Practical Approaches for Implementing Forward Genetic Strategies in Zebrafish

The tropical fresh water minnow, Danio rerio , more commonly known as zebrafish, has emerged rapidly over the last decade as a powerful tool for developmental geneticists. External fertilization, high fecundity, a short generation time, and optical transparency of embryos during early development combined with the amenability to a variety of genetic manipulations constitute in the zebrafish the convergence of several unique advantages for a vertebrate model system. Traditional forward genetic screens, which employ the use of a chemical mutagen such as N -ethyl-N -nitrosourea to induce mutations in the male genome, have also proven to be highly successful in the zebrafish. This chapter provides experimental approaches to successfully induce pre-meiotic mutations in the male zebrafish germline and genetic strategies to recover and maintain such mutations in subsequent generations (Section 3.1 ). Though discussed specifically in the context of zebrafish research in this chapter, many of these genetic approaches may also be broadly applicable in other model systems. We also discuss experimental techniques to manipulate the ploidy of zebrafish embryos, which when used in combination with the standard mutagenesis protocol significantly expedite the identification of the induced mutations (Section 3.2 ). Additional stand-alone procedures are provided in Section 3.3 , which are also required for the execution of the experiments discussed in its preceding sections.