Is DNA methylation modulated by wounding-induced oxidative burst in maize?

Plants respond to environmental changes by modifying gene expression. One of the mechanisms regulating gene expression is methylation of cytosine to 5-methylcytosine (m5C) which modulates gene expression by changing chromatin structure. Methylation/demethylation processes affect genes that are controlled upon environmental stresses. Here, on account of the regulatory role of m5C, we evaluate the content of m5C in DNA from normal and wound-damaged maize leaves. Wounding leads to a transient decrease of the global DNA methylation level ca 20-30% 1 hour after the treatment followed by a return to the initial level within the next hours. Similar results were obtained using of radio-labelled nucleotides separated by Thin Layer Chromatography (TLC) or using m5C-specific Enzyme-Linked Immunosorbent Assay (ELISA). Wounding induced in maize leaves a two-step oxidative stress, an early one just after wounding and the second two hours later. It coincides with the transient changes of the cytosine methylation level. In the stress-inducible maize calcium-dependent protein kinase ZmCPK11 gene wounding transiently reduced methylation of cytosines 100 and 126 in the first exon

Vernalization and photoperiod-related changes in the DNA methylation state in winter and spring rapeseed

Vernalization-induced flowering is an effect of the epigenetic regulation of gene expression through DNA methylation and histone modifications. Vernalization-mediated silencing of a floral repressor through histone modifications was shown in Arabidopsis thaliana. However, for Brassica napus L., the mechanism underlying vernalization is unclear, and the roles of DNA methylation and histone modifications have not been established. This study revealed the profiles of changes in the DNA methylation state during vernalization (after 14, 35, 56 days) and the subsequent growth in long- or short-day photoperiods (after 2, 7, 14 days) in the winter and spring rapeseed using TLC and MSAP techniques. TLC analysis showed a significant decrease in the amount of 5-methylcytosine (m5C) in genomic DNA in both cultivars at the beginning of vernalization, but upon its termination, the winter rape showed a reduced level of m5C contrary to a significantly increased level in the spring rape. MSAP analysis revealed that winter and spring rapeseed differed in the MSAP loci which were demethylated/methylated in the course of the experiment and presented diverse profiles of changes in the methylation state. The winter rape showed permanent demethylations at 69. 2 % of MSAP loci in the course of vernalization that were mostly preserved upon its termination. The spring rape showed similar numbers of demethylations and methylations that were mainly transient. The study provides evidence of the role of DNA methylation in vernalization for rapeseed and for the significant prevalence of demethylations at the beginning of vernalization, which is necessary for the transition to reproductive growth

The degree of global DNA hypomethylation in peripheral blood correlates with that in matched tumor tissues in several neoplasia.

There are no good blood and serum biomarkers for detection, follow up, or prognosis of brain tumors. However, they are needed for more detailed tumor classification, better prognosis estimation and selection of an efficient therapeutic strategy. The aim of this study was to use the epigenetic changes in DNA of peripheral blood samples as a molecular marker to diagnose brain tumors as well as other diseases. We have applied a very precise thin-layer chromatography (TLC) analysis of the global amount of 5-methylcytosine (m(5)C) in DNA from brain tumors, colon and breast cancer tissues and peripheral blood samples of the same patients. The m(5)C level in tissue DNA from different brain tumor types, expressed as R coefficient, changes within the range of 0.2-1.6 and overlaps with R of that of blood samples. It negatively correlates with the WHO malignancy grade. The global DNA hypomethylation quantitative measure in blood, demonstrates a big potential for development of non-invasive applications for detection of a low and a high grade brain tumors. We have also used this approach to analyze patients with breast and colon cancers. In all these cases the m(5)C amount in DNA cancer tissue match with data of blood. This study is the first to demonstrate the potential role of global m(5)C content in blood DNA for early detection of brain tumors and others diseases. So, genomic DNA hypomethylation is a promising marker for prognosis of various neoplasms as well as other pathologies

The list of brain tumor types identified in 183 patients for whom DNA from brain tumor tissue and peripheral blood samples was isolated and analyzed for the content of m⁵C in DNA.

<p>Specific R coefficient was calculated as (m5dC/m5dC+dC+dT)×100 on the basis of analysis TLC plate exposed to Phosphoimager. Histopathological analysis revealed the WHO grade. Sex is also mentioned.</p

Effect of brain tumor tissue handling on content of m⁵C in DNA.

<p>The level of m⁵C content (R) in DNA isolated from resected meningioma tissue (WHO grade I) stored at −80°C (grey bar), formalin-fixed paraffin-embedded (FFPE) (empty bar) and exposed to room temperature for 3 h (black bar). Analysis was done for 5 samples in each conditions. Standard deviations for R is shown.</p