XB-IMG-150758
Xenbase Image ID: 150758
|
Figure 2. DmHKT1-Driven Na+ Flux Is Not Coupled to Other Ions.(A) In MIFE experiments with unstimulated and COR-treated Dionaea traps, net Na+ and K+ influxes were measured simultaneously under the indicated external Na+ concentrations. Unstimulated traps under these conditions showed only a small Na+ uptake of 310 ± 415 nmol m−2 s−1. Only stimulated traps revealed a clear Na+ influx, even under low external sodium concentrations, which increases up to 1683 ± 218 nmol m−2 s−1 with 50 mM external NaCl. K+ influx was not significantly affected by a change in the external Na+ concentration in either unstimulated or COR-treated traps (n ≥ 7, mean ± SD; P > 0.5, one-way ANOVA).(B) Na+ influx in Dionaea glands is H+-independent. Normalized Na+ fluxes from COR-stimulated Venus flytraps were measured in low (0.1 mM; left) and high (10 mM; middle) NaCl concentrations at a pH of 4. Under low external NaCl, the Na+ influx was only 3.7% ± 5.8% of that in the high external sodium. Increasing the external pH from 4 to 8 (without changing Na+ concentration; right) did not significantly influence the Na+ flux (109% ± 19%) (n ≥ 7, mean ± SD; P > 0.5 by one-way ANOVA).(C) For different monovalent cations at a concentration of 100 mM, the chord conductance was calculated and plotted against the applied voltage range of −40 to −200 mV (n = 4, mean ± SD). DmHKT1 was only permeable for sodium.(D) DmHKT1-mediated inward currents in 5 mM NaCl of a representative Xenopus oocyte when the membrane was clamped to −140 mV. The current amplitude did not change significantly by applying Ca2+ concentrations of 0.1, 1, and 10 mM (as indicated). Image published in: Böhm J et al. (2016) © 2016 The Authors. This image is reproduced with permission of the journal and the copyright holder. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives license Larger Image Printer Friendly View |