HAsh-MaP-ERadicator: Filtering Non-Target Sequences from Next Generation Sequencing Reads

Contemporary DNA sequencing technologies are continuously increasing throughput at ever decreasing costs. Moreover, due to recent advances in sequencing technology new platforms are emerging. As such computational challenges persist. The average read length possible has taken a giant leap forward with the PacBio and Nanopore solutions. Regardless of the platform used, impurities within the DNA preparation of the sample - be it from unintentional contaminants or pervasive symbiots - remains an issue. We have developed a new tool, HAsh-MaP-ERadicator (HAMPER), for the detection and removal of non-target, contaminating DNA sequences. Integrating hash-based and mapping-based strategies, HAMPER is both memory and time efficient while maintaining a high level of sensitivity. Moreover, HAMPER was designed for flexibility: reads of any size can be efficiently examined and the user can set parameters specific for the analysis of reads produced by a particular sequencer. To evaluate our method, mock sequencing runs were generated including various contaminating species and with variable rates of mutation revealing a high level of sensitivity and specificity. Reads that are not of interest can quickly be removed using HAMPER thus improving downstream analyses

Exploring the Diversity of Bacillus Whole Genome Sequencing Projects Using Peasant, the Prokaryotic Assembly and Annotation Tool

The persistent decrease in cost and difficulty of whole genome sequencing of microbial organisms has led to a dramatic increase in the number of species and strains characterized from a wide variety of environments. Microbial genome sequencing can now be conducted by small laboratories and as part of undergraduate curriculum. While sequencing is routine in microbiology, assembly, annotation and downstream analyses still require computational resources and expertise, often necessitating familiarity with programming languages. To address this problem, we have created a light-weight, user-friendly tool for the assembly and annotation of microbial sequencing projects. The Prokaryotic Assembly and Annotation Tool, Peasant, automates the processes of read quality control, genome assembly, and annotation for microbial sequencing projects. High-quality assemblies and annotations can be generated by Peasant without the need of programming expertise or high-performance computing resources. Furthermore, statistics are calculated so that users can evaluate their sequencing project. To illustrate the computational speed and accuracy of Peasant, the SRA records of 322 Illumina platform whole genome sequencing assays for Bacillus species were retrieved from NCBI, assembled and annotated on a single desktop computer. From the assemblies and annotations produced, a comprehensive analysis of the diversity of over 200 high-quality samples was conducted, looking at both the 16S rRNA phylogenetic marker as well as the Bacillus core genome. Peasant provides an intuitive solution for high-quality whole genome sequence assembly and annotation for users with limited programing experience and/or computational resources. The analysis of the Bacillus whole genome sequencing projects exemplifies the utility of this tool. Furthermore, the study conducted here provides insight into the diversity of the species, the largest such comparison conducted to date

Bacteriophages of the Urinary Microbiome

Bacterial viruses (bacteriophages) play a significant role in microbial community dynamics. Within the human gastrointestinal tract, for instance, associations amongst bacteriophages (phages), microbiota stability, and human health have been discovered. In contrast to the gastrointestinal tract, the phages associated with the urinary microbiota are largely unknown. Preliminary metagenomic surveys of the urinary virome indicate a rich diversity of novel lytic phage sequences, at an abundance far outnumbering eukaryotic viruses. These surveys, however, exclude the lysogenic phages residing within the bacteria of the bladder. To characterize this phage population, we examined 181 genomes representative of the phylogenetic diversity of bacterial species within the female urinary microbiota and found 457 phage sequences, 226 of which were predicted with high confidence. Phages were prevalent within the bladder bacteria: 86% of the genomes examined contained at least one phage sequence. Most of these phages are novel, exhibiting no discernible sequence homology to public data repositories. The presence of phages with substantial sequence similarity within the microbiota of different women supports the existence of a core community of phages within the bladder. Furthermore, the observed variation between the phage populations of women with and without overactive bladder symptoms suggests that phages may contribute to urinary health. To complement our bioinformatic analyses, viable phages were cultivated from the bacterial isolates for characterization; a novel coliphage was isolated, which is obligately lytic in the laboratory strain E. coli C. Sequencing of bacterial genomes facilitates a comprehensive cataloguing of the urinary virome while also revealing phage-host interactions.Importance Bacteriophages are abundant within the human body. But while some niches have been well surveyed, the phage population within the urinary microbiome is largely unknown. Our study is the first survey of the lysogenic phage population within the urinary microbiota. Most notably, the abundance of prophage exceeds that of the bacteria. Furthermore, many of the prophage sequences identified exhibited no recognizable sequence homology to data repositories. This suggests a rich diversity of uncharacterized phage species present in the bladder. Additionally, we observed a variation in the abundance of phages between bacteria isolated from asymptomatic \u27healthy\u27 individuals and those with urinary symptoms thus suggesting that, like phages within the gut, phages within the bladder may contribute to urinary health

Impact of Cigarette Smoke Exposure on Innate Immunity: A Caenorhabditis elegans Model

