Fig. 4

Genetic Mosaic Analysis Reveals Spatially Restricted Requirements for Cxcr7 and Cxcr4b during Lateral-Line Primordium Migration

(A) A 10× overview of wild-type cells (red labeled, lyn-dtTomato mRNA) transplanted into a Cxcr7 morphant embryo at 34 hpf. Time-lapse analysis of a Cxcr7 morphant primordium displays a contiguous clone of wild-type cells in the trailing region. Migration of the primordium is efficiently rescued only up until the point when wild-type cells are deposited. The scale bar represents 20 μm.

(B) Time-lapse analysis of a Cxcr7 morphant revealing that wild-type cells transplanted at the leading edge of the primordium cannot rescue the migration of a Cxcr7 morphant embryo. The scale bar represents 20 μm.

(C) Embryos were screened for the localization of wild-type cells inside the morphant primordia (at the back or at the front). Migration of rescued primordia similar to that of the wild-type was observed in those cases with large clones of cells at the back but not at the front of the primordium.

(D) Time-lapse analysis shows that clones of Cxcr7 morphant cells can efficiently rescue migration of cxcr4b mutant primordia. Donor embryos were kept to ensure that Cxcr7 was efficiently knocked down in transplanted cells. The scale bar represents 20 μm.

(E) Rhodamine labeled cxcr4b mutant cells were transplanted into Cxcr7 morphants. Transplanted wild-type cells rescue the migration defect of Cxcr7 morphant primordia when present in the trailing regions of the primordium. The scale bar represents 20 μm.