Biology subjects

Iraola, G.

Publications and source records attributed to Iraola, G..

7 recordsLinked to original sources

bioRxiv2022

Improved detection and classification of plasmids from circularized and fragmented assemblies

Plasmids are mobile genetic elements important for bacterial adaptation. The study of plasmids from sequencing data is challenging because short reads produce fragmented assemblies, requiring of subsequent discrimination between chromosome and plasmid sequences. Although circularized assemblies are now possible using long-read data, there is still a need to differentiate plasmids from other circular elements. Here, we present plaSquid, a dockerized tool developed in Nextflow that expands plasmid detection and improves replicon typing and mobility groups classification schemes, outperforming previously available methods in both precision and sensitivity. When applied to [~]10.5 million metagenomic contigs, plaSquid revealed a 2.7-fold increase in plasmid phylogenetic diversity. Also, we used plaSquid to uncover a significant role of plasmids in the widespread distribution of clinically-relevant antimicrobial resistance genes in the built environment, from cities to spacecraft. Together, we present an improved approach to study plasmid biology from fragmented or circularized genomic and metagenomic assemblies.

bioinformatics↗

bioRxiv2020

Straightforward and reproducible analysis of bacterial pangenomes using Pagoo

Pangenome analysis is fundamental to explore evolutionary processes occurring in bacterial populations. However, the lack of standardized methods for handling diverse pangenomic datasets and complex metadata hinders more straightforward and reproducible downstream analyses. To fill this gap, we introduce Pagoo, a new framework that integrates pangenome data, analytical methods and visualization tools in a single object that can be easily stored, shared and responsively queried for improved biological interpretation of bacterial evolution.

bioinformatics↗

bioRxiv2020

Multiple introductions, regional spread and local differentiation during the first week of COVID-19 epidemic in Montevideo, Uruguay

BackgroundAfter its emergence in China in December 2019, the new coronavirus disease (COVID-19) caused by SARS-CoV-2, has rapidly spread infecting more than 3 million people worldwide. South America is among the last regions hit by COVID-19 pandemic. In Uruguay, first cases were detected on March 13 th 2020 presumably imported by travelers returning from Europe. MethodsWe performed whole-genome sequencing of 10 SARS-CoV-2 from patients diagnosed during the first week (March 16th to 19th) of COVID-19 outbreak in Uruguay. Then, we applied genomic epidemiology using a global dataset to reconstruct the local spatio-temporal dynamics of SARS-CoV-2. ResultsOur phylogeographic analysis showed three independent introductions of SARS-CoV-2 from different continents. Also, we evidenced regional circulation of viral strains originally detected in Spain. Introduction of SARS-CoV-2 in Uruguay could date back as early as Feb 20th. Identification of specific mutations showed rapid local genetic differentiation. ConclusionsWe evidenced early independent introductions of SARS-CoV-2 that likely occurred before first cases were detected. Our analysis set the bases for future genomic epidemiology studies to understand the dynamics of SARS-CoV-2 in Uruguay and the Latin America and the Caribbean region.

microbiology↗

bioRxiv2019

Pangenome analysis reveals genetic isolation in Campylobacter hyointestinalis subspecies adapted to different mammalian hosts

Campylobacter hyointestinalis is an emerging pathogen currently divided in two subspecies: C. hyointestinalis subsp. lawsonii which is restricted to pigs, and C. hyointestinalis subsp. hyointestinalis which can be found in a much wider range of mammalian hosts. Despite C. hyointestinalis has been reported as an emerging pathogen, its evolutionary and host-associated diversification patterns are still vastly unexplored. For this reason, we whole-genome sequenced 13 C. hyointestinalis subsp. hyointestinalis strains and performed a comprehensive comparative analysis including publicly available genomes of C. hyointestinalis subsp. hyointestinalis and C. hyointestinalis subsp. lawsonii to gain insight into the genomic variation of these differentially-adapted subspecies. Both subspecies are distinct phylogenetic lineages which present a barrier to homologous recombination, suggesting genetic isolation. This is further supported by accessory gene patterns that recapitulate the core genome phylogeny. Additionally, C. hyointestinalis subsp. hyointestinalis presents a bigger and more diverse accessory genome, which probably reflects its capacity to colonize different mammalian hosts unlike C. hyointestinalis subsp. lawsonii that is host-restricted. This greater plasticity in the accessory genome of C. hyointestinalis subsp. hyointestinalis correlates to a higher incidence of genome-wide recombination events, that may be the underlying mechanism driving its diversification. Concordantly, both subspecies present distinct patterns of gene families involved in genome plasticity and DNA repair like CRISPR-associated proteins and restriction-modification systems. Together, our results provide an overview of the genetic mechanisms shaping the genomes of C. hyointestinalis subspecies, contributing to understand the biology of Campylobacter species that are increasingly found as emerging pathogens.

