A caged retinoic acid for one- and two-photon excitation in zebrafish embryos
(Chemical Equation Presented) Escaping the cage: Retinoic acid (RA), a crucial signaling molecule for the embryogenesis of vertebrates, can be photoreleased from a simple caged derivative (cRA) upon illumination. In zebrafish embryos, cRA causes RA-induced phenotypes with one- and two-photon excitation (see picture), which opens a route to the noninvasive generation of controlled RA concentration patterns in vivo.