Ltd 2005