Fig. S2

Response of hoxb1a to transient exposure to all-trans RA. Quantification of the response of hoxb1a to various transient exposures to alltrans RA (tRA) and 13-cis RA (cisRA). The embryos were incubated from sphere stage in 10 mM DEAB (except for the control incubated in embryo medium, EM), exposed at 90% epiboly for 5 minutes to various concentrations of all-trans RA and 13-cis RA and UV illuminated (for 1 minute) or not. (A) In situ hybridization at the 1- to 2-somite stage against hoxb1a1 (blue) for embryos incubated in DEAB with or without 5 nM 13-cis RA, DEAB + 1 nM all-trans RA and DEAB + 5 nM 13-cis RA + 1 minute UV illumination (rescue of hoxb1a expression is visible). (B) Quantification of the expression of hoxb1a by RT-qPCR in various conditions. Note that the expression of hoxb1a in 1 nM all-trans RA is similar to the expression in 5 nM 13-cis RA + UV. Note further that the expression of hoxb1a is similar in 1 nM all-trans RA and 13-cis RA after UV illumination, as expected since in each case the concentration of all-trans RA after illumination is the same. Error bars are statistical errors on the mean from five experiments (each RT-qPCR assay was performed in triplicate).