Fig. 3

Phenotypic Analysis of Primordium Behavior after Cxcr7 Knockdown

(A) Representative example of a Cxcr7 morphant primordium of the stretched class. The upper panel shows a 10× overview at 32 hpf. Below: frames taken from a 1 hr time-lapse movie (40×) that shows a stretched primordium, which does not migrate. The asterisk indicates the deposited cells, the arrowheads show cell motility at the rear of the primordium, and the arrow depicts the stretching of the leading cells. The scale bar represents 20 μm. A kymograph confirms that tip cells dynamically elongate and retract and indicates that cells within the tissue are motile but do not move (Figure S5A).

(B) Time-lapse analysis of a Cxcr7 morphant embryo at 32 hpf showing the conversion from a stretched to a rounded primordium in 300 min. The arrows show the behavior of the leading cells.The scale bar represents 20 μm.

(C) Example of a Cxcr7 morphant embryo at 34 hpf where primordium splits. The scale bar represents 20 μm.

(D) Fluorescent in situ hybridization of krt15 in wild-type and Cxcr7 morphants at 36 hpf. Expression of krt15 is restricted to the rear of the primordium and to the deposited chain cells in both cases.

(E) In situ hybridization of Cxcr4b (left panel) and Cxcr7 (right panel) in wild-type, cxcr4b mutant, sdf1a mutant, and Cxcr7 morphant embryos at 36 hpf. Although the morphology of the primordium varies between genotypes, it is clear that the relative expression domains of Cxcr4b and Cxcr7 are unaffected in the different backgrounds.