Fig. 2. Synergistic interaction between pertussis toxin and CXCR4b. (A) The severity of PGC migration phenotype induced by PTX RNA or CXCR4b morpholino (MO) is concentration dependent. Different amounts either of control RNA and control morpholino (turquoise), CXCR4b morpholino (green) or PTX RNA (blue) were injected. The arrow indicates the amount used for the synergism experiment. (B) Injections of control RNA and control morpholino (turquoise, n=67 embryos), CXCR4b morpholino (green, n=64 embryos) or PTX-nos1-3'UTR RNA (blue, n=84 embryos) result in 0.1, 1.3 and 2.3 average number of ectopic PGCs per embryo at 24 hpf, respectively. Injection of both CXCR4b morpholino and PTX-nos1-3'UTR RNA (red, n=110 embryos) results on average in 7.3 ectopic PGCs per embryo. (C) Representative images of 24 hpf embryos from the experiment presented in (B).