A chromatographic comparison of the nucleic acids from isologous newborn, adult, and neoplastic thymus.

The total tissue nucleic acids (DNA and RNA) have been isolated from normal and neoplastic mouse thymus glands and chromatographically fractionated. Significant differences in the chromatographic distribution of the nucleic acids from normal adult thymus and x-radiation-induced thymic lymphosarcoma were found. Chromatographic patterns intermediate between normal and tumor were found in the thymuses of irradiated animals prior to gross tumor formation. Since changes in the RNA fraction accounted for the major differences between the samples studied, RNA was then isolated from newborn, adult, and neoplastic thymus glands and chromatographically compared. The RNA distribution patterns for normal adult and tumor-containing thymus were significantly different, but the patterns for the RNA from the thymuses of newborn animals were very similar to those for the tumors. Since mitotic proliferation and immature cell forms are plentiful in rapidly growing newborn thymus, but not in adult thymus, this result suggests that the altered chromatographic pattern of RNA from tumor-containing thymus glands may be a manifestation of rapid growth and/or cell immaturity, rather than an intrinsic property of the neoplastic state.