Zebrafish genetic mosaics are created by transplanting labeled donor cells of one genotype into unlabelled host embryos of another genotype at blastula or early gastrula stages, and then later assaying the fates of labeled donor cells.

In this experiment, wild-type donor cells (green) and spadetail mutant donor cells (red) were transplanted into the same position in wild-type host blastula. In this live host embryo about 30 hours later, we see that the green wild-type cells adopted trunk and tail muscle fates. The red spadetail mutant cells did not adopt these fates, but instead migrated to the tail tip and formed mostly fin cells. This demonstrates that spadetail gene function is required in muscle cell precursors to get them to the right place at the right time and to promote muscle cell fate.

Work on the genetics of zebrafish is central to the research of Sharon Amacher in the Department of Molecular and Cell Biology.