Recovery of cable bacteria genomes from metagenomic samples
Ontology highlight
ABSTRACT: Metagenome sequencing of samples suspected of featuring cable bacteria genomic DNA with short (Illumina NovaSeq) and long read (Nanopore R9.4.1) sequencing platforms.
Project description:Cable bacteria of the family Desulfobulbaceae form centimeter-long filaments comprising thousands of cells. They occur worldwide in the surface of aquatic sediments, where they connect sulfide oxidation with oxygen or nitrate reduction via long-distance electron transport. In the absence of pure cultures, we used single-filament genome amplification and metagenomics to retrieve draft genomes of three marine Candidatus Electrothrix and one freshwater Ca. Electronema species. These genomes contain >50% of unknown genes but still largely share their core genomic makeup with sulfate-reducing and sulfur-disproportionating Desulfobulbaceae, with few genes lost and 212 unique genes conserved among cable bacteria. Last common ancestor analysis indicated gene divergence and lateral gene transfer as equally important origins of these unique genes. With support from metaproteomic data of Ca. Electronema, the genomes suggest that cable bacteria oxidize sulfide by inversing the canonical sulfate reduction pathway and fix CO2 using the Wood-Ljungdahl pathway. Cable bacteria show limited organotrophic potential, may assimilate smaller organic acids and alcohols, fix N2, and synthesize polyphosphates and polyglucose as storage compounds; several of these traits were confirmed by cell-level experimental analyses. We propose a model for electron flow from sulfide to oxygen that involves periplasmic cytochromes, type IV pili as integral components of conductive periplasmic fibers, and periplasmic oxygen reduction. This model proposes that an active cable bacterium gains energy in the anodic, sulfide-oxidizing cells, while cells in the oxic zone flare off electrons through intense cathodic oxygen respiration without energy conservation; this peculiar form of multicellularity seems unparalleled in the microbial world.
Project description:Low-GC Actinobacteria are among the most abundant and widespread microbes in freshwaters and have largely resisted all cultivation efforts. Consequently, their phages have remained totally unknown. In this work, we have used deep metagenomic sequencing to assemble eight complete genomes of the first tailed phages that infect freshwater Actinobacteria. Their genomes encode the actinobacterial-specific transcription factor whiB, frequently found in mycobacteriophages and also in phages infecting marine pelagic Actinobacteria. Its presence suggests a common and widespread strategy of modulation of host transcriptional machinery upon infection via this transcriptional switch. We present evidence that some whiB-carrying phages infect the acI lineage of Actinobacteria. At least one of them encodes the ADP-ribosylating component of the widespread bacterial AB toxins family (for example, clostridial toxin). We posit that the presence of this toxin reflects a 'trojan horse' strategy, providing protection at the population level to the abundant host microbes against eukaryotic predators.
Project description:The Pan-Cancer Analysis of Whole Genomes (PCAWG) study is an international collaboration to identify common patterns of mutation in more than 2,800 cancer whole genomes from the International Cancer Genome Consortium. Building upon previous work which examined cancer coding regions, this project is exploring the nature and consequences of somatic and germline variations in both coding and non-coding regions, with specific emphasis on cis-regulatory sites, non-coding RNAs, and large-scale structural alterations. Read more on the <a href=\"https://dcc.icgc.org/pcawg\" target=\"_blank\">project website</a>.<br>This is a subset featuring RNA-seq transcription profiling data of 27 cancer subtypes in 19 tissues. Some donors have matched normal tissue. As general reference, a subset of normal tissue samples from the GTEx project were included in this experiment.
Project description:RNA viruses cause significant human pathology and are responsible for the majority of emerging zoonoses. Mainstream diagnostic assays are challenged by their intrinsic diversity, leading to false negatives and incomplete characterisation. New sequencing techniques are expanding our ability to agnostically interrogate nucleic acids within diverse sample types, but in the clinical setting are limited by overwhelming host material and ultra-low target frequency. Through selective host RNA depletion and compensatory protocol adjustments for ultra-low RNA inputs, we are able to detect three major blood-borne RNA viruses - HIV, HCV and HEV. We recovered complete genomes and up to 43% of the genome from samples with viral loads of 104 and 103 IU/ml respectively. Additionally, we demonstrated the utility of this method in detecting and characterising members of diverse RNA virus families within a human plasma background, some present at very low levels. By applying this method to a patient sample series, we have simultaneously determined the full genome of both a novel subtype of HCV genotype 6, and a co-infecting human pegivirus. This method builds upon earlier RNA metagenomic techniques and can play an important role in the surveillance and diagnostics of blood-borne viruses.
Project description:The Pan-Cancer Analysis of Whole Genomes (PCAWG) study is an international collaboration to identify common patterns of mutation in more than 2,800 cancer whole genomes from the International Cancer Genome Consortium. Building upon previous work which examined cancer coding regions, this project is exploring the nature and consequences of somatic and germline variations in both coding and non-coding regions, with specific emphasis on cis-regulatory sites, non-coding RNAs, and large-scale structural alterations. Read more on the <a href=\"https://dcc.icgc.org/pcawg\" target=\"_blank\">project website</a>.<br>This is a subset featuring RNA-seq transcription profiling data of 27 cancer subtypes in 19 tissues. Some donors have matched normal tissue.<br>This is the alternative view of the experiment for Expression Atlas to show gene expression per donor.