Martello G, Zacchigna L, Inui M, Montagner M, Adorno M, Mamidi A, Morsut L, Soligo S, Tran U, Dupont S, Cordenonsi M, Wessely O & Piccolo S. MicroRNA control of Nodal signalling. Nature Advance Online Publication, August 2007. doi:10.1038/nature06100

Morpholinos blocking miRNA have been shown to be effective in Xenopus laevis. Acvr2a (activin receptor IIA) is a receptor for Nodal which has a target site in its 3'-UTR that can interact with the seed sequence of xla-miR-15 and xla-mir-16. A mixture of four Morpholinos targeting xla-miR-15 and xla-mir-16 caused Spemann's organizer to increase in size, expected from an increased response to Nodal. 35 nanograms of each Morpholino was mixed into the bolus, which was radially injected into the 4-cell stage embryo. This effect was reversed by coinjection of Cerebrus short (CerS) mRNA, which encodes a Nodal antagonist. Embryos in which Acvr2a was overexpressed by injection of an Acvr2a coding sequence with a modified 3'-UTR lacking targets for xla-miR-15 and xla-mir-16 appeared similar to the embryos which had been treated with Morpholinos targeting xla-miR-15 and xla-mir-16, including increased areas displaying Chd and Pintallavis mRNA (Organizer markers) after in situ hybridizations.