A High-Resolution HAPPY Map of Dictyostelium discoideum Chromosome 6

We have made a high-resolution HAPPY map of chromosome 6 of Dictyostelium discoideum consisting of 300 sequence-tagged sites with an average spacing of 14 kb along the approximately 4-Mb chromosome. The majority of the marker sequences were derived from randomly chosen clones from four different chromosome 6-enriched plasmid libraries or from subclones of YACs previously mapped to chromosome 6. The map appears to span the entire chromosome, although marker density is greater in some regions than in others and is lowest within the telomeric region. Our map largely supports previous gene-based maps of this chromosome but reveals a number of errors in the physical map. In addition, we find that a high proportion of the plasmid sequences derived from gel-enriched chromosome 6 (and that form the basis of a chromosome-specific sequencing project) originates from other chromosomes.