Zebrafish embryos treated with Retinoic Acid or Retinoic acid antagonist during gastrulation and early somitogenesis.. Danio rerio

Retinoic acid (RA) is an important developmental signaling molecule responsible for the patterning of multiple vertebrate tissues. RA is also a potent teratogen, causing multi-organ birth defects in humans. Endogenous RA levels must therefore be tightly controlled in the developing embryo. In order to understand the RA function and regulation at the genomic level, we used a microarray approach to identify genes that function as negative feedback regulators of retinoic acid signaling. To that end, we treated embryos with different chemicals: DMSO as control, AGN193019 as RA antagonist at high concentration 10uM and low concentration 1uM, as well as 0.33uM RA. Each treatment has four biological replicates. We screened for genes expressed in early somite-stage embryos that respond oppositely to treatment with RA versus RA antagonists, and validated them by whole-mount RNA in situ hybridization. Overall design: Each treatment was performed four times, for a total of 16 independent samples (4 x 0.33 µM RA, 4 x 10 µM AGN193109, 4 x 1 µM AGN193109 and 4 x DMSO control).