Cytochemical localization of mercury in Saccharomyces cerevisiae treated with mercuric chloride

We describe a cytochemical method for localizing mercury at the electron microscopic level in the yeast Saccharomyces cerevisiae. After addition of a lethal concentration of mercuric chloride to growing yeast cells, mercury was associated with the cell wall and cytoplasmic membrane. Little or no mercury was present in the cytoplasm. Electron probe X-ray microanalysis (EPMA) confirmed that the cytochemical reaction, visualized as mercury-silver complexes, was localized in dense bodies consisting of a core of mercury sulfide polymers surrounded by a shell of silver atoms.