A genetic linkage map for zebrafish: Comparative analysis and localizationof genes and expressed sequences

Genetic screens in zebrafish (Danio rerio) have isolated mutations in hundr eds of genes with essential functions. To facilitate the identification of candidate genes For these mutations, we have genetically mapped 104 genes a nd expressed sequence tags by scoring single-strand conformational polymorp hisms in a panel of haploid siblings. To integrate this map with existing g enetic maps, we also scored 275 previously mapped genes, microsatellites, a nd sequence-tagged sites in the same haploid panel. Systematic phylogenetic analysis defined likely mammalian orthologs of mapped zebrafish genes, and comparison of map positions in zebrafish and mammals identified significan t conservation of synteny. This comparative analysis also identified pairs of zebrafish genes that appear to be orthologous to single mammalian genes, suggesting that these genes arose in a genome duplication that occurred in the teleost lineage after the divergence of fish and mammal ancestors. Thi s comparative map analysis will be useful in predicting the locations of ze brafish genes from mammalian gene maps and in understanding the evolution o f the vertebrate genome.