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Biomedical subjects

D Maryanka

Publications and source records attributed to D Maryanka.

7 recordsLinked to original sources
PubMed1983

Multiple differentiation programs in K562 erythroleukemia cells and their regulation.

The chronic myeloid leukemia-derived cell line K562 expresses, in its uninduced state, notable erythroid features. However, in addition to the presence of well-characterized "erythroid-specific" molecules, such as hemoglobin and glycophorin A, there is increasing evidence of both granulopoietic and megakaryocytic differentiation in this cell line. In this chapter we have further characterized erythroid and nonerythroid features in order to investigate the range of differentiation programs expressed by uninduced K562 cells. Also we have extended these observations by attempting to manipulate the expression of the different lineage-specific components of the phenotype of the K562 cell line in induction experiments. The aim of these studies was to attempt to determine the extent and significance of multipotentiality in K562. The relationship of our findings on the phenotype of K562 to the nature of multipotent hemopoietic stem cells and their differentiated progeny in normal and malignant hemopoiesis is discussed.

Animals↗
PubMed1979

Pathway-dependent reconstitution of chromatin structure from separated constituents.

Chicken reticulocyte chromatin can be reassembled from its separated constituents, viz. DNA, H1 plus H5, core histones, and non-histone proteins, to yield a product resembling the native starting material by a series of structural criteria. In particular, it possesses nucleosomes separated by spacer regions; the particles contain DNA with a unit length of approximately 200 base pairs. The recovery of the correctly reassembled product depends critically on the annealing conditions: the components are initially mixed in 2 M NaCl and 5 M urea, and it seems to be important to remove urea at a relatively high salt concentration. The results suggest that the characteristic chromatin structure is formed only when core histones bind to DNA in their native conformation and are followed by the addition of H1 and H5 to the spacer regions.

Animals↗
PubMed1974

Nonhistone proteins control gene expression in reconstituted chromatin.

Chromatin was reconstituted from the purified DNA and histones of chicken erythrocytes and the nonhistone proteins of either chicken reticulocytes or chicken liver. Reconstituted chromatins, native chicken reticulocyte chromatin, and free DNA were transcribed with Escherichia coli RNA polymerase and the concentrations of globin-specific sequences in the RNA products were measured by hybridization with [(3)H]DNA complementary to chicken globin messenger RNA. Reticulocyte, but not liver, nonhistone proteins were shown to activate the globin genes in reconstituted erythrocyte chromatin. The transcripts of native and reconstituted chromatins were indistinguishable in respect of both the total yield of the RNA and the fractional yield of globin-specific sequences.

Animals↗
PubMed1973

Transcription of rat-liver chromatin with homologous enzyme.

The product of transcription of rat-liver chromatin with homologous rat-liver Form-B polymerase in vitro is high molecular weight RNA with sedimentation coefficients principally in the range of 18-45 S. The average size is somewhat smaller than that of the heterogeneous high molecular weight RNA synthesized by the endogenous enzyme in vivo (or in isolated nuclei). We have excluded the possibility that this difference can be attributed to degradation of the nascent RNA occurring under the conditions of our experiments. The size of the RNA produced by the homologous enzyme nevertheless approaches that of the natural transcripts much more closely than does that of the RNA produced by bacterial RNA polymerases, which we, in addition to other authors, have found to sediment around 10 S.

Animals↗