MITOGENIC STIMULATION IN ISOPROTERENOL TREATED CELLS OF DICTYOSTELIUM DISCOIDEUM

Amoebae of the cellular slime mould Dictyostelium discoideum showed stimulated mitogenic activity when exposed to 200μM isoproterenol, an activator of adenyl cyclase, for 30min. Approximately 40% increase in cell proliferation was found at 48h after isoproterenol treatment. A faster and larger plaque formation as well as higher uptake of FITC‐labelled E. coli indicates greater phagocytotic activity in the treated cells. A concurrent increase in DNA and protein syntheses was also recorded in the treated cells. Administration of 400μM caffeine or 200μM (+) propranolol brought down the isoproterenol‐induced elevation in the cell division rate to control levels. These results are discussed in relation to a precocious activation of adenyl cyclase in the treated cells leading to a transient but significant increase in cell division in this organism.