A NOVEL SOURCE OF HIGHLY SPECIFIC CHROMOSOME PAINTING PROBES FOR HUMAN KARYOTYPE ANALYSIS DERIVED FROM PRIMATE HOMOLOGS

We have established a series of highly specific painting probes for hu man acrocentric chromosomes, These chromosomes are involved in the for mation of the nucleolar organizer region (NOR) and show DNA sequence h omologies within their pericentric heterochromatin. To date, these chr omosomes have shown considerable cross hybridization in chromosome pai nting experiments. Our probe set has been established from primate hom ologues that are not involved in the NOR in that particular species or from species in which highly repetitive sequences have undergone rapi d sequence divergence. The new painting probes should be of particular value for automated microscopy, for which highly specific signals are required as they are recorded at low magnification, e.g. when scoring chromosome 21 domains in interphase nuclei.