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B Tyniec

Publications and source records attributed to B Tyniec.

4 recordsLinked to original sources
PubMed1978

Effect of ethidium bromide on the digestion of chromatin DNA with micrococcal nuclease.

Intercalation of ethidium bromide into DNA influences the rate of its digestion with micrococcal nuclease in opposite directions depending on whether it is free DNA or DNA in chromatin. In the case of free DNA the binding of ethidium bromide, starting from a very low concentration, results in the inhibition of the rate of digestion (increasing constantly with the increase of the ethidium bromide/nucleotide ratio). In contrast to free DNA the digestion rate as well as the overall amount of nuclease susceptible DNA is increased upon ethidium bromide binding to chromatin, with maximum enhancement around the saturation of intercalation sites. The saturation of intercalation sites in chromatin leads also to the disappearance of the typical micrococcal nuclease digestion pattern of DNA upon gel electrophoresis. Instead, a random cleavage pattern is observed. These data indicate that partial unwinding of chromatin DNA by ethidium bromide results in unmasking new sites for nuclease action. Interpretation of this finding in terms of the nucleosomal structure of chromatin and the mode of ethidium bromide binding to chromatin DNA indicates that newly unmasked sites are localized within the core particle DNA.

Animals↗
PubMed1978

Comparison of susceptibility to staphylococcal nuclease and behaviour in metrizamide gradients of normal and 5-bromodeoxyuridine-substituted chromatin from Physarum polycephalum.

Replacement of 20--30% of thymine by 5-bromodeoxyuridine in chromatin DNA of Physarum polycephalum does not cause any visible change in a typical, regular pattern of DNA products obtained upon digestion of chromatin with staphylococcal nuclease. The time course of digestion is similar for normal and substituted chromatin even under conditions when the nuclease cleaves preferentially the dAT regions in DNA. 5-Bromodeoxyuridine label does not significantly affect the DNA/protein ratio in chromatin; this is reflected by similar behaviour of normal and substituted chromatin in metrizamide-density gradients.

Bromodeoxyuridine↗
PubMed1977

Nucleoprotein chromatin subunit from Physarum polycephalum.

The nucleoproteins resulting from digestion of the nuclei of the true slime mold Pysarum polycephalum with micrococcal nuclease have been resolved according to the size classes in linear sucrose gradients containg 0.5 M NaCl, and analysed for DNA, RNA and protein content. The basic nucleoprotein subunit has been found to contain a DNA fragment of about 150--170 base pairs complexed with an approximately equal amount, on a weight basis, of basic proteins and a relatively small amount of non-histone proteins (about 35% of the amount of DNA). Higher nucleoprotein oligomers were shown to contain spacer DNA fragments between adjacent subunits and a considerably higher ratio of non-histone proteins to DNA than the basic subunit. Both the basic subunit and higher nucleoprotein oligomers of Physarum chromatin contain some amount of tightly bound RNA. However, in contrast to the distribution of the non-histone proteins, the ratio of RNA to RNA is similar in both fractions.

Chromatin↗