A quantitative study of the phagocytosis of Escherichia coli by myxamoebae of the slime mould Dictyostelium discoideum.
A method is described for the rapid and sensitive assay of phagocytosis which utilizes radioactively labelled bacteria. Ingestion is proportional to the concentration of amoebae in the incubation mixture and a double reciprocal plot of the initial rate of ingestion versus bacterial concentration yields a straight line. In the presence of excess bacteria, the kinetics of ingestion are approximately linear during the early stages of the time course, and then continue at a steadily decreasing rate, eventually levelling off after about 60 min incubation. At this stage, the average number of bacteria per amoebae is between 65 and 70. Phagocytosis is sensitive to low temperature and inhibitors of aerobic respiration but is unaffected by substances which block glycolysis. Digestion of the engulfed bacteria begins rapidly and can apparently proceed to completion since very little radioactivity is lost to the medium for a period of 8 h following ingestion.
D004023:Dictyostelium / Q000502:physiology* / Q000648:ultrastructure; D004140:Dinitrophenols / Q000494:pharmacology; D004926:Escherichia coli; D005947:Glucose / Q000494:pharmacology; D006019:Glycolysis; D007700:Kinetics; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption; D010587:Phagocytosis / Q000187:drug effects; D012969:Sodium Fluoride / Q000494:pharmacology
D004140:Dinitrophenols; D012969:Sodium Fluoride; D005947:Glucose