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Fig. S2
Optical control of constitutive expression by Cre-recombinase. (A, left panel) Tg(ubi:Gal4-ERT2) embryos were injected at the one-cell stage with UAS:Cre; ubi:Eos and ubi:loxP-Eos-loxP-kRAS-T2A-mTFP plasmids. At 32 hpf, embryos displayed expression of mTFP in spite of absence of cyclofen, indicative of residual activity of Cre-recombinase possibly due to leakage of the UAS promoter. (B) Upon cyclofen treatment at 32 hpf, the expression of mTFP at 2dpf and 3dpf was higher than the control (without cyclofen) . (A, middle panel) Injection of ubi:loxP-Eos-stop-loxP-kRASG12V-T2A-mTFP plasmid into Tg(ubi:Cre-ERT2) embryos display no leakage in most of the non-activated embryos, as evidenced by the absence of mTFP expression following incubation in caged cyclofen without UV uncaging (despite autofluorescence from the yolk). (A, right panel and C) On the other hand, upon UV illumination and release of cyclofen, the Eos sequence was effectively excised (resulting in lower fluorescence in the EosFP channel) and the mTFP expression (and fluorescence) was turned on. (D) With Tg(ubi:Cre-ERT2) embryos injected with ubi:loxP-Eos-stop-loxP-kRASG12V-T2A-mTFP plasmid, RT-qPCR analysis of Eos and kRASG12V mRNA showed significant increase of kRAS/Eos ratio upon cyclofen activation. Scale bar: 200 μm. Data are presented as mean ± SEM. **p < 0.01; ***p < 0.001; N.S, not significant.