Project description:While Neanderthals are extinct, fragments of their genome still persist in the genomes of contemporary humans. Here, we show that such Neanderthal-like sequences are not distributed randomly in contemporary human genomes. Specifically, while genome-wide frequency of Neanderthal-like sites is close to 6% in all out-of-Africa populations, genes involved in lipid catabolism contain large excess Neanderthal-like sequences in Europeans (24.3%), but not in Asians (12.4%). While lipid catabolism cannot be assayed in Neanderthals, we took advantage of genetic divergence between human populations, chimpanzees and Neanderthals to predict metabolic divergence expected from the observed excess of Neanderthal gene flow into Europeans. We confirmed predicted changes in lipid catabolism using hydrophobic metabolome measurements in the brain tissue and further linked these metabolic changes to gene expression divergence. 14 human and 6 chimpanzee samples were sequenced.
Project description:While Neanderthals are extinct, fragments of their genome still persist in the genomes of contemporary humans. Here, we show that such Neanderthal-like sequences are not distributed randomly in contemporary human genomes. Specifically, while genome-wide frequency of Neanderthal-like sites is close to 6% in all out-of-Africa populations, genes involved in lipid catabolism contain large excess Neanderthal-like sequences in Europeans (24.3%), but not in Asians (12.4%). While lipid catabolism cannot be assayed in Neanderthals, we took advantage of genetic divergence between human populations, chimpanzees and Neanderthals to predict metabolic divergence expected from the observed excess of Neanderthal gene flow into Europeans. We confirmed predicted changes in lipid catabolism using hydrophobic metabolome measurements in the brain tissue and further linked these metabolic changes to gene expression divergence.
Project description:Single Centre, open label assignment phase II clinical study.
To evaluate the effect of oral 200mg Methylene Blue tablets (administered 8x25mg) prior to endoscopy on double stranded DNA breaks in colonic biopsy samples assessed by histone gamma H2AX analysis, compared to control biopsies.
Project description:Whole-genome bisulfite sequencing (BS-Seq) measures cytosine methylation changes at single-base resolution and can be used to profile cell-free DNA (cfDNA). In plasma, ultrashort single-stranded cfDNA (uscfDNA, ~50 nt) has been identified together with 167 bp double-stranded mononucleosomal cell-free DNA (mncfDNA). However, the methylation profile of uscfDNA has not been described. Conventional BS-Seq workflows may not be helpful because bisulfite conversion degrades larger DNA into smaller fragments, leading to erroneous categorization as uscfDNA. We describe the “5mCAdpBS-Seq” workflow in which pre-methylated 5mC (5-methylcytosine) single-stranded adapters are ligated to heat-denatured cfDNA before bisulfite conversion. This method retains only DNA fragments that are unaltered by bisulfite treatment, resulting in less biased uscfDNA methylation analysis. Using 5mCAdpBS-Seq, uscfDNA had lower levels of DNA methylation (~15%) and was enriched in promoters and CpG islands. Hypomethylated uscfDNA fragments were enriched in upstream transcription start sites (TSSs), and the intensity of enrichment positively affected gene expression of hemopoietic cells. Using tissue-of-origin deconvolution, we inferred that uscfDNA is derived primarily from eosinophils, neutrophils, and monocytes. As proof-of-principle, we show that characteristics of the methylation profile of uscfDNA can distinguish non-small cell lung carcinoma from non-cancer samples. The 5mCAdpBS-Seq workflow is recommended for any cfDNA methylation-based investigations.
Project description:A ssDNA library protocol was applied to cfDNA from plasma samples obtained from different DNA extraction methods and revealed significant differences in DNA fragmentation patterns in comparison to dsDNA-based protocols. In particular, a specific combination of methods revealed a population of ultrashort fragments, organized at ~50 bp. We observed significant differences in the relative abundance of these ultrashort DNA fragments in plasma from healthy individuals and cancer patients. Through shallow whole genome sequencing (sWGS, <0.5-fold coverage) and the analysis of somatic copy number aberrations (SCNA), we determined the landscape of genetic alterations in this newly identified population of cfDNA fragments. In addition, we studied their potential link with regulatory regions by investigating the genome-wide coverage patterns at transcription start sites (TSS). Furthermore, we demonstrated that the ultrashort cfDNA fragments map to regions associated with secondary DNA structures, G-quadruplexes (G4s).
Project description:Facial appearance is one of the most variable morphological traits in humans, influenced by both rare and common genetic variants that can impact facial form between individuals and in disease. Deletion of an enhancer cluster 1.45 megabases upstream of the SOX9 gene (EC1.45) results in Pierre Robin sequence, a human craniofacial disorder characterised by underdevelopment of the lower jaw and frequently associated with cleft palate. We reasoned that single nucleotide variants in EC1.45 may cause more subtle alterations to facial morphology. Here, we took advantage of recent human evolution, and the distinct morphology of the Neanderthal lower jaw, to investigate the impact of three Neanderthal-derived single nucleotide variants on EC1.45 function and jaw development. Utilising a dual enhancer-reporter system in zebrafish, we observed enhanced Neanderthal regulatory activity relative to the human orthologue during a specific developmental window. At this same stage, we show that EC1.45 appears to be selectively active in neural crest- derived progenitor cells which lie in close apposition with and are transcriptionally related to precartilaginous condensations that contribute to craniofacial skeletal development. To examine the potential consequences of increased SOX9 expression in this specific cellular population during jaw development, we overexpressed human SOX9 specifically in EC1.45-active cells and observed an increase in the volume of developing cartilaginous precursors. Taken together, our work implicates Neanderthal-derived variants in increased regulatory activity for a disease- associated enhancer with the potential to impact craniofacial skeletal development and jaw morphology across recent hominin evolution.