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Ryszard Olinski - One of the best experts on this subject based on the ideXlab platform.

  • are 8 oxoguanine 8 oxogua and 5 hydroxymethyluracil 5 hmura oxidatively damaged dna bases or transcription epigenetic marks
    Mutation Research-genetic Toxicology and Environmental Mutagenesis, 2014
    Co-Authors: Ewelina Zarakowska, Daniel Gackowski, Marek Foksinski, Ryszard Olinski
    Abstract:

    The oxidatively modified DNA base 8-oxo-7,8-dihydroguanine (8-oxoGua) is nontoxic and weakly mutagenic. Here we report on new data suggesting a potential for 8-oxoGua to affect the expression of several genes via epigenetic changes resulting in chromatin relaxation. Using pig Thymus Extract, we analyzed the distribution of 8-oxoGua among different nuclei fractions representative of transcriptionally active and silenced regions. The levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) found in transcriptionally active euchromatin (4.37/10(6) nucleotides) and in the matrix fraction (4.16/10(6) nucleotides) were about 5 times higher than in transcriptionally silenced heterochromatin (0.91/10(6) nucleotides). Other experimental data are presented which suggest that 8-oxoGua present in specific DNA sequences may be widely used for transcription regulation. Like 8-oxoGua, 5-hydroxymethyluracil (5-hmUra) is another oxidatively modified DNA base (the derivative is formed by thymine oxidation). Recent experimental evidence supports the notion that 5-hmUra plays an important role in active DNA demethylation. This involves overexpression of activation-induced cytidine deaminase (AID) and ten-eleven translocation 1 (TET1) protein (the key proteins involved in active demethylation), which leads to global accumulation of 5-hmUra. Our preliminary data demonstrate a significant increase of the 5-hmUra levels in pig brain Extract when compared with liver Extract. The lack of 5-hmUra in Escherichia coli DNA also speaks for a role of this modification in the active demethylation process. It is concluded that 8-oxodG and 5-hmUra in DNA may be considered as epigenetic marks.

Ewelina Zarakowska - One of the best experts on this subject based on the ideXlab platform.

  • are 8 oxoguanine 8 oxogua and 5 hydroxymethyluracil 5 hmura oxidatively damaged dna bases or transcription epigenetic marks
    Mutation Research-genetic Toxicology and Environmental Mutagenesis, 2014
    Co-Authors: Ewelina Zarakowska, Daniel Gackowski, Marek Foksinski, Ryszard Olinski
    Abstract:

    The oxidatively modified DNA base 8-oxo-7,8-dihydroguanine (8-oxoGua) is nontoxic and weakly mutagenic. Here we report on new data suggesting a potential for 8-oxoGua to affect the expression of several genes via epigenetic changes resulting in chromatin relaxation. Using pig Thymus Extract, we analyzed the distribution of 8-oxoGua among different nuclei fractions representative of transcriptionally active and silenced regions. The levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) found in transcriptionally active euchromatin (4.37/10(6) nucleotides) and in the matrix fraction (4.16/10(6) nucleotides) were about 5 times higher than in transcriptionally silenced heterochromatin (0.91/10(6) nucleotides). Other experimental data are presented which suggest that 8-oxoGua present in specific DNA sequences may be widely used for transcription regulation. Like 8-oxoGua, 5-hydroxymethyluracil (5-hmUra) is another oxidatively modified DNA base (the derivative is formed by thymine oxidation). Recent experimental evidence supports the notion that 5-hmUra plays an important role in active DNA demethylation. This involves overexpression of activation-induced cytidine deaminase (AID) and ten-eleven translocation 1 (TET1) protein (the key proteins involved in active demethylation), which leads to global accumulation of 5-hmUra. Our preliminary data demonstrate a significant increase of the 5-hmUra levels in pig brain Extract when compared with liver Extract. The lack of 5-hmUra in Escherichia coli DNA also speaks for a role of this modification in the active demethylation process. It is concluded that 8-oxodG and 5-hmUra in DNA may be considered as epigenetic marks.

Myra Small - One of the best experts on this subject based on the ideXlab platform.

  • STUDIES ON SOME PHYSICOCHEMICAL PROPERTIES OF A Thymus HUMORAL FACTOR CONFERRING IMMUNOCOMPETENCE ON
    2013
    Co-Authors: Lymphoid Cells, Nathan Trainin, Myra Small
    Abstract:

