Live Imaging of C. elegans Embryo Division

For AB–P₁ division measurements, embryos were obtained by dissecting worms microinjected with MOs and then mounted in egg buffer (Edgar, 1995 (link)). Live imaging was performed at room temperature at 18–28 h after microinjection, with a Leica SP5 inverted scanning laser microscope and 63×1.2 NA Olympus water immersion objective, using DIC settings. Images were acquired with Leica LAS AF imaging software as z-stacks of nine levels taken every ∼12 s for durations that covered the time from P₀ cytokinesis until the four-cell stage. Images were processed using ImageJ. Timing of nuclear envelope breakdown (NEBD) (measured at disappearance of nuclear membranes) and cytokinesis (measured at onset of cortical furrowing) in P₀, AB and P₁ blastomeres was determined as described previously (Benkemoun et al., 2014 (link); Brauchle et al., 2003 (link); Edgar and McGhee, 1988 (link)).