Radiation hybrid mapping of the zebrafish genome

The zebrafish is an excellent genetic system for the study of vertebrate de velopment and disease. In an effort to provide a rapid and robust tool for zebrafish gene mapping, a panel of radiation hybrids (RH) was produced by f usion of irradiated zebrafish AB9 cells with mouse B78 cells. The overall r etention of zebrafish sequences in the 93 RH cell lines that constitute the LN54 panel is 22%. Characterization of the LN54 panel with 849 simple sequ ence length polymorphism markers, 84 cloned genes and 122 expressed sequenc e tags allowed the production of an RH map whose total size was 11,501 cent iRays. From this value, we estimated the average breakpoint frequency of th e LN54 RH panel to correspond to 1 centiRay = 148 kilobase. Placement of a group of 235 unbiased markers on the RH map suggests that the map generated for the LN54 panel, at present, covers 88% of the zebrafish genome. Compar ison of marker positions in RH and meiotic maps indicated a 96% concordance . Mapping expressed sequence tags and cloned genes by using the LN54 panel should prove to be a valuable method for the identification of candidate ge nes for specific mutations in zebrafish.