Fig. 4

BMP2/GDF5 heterodimer signals more effectively than BMP2 or GDF5 homodimers in developing Zebrafish blastula. A–E Representative images of individual zebrafish embryos with quantitative fluorescence for nuclear phosphorylated SMAD5 (pSMAD5). Each dot depicts the average fluorescence of -pSMAD5 in a single nucleus, reds are brighter, and blues are dimmer. A WT embryo at 6 hpf. B–E bmp7−/− embryos at 3 hpf. Embryos were injected with 0.08 fmol protein and then fixed 30 min after injection. F Quantification of the nuclear pSMAD5 fluorescence in embryos was done by calculating the average intensity of the brightest 75% of nuclei minus the average intensity of the dimmest 25% (assumed background). Each black dot is a single embryo. Means are denoted by red diamonds. Experimental groups contained n = 3 (WT), 7 (uninjected), 12 (BMP2), 10 (GDF5), or 11 (BMP2/GDF5) embryos. *: P<0.05, ***: P<0.001 by T-test