GROWTH-RESPONSES OF ACHLOROPHYLLOUS EUGLENA-GRACILIS TO SELECTED CONCENTRATIONS OF CADMIUM AND PENTACHLOROPHENOL

The growth response of a wild achlorophyllous Euglena gracilis mutant was studied during exposure to cadmium and pentachlorophenol (PCP). Ca dmium gradually reduced the growth rate and terminal cell density; PCP only lengthened the initial lag phase relative to control cultures. F low cytometry showed that cadmium altered the cell cycle by delaying l ate S and G2/M phases; PCP did not disturb the cell cycle, but markedl y affected DNA staining: the intercalating dyes ethidium bromide and p ropidium iodide showed little staining compared to controls. However, replication and transcription processes were not altered by PCP, as ce ll division occurred normally. Cells surviving after PCP treatment app arently developed an adaptative response during the lag phase.