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N N Burtseva

Publications and source records attributed to N N Burtseva.

5 recordsLinked to original sources
PubMed1979

[Tissue specificity of the decrease of cattle lymphocyte DNA methylation during chronic lymphoid leukemia].

It has been found that the content of m5C in the DNA preparations tested have been revealed. The DNAs from normal and leukemic lymphocytes of blood, lymphonodi and spleen differ in ther acceptor ability in the reaction of heterologous methylation in vitro, induced by DNA-methylase from Enterobacter cloacea in the presence of [3H-methyl]S-adenosyl methionine: the ratio of radioactivities in methylated cytosine and adenine residues (m5C/m6A) in leukemic lymphocyte DNA is much lower than in healthy animals' lymphocytes. The decrease in the methylation of DNAs from various lymphoid organs of animals with chronic lymphoid leukemia is well correlated with the impairment. No significant changes of the m5C level and the acceptor ability of the in vitro reaction of heterologous methylation of cow lymph lymphocyte DNA have been observed. The data obtained may be interpreted in terms of tissue (cell) specificity or differences in the degree of DNA methylation under conditions of chronic lymphoid leukemia. It is assumed that the changes in DNA methylation may underlie the disturbances in the regulation of activity of the leukemic cell genetic mechanisms.

Animals↗
PubMed1979

[Intragenome distribution of 5-methyl cytosine and reassociation kinetics of cow blood lymphocyte DNA under normal conditions and in chronic lymphoid leukemia].

The DNA from cow blood lymphocytes is methylated in a varying degree: the maximal content of 5-methyl cytosine (2,3 mol%) is found in the "instantly" renaturating sequences (Cot lett than 10(-4)), a relatively large amount (1,4 mol%)--in moderately repeated sequences (Cot = 10(-4)--400) and the minimal amount (0,9 mol%) in the unique sequences (Cot greater than 400). In their reassociation kinetics, GC-content and other physico-chemical properties the blood lymphocyte DNA of the controls and of animals with chronic lymphoid leukemia appear to be similar. Consequently, the genome organization of leukemic animals does not change significantly; a considerable decrease of 5-methyl cytosine of lymphocyte DNA in lymphoid leukemia parallels the decrease of genome methylation in the leukemic cells. This decrease does not affect the unique sequences, but involves all types of repeated sequences (moderately and frequently repeated ones and palindromes). It is assumed that the specific disturbances in genome methylation under lymphoid leukemia may be a cause of transcription deficiences and cell transformations.

Animals↗
PubMed1978

[Changes in the specificity of DNA methylation in cattle blood lymphocytes under chronic lymphoid leukemia].

Under conditions of chronic (spontaneous) lympholeucosis the amount of 5-methylcytosine in cattle blood lymphocyte DNA is decreased approximately by 30%. No other changes in the DNA (e. g. GC-content, Tm, amount of pyrimidine sequences differing in their lengths and composition) were observed. Thus, the decrease in the amount of 5-methylcytosine in lymphocyte DNA is due to a decrease in DNA methylation. This decrease is non-random and involves mainly the Pu-m5C-Pu sequences without affecting the long pyrimidine blocks. In nuclear extracts from lymphocytes of healthy animals the DNA-methylase activity having an optimum at pH 6,0 was found; the DNA-methylase activities found in the nuclear extracts of leukaemic cow lymphocytes had their optima at pH 5,5 and 7,5. In vitro the DNA-methylase activities of leukaemic lymphocytes nuclei methylate the cytosine residues of DNA in other sequences than enzyme(s) of the extracts from normal lymphocyte nuclei. Changes in the pattern of DNA-methylase activities as well as the decrease and distortions in the character of DNA methylation may underlie the disturbances in the regulation of transcription of genome and cause the transformation of cells under conditions of lympholeucosis.

Animals↗
PubMedDate not supplied

[Conditions of dextranase formation by Penicillium funiculosum 15].

The influence of the following factors on the synthesis of extracellular dextranase by Pen. funiculosum 15 has been studied: the quantity and age of the inoculum, pH of the cultivation medium, stimulants of the microbial growth, cultivation temperature and time. The optimal amount of dextranase has been found to form under the following conditions: inoculum--3 day mycelium constituting 4%, cultivation time--4 to 7 days, temperature--28 to 29 degrees C, initial pH of the medium--6.0.

Culture Media↗