Fig. 2

Onset/offset of Yap/Taz-TEAD activity in the hindbrain boundaries. (A-C) Tg[4×GTIIC:GFP] embryos at the indicated stages assayed for a whole-mount in situ hybridization using a gfp RNA probe. Expression of gfp, and therefore Yap/Taz-activity, is already visible in the boundaries at 20 hpf. Lateral views with anterior to the left. (D-G) Expression of GFP in the hindbrain boundaries in Tg[4xGTIIC:GFP] embryos at the indicated stages. GFP is first observed at 25 hpf. GFP expression persists for up to 72 hpf (data not shown). Dorsal views with anterior to the left. (H) Scheme depicting the photoconversion experiment: Kaede^G in the hindbrain boundary cells of Tg[4xGTIIC:Gal4FF;UAS:KAEDE] embryos was photoconverted to Kaede^R at T₀, and embryos were allowed to develop up to the desired stage (T₁). (I-I″,J-J″) Embryo in which Kaede^G was photoconverted to Kaede^R at T₀₌30 hpf (I-I″) and which was analyzed at T₁₌48 hpf (J-J″). New Kaede^G is generated in cells between 30 hpf and 48 hpf (see merged channels in J″,J‴). (K-L″) Embryo in which Kaede^G was photoconverted to Kaede^R at T₀₌48 hpf (K-K″) and which was further analyzed at T₁₌72 hpf (L-L″). No new Kaede^G-expressing cells were observed after photoconversion (L-L‴), suggesting that the decline of Yap/Taz-activity was before 48 hpf. (I-I″,J-J″,K-K″,L-L″) Reconstructed transverse sections of embryos are displayed in I‴,J‴,K‴,L‴ as dorsal views with anterior to the left. Scale bars: 30 μm in A-C; 50 μm in D-G,I-L″′.