Fig. 1. Self-assembly of VENUS fragments is prevented by specific mutations. RNA encoding the indicated combinations of wild-type or mutated VENUS fragments (500 pg of each) was injected into Xenopus embryos at the one-cell stage in the presence of RNA encoding monomeric red fluorescent protein (mRFP1; 500 pg) as a lineage marker. Embryos were cultured to midblastula stage 9 and examined using a fluorescence dissecting microscope to visualise mRFP1 (top of each panel) or VENUS (bottom of each panel). (A) Strong fluorescence is observed following injection of mRNA encoding VN154 and VC155. (B) Mutation of VN154 to create VNm9 abolishes self-assembly and fluorescence. (C) Injection of mRFP1 alone. (D) Strong fluorescence is observed following injection of mRNA encoding VN144 and VC145. (E) VENUS fluorescence does not occur in embryos injected with RNA encoding VNm3 and VCm5 and only background level of fluorescence is observed. (F) An uninjected embryo illustrating background fluorescence.