Figure 5. Elevated DeltaD increases the strength of coupling in the segmentation clock.

(a) Schematic of DAPT pulse-chase synchrony rescue assay for estimating relative coupling strength. Presumptive synchrony level (Z) versus experimental time scale shown in upper panel. Z is an order parameter that measures the degree of synchrony between neighbouring oscillators, with 1 indicating perfect synchrony and 0 indicating complete lack of temporal correlation, as defined in ref. 11. Z₀, initial synchrony level at shield stage (6 h.p.f.); Z_c, critical level of synchrony for forming non-defective segment boundaries; Z_min, putative minimal synchrony at de-synchronized state; darkness of blue lines depict relative coupling strength. Time intervals (T_Re-sync) between DAPT wash-out and resynchronized states reflect coupling strength (ɛ). (b) Segment boundaries after DAPT pulse-chase in mutant and transgenic backgrounds. Numbers above arrowheads indicate the values of ALD (red triangle) or FRS (blue triangle). Scale bar, 300 μm. (c) Quantification of DAPT pulse-chase experiments. ALD (red) and FRS (blue) from left or right side independently, as shown in a. Data from aei^+/− (n=48), WT (n=94), Dover^tg/+ (n=43), Dover^tg/tg (n=36) and Damascus^tg/+ (n=78) pooled from three independent trials. Data is mean value with error bars showing 5th and 95th percentiles. *P≤0.05, ***P≤0.001, NS, not significant (P>0.05), Student's t-test.