Preliminary studies on the differential removal of products formed in the DNA of various rat organs after chronic administration of a low dose of zinc

Metals can bind to various sites on the bases, the phosphate groups and/or sugars in DNA, depending on the physico-chemical characteristics of the metal ion. Up till now most studies concerned with the interaction of metal ions with DNA and polynucleotides have been carried out in vitro. In the present study, 23 ppm Zn 2+ was administered chronically to rats in the drinking water for periods up to 1 week, after which the DNA was isolated from liver, kidney, ileum, colon and brain. The DNA was subsequently hydrolysed and the purine bases separated on Sephadex G-10. Three products of metalation were eluted. There were differences in the overall levels of metalation and in the capacity of the different organs to remove the major product of metalation from the DNA: after 7 days the Zn 2+ content of this adduct in brain and kidney was 2 and 4 times respectively that of the controls, but in colon and ileum it had returned to control values, despite the continued administration of Zn 2+.