title: Cytological evidence for switches in polarity of chromosomal DNA.
abstract: From the types of ring chromosomes induced in x-irradiated Chinese hamster ovary (CHO) cells, we deduce the existence of switches in the polarity of chromosomal DNA; if there is a continuous DNA double helix along the full length of the chromosome then the polarity switches imply 3'-3' and 5'-5' phosphodiester linkages. The resolution of the method is such that we estimate that there is one polarity switch for every 10(9) normal 3'-5' phosphodiester bonds.
mesh_terms: D002460:Cell Line; D002842:Chromatids / Q000378:metabolism*; D002875:Chromosomes / Q000528:radiation effects / Q000648:ultrastructure*; D003434:Crossing Over, Genetic; D008954:Models, Biological; D011830:Radiation Effects; D014965:X-Rays