Embryo-Based Chemical Toxicity Screen: Assessing Effects on Developing Zebrafish Embryos

- Begin by adding 5 embryos in E3 medium to each well of a 96-well plate, and remove the excess medium with a pipette. Add E3 medium containing kanamycin into each well to prevent contamination. Let the embryos grow at 28 degrees Celsius.

Dilute the compound of interest with an appropriate solvent, such as DMSO, to prepare several concentrations or doses, and test the effect of each dose on developing embryos. Once the embryos reach the desired stage, pipette each stock solution into individual wells. Cover the plate with a lid and gently swirl it to mix the contents. Let the embryos in the well plate grow at 28 degrees Celsius.

At the desired time in embryonic development, place the well plate under a suitable microscope to examine the embryos' phenotype. You may observe phenotypes such as loss of eyes, delayed growth, or loss of melanocytes in the developing embryos. In the following protocol, we will test a compound library for small molecule inhibitors of forebrain development.

- Small molecule libraries are typically supplied in a 96-well source plate with each compound stored in DMSO as a 10 millimolar stock. About 60 minutes before the embryos reach the desired stage, thaw a