36 research outputs found

    Complete Genome Sequence of the Aerobic CO-Oxidizing Thermophile Thermomicrobium roseum

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    In order to enrich the phylogenetic diversity represented in the available sequenced bacterial genomes and as part of an “Assembling the Tree of Life” project, we determined the genome sequence of Thermomicrobium roseum DSM 5159. T. roseum DSM 5159 is a red-pigmented, rod-shaped, Gram-negative extreme thermophile isolated from a hot spring that possesses both an atypical cell wall composition and an unusual cell membrane that is composed entirely of long-chain 1,2-diols. Its genome is composed of two circular DNA elements, one of 2,006,217 bp (referred to as the chromosome) and one of 919,596 bp (referred to as the megaplasmid). Strikingly, though few standard housekeeping genes are found on the megaplasmid, it does encode a complete system for chemotaxis including both chemosensory components and an entire flagellar apparatus. This is the first known example of a complete flagellar system being encoded on a plasmid and suggests a straightforward means for lateral transfer of flagellum-based motility. Phylogenomic analyses support the recent rRNA-based analyses that led to T. roseum being removed from the phylum Thermomicrobia and assigned to the phylum Chloroflexi. Because T. roseum is a deep-branching member of this phylum, analysis of its genome provides insights into the evolution of the Chloroflexi. In addition, even though this species is not photosynthetic, analysis of the genome provides some insight into the origins of photosynthesis in the Chloroflexi. Metabolic pathway reconstructions and experimental studies revealed new aspects of the biology of this species. For example, we present evidence that T. roseum oxidizes CO aerobically, making it the first thermophile known to do so. In addition, we propose that glycosylation of its carotenoids plays a crucial role in the adaptation of the cell membrane to this bacterium's thermophilic lifestyle. Analyses of published metagenomic sequences from two hot springs similar to the one from which this strain was isolated, show that close relatives of T. roseum DSM 5159 are present but have some key differences from the strain sequenced

    Comprehensive Cancer-Predisposition Gene Testing in an Adult Multiple Primary Tumor Series Shows a Broad Range of Deleterious Variants and Atypical Tumor Phenotypes.

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    Multiple primary tumors (MPTs) affect a substantial proportion of cancer survivors and can result from various causes, including inherited predisposition. Currently, germline genetic testing of MPT-affected individuals for variants in cancer-predisposition genes (CPGs) is mostly targeted by tumor type. We ascertained pre-assessed MPT individuals (with at least two primary tumors by age 60 years or at least three by 70 years) from genetics centers and performed whole-genome sequencing (WGS) on 460 individuals from 440 families. Despite previous negative genetic assessment and molecular investigations, pathogenic variants in moderate- and high-risk CPGs were detected in 67/440 (15.2%) probands. WGS detected variants that would not be (or were not) detected by targeted resequencing strategies, including low-frequency structural variants (6/440 [1.4%] probands). In most individuals with a germline variant assessed as pathogenic or likely pathogenic (P/LP), at least one of their tumor types was characteristic of variants in the relevant CPG. However, in 29 probands (42.2% of those with a P/LP variant), the tumor phenotype appeared discordant. The frequency of individuals with truncating or splice-site CPG variants and at least one discordant tumor type was significantly higher than in a control population (χ2 = 43.642; p ≤ 0.0001). 2/67 (3%) probands with P/LP variants had evidence of multiple inherited neoplasia allele syndrome (MINAS) with deleterious variants in two CPGs. Together with variant detection rates from a previous series of similarly ascertained MPT-affected individuals, the present results suggest that first-line comprehensive CPG analysis in an MPT cohort referred to clinical genetics services would detect a deleterious variant in about a third of individuals.JW is supported by a Cancer Research UK Cambridge Cancer Centre Clinical Research Training Fellowship. Funding for the NIHR BioResource – Rare diseases project was provided by the National Institute for Health Research (NIHR, grant number RG65966). ERM acknowledges support from the European Research Council (Advanced Researcher Award), NIHR (Senior Investigator Award and Cambridge NIHR Biomedical Research Centre), Cancer Research UK Cambridge Cancer Centre and Medical Research Council Infrastructure Award. The University of Cambridge has received salary support in respect of EM from the NHS in the East of England through the Clinical Academic Reserve. The views expressed are those of the authors and not necessarily those of the NHS or Department of Health. DGE is an NIHR Senior Investigator and is supported by the all Manchester NIHR Biomedical Research Centre

