Effects of trimethyltin on pinocytosis of Dictyostelium discoideum

The effect of trimethyltin (TMT) on viability, morphology and pinocytosis i n the cellular slime mould Dictyostelium discoideum were examined. Pinocyto tic activity was determined using a fluorescent dye, Lucifer yellow (LY), a s a marker of fluid phase endocytosis and quantitative image cytometry with epi-fluorescence computer-aided methods. Treatment of cells with trimethyl tin chloride at concentrations from 5 to 20 muM causes inhibition in the pi nocytotic uptake of LY in growing D. discoideum cells in a dose-dependent a nd time-dependent manner without changing the cell viability, as. assessed with the FDA and ethidium bromide viability test. These results are discuss ed in the light of known actions of organotin compound that affect, various cellular functions.