Figure 2: Lineage tracing and characterization of blastoderm clones in wild-type and Eve RNAi embryos.

(a) Number of segments occupied by clones in the extended germband versus original axial blastoderm position. Bars with different letters (a and b) are significantly different. (b) In wild-type embryos, clones at 60–80% egg length (EL) change their aspect ratio more than clones from other positions (analysis of variance, P<0.0001), a result lost in eve RNAi embryos. (c) Doubling of initial clone cell numbers versus original axial blastoderm position show no significant correlation, (linear regression: R²=0.009, P>0.05, n=65). (d) Doubling of 60–80% EL clones in wild-type and eve RNAi embryos do not differ significantly (P>0.05, unpaired t-test). Numbers in parentheses indicate sample sizes for each group in a,b and d. (e) Cell lineage tracing of the blastoderm clones. In blastoderm stage embryos, a small population of the cells is labelled with fluorescein (green, left column). Corresponding later stage embryos (right column) are stained with anti-fluorescein antibody (green), anti-engrailed (red) and DAPI (blue). (E1) 28–40% clone; progeny in the head lobe (Hl). (E2) 41–51% clone; progeny in the maxillary (Mx) and labial (La) segments. (E3) 53–64% clone; progeny in the second and third thoracic segment (T2, T3). (E4) 62–74% clone; progeny in the second to the sixth abdominal segment (A2, A6). (E5) 74–85% clone; progeny in the third to the eighth abdominal segment (A3, A8). (E6) 81–95% clone; progeny in the seventh to the posterior end (A7, A10). Scale bars; 100 μm. (f) Cell lineage tracing of 60–80% EL clones in control and eve RNAi embryos. In the control embryo (F1), the clone undergoes extensive elongation along anteroposterior axis and the descendants occur from the fourth to the seventh abdominal segment (A4, A7). By contrast, in the eve RNAi embryos (F2, F3), clones fail to extend and the descendants remain clustered within the embryos. Scale bar, 100 μm.