a, Schematic (left) and representative images (right) depicting an assay to monitor the effect of equatorial FLIRT on cell polarity and daughter size asymmetry in one-cell embryos expressing PAR-6 (PARtitoning defective) and PAR-2. Quantification of cell polarity and daughter cell asymmetry during cell division (bottom center) and at the two-cell stage (bottom right). N = 7 biologically independent embryos for 16 °C (0 mW), 7 for 16 °C (8.5 mW), 6 for 14 °C (0 mW), and 7 for 14 °C (10.1 mW). Unpaired two-tailed t-test; n.s., no significance, P > 0.05. Error bars, mean +/− s.d.; see Supplementary Table 1 for statistical analysis. b, Experimental timeline for post-FLIRT viability assay. The yellow arrowhead indicates embryo transfer to a worm plate, gray arrowheads indicate developmental imaging, and yellow arrows indicate embryo location on a worm plate. Images of a representative individual control embryo rescued after equatorial FLIRT (top row—and shown at the two-cell stage in the micrograph indicating the FLIRT ROI) or dissected at the one-cell stage (no FLIRT control, bottom) throughout development. Quantification of embryonic viability for isolated one-cell-stage embryos (right). Red (schematic) and white (images) dashed circles indicate FLIRT-targeted ROIs. Time is in minutes after FLIRT initiation. The number of biologically independent experimental replicates (N) is indicated on individual bar graphs. White scale bars, 10 µm; yellow scale bar, 100 µm.