BACKGROUND: Cigarette smoking is the major cause of chronic obstructive pulmonary disease (COPD) and lung cancer. Respiratory bacterial infections have been shown to be involved in the development of COPD along with impaired airway innate immunity. METHODOLOGY/PRINCIPAL FINDINGS: To address the in vivo impact of cigarette smoke (CS) exclusively on host innate defense mechanisms, we took advantage of Caenorhabditis elegans (C. elegans), which has an innate immune system but lacks adaptive immune function. Pseudomonas aeruginosa (PA) clearance from intestines of C. elegans was dampened by CS. Microarray analysis identified 6 candidate genes with a 2-fold or greater reduction after CS exposure, that have a human orthologue, and that may participate in innate immunity. To confirm a role of CS-down-regulated genes in the innate immune response to PA, RNA interference (RNAi) by feeding was carried out in C. elegans to inhibit the gene of interest, followed by PA infection to determine if the gene affected innate immunity. Inhibition of lbp-7, which encodes a lipid binding protein, resulted in increased levels of intestinal PA. Primary human bronchial epithelial cells were shown to express mRNA of human Fatty Acid Binding Protein 5 (FABP-5), the human orthologue of lpb-7. Interestingly, FABP-5 mRNA levels from human smokers with COPD were significantly lower (p = 0.036) than those from smokers without COPD. Furthermore, FABP-5 mRNA levels were up-regulated (7-fold) after bacterial (i.e., Mycoplasma pneumoniae) infection in primary human bronchial epithelial cell culture (air-liquid interface culture). CONCLUSIONS: Our results suggest that the C. elegans model offers a novel in vivo approach to specifically study innate immune deficiencies resulting from exposure to cigarette smoke, and that results from the nematode may provide insight into human airway epithelial cell biology and cigarette smoke exposure

Membrane Invaginations Reveal Cortical Sites that Pull on Mitotic Spindles in One-Cell C. elegans Embryos

Asymmetric positioning of the mitotic spindle in C. elegans embryos is mediated by force-generating complexes that are anchored at the plasma membrane and that pull on microtubules growing out from the spindle poles. Although asymmetric distribution of the force generators is thought to underlie asymmetric positioning of the spindle, the number and location of the force generators has not been well defined. In particular, it has not been possible to visualize individual force generating events at the cortex. We discovered that perturbation of the acto-myosin cortex leads to the formation of long membrane invaginations that are pulled from the plasma membrane toward the spindle poles. Several lines of evidence show that the invaginations, which also occur in unperturbed embryos though at lower frequency, are pulled by the same force generators responsible for spindle positioning. Thus, the invaginations serve as a tool to localize the sites of force generation at the cortex and allow us to estimate a lower limit on the number of cortical force generators within the cell

Effects of a high-dose 24-h infusion of tranexamic acid on death and thromboembolic events in patients with acute gastrointestinal bleeding (HALT-IT): an international randomised, double-blind, placebo-controlled trial

Background: Tranexamic acid reduces surgical bleeding and reduces death due to bleeding in patients with trauma. Meta-analyses of small trials show that tranexamic acid might decrease deaths from gastrointestinal bleeding. We aimed to assess the effects of tranexamic acid in patients with gastrointestinal bleeding. Methods: We did an international, multicentre, randomised, placebo-controlled trial in 164 hospitals in 15 countries. Patients were enrolled if the responsible clinician was uncertain whether to use tranexamic acid, were aged above the minimum age considered an adult in their country (either aged 16 years and older or aged 18 years and older), and had significant (defined as at risk of bleeding to death) upper or lower gastrointestinal bleeding. Patients were randomly assigned by selection of a numbered treatment pack from a box containing eight packs that were identical apart from the pack number. Patients received either a loading dose of 1 g tranexamic acid, which was added to 100 mL infusion bag of 0·9% sodium chloride and infused by slow intravenous injection over 10 min, followed by a maintenance dose of 3 g tranexamic acid added to 1 L of any isotonic intravenous solution and infused at 125 mg/h for 24 h, or placebo (sodium chloride 0·9%). Patients, caregivers, and those assessing outcomes were masked to allocation. The primary outcome was death due to bleeding within 5 days of randomisation; analysis excluded patients who received neither dose of the allocated treatment and those for whom outcome data on death were unavailable. This trial was registered with Current Controlled Trials, ISRCTN11225767, and ClinicalTrials.gov, NCT01658124. Findings: Between July 4, 2013, and June 21, 2019, we randomly allocated 12 009 patients to receive tranexamic acid (5994, 49·9%) or matching placebo (6015, 50·1%), of whom 11 952 (99·5%) received the first dose of the allocated treatment. Death due to bleeding within 5 days of randomisation occurred in 222 (4%) of 5956 patients in the tranexamic acid group and in 226 (4%) of 5981 patients in the placebo group (risk ratio [RR] 0·99, 95% CI 0·82–1·18). Arterial thromboembolic events (myocardial infarction or stroke) were similar in the tranexamic acid group and placebo group (42 [0·7%] of 5952 vs 46 [0·8%] of 5977; 0·92; 0·60 to 1·39). Venous thromboembolic events (deep vein thrombosis or pulmonary embolism) were higher in tranexamic acid group than in the placebo group (48 [0·8%] of 5952 vs 26 [0·4%] of 5977; RR 1·85; 95% CI 1·15 to 2·98). Interpretation: We found that tranexamic acid did not reduce death from gastrointestinal bleeding. On the basis of our results, tranexamic acid should not be used for the treatment of gastrointestinal bleeding outside the context of a randomised trial

