Transgenic Zebrafish

The zebrafish has become a popular model system for genetic studies of vertebrate development. Zebrafish are amenable to such studies because the generation time of zebrafish is short, adults are small and easy to maintain, and females typically lay up to several hundred eggs per mating. Early development occurs rapidly outside the mother and the embryos are transparent, making the observation and manipulation of the embryos quite simple (1 ). Recently, large-scale chemical mutagenesis screens in zebrafish have identified over 1000 mutations, including hundreds of genes essential for embryogenesis (2 ,3 ). However, to maximally benefit from genetic analysis of embryogenesis using zebrafish, a number of additional challenges must be overcome. First, the chemically induced mutant genes must be identified. Second, the mutations must be analyzed in vivo at the cellular and molecular levels. Third, those functional genes that have been missed by the two screens must be identified. The generation of transgenic zebrafish can provide useful tools for overcoming each of these challenges.