STRUCTURAL-ANALYSIS OF THE AMPLIFIED IFN-BETA AND DHFR GENES IN A CHINESE-HAMSTER OVARY CELL-LINE USING MULTICOLOR FISH ANALYSIS

Multicolour FISH was used to get insight into the structural arrangeme nt of a homogeneously staining region which bears the co-transfected a nd subsequently co-amplified IFN-beta and DHFR genes in a CHO cell lin e. On metaphase chromosomes an arrangement of multiple bands with regu lar spacing is revealed. On extended chromatin fibres a cluster of dir ectly repeated and interspersed IFN-beta and DHFR genes is visible. Up to three clusters were found arranged in tandem. The different chromo somal mechanisms leading to gene amplification are discussed.