Figure 3
Specificity of the array-CGH mapping method for mapping a complementing gene. Total genomic DNA of the complemented HPRT-deficient CHO-human radiation hybrid cells was co-hybridized with total genomic DNA from wild-type CHO cells on the microarray. The complemented hybrid cells contain the complete CHO genome and human chromosomal fragments. The human sequences are enriched in fragments bearing the complementing human HPRT gene. The magnitude of the increase in fluorescence ratio between the test and reference samples is indicated by the height of the red line (log10 scale) compared with the baseline, which has a fluorescence ratio of 1. Fluorescence ratios are drawn as a moving average of five adjacent genes/ESTs along the chromosome. Note that the region around the HPRT locus at Xq26 (inset) corresponds to a sharp maximum in the fluorescence ratio increase, indicating a corresponding gain in DNA copy number for genomic elements in that region. No such consistent copy-number gains were observed in other parts of the genome.