Fig. 7. Phenotype of a severely C-terminally truncated form of Cullin1, Cul1-C477. In order to ensure that the C-terminally truncated Cul1-C75 does not act as wild-type form of Cullin-1, we made a Cullin-1 construct (Cul1-C477) that is lacking all of the C terminus (Fig. 1B). A 250 pg dose of this construct together with the lineage tracer lacZ (light blue) were injected animally at the two-cell stage into X. laevis embryos. Embryos were analysed at tadpole stages for morphological defects. Injected embryos (A-C,E) showed an accumulation of melanocytes (A-C, arrow in C), secondary axes (B) and ectopic tissue (C), all phenotypes previously observed with the other Cullin-1 constructs. For comparison, uninjected control embryos are shown (D,F). This indicates that all of these constructs act in the same manner, which is most likely to be a dominant-negative mechanism. All embryos are shown laterally. In A-D, anterior is towards the left; in E,F, embryos are facing each other.