OXYGEN AND DIFFERENTIATION IN DICTYOSTELIUM-DISCOIDEUM

We showed previously that if Dictyostelium discoideum cells are sucked up into a small glass capillary with air at one end and plugged with mineral oil at the other, a sharp band of fast moving cells with prest alk characteristics formed within a minute at the air end of the cell mass. We now demonstrate that oxygen inside the capillary is responsib le for the initiation and positioning of the sharp division line betwe en prestalk-like and prespore-like cells, and that the length of the p restalk zone is regulated by the oxygen concentration. Our results are compared to a quantitative theory, showing good agreement with the ex periments. We also discuss the relevance of these observations to the differentiation of prestalk and prespore zones in normal slugs and the origins of polarity in this organism.