Figure 5.

GEX1 is required for timely nuclear fusion in Chlamydomonas. (A) Fluorescence images of groups of zygotes. DNA of zygotes was labeled with SYTOX Green before gametes were mixed. Bar, 10 μm. (B) Nuclear fusion expressed as a percentage of zygotes with a single nucleus as determined by observing >100 SYTOX Green-stained cells per time point. Error bars show the standard error of the mean (SEM) from three independent experiments. (C) Transmission electron micrographs of wild-type and gex1/gex1 zygotes at the indicated times after plus and minus gametes were mixed together to undergo fusion. (n) Nucleus; (nc) nucleolus. Arrows point to sites where nuclear envelopes are in close apposition but not fused. The bottom left panel is a higher-magnification view of the interacting nuclei from the panel above it. Bars: bottom left panel, 0.5 μm; other panels, 1 μm.