The goal of the work proposed is the establishment of technologies and resources that will facilitate the genetic analysis of vertebrate development using zebrafish. The zebrafish is an attractive, easily accessible animal model to study the genetics of embryogenesis. Already, chemical mutagenesis screens have generated more than one thousand mutants that have defects in most developmental processes. This proposal consists of three parts. The first part describes the generation of balancer chromosomes with a transgene marker that will facilitate identification of zebrafish mutants. The second part describes the development of transgenic technology using yeast and bacterial artificial chromosomes in the zebrafish. This technology will be useful for identifying the chemically induced mutant genes after they have been mapped to specific chromosomal loci. In addition, artificial chromosomes can be used to study the regulation of gene expression by allowing one to identify cis-acting regulatory regions that lie many kilobases away from a gene's transcription initiation site. The third part describes the generation of transgenic zebrafish lines that express the green fluorescent reporter gene in each of the major tissues including the notochord, the nervous system, the brain, heart, and others. These transgenic fish will be available for use by anyone in the zebrafish community.