Figure 2. Elevated DeltaD speeds somitogenesis.

(a) Representative embryos at 36 h post fertilization (h.p.f.) stained with segment boundary marker cb1045 (xirp2a). Rescue of segmentation defects in aei^−/− genotype background by dover and damascus. Numbers above arrowheads indicate the posterior boundaries of the corresponding ordinal segments. Orange triangle, segment boundary aligned with proctodeum; purple triangle, last segment boundary observed; grey triangle, defective segment boundaries or onset of defects. Scale bar=300 μm. (b) Distribution of somite defects showing deltaD-venus rescues aei^−/− throughout somitogenesis. No defective boundaries observed in WT AB (n=74), aei^+/− (n=76), Dover^tg/+ (n=95) and Dover^tg/tg (n=60) (blue line). Damascus showed low penetrance of defects (2.6% from the 1st to 30th segments, n=64) (green line). aei^−/− siblings (sib) of dover (n=29) or Damascus (n=33) showed typical deltaD lost-of-function phenotypes, mean ALD around eight (red lines). (c) Damascus has more segments and shifted segmental position of proctodeum. Quantification from embryos as shown in a. Orange, level of proctodeum; magenta, total segment number; grey bars, extreme values. (d) Somitogenesis period of trunk region (s4–s19) measured at 28.3±0.3 °C by multiple embryo time-lapse imaging. Mean periods normalized to WT AB. Data pooled from ⩾3 independent trials (n⩾12 embryos for each condition), except aei^−/− siblings from 1 trial (n=6). (e) Total segmentation time is the interval between the 4th segment to the last segment observed in time-lapse movies. Quantification of corresponding movies described in b. Data pooled from ⩾3 independent trials (n⩾12 embryos for each condition). Mean durations normalized to WT AB (f) Axis elongation and PSM shortening are not altered in Damascus. Data analyzed from same time-lapse movies as d. Time 0 is defined at 5 ss. ***P≤0.001, NS, not significant (P>0.05), Student's t-test. Error bars show the 5th and 95th percentiles of the data.