REGIONAL LOCALIZATION OF 56 NEW HUMAN CHROMOSOME-18 SPECIFIC YEAST ARTIFICIAL CHROMOSOMES

Fifty-six chromosome 18-specific yeast artificial chromosomes (YAC) we re isolated from a human monochromosomal somatic cell hybrid DNA libra ry. Fluorescence in situ hybridization revealed that the clones were e venly distributed throughout the chromosome. The clones, with an avera ge insert size of 250 kb, cover about 18% of the euchromatic part of c hromosome 18. Of 90 STS markers tested, 17 were represented in this YA C collection. Together with our previously reported set of unique chro mosome 18-specific YACs, we now have available 111 regionally mapped, essentially nonchimeric, clones that provide more than 30% coverage an d form a framework for the complete physical map.