Influence of S-adenosylmethionine on DAPI-induced fluorescence of polyphosphate in the yeast vacuole

Abstract

Use of the fluorochrome 4'',6-diamidino-2-phenylindole.cntdot.2 HCl (DAPI) in UV microscopy revealed fluorescent objects in Brownian motion within the vacuoles of 7 spp. of yeast. The abundance of these bodies increased when cells of Saccharomyces cerevisiae were transferred from growth medium to a glucose-phosphate solution, indicating that they contain polyphosphate. In addition, the effect on vacuolar florescence of supplementing a defined growth medium with amino acids provided evidence that they also contained S-adenosylmethionine. These deductions were supported by in vitro studies of the interaction and fluorescence of polyphosphate, S-adenosylmethionine and DAPI. Vacuolar fluorescence of cells in suspension in glucose-phosphate solution was less after addition of exogenous arginine, lysine or glutamine but not after addition of alanine, aspartic acid or methionine. Mithramycin was superior to DAPI as a fluorochrome for UV demonstration of yeast nuclei since it stained the nuclei much more intensely and did not fluoresce with other material in the cells.