SARS-CoV-2 susceptibility and COVID-19 disease severity are associated with genetic variants affecting gene expression in a variety of tissues

Variability in SARS-CoV-2 susceptibility and COVID-19 disease severity between individuals is partly due to genetic factors. Here, we identify 4 genomic loci with suggestive associations for SARS-CoV-2 susceptibility and 19 for COVID-19 disease severity. Four of these 23 loci likely have an ethnicity-specific component. Genome-wide association study (GWAS) signals in 11 loci colocalize with expression quantitative trait loci (eQTLs) associated with the expression of 20 genes in 62 tissues/cell types (range: 1:43 tissues/gene), including lung, brain, heart, muscle, and skin as well as the digestive system and immune system. We perform genetic fine mapping to compute 99% credible SNP sets, which identify 10 GWAS loci that have eight or fewer SNPs in the credible set, including three loci with one single likely causal SNP. Our study suggests that the diverse symptoms and disease severity of COVID-19 observed between individuals is associated with variants across the genome, affecting gene expression levels in a wide variety of tissue types

A first update on mapping the human genetic architecture of COVID-19

peer reviewe

Survey of the Heritability and Sparse Architecture of Gene Expression Traits across Human Tissues

Understanding the genetic architecture of gene expression traits is key to elucidating the underlying mechanisms of complex traits. Here, for the first time, we perform a systematic survey of the heritability and the distribution of effect sizes across all representative tissues in the human body. We find that local h2 can be relatively well characterized with 59% of expressed genes showing significant h2 (FDR \u3c 0.1) in the DGN whole blood cohort. However, current sample sizes (n ≤ 922) do not allow us to compute distal h2. Bayesian Sparse Linear Mixed Model (BSLMM) analysis provides strong evidence that the genetic contribution to local expression traits is dominated by a handful of genetic variants rather than by the collective contribution of a large number of variants each of modest size. In other words, the local architecture of gene expression traits is sparse rather than polygenic across all 40 tissues (from DGN and GTEx) examined. This result is confirmed by the sparsity of optimal performing gene expression predictors via elastic net modeling. To further explore the tissue context specificity, we decompose the expression traits into cross-tissue and tissue-specific components using a novel Orthogonal Tissue Decomposition (OTD) approach. Through a series of simulations we show that the cross-tissue and tissue-specific components are identifiable via OTD. Heritability and sparsity estimates of these derived expression phenotypes show similar characteristics to the original traits. Consistent properties relative to prior GTEx multi-tissue analysis results suggest that these traits reflect the expected biology. Finally, we apply this knowledge to develop prediction models of gene expression traits for all tissues. The prediction models, heritability, and prediction performance R2 for original and decomposed expression phenotypes are made publicly available (https://github.com/hakyimlab/PrediXcan)

Survey of the Heritability and Sparse Architecture of Gene Expression Traits across Human Tissues

Understanding the genetic architecture of gene expression traits is key to elucidating the underlying mechanisms of complex traits. Here, for the first time, we perform a systematic survey of the heritability and the distribution of effect sizes across all representative tissues in the human body. We find that local h2&nbsp;can be relatively well characterized with 59% of expressed genes showing significant h2&nbsp;(FDR &lt; 0.1) in the DGN whole blood cohort. However, current sample sizes (n&nbsp;&le; 922) do not allow us to compute distal h2. Bayesian Sparse Linear Mixed Model (BSLMM) analysis provides strong evidence that the genetic contribution to local expression traits is dominated by a handful of genetic variants rather than by the collective contribution of a large number of variants each of modest size. In other words, the local architecture of gene expression traits is sparse rather than polygenic across all 40 tissues (from DGN and GTEx) examined. This result is confirmed by the sparsity of optimal performing gene expression predictors via elastic net modeling. To further explore the tissue context specificity, we decompose the expression traits into cross-tissue and tissue-specific components using a novel Orthogonal Tissue Decomposition (OTD) approach. Through a series of simulations we show that the cross-tissue and tissue-specific components are identifiable via OTD. Heritability and sparsity estimates of these derived expression phenotypes show similar characteristics to the original traits. Consistent properties relative to prior GTEx multi-tissue analysis results suggest that these traits reflect the expected biology. Finally, we apply this knowledge to develop prediction models of gene expression traits for all tissues. The prediction models, heritability, and prediction performance R2&nbsp;for original and decomposed expression phenotypes are made publicly available (https://github.com/hakyimlab/PrediXcan). </div