Introduction Genomic DNA methylation is one of the most important epigenetic modifications in eukaryotes. It is essential for life and its alteration is often associated with disease. In animals, most of the methylation occurs at the 5 position of the pyrimidine ring of the cytosine. The resulting methylcytosine (mC) is mainly found in cytosine-guanine (CpG) dinucleotides. The presence of 5-mC in the promoter of specific genes alters the binding of transcriptional factors and other proteins to DNA and recruits methyl-DNA-binding proteins and histone deacetylases that compact the chromatin around the gene-transcription start site. Both mechanisms block transcription and cause gene silencing. Methylation of cytosine residues in genomic DNA plays a key role in the regulation of gene expression. There is an extensive range of methods based on the sodium bisulfite treatment for quantifying the methylation status of cytosines located in specific DNA regions. Bisulfite modification converts unmethylated cytosine to uracil, while methylated cytosine does not react (Figure 1). After denaturation and bisulfite modification, double-stranded DNA is obtained by primer extension and the fragment of interest is amplified by PCR. Procedure DNA Extraction from Frozen Tissue Sections
The design of a tax system is a daunting task. Economies have become increasingly complex, which makes the design of taxes has to take into account behavioral taxpayers' responses - including mobility -, but also tax planning issues. Additionally, increasing inequality trends put more pressure on design. This complex framework increases the need of complete and constantly updated information about the functioning of the system to carry out welfare-enhancing reforms and having stable sources of public funding. It seems now the moment the Spanish tax system takes advantage of all sources of information to undertake a necessary reform. For this ambitious purpose, we aim at providing a novel source of information: the (objective) opinion of tax professionals. From a survey all over Spain, tax professionals unanimously conclude the current tax system is unfair, while the main inefficiencies, rather than due to traditional responses, come out as a consequence of tax planning and tax mobility. We hope the complete results of the survey are a useful source of information.
Members of the Polycomb-group (PcG) family of proteins, including EZH2 (enhancer of zeste homolog 2), are involved in establishing epigenetic silencing of developmental genes in adult and embryonic stem cells, and their deregulation has been implicated in cancer. In a recent report, EZH2-mediated epigenetic repression of DNA damage repair in breast tumor initiating cells (BTICs) was identified as a mechanism that could promote expansion of BTICs, and may contribute to cancer progression.
Describing the relation DNA methylation has to gene silencing in disease, this book explores its promising role in treating cancer. Written by leaders in the field, it outlines the best techniques to use when addressing questions concerning the cytosine methylation status of genomic DNA. Including concepts, experimental models, and clinical uses of demethylating agents, the book provides articles clarifying methodological details and more general review chapters that offer broad biological perspectives on DNA methylation. This is an invaluable handbook for researchers and clinicians interested in genetics and molecular biology, particularly epigenetic therapies and gene silencing.
