As genomic sequencing generates more potential target genes with unknown function, the need is increasing for model systems to evaluate the targets. While mice are reasonably relevant to human physiology, genetics and gene knockouts are difficult and time-consuming in mice. However, the zebrafish is emerging as a model system that combines vertebrate physiology, experimentally tractable development, and ease of generating large numbers of animals for genetic analysis (see BioCentury, Dec. 8). Last week researchers further increased the utility of this model