What is the role of methylation in gene expression?5 answersDNA methylation plays a crucial role in gene expression regulation. Initially established patterns of DNA methylation in early development maintain a genome-wide network of gene regulatory elements in an inaccessible chromatin structure, influencing cell identity through gene expression profiles. DNA methylation can act as a repressive or activating mark for gene expression, interacting with histone modifiers to modulate transcriptional machinery binding. In plants, DNA methylation represses transposon activity and contributes to chromatin structure, with gene body methylation (gbM) positively correlating with gene expression levels. In Graves' orbitopathy, DNA methylation changes in orbital fibroblasts under autoimmune conditions lead to altered gene expression, affecting cell function and potentially contributing to the disease phenotype.
How and Where Are Genes Methylated?5 answersGenes are methylated through the addition of methyl groups to DNA bases, primarily at cytosine residues proximal to guanine bases. This methylation process is catalyzed by DNA methyltransferases, enzymes that utilize S-adenosylmethionine as the methyl group donor. DNA methylation plays a crucial role in regulating gene expression, impacting genome stability, and influencing development. It is involved in epigenetic modifications, imprinting, and silencing of genes, contributing to various biological processes such as gametogenesis, embryo development, and chromatin accessibility. The location-specific relationship between DNA methylation and gene expression underscores its significance in understanding disease processes and maintaining proper genomic function.
Are the genomes of pathogenic fungi methylated?4 answersYes, the genomes of pathogenic fungi are methylated. DNA methylation, specifically cytosine DNA methylation (5mC), has been observed in various pathogenic fungi such as Beauveria bassiana, Zymoseptoria tritici, and other phytopathogenic fungi. In these fungi, DNA methylation is found in transposable elements (TEs), gene promoter regions, and repetitive DNA sequences. The presence of functional DNA methyltransferase genes, such as Dim-2 and Dnmt5, correlates with high levels of 5mC in TEs, suggesting a role in genome defense. Additionally, DNA methylation has been associated with the regulation of gene expression, transposon silencing, and the modulation of development, pathogenicity, and secondary metabolism in fungal plant pathogens. These findings indicate that DNA methylation plays an important role in the biology and genome stability of pathogenic fungi.
What are the advantages and disadvantages of DNA methylation over SNPs?5 answersDNA methylation has several advantages over SNPs. First, DNA methylation can provide information about epigenetic variation, which can influence qualitative and quantitative traits in plants. Additionally, DNA methylation can regulate and stabilize gene expression patterns, contributing to cell identity and disease development, such as in type 2 diabetes. Furthermore, DNA methylation haplotypes can be identified using whole-genome bisulfite sequencing data, providing a clearer picture of the effect of DNA methylation on gene expression and chromosome structure. On the other hand, one disadvantage of DNA methylation is that current array-based methods rely on sodium bisulfite conversion, which can lead to ambiguity in data interpretation when there are polymorphisms at a methylation probe site. This can result in data loss and the exclusion of potentially informative sites.
How can I best normalise my samples from amplicon data?5 answersTo best normalize samples from amplicon data, the ONCOCNV method can be used. ONCOCNV includes a multifactor normalization and annotation technique that enables the detection of large copy number changes from amplicon sequencing data. This method has been validated on high and low amplicon density datasets and has shown comparable precision to array CGH techniques in detecting copy number aberrations. Using ONCOCNV eliminates the need for additional array CGH or SNP array experiments, making it a more efficient approach for copy number analysis in amplicon sequencing data.
What is the allelic frequency of the a allele globally?5 answersThe allelic frequency of the a allele globally is not provided in the abstracts.