Search results for " evolution."

The Palliative Care in the Metastatic Spinal Tumors. A Systematic Review on the Radiotherapy and Surgical Perspective

2022

Spine represents the most common site for metastatic disease involvement. Due to the close relationship between the spinal cord and critical structures, therapeutic management of spinal metastases remains challenging. Spinal localization can lead to neurological sequelae, which can significantly affect the quality of life in patients with a limited life expectancy. The authors conducted a systematic literature review according to PRISMA guidelines in order to determine the impact of the most updated palliative care on spinal metastases. The initial literature search retrieved 2526 articles, manually screened based on detailed exclusion criteria. Finally, 65 studies met the inclusion criteri…

Evolutionary Dynamics of Pathoadaptation Revealed by Three Independent Acquisitions of the VirB/D4 Type IV Secretion System in Bartonella

2017

The α-proteobacterial genus Bartonella comprises a group of ubiquitous mammalian pathogens that are studied as a model for the evolution of bacterial pathogenesis. Vast abundance of two particular phylogenetic lineages of Bartonella had been linked to enhanced host adaptability enabled by lineage-specific acquisition of a VirB/D4 type IV secretion system (T4SS) and parallel evolution of complex effector repertoires. However, the limited availability of genome sequences from one of those lineages as well as other, remote branches of Bartonella has so far hampered comprehensive understanding of how the VirB/D4 T4SS and its effectors called Beps have shaped Bartonella evolution. Here, we repor…

Experimental evolution of an RNA virus in cells with innate immunity defects

2015

Experimental evolution studies have shown that RNA viruses respond rapidly to directional selection and thus can adapt efficiently to changes in host cell tropism, antiviral drugs, or other imposed selective pressures. However, the evolution of RNA viruses under relaxed selection has been less extensively explored. Here, we evolved vesicular stomatitis virus in mouse embryonic fibroblasts knocked-out for PKR, a protein with a central role in antiviral innate immunity. Vesicular stomatitis virus adapted to PKR-negative mouse embryonic fibroblasts in a gene-specific manner, since the evolved viruses exhibited little or no fitness improvement in PKR-positive cells. Full-length sequencing revea…

Evidence for Positive Selection in the Capsid Protein-Coding Region of the Foot-and-Mouth Disease Virus (FMDV) Subjected to Experimental Passage Regi…

2001

We present sequence data from two genomic regions of foot-and-mouth disease virus (FMDV) subjected to several experimental passage regimens. Maximum-likelihood estimates of the nonsynonymous-to-synonymous rate ratio parameter (dN/dS) suggested the action of positive selection on some antigenic sites of the FMDV capsid during some experimental passages. These antigenic sites showed an accumulation of convergent amino acid replacements during massive serial cytolytic passages and also in persistent infections of FMDV in cell culture. This accumulation was most significant at the antigenic site A (the G-H loop of capsid VP1), which includes an Arg-Gly-Asp (RGD) cellular recognition motif. Our …

When earwig mothers do not care to share: Parent–offspring competition and the evolution of family life

2017

Kin competition often reduces – and sometimes entirely negates – the benefits of cooperation among family members. Surprisingly, the impact of kin competition on the fitness effects of family life only received close scrutiny in studies on sibling rivalry, whereas the possibility of parent–offspring competition has attracted much less attention. As a consequence, it remains unclear whether and how parent–offspring competition could have affected the early evolution of parental care and family life. Here, we examined the occurrence and consequences of parent–offspring competition over food access in the European earwig Forficula auricularia, an insect with facultative family life reminiscent…

La difficile instauration du partenariat dans le secteur du bâtiment et des travaux publics: une analyse par les mécanismes de contrôle

1999

From an empirical study on one firm with network type organizational structure, this article explains the configurations of control in the coordination of partners. Investigations on the implemented control system have specified risks and control mechanisms associated to the levels of the networking development. This work shows that two different shapes of control are in use within one organization. Control is transactional-oriented between institutions and relational-oriented between individuals.

Genomic evolution of bacterial populations under co-selection by antibiotics and phage

2017

Bacteria live in dynamic systems where selection pressures can alter rapidly, forcing adaptation to the prevailing conditions. In particular, bacteriophages and antibiotics of anthropogenic origin are major bacterial stressors in many environments. We previously observed that populations of the bacterium Pseudomonas fluorescens SBW25 exposed to the lytic bacteriophage SBW25Φ2 and a noninhibitive concentration of the antibiotic streptomycin (coselection) achieved higher levels of phage resistance compared to populations exposed to the phage alone. In addition, the phage became extinct under coselection while remaining present in the phage alone environment. Further, phenotypic tests indicate…

Fight evolution with evolution: plasmid‐dependent phages with a wide host range prevent the spread of antibiotic resistance

2013

The emergence of pathogenic bacteria resistant to multiple antibiotics is a serious worldwide public health concern. Whenever antibiotics are applied, the genes encoding for antibiotic resistance are selected for within bacterial populations. This has led to the prevalence of conjugative plasmids that carry resistance genes and can transfer themselves between diverse bacterial groups. In this study, we investigated whether it is feasible to attempt to prevent the spread of antibiotic resistances with a lytic bacteriophage, which can replicate in a wide range of gram‐negative bacteria harbouring conjugative drug resistance–conferring plasmids. The counter‐selection against the plasmid was sh…

A lift in snail's gut provides an efficient colonization route for tardigrades.

2022

De novo Transcriptome Assembly and Comparison of C3, C3-C4, and C4 Species of Tribe Salsoleae (Chenopodiaceae)

2017

C4 photosynthesis is a carbon-concentrating mechanism that evolved independently more than 60 times in a wide range of angiosperm lineages. Among other alterations, the evolution of C4 from ancestral C3 photosynthesis requires changes in the expression of a vast number of genes. Differential gene expression analyses between closely related C3 and C4 species have significantly increased our understanding of C4 functioning and evolution. In Chenopodiaceae, a family that is rich in C4 origins and photosynthetic types, the anatomy, physiology and phylogeny of C4, C2, and C3 species of Salsoleae has been studied in great detail, which facilitated the choice of six samples of five representative …