Phagocytosis of bacteria and yeast by rosette colonies.

<p>(A) DIC image of live <i>S. rosetta</i> colony showing that under conditions of high bacterial cell density, the bacteria pack tightly along the lengths of the collars of rosette colony cells. (B, C) SEM images of two cells from rosette colonies show that phagocytic cups form directly from the collar ∼700 nm from the collar base. (D) Bacteria are engulfed directly into collar microvilli that are often fused together, as revealed by SEM imaging of a rosette colony cell. (E) A TEM image of phagocytosis shows a bacterium that has been engulfed by membrane associated with the feeding collar membrane. (F) SEM image shows phagocytosis of <i>Saccharomyces cerevisiae</i>. (G, H) SEM images of the links between adjacent microvilli at the base of the collar, with (H) showing higher magnification of square in (G). Key: f = flagellum, c = collar microvilli, b = bacterium, p = phagocytic cup, y = <i>S. cerevisiae</i>, e = extracellular matrix, l = collar links.