First published online July 23, 2003
Seasonal acclimatization in water flux rate, urine osmolality and kidney water channels in free-living degus: molecular mechanisms, physiological processes and ecological implications
Francisco Bozinovic1,*,
Pedro A. Gallardo2,
G. Henk Visser3,4 and
Arturo Cortés5
1 Center for Advanced Studies in Ecology & Biodiversity and Departamento
de Ecología, Facultad de Ciencias Biológicas, Pontificia
Universidad Católica de Chile, Santiago, Chile, 6513677
2 Laboratorio de Fisiopatología Molecular, Programa de
Fisiopatología, ICBM, Facultad de Medicina, Universidad de Chile,
Santiago, Chile, 6513677
3 Centre for Isotope Research, Nijenborgh 4, 9747 AG Groningen, The
Netherlands
4 Zoological Laboratory, PO Box 14, 9750 AA Haren, The
Netherlands
5 Departamento de Biología, Facultad de Ciencias Universidad de La
Serena, Casilla 599, La Serena Chile

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Fig. 1. Seasonal pattern of variation in (A) precipitation in the semi-arid
habitats of north-central Chile, (B) water influx and efflux in free-living
Octodon degus and (C) field urine osmolality in free-living degus.
Values are means ± 1 S.D. Sample size (N) is shown
in parentheses, and further statistical details are found in Tables
1 and
2.
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Fig. 2. Seasonal pattern of variation in aquaporin-2 (AQP-2) distribution and
regulation in cells of the renal medulla. (A) Immunolabeling for AQP-2 in
apical membrane (vertical arrow) and cytosol of inner medullary collecting
duct cells during summer. (B) Scarce immunolabeling for AQP-2 can be observed
in the same cells during winter. Unlabeled cells in A and B may correspond to
intercalated cells. (C,D) Double immunolabeling for AQP-2 (inner medullary
collecting duct cells; brown) and AQP-1 (thin descending cells of Henle's
loop; blue) during summer and winter, respectively. Note the change in AQP-2
but not in AQP-1 immunoreactivity. (E) Immunoblot of proteins from renal
medulla for AQP-2 during summer (lanes 1 and 2) and winter (lanes 3 and 4).
Scale bar represents 100 µm in A-D and 50 µm in inserts of A and B.
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© The Company of Biologists Ltd 2003