    Clinical Utility of Genotyping the 677C>T Variant of Methylenetetrahydrofolate Reductase in Humans Is Decreased in the Post-Folic Acid Fortification Era12

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    Moderate hyperhomocysteinemia is associated with many diseases. Major factors affecting plasma total homocysteine (tHcy) concentrations include folate concentrations and polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene. Because U.S.-mandated fortification of grain products with folic acid has improved folate and tHcy status in Americans, we investigated the effect of the MTHFR 677C>T variant before and after fortification. We determined tHcy and folate concentrations in sera from 844 Caucasian and 587 African American participants in the Coronary Artery Risk Development in Young Adults study before and after fortification and we genotyped the MTHFR 677C>T variant. MTHFR 677TT homozygotes had higher (P < 0.01) tHcy concentrations both before and after fortification compared with MTHFR 677CC homozygotes. However, the difference between these 2 genotypes decreased from 2.5 μmol/L before fortification to <0.7 μmol/L postfortification (P < 0.01). In addition, the prevalence of moderate hyperhomocysteinemia (tHcy > 13 μmol/L) in 677TT homozygotes decreased from 33% before fortification to 12% postfortification (P < 0.01). Using a cutoff value of 13 μmol/L to define moderate hyperhomocysteinemia, the sensitivity of the MTHFR 677TT genotype to predict elevations in homocysteine was low (∼30%) both before and after folic acid fortification. Increasing the cutoff from 13 to 19 μmol/L increased the sensitivity of the assay before fortification to 62% but decreased the sensitivity to 17% postfortification. We conclude that after folic acid fortification in the US, measurement of tHcy rather than genotyping of MTHFR 677TT should be used as the primary assay for the diagnosis and monitoring of moderate hyperhomocysteinemia

    Soluble P-selectin predicts lower extremity peripheral artery disease incidence and change in the ankle brachial index: The Multi-Ethnic Study of Atherosclerosis (MESA)

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    ObjectiveTo determine the association of circulating P-selectin with prevalent and incident peripheral artery disease (PAD), the ankle brachial index (ABI), and change in the ABI.MethodsThe Multi-Ethnic Study of Atherosclerosis (MESA) is a prospective population-based cohort study including 6814 European descent, African American, Hispanic and Chinese men and women aged 45-84 at baseline. Four clinical exams took place after the baseline exam. After excluding those with ABI&gt;1.4, prevalent and incident PAD were defined as an ABI≤0.90. ABI progression was defined as progression from a normal ABI (0.91-1.4) to abnormal (≤0.90 or &gt;1.4) at a later exam.ResultsIn adjusted models, each SD (13 ng/mL) higher P-selectin was significantly associated with 0.007 lower ABI (95% CI ((-0.011, -0.004)), p &lt; 0.001), and an average change in the ABI of -0.006 ((-0.010, -0.003, p &lt; 0.001). P-selectin was significantly associated with a 1.17-fold greater odds of prevalent PAD ((1.02, 1.33), p = 0.03), and a 30% greater risk of incident PAD ((1.11, 1.53), p = 0.001), as well as progression from a normal ABI to an ABI≤ 0.90 (p = 0.003), but not to an ABI&gt;1.4 (p = 0.96). Addition of P-selectin to models containing traditional PAD risk factors and markers of inflammation/coagulation significantly improved the net reclassification for ABI progression (p = 0.03), but was only marginally significant for incident PAD (p = 0.06).ConclusionsP-selectin is significantly associated with the development of PAD. However, further research is needed in population-based studies to confirm prospective associations of P-selectin with incident PAD and change in the ABI, as well as its potential predictive ability
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