genomics↗

bioRxiv2018

Nanopore sequencing significantly improves genome assembly of the eukaryotic protozoan parasite Trypanosoma cruzi

Chagas disease was described by Carlos Chagas, who first identified the parasite Trypanosoma cruzi from a two-year-old girl called Berenice. Many T. cruzi sequencing projects based on short reads have demonstrated that genome assembly and downstream comparative analyses are extremely challenging in this species, given that half of its genome is composed of repetitive sequences. Here, we report de novo assemblies, annotation and comparative analyses of the Berenice strain using a combination of Illumina short reads and MinION long reads. Our work demonstrates that Nanopore sequencing improves T. cruzi assembly contiguity and increases the assembly size in ~16 Mb. Specifically, we found that assembly improvement also refines the completeness of coding regions for both single copy genes and repetitive transposable elements. Beyond its historical and epidemiological importance, Berenice constitutes a fundamental resource since it now represents the best-quality assembly available for TcII, a highly prevalent lineage causing human infections in South America. The availability of Berenice genome expands the known genetic diversity of T. cruzi and facilitates more comprehensive evolutionary inferences. Our work represents the first report of Nanopore technology used to resolve complex protozoan genomes, supporting its subsequent application for improving trypanosomatid and other highly repetitive genomes.

genomics↗

bioRxiv2018

City-wide metagenomics uncover antibiotic resistance reservoirs in urban beach and sewage waters

BackgroundMicrobial communities present in environmental waters constitute a reservoir for antibiotic-resistant pathogens that impact human health. For this reason a diverse variety of water environments are being analyzed using metagenomics to uncover public health threats. However, the composition of these communities along the coastal environment of a whole city where sewage and beach waters are mixed, is poorly understood.\n\nResultsWe shotgun-sequenced 20 coastal areas from the city of Montevideo (capital of Uruguay) including beach and sewage water samples to characterize bacterial communities and their virulence and antibiotic resistance repertories. We found that sewage and beach environments presented significantly different bacterial communities. Sewage waters harbored a higher prevalence and a more diverse repertory of virulence and antibiotic resistant genes mainly from well-known enterobacteria, including carbapenemases and extended-spectrum betalactamases reported in hospital infections in Montevideo. Additionally, we were able to genotype the presence of both globally-disseminated pathogenic clones as well as emerging antibiotic-resistant bacteria in sewage waters.\n\nConclusionsOur study represents the first in using metagenomics to jointly analyze beaches and the sewage system from an entire city, allowing us to characterize antibiotic-resistant pathogens circulating in urban waters. The data generated in this initial study represent a baseline metagenomic exploration to guide future longitudinal (time-wise) studies, whose systematic implementation will provide useful epidemiological information to improve public health surveillance.

genomics↗

bioRxiv2018

The Tritryps comparative repeatome: insights on repetitive element evolution in Trypanosomatid pathogens

The major human pathogens Trypanosoma cruzi, Trypanosoma brucei and Leishmania major are collectively known as the Tritryps. The initial comparative analysis of their genomes has uncovered that Tritryps share a great number of genes, but repetitive DNA seems to be extremely variable between them. However, the in-depth characterization of repetitive DNA in these pathogens has been in part neglected, mainly due to the well-known technical challenges of studying repetitive sequences from de novo assemblies using short reads. Here, we compared the repetitive DNA repertories between the Tritryps genomes using genome-wide, low-coverage Illumina sequencing coupled to RepeatExplorer analysis. Our work demonstrates that this extensively implemented approach for studying higher eukaryote repeatomes is also useful for protozoan parasites like trypanosomatids, as we recovered previously observed differences in the presence and amount of repetitive DNA families. Additionally, our estimations of repetitive DNA abundance were comparable to those obtained from enhanced-quality assemblies using longer reads. Importantly, our methodology allowed us to describe a previously unknown transposable element in Leishmania major (TATE family), highlighting its potential to accurately recover distinctive features from poorly characterized repeatomes. Together, our results support the application of this low-cost, low-coverage sequencing approach for the extensive characterization of repetitive DNA evolutionary dynamics in trypanosomatid and other protozooan genomes.

genomics↗