    A humoral component of the Thymus appears to be involved in the process leading to attainment of immunological competence by lymphoid cells (1-4). In previous experiments we have demonstrated that this action of a Thymus humoral factor can be exerted directly upon dissociated cells from lymphoid tissue. Spleen cells from neonatally thymectomized mice exposed to Extracts prepared from Thymus of syngeneic origin acquired the capacity to initiate a graft-versus-host reaction against F1 spleen explants (5). This assay seemed to us a useful tool to answer further questions related to the chemical nature of the thymic factor and to the mechanism of its interaction with target cells. The present communication describes experiments aimed towards characterization of some physicochemical properties of the active agent of Thymus Extracts and investigation of the effects of these preparations when injected into normal and thymectomized mice. In order to obtain larger quantities of material for fractionation, xenogeneic Thymus Extract was required. Thus it was first necessary to determine that direct in vitro induction of immune competence of lymphoid cells can be achieved by Thymus Extracts of nonsyngeneic origin, and the activity of xenogeneic as well as allogeneic preparations on spleen cells from neonatally thymectomized mice was assayed. Fractions prepared from xenogeneic Extracts by prolonged centrifugation, dialysis, and ultrafiltration were then assayed in the in vitro test of graft-versus-host reactivity. In addition some of the active preparations were injected into neonatally thymectomized or intact mice and the immunocompetence of spleen cells of these mice was evaluated either by the in vitro graft-versus-host reaction (6) or by the in vivo Simonsen assay (7)

Marek Foksinski - One of the best experts on this subject based on the ideXlab platform.

  • are 8 oxoguanine 8 oxogua and 5 hydroxymethyluracil 5 hmura oxidatively damaged dna bases or transcription epigenetic marks
    Mutation Research-genetic Toxicology and Environmental Mutagenesis, 2014
    Co-Authors: Ewelina Zarakowska, Daniel Gackowski, Marek Foksinski, Ryszard Olinski
    Abstract:

    The oxidatively modified DNA base 8-oxo-7,8-dihydroguanine (8-oxoGua) is nontoxic and weakly mutagenic. Here we report on new data suggesting a potential for 8-oxoGua to affect the expression of several genes via epigenetic changes resulting in chromatin relaxation. Using pig Thymus Extract, we analyzed the distribution of 8-oxoGua among different nuclei fractions representative of transcriptionally active and silenced regions. The levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) found in transcriptionally active euchromatin (4.37/10(6) nucleotides) and in the matrix fraction (4.16/10(6) nucleotides) were about 5 times higher than in transcriptionally silenced heterochromatin (0.91/10(6) nucleotides). Other experimental data are presented which suggest that 8-oxoGua present in specific DNA sequences may be widely used for transcription regulation. Like 8-oxoGua, 5-hydroxymethyluracil (5-hmUra) is another oxidatively modified DNA base (the derivative is formed by thymine oxidation). Recent experimental evidence supports the notion that 5-hmUra plays an important role in active DNA demethylation. This involves overexpression of activation-induced cytidine deaminase (AID) and ten-eleven translocation 1 (TET1) protein (the key proteins involved in active demethylation), which leads to global accumulation of 5-hmUra. Our preliminary data demonstrate a significant increase of the 5-hmUra levels in pig brain Extract when compared with liver Extract. The lack of 5-hmUra in Escherichia coli DNA also speaks for a role of this modification in the active demethylation process. It is concluded that 8-oxodG and 5-hmUra in DNA may be considered as epigenetic marks.

Daniel Gackowski - One of the best experts on this subject based on the ideXlab platform.

  • are 8 oxoguanine 8 oxogua and 5 hydroxymethyluracil 5 hmura oxidatively damaged dna bases or transcription epigenetic marks
    Mutation Research-genetic Toxicology and Environmental Mutagenesis, 2014
    Co-Authors: Ewelina Zarakowska, Daniel Gackowski, Marek Foksinski, Ryszard Olinski
    Abstract:

    The oxidatively modified DNA base 8-oxo-7,8-dihydroguanine (8-oxoGua) is nontoxic and weakly mutagenic. Here we report on new data suggesting a potential for 8-oxoGua to affect the expression of several genes via epigenetic changes resulting in chromatin relaxation. Using pig Thymus Extract, we analyzed the distribution of 8-oxoGua among different nuclei fractions representative of transcriptionally active and silenced regions. The levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) found in transcriptionally active euchromatin (4.37/10(6) nucleotides) and in the matrix fraction (4.16/10(6) nucleotides) were about 5 times higher than in transcriptionally silenced heterochromatin (0.91/10(6) nucleotides). Other experimental data are presented which suggest that 8-oxoGua present in specific DNA sequences may be widely used for transcription regulation. Like 8-oxoGua, 5-hydroxymethyluracil (5-hmUra) is another oxidatively modified DNA base (the derivative is formed by thymine oxidation). Recent experimental evidence supports the notion that 5-hmUra plays an important role in active DNA demethylation. This involves overexpression of activation-induced cytidine deaminase (AID) and ten-eleven translocation 1 (TET1) protein (the key proteins involved in active demethylation), which leads to global accumulation of 5-hmUra. Our preliminary data demonstrate a significant increase of the 5-hmUra levels in pig brain Extract when compared with liver Extract. The lack of 5-hmUra in Escherichia coli DNA also speaks for a role of this modification in the active demethylation process. It is concluded that 8-oxodG and 5-hmUra in DNA may be considered as epigenetic marks.