Models have real value.

Abstract

Those of you who have kept tropical fish will almost certainly have had the Zebrafish ( Daneo rerio ) in your menagerie. You may not know that this fish is now perhaps the most important tool in the investigation of normal development and in the identification of candidate genes that play a determining role in human malformation syndromes. A deliberate programme of chemical mutagenesis has identified hundreds of mutations that affect vertebrate development affecting the form of the embryo, the generation of the germ layers, organogenesis, differentiation, the cytoarchetectonics of the brain and the vasculature (of which more later). In the Zebrafish, it is possible to explore the important area of how single gene changes may affect the structural adaptations that occur during evolution, as well as the kind of change in gene function that occurs in the evolution of multigene families (such as the homeoboxes). What was the problem with other systems? It was really the difficulty with which selected mutant phenotypes could be recovered in a diploid vertebrate embryo. Since one of a very large number of genes might be the one involved in a developmental …