ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
The electrical resting potential across the plasmalemma of Lemna gibba L. (G 1) cells is −230 to −250 mV and the diffusion potential in the presence of 1 mol m−3 KCN + 1 mol m−3 salicylhydroxamic acid is about −100 mV. A concentration of 0.01 mol m−3 HgCl2 depolarises the transmembrane electrical potential in a largely reversible way. When the cells after 16 min of HgCl2-application are returned to Hg-free solution, the transmembrane electrical potential is only depolarised by 24 × 13 mV (SD, n = 13) compared with the potential prior to HgCl2 treatment. In contrast, a 16 min pretreatment with HgCl2 followed by a wash with mercury-free solution reduces the transient depolarisations of transmembrane potential observed after addition of 5 mol m−3 D-glncose or 1 mol m−3 L-alaoine to about 60% of controls. These transient depolarisations are due to the onset of solute uptake. Accordingly, HgCl2-pretreatment inhibits uptake of 14C-3-O-methyl-d-glucose by more than 50% and uptake of 14C-l-alanine by more than 70%. Washing with 1 mol m−3 1,4-dithiothreitol does not reverse this inhibition. It is, therefore, concluded that Hg2+ irreversibly binds to essential SH-groups of the H+-hexose and the H+-amino-acid cotransport carriers of Lemna gibba and inhibits these carriers without appreciably affecting the electrogenic proton-extrusion pump.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1399-3054.1983.tb00730.x
