Plant & Animal Genome VI Conference

S18

THE ZEBRAFISH GENETIC MAP: IMPLICATIONS FOR THE EVOLUTION OF THE VERTEBRATE GENOME

University of Oregon

To investigate the evolution of the vertebrate genome, we have placed 150 cloned genes on the zebrafish genetic map. The results revealled extensive conservation of chromosome segments between zebrafish and mammals. Chromosome segments that appear in multiple paralogous copies in mammalian genomes were also present in multiple copies in zebrafish, and the mammalian orthologues of zebrafish chromosome segments were usually apparent. In some cases, paralogous chromosome segments in zebrafish retain functional gene copies that have apparently become non-functional in mammals, and in other cases, zebrafish appear to have two copies of some mammalian chromosome segments. These results show that polyploidization events were major contributors to the origin of multiple gene families among vertebrates, and that at least two events occurred before the divergence of the evolutionary lines leading to zebrafish and mammals. The correlation of zebrafish and human genomes promises to aid in the molecular identification of genes disrupted by mutation in zebrafish, and thereby suggest functions for human genes known only by sequence.