Gating of aquaporins by heavy metals in Allium cepa L. epidermal cells.
Changes in the water permeability, aquaporin (AQP) activity, of leaf cells were investigated in response to different heavy metals (Zn(2+), Pb(2+), Cd(2+), Hg(2+)). The cell pressure probe experiments were performed on onion epidermal cells as a model system. Heavy metal solutions at different concentrations (0.05 μM-2 mM) were used in our experiments. We showed that the investigated metal ions can be arranged in order of decreasing toxicity (expressed as a decrease in water permeability) as follows: Hg>Cd>Pb>Zn. Our results showed that β-mercaptoethanol treatment (10 mM solution) partially reverses the effect of AQP gating. The magnitude of this reverse differed depending on the metal and its concentration. The time course studies of the process showed that the gating of AQPs occurred within the first 10 min after the application of a metal. We also showed that after 20-40 min from the onset of metal treatment, the water flow through AQPs stabilized and remained constant. We observed that irrespective of the metal applied, the effect of AQP gating can be recorded within the first 10 min after the administration of metal ions. More generally, our results indicate that the toxic effects of investigated metal ions on the cellular level may involve AQP gating.
Department of Molecular Plant Physiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland. przedpelska@biol.uw.edu.pl
Ewa Maria
EM
Przedpelska-Wasowicz
Malgorzata
M
Wierzbicka
D020346:Aquaporins / Q000187:drug effects / Q000378:metabolism*; D002463:Cell Membrane Permeability; D015640:Ion Channel Gating; D008623:Mercaptoethanol / Q000494:pharmacology; D019216:Metals, Heavy / Q000378:metabolism* / Q000494:pharmacology; D019697:Onions / Q000187:drug effects / Q000378:metabolism*; D019441:Plant Epidermis / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D010940:Plant Proteins / Q000187:drug effects / Q000378:metabolism; D011312:Pressure; D013997:Time Factors; D014867:Water / Q000378:metabolism
D020346:Aquaporins; D019216:Metals, Heavy; D010940:Plant Proteins; D014867:Water; D008623:Mercaptoethanol