Biology subjects

Morselli, M.

Publications and source records attributed to Morselli, M..

3 recordsLinked to original sources

bioRxiv2017

DNA methylation estimation using methylation-sensitive restriction enzyme bisulfite sequencing (MREBS)

Whole-genome bisulfite sequencing (WGBS) and reduced representation bisulfite sequencing (RRBS) are widely used for measuring DNA methylation levels on a genome-wide scale(1). Both methods have limitations: WGBS is expensive and prohibitive for most large-scale projects; RRBS only interrogates 6-12% of the CpGs in the human genome(16,19). Here, we introduce methylation-sensitive restriction enzyme bisulfite sequencing (MREBS) which has the reduced sequencing requirements of RRBS, but significantly expands the coverage of CpG sites in the genome. We built a multiple regression model that combines the two features of MREBS: the bisulfite conversion ratios of single cytosines (as in WGBS and RRBS) as well as the number of reads that cover each locus (as in MRE-seq(12)). This combined approach allowed us to estimate differential methylation across 60% of the genome using read count data alone, and where counts were sufficiently high in both samples (about 1.5% of the genome), our estimates were significantly improved by the single CpG conversion information. We show that differential DNA methylation values based on MREBS data correlate well with those based on WGBS and RRBS. This newly developed technique combines the sequencing cost of RRBS and DNA methylation estimates on a portion of the genome similar to WGBS, making it ideal for large-scale projects of mammalian genomes.

genomics↗

bioRxiv2017

A Novel Uropathogenic Escherichia Coli Genome (strain D3) and Comparative Analysis with Other Uropathogenic and Nonpathogenic Strains

BackgroundBacterial urinary tract infections are extremely prevalent, with half of women having at least one infection at some point in their lives. Most often the causative pathogen is the common gut microbe Escherichia coli. One such E. coli, strain D3, caused a bladder infection in a male adult, and was resistant to multiple antibiotics. We sequenced and assembled the genome of D3, and present it along with a comparative analysis against other pathogenic and nonpathogenic E. Coli strains.\n\nResultsBy comparing the predicted proteins of D3 with those from 5 uropathogenic and 7 nonpathogenic E. Coli strains, we generated a list of 38 genes present in most (4-5) pathogenic strains, but absent in all nonpathogenic strains. Among these were 9 proteins of the Pap fimbrial operon, which has previously been associated with cell adherence and the formation of biofilms. Lastly, we analyzed the list of predicted genes uniquely present in D3 compared to all other strains, and identified multiple transposable elements.\n\nConclusionsThe presence of fimbria in most pathogenic E. coli strains, and their absence in nonpathogenic ones, suggests that they play a role in pathogenicity, a notion supported by previous work. We also found that D3-specific genes are strongly enriched with transposases, recombinases, and integrase, suggesting that these mobile elements have been inserted or expanded in D3, relative to other strains in the study.

pathology↗

bioRxiv2017

Histone demethylation and c-MYC activation enhance translational capacity in response to amino acid restriction

Nutrient limitation may elicit adaptive epigenetic changes but the nature and mechanisms of the cellular response to specific nutrient deficiencies are incompletely understood. We report that depriving human cells of amino acids (AAs) induces specific loss of H4K20me1 from gene bodies and elevated binding of c-MYC at promoters genome-wide. These effects are most pronounced at ribosomal protein and translation initiation genes, which are upregulated, leading to enhanced protein synthetic capacity. Combination of H4K20 methyltransferase depletion and c-MYC over-expression in rich media is required and sufficient to recapitulate the effects of AA restriction. Our data reveal an unexpected and epigenetically implemented increase in translational capacity when AAs are limiting, likely to safeguard the proteome by making effective use of limited resources.\n\nOne Sentence Summary: Combination of H4K20me1 demethylation and c-MYC activation enhance translational capacity in response to amino acid restriction.

molecular biology↗