Fig. 7

Regulation of reverse migration of PGCs by receptor internalization.

(A) Tracks of PGCs with respect to domains in the embryo expressing low or high levels of Cxcl12a, in embryos lacking the endogenous ligand. PGCs migrated into domains expressing low levels of the attractant and remained within them, while the cells turned away when the domains expressed high levels of Cxcl12a. (B) Graph showing percentage of cells that moved away from the Cxcl12a expressing domains (2.6% in the case of low Cxcl12a expression and 57.1% in the case of high Cxcl12a levels). (C) Graph showing the percentage of cells that remained for 90 minutes or more within the Cxcl12a expressing area 97.4% in the case of the low expression of the chemokine and 12.2% in the case of high Cxcl12a expression). (D) High-magnification images of PGCs expressing EGFP-tagged Cxcr4b and farnesylated mCherry on their membranes. The cells interacted with low and high Cxcl12a expressing domains as in A. (E) Graph showing the level of Cxcr4b on the PGC membrane as a ratio between the EGFP signal and that of the farnesylated mCherry in cells exposed to low and high concentrations of the ligand. 20 pg of cxcr4b-nanos, 400 pg and 25 pg of cxcl12a RNA was injected to achieve high and low expression domains; 60 pg of mGFP-nanos was used to label the PGCs; 30 pg of m-cherry-H2B was used to label the cells expressing Cxcl12; and 2 pg of TARAM-A*. 101 pg of cxcr4b-EGFP-nanos was used in the receptor internalization assay and 60 pg of m-cherry-nanos was used to label the membrane of PGCs. 0.2 pmol of Cxcl12a morpholino was used. Equimolar amounts of control RNA were used. For raw data see Figure 7—source data 1.