Fig. 2. Images of T. gondii expressing histone 2b-YFP fusion protein. The h2b-YFP appears green and parasites were also stained with anti-IMCI antibody to show the inner membrane complex (cyan) and DAPI to visualize DNA (red). The images are the sum of two optical sections close to the middle of the parasites, taken from a deconvolved 3D stack of 15 optical sections 0.3 µm apart. (Upper left panels) Overview DIC and DIC/fluorescence overlay images showing three parasite-containing vacuoles and portions of three host cells. (Upper right and lower panels) Enlarged views of the rightmost vacuole, containing four parasites, of which parasites 1 and 2 are both forming two daughters, parasite 3 is at the very beginning of daughter cell formation where only traces of daughter scaffold can be seen, and parasite 4 is assembling four daughters. The three seemingly separate nuclei of parasite 4 were found to be interconnected in adjacent optical sections (not shown). Chromosome-like aggregations of condensed chromatin (arrowheads) are clearly visible in the segregating nuclei. Apicoplast DNA is also visible (arrows) labeled with DAPI only (red), not with H2b-YFP. In all other regions, the H2b-YFP distribution corresponds precisely to the DNA distribution stained by DAPI.