[Effect of mammalian and Escherichia coli DNA on rat somatic cell chromosomes]

High-polymer DNA isolated from mammalian lymphoid tissues (rat spleen, calf thymus) and from Escherichia coli increases the frequency of quantitative lesions in bone marrow cells of normal Wistar rats. The highest percentage of aberrant metaphases was revealed 24 hours after the injection of mammalian DNA, the frequency of aberrations being 9 times higher than the control values after the injection of heterologous DNA and 6 times higher-after the injection of homologous DNA. The effect observed was not a prolonged one, and 72 hours following the DNA injection the numbers of aberrant cells decreased to the control level. The maximal frequency of aberrations in bone marrow cells of rats treated with bacterial DNA was found 72 hours after the injection, when a 4-fold increase above the spontaneous aberration level was observed. Definite differences in the character of structural changes of chromosomes induced by DNA of different origin were revealed. Mammalian DNA injected produced the chromatid-type aberrations only. The injection of bacterial DNA led to the formation of both chromatid and chromosome aberrations. Possible mechanisms of the increase of chromosome aberration frequency in rat somatic cells under the action of high-polymer DNA of different origin are discussed.