Alterations induced by dimethyl sulfoxide in Euglena gracilis with emphasis on the side effects

In a previous study, we demonstrated that 5% dimethyl sulfoxide (DMSO) alters the contractile system responsible for cell motility (euglenoid movements) and cytokinesis in Euglena gracilis. However, the nucleus continued to divide and most cells were larger than normal and binucleated. The present study reveals that DMSO, besides altering the cell functions requiring microfilaments, also affects other cell parts. More precisely, the materials normally covering the plasma membrane detach from it; the nucleus shows an irregular outline and aberrations in the nucleolus and chromosomes; the chloroplasts decompose the internal structures and, in a number of cells, transform into proplastid-like organelles. Also, the development of the proplastid into chloroplast in etiolated algae exposed to the light in the presence of DMSO is highly disturbed. These results show that DMSO has remarkable side effects like all the cytoskeletal poisons experimented up to now. An interpretation of the nuclear and chloroplast alterations is advanced.