Mercury-induced loss of K+ from yeast cells investigated by electron probe x-ray microanalysis.

According to Passow & Rothstein (1960), the mercury-induced loss of K+ from yeast cells is an all-or-none effect. This hypothesis was tested by analysing individual yeast cells by means of energy-dispersive X-ray microanalysis. A dual effect of mercury was observed. The cell population was split into two parts: one part consisted of cells that had suffered a (nearly) complete loss of K+- the number of these cells increased with increasing concentrations of HgCl2; the other consisted of cells that had only lost part of their K+ content--these cells showed a normal distribution around a central value that decreased with increasing concentrations of HgCl2. Our analysis shows that the effect of mercury is more complex than originally suggested and that, in addition to an all-or-none effect, a gradual loss of K+ occurs.