Radiation-Induced Changes in Tissue Nucleic Acids: Release of Soluble Deoxypolynucleotides in the Spleen

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Abstract
Subsequent to whole-body X-irradiation of mice at the LD100 dose level (810 to 850 r), a significant increase in the level of free deoxypolynucleotide is evident as early as 1 hour postirradiation. The maximum (350 [mu]g of deoxypolynucleotide per spleen) is reached 4 to 6 hours postexposure, and then declines steadily. By 14 hours the level is essentially zero and remains so for the 4-day period studied. The maximum release of polynucleotide occurs when the total spleen weight is decreasing and the DNA-nucleoprotein content of the spleen is falling precipitously. In nonirradiated mouse spleen the deoxypolynucleotide content is 20 ug per spleen-approximately 1% of the total DNA in this tissue. A new chemical fractionation of spleen makes possible the partition and chemical determination of deoxypolynucleotide in the presence of deoxyribonucleoprotein. The polynucleotide has been characterized by its solubility in [image]/15 phosphate buffer, insolubility in cold 0.2 [image] perchloric acid, ultraviolet absorption characteristics, positive Dische diphenylamine reaction, extinction coefficient per mole of phosphorus, and resistance to ribonuclease. The question as to whether the radiation-induced splenic polynucleotide formation is a primary radiation effect or is secondary to cell death is discussed.