DNA adducts in tissues of germ-free and conventional rats fed high- and low-esterified pectins

Tissue samples from germ-free and conventional rats fed pectins with different degrees of esterification (DE) were tested for containing indigenous DNA adducts (I-compounds). For 21 days groups of six germ-free and 10 conventional rats each were fed either pectin-free or with diets containing 7.5% of three differently esterified pectin preparations (Pectin A, DE 92.6%; Pectin B, DE 70.8%; Pectin C, DE 34.5%). DNA was isolated from colonic mucosa, liver, lung, kidney and analysed for DNA adducts by the 32P-postlabelling assay. The experiments showed a tendency to a higher number and intensity of DNA-adduct-like spots (1) in the colonic mucosa compared with liver, lung, and kidney, (2) in germ-free compared with conventional rats, (3) with pectin-free compared with pectin-containing diets, (4) under the low-esterified compared with the higher-esterified pectins.