Ten percent digestion of isolated nuclei by pancreatic deoxyribonuclease I preferentially removes globin DNA sequences from nuclei obtained from chick red blood cells but not from nuclei obtained from fibroblasts, from brain, or from a population of red blood cell precursors. Moreover, the nontranscribed ovalbumin sequences in nuclei isolated from red blood cells and fibroblasts are retained after mild deoxyribonuclease I digestion. This suggests that active genes are preferentially digested by deoxyribonuclease I. In contrast, treatment of red cell nuclei with staphylococcal nuclease results in no preferential digestion of active globin genes. When the 11S monomers obtained after staphylococcal nuclease digestion of nuclei are then digested with deoxyribonuclease I, the active globin genes are again preferentially digested. The results indicate that active genes are probably associated with histones in a subunit conformation in which the associated DNA is particularly sensitive to digestion by deoxyribonuclease I.

Chromosomal subunits in active genes have an altered conformation

Large contrasts are observed between the messenger RNA populations of different tissues and of embryos at different stages of development. Nevertheless, coding sequences for genes not expressed in a cell appear to be present in its nuclear RNA. Though many nuclear RNA transcripts of single copy DNA sequences are held in common between tissues, an additional set, probably consisting of non-message sequences, is not shared. Nuclear RNA also contains transcripts of repetitive DNA sequences. Certain repeat families are represented at high levels in the nuclear RNA of particular tissues and much lower levels in others. It is surprising that both complements of most repeat sequences are present in nuclear RNA. These observations lead to model for regulation of gene expression in which the formation of repetitive RNA-RNA duplexes controls the production of messenger RNA.

https://science.sciencemag.org/content/sci/204/4397/1052.full.pdf

Regulation of gene expression: possible role of repetitive sequences

https://www.cell.com/cell/pdf/0092-8674(76)90139-2.pdf

The expression of three abundance classes of messenger RNA in mouse tissues

https://www.cell.com/cell/pdf/0092-8674(80)90410-9.pdf

Interaction of HMG 14 and 17 with actively transcribed genes

Structural Gene Sets Active in Embryos and Adult Tissues of the Sea Urchin

https://www.cell.com/cell/pdf/0092-8674(75)90118-X.pdf

A kinetic estimation of base sequence complexity of nuclear poly(A)-containing RNA in mouse Friend cells.

The diversity of the messenger RNA population in growing friend cells

The base-sequence complexities of polysomal poly(A)+ RNA, nuclear poly(A)+ RNA, and total nuclear RNA from Friend erythroleukemia cells in logarithmic phase of growth were determined by measuring the proportion of labeled unique mouse DNA sequences which formed hybrids when incubated with a vast excess of each RNA. It was estimated that the RNAs had been transcribed from 1.8, 7.6, and 8.3%, respectively, of the haploid mouse genome. Although these estimates for polysomal and nuclear poly(A)+ RNAs were 2.5 times greater than those previously determined by analysis of the kinetics of the hybridization reactions between the RNAs and the cDNAs transcribed from them, they confirmed that the base-sequence complexity of nuclear poly(A)+ RNA in these cells is at least four times greater than that of polysomal poly(A)+ RNA.

B.D. Young

Papers

A kinetic estimation of base sequence complexity of nuclear poly(A)-containing RNA in mouse Friend cells.

The diversity of the messenger RNA population in growing friend cells

Comparison of the base-sequence complexities of polysomal and nuclear RNAs in growing Friend erythroleukemia cells