Figure 1

Figure 1

Endothelial cells sprout from the PCV in G1 phase

(A) Schematic representation of cell cycle stages in ECs as highlighted by the Tg(fli1a:Gal4FF;UAS:FUCCI) reporter.

(B–E) Selected confocal snapshots from a time-lapse series of a Tg(fli1a:Gal4FF;UAS:FUCCI;kdrl:tagBFP) embryo depicting the distribution of late G1 (red) ECs in the PCV (outlined by dashed lines) at 26 (B and C, light-blue arrowheads) and 42 (D and E, light-blue arrowheads) hpf.

(F) Fraction of late-G1 ECs out of total PCV cells (n_{26 hpfembryos} = 11; n_{42hpf embryos} =9 ). Data show mean ± SEM (unpaired t test).

(G) Spatial distribution of late-G1 ECs in the PCV at 26 and 42 hpf (n_{26 hpf embryos} = 11; n_{42 hpf embryos} =9 ). Data show mean ± SEM (unpaired t test).

(H–O) Selected snapshots from a time-lapse series of a Tg(fli1a:Gal4FF;UAS:FUCCI;UAS:Kaede) embryo showing two different ECs budding off the PCV in late-G1 stage (H and L, white arrowheads) and re-entering cell cycle upon crossing the DA (K and N, purple arrowhead).

(P–S) Confocal images of 30 (P and R) and 48 (Q and S) hpf Tg(fli1:EGFP) embryos immuno-stained with p53 (P and Q, light-blue arrowheads) or p27 (R and S, light-blue arrowheads) antibodies. Co-localization channel is shown in yellow, and PCV is outlined by dashed lines.

(T and U) Spatial distribution of p53+ (n_{30 hpf} = 7, n_{48 hpf} = 4) (T) and p27+ (n_{30 hpf} = 18, n_{48 hpf} = 8) (U) ECs in the PCV. Data show mean ± SEM (one-way ANOVA plus Tukey`s post-hoc test). Scale bars: 40 μm (B–E and H–O), 70 μm (P–S); ^∗p < 0.05, ^∗∗∗p < 0.001, ^∗∗∗∗p < 0.0001; ns, not significant.