New gene expression in dimethylsulfoxide-treated friend erythroleukemia cells

Manifold expression of new cellular genes in human lymphoid neoplasia.

“…In cells transformed by virus genomes integrated into the host genome, ssDNA was greatly enriched with virus-specific coding DNA sequences, as compared with nDNA, but contained few, if any, sequences from the noncoding DNA strand or from the nonexpressed virus genes (9)(10)(11). In rat myogenic cells (12) or mouse erythroleukemia cells (13) undergoing differentiation, the analysis of ssDNA reflected the changes in transcriptional activity.…”

“…Over the past few years, such a fraction has been isolated in our laboratory in the form of a minor single-stranded component (ssDNA). In all normal or malignant cell systems studied, from human, murine, or avian origin, ssDNA amounted to 1.5-2% of the total nuclear DNA (nDNA); most of the ssDNA could be reassociated with unique-copy nDNA and 30-35% hybridized with homologous cytoplasmic RNAs (7)(8)(9)(10)(11)(12)(13)(14). It was also shown that 70-0% of ssDNA from the various cell systems (9)(10)(11)(12)(13)(14) consists ofnon-selfreassociating DNA chains, which can be reassociated with nonrepetitive nDNA and contains nearly all the ssDNA sequences hybridizable with homologous mRNAs (10).…”

“…Aliquots were distributed in sealed tubes (covered with paraffin oil before sealing) and incubated in a water bath at 66°C. The fraction of DNA in hybrid form was usually determined by treating aliquots with SI nuclease and measuring the trichloroacetic acid-precipitable radioactivity (9)(10)(11)(12)(13)(14). The results were expressed as percentages of the input radioactivity rendered S1 nuclease resistant, after deduction ofcontrol values (time 0, "2I-labeled DNA incubated with yeast RNA), which usually did not exceed 2-3%.…”

“…Cell nuclei were prepared as indicated above, nDNA was purified, and ssDNA was isolated by the improved method of hydroxylapatite chromatography (9-12) and purified by a second step ofhydroxylapatite chromatography. Labeling with "I was performed as described (13). The specific radioactivity, determined by measuring aliquots in gamma counter, was in the range of 1-3 * 107 cpm/,ug.…”

“…The results were expressed as percentages of the input radioactivity rendered S1 nuclease resistant, after deduction ofcontrol values (time 0, "2I-labeled DNA incubated with yeast RNA), which usually did not exceed 2-3%. For iterative cross-hybridization assays, S1 nuclease treatment was omitted, DNARNA hybrids were treated with pancreatic ribonuclease (RNase A, 25 ,g/ml) and TI RNase (10 yg/ml, 30 min at 25°C), and DNARNA hybrids were separated by centrifuging to equilibrium in a CsS04 gradient as previously described (11)(12)(13) and as shown in Fig. 1.…”