PCR cloning of a repeated DNA fragment from Chinese hamster ovary (CHO) cell X chromosomes and mapping by fluorescence in situ hybridization.

Hamster chromosome-specific DNA sequences were amplified by primer directed DNA amplification using mixed base oligonucleotides in an arbitrarily primed polymerase chain reaction (AP-PCR) protocol. The template DNA was comprised of approximately 3000 chinese hamster ovary cell (CHO) chromosomes enriched by flow sorting from a human x hamster hybrid cell line. Labeling of the PCR product pool and fluorescence in situ hybridization (FISH) demonstrated preferential binding to the distal long arm of the CHO X chromosome. The PCR products were cloned, labeled by PCR and hybridized to metaphase spreads. Clones containing highly reiterated DNA were identified by FISH and sequenced. Here, we present the sequence and chromosomal location of one of the repeat clones that maps close to the secondary constriction on the long arm of the CHO X chromosome, pCAT2066-24.