Search results for "Bacterial genome size"

Random Genetic Drift and Selective Pressures Shaping the Blattabacterium Genome

2018

AbstractEstimates suggest that at least half of all extant insect genera harbor obligate bacterial mutualists. Whereas an endosymbiotic relationship imparts many benefits upon host and symbiont alike, the intracellular lifestyle has profound effects on the bacterial genome. The obligate endosymbiont genome is a product of opposing forces: genes important to host survival are maintained through physiological constraint, contrasted by the fixation of deleterious mutations and genome erosion through random genetic drift. The obligate cockroach endosymbiont, Blattabacterium – providing nutritional augmentation to its host in the form of amino acid synthesis – displays radical genome alterations…

Evolutionary Changes after Translational Challenges Imposed by Horizontal Gene Transfer

2019

International audience; Genes acquired by horizontal gene transfer (HGT) may provide the recipient organism with potentially new functions, but proper expression level and integration of the transferred genes in the novel environment are not granted. Notably, transferred genes can differ from the receiving genome in codon usage preferences, leading to impaired translation and reduced functionality. Here, we characterize the genomic and proteomic changes undergone during experimental evolution of Escherichia coli after HGT of three synonymous versions, presenting very different codon usage preference, of an antibiotic resistance gene. The experimental evolution was conducted with and without…

Whole-genome sequencing of Neisseria gonorrhoeae in a forensic transmission case.

2019

Abstract Molecular epidemiology and phylogenetic analyses are frequently used in the investigation of viral transmission cases in forensic contexts. Here, we present the methods and results of the analysis of a bacterial transmission episode in an alleged child abuse case using complete genome sequences obtained by high-throughput sequencing (HTS) methods. We obtained genomes of Neisseria gonorrhoeae from the victim, the suspect, and 29 unrelated controls. The analysis of the genomes revealed that the victim and suspect isolates had identical sequences in both the bacterial chromosome and the single plasmid present in them. One of the local controls was very similar (differing in only 2 SNP…

Dissecting genome reduction and trait loss in insect endosymbionts

2016

Symbiosis has played a major role in eukaryotic evolution beyond the origin of the eukaryotic cell. Thus, organisms across the tree of life are associated with diverse microbial partners, conferring to the host new adaptive traits that enable it to explore new niches. This is the case for insects thriving on unbalanced diets, which harbor mutualistic intracellular microorganisms, mostly bacteria that supply them with the required nutrients. As a consequence of the lifestyle change, from free-living to host-associated mutualist, a bacterium undergoes many structural and metabolic changes, of which genome shrinkage is the most dramatic. The trend toward genome size reduction in endosymbiotic …

The Metabolic Building Blocks of a Minimal Cell

2020

This article belongs to the Section Evolutionary Biology.

panISa: ab initio detection of insertion sequences in bacterial genomes from short read sequence data.

2018

Abstract Motivation The advent of next-generation sequencing has boosted the analysis of bacterial genome evolution. Insertion sequence (IS) elements play a key role in prokaryotic genome organization and evolution, but their repetitions in genomes complicate their detection from short-read data. Results PanISa is a software pipeline that identifies IS insertions ab initio in bacterial genomes from short-read data. It is a highly sensitive and precise tool based on the detection of read-mapping patterns at the insertion site. PanISa performs better than existing IS detection systems as it is based on a database-free approach. We applied it to a high-risk clone lineage of the pathogenic spec…

2021

CRISPR-Cas immune systems adapt to new threats by acquiring new spacers from invading nucleic acids such as phage genomes. However, some CRISPR-Cas loci lack genes necessary for spacer acquisition despite variation in spacer content between microbial strains. It has been suggested that such loci may use acquisition machinery from cooccurring CRISPR-Cas systems within the same strain. Here, following infection by a virulent phage with a double-stranded DNA (dsDNA) genome, we observed spacer acquisition in the native host Flavobacterium columnare that carries an acquisition-deficient CRISPR-Cas subtype VI-B system and a complete subtype II-C system. We show that the VI-B locus acquires spacer…

Ancient bacterial genomes reveal a formerly unknown diversity ofTreponema pallidumstrains in early modern Europe

2020

SummarySexually transmitted (venereal) syphilis marked European history with a devastating epidemic at the end of the 15thcentury, and is currently re-emerging globally. Together with non-venereal treponemal diseases, like bejel and yaws, found in subtropical and tropical regions, it poses a prevailing health threat worldwide. The origins and spread of treponemal diseases remain unresolved, including syphilis’ potential introduction into Europe from the Americas. Here, we present the first genetic data from archaeological human remains reflecting a previously unknown diversity ofTreponema pallidumin historical Europe. Our study demonstrates that a variety of strains related to both venereal…

The effect of a temperature-sensitive prophage on the evolution of virulence in an opportunistic bacterial pathogen

2019

AbstractViruses are key actors of ecosystems and have major impacts on global biogeochemical cycles. Prophages deserve particular attention as they are ubiquitous in bacterial genomes and can enter a lytic cycle when triggered by environmental conditions. We explored how temperature affects the interactions between prophages and other biological levels by using an opportunistic pathogen, the bacterium Serratia marcescens, that harbours several prophages and that had undergone an evolution experiment under several temperature regimes. We found that the release of one of the prophages was temperature-sensitive and malleable to evolutionary changes. We further discovered that the virulence of …

A gene transfer agent and a dynamic repertoire of secretion systems hold the keys to the explosive radiation of the emerging pathogen Bartonella

2013

Gene transfer agents (GTAs) randomly transfer short fragments of a bacterial genome. A novel putative GTA was recently discovered in the mouse-infecting bacterium Bartonella grahamii. Although GTAs are widespread in phylogenetically diverse bacteria, their role in evolution is largely unknown. Here, we present a comparative analysis of 16 Bartonella genomes ranging from 1.4 to 2.6 Mb in size, including six novel genomes from Bartonella isolated from a cow, two moose, two dogs, and a kangaroo. A phylogenetic tree inferred from 428 orthologous core genes indicates that the deadly human pathogen B. bacilliformis is related to the ruminant-adapted clade, rather than being the earliest diverging…