Biology subjects

Sanchez-Martinez, R.

Publications and source records attributed to Sanchez-Martinez, R..

4 recordsLinked to original sources

bioRxiv2025

Biological context modulates virus-host dynamics and diversification

Virus-host interactions are fundamental to microbial ecology and evolution, yet they are often studied in simplified systems. To assess the impact of biological complexity, we examined the halophilic bacterium Salinibacter ruber strain M1 and the EM1 virus, a bacteriophage that infects M1, in the presence of additional strains and viruses. In the short term, the presence of a biotic background delayed population-level lysis and reduced EM1 production. In the long term, both M1 and EM1 persisted across all conditions, but their evolutionary trajectories diverged. The virus accumulated many mutations, showed reduced infectivity against its native host, and expanded its host range in the presence of other viruses, highlighting a role of virus-virus interactions in promoting diversification. In contrast, the host accumulated more mutations when evolving with other bacterial strains. Taken together, these findings demonstrate that biological complexity shapes both the ecological dynamics and evolutionary trajectories of virus-host interactions.

microbiology↗

bioRxiv2024

Episomal virus maintenance enables bacterial population recovery from infection and virus-bacterial coexistence

Hypersaline environments harbor the highest concentrations of virus-like particles (VLPs) reported for aquatic ecosystems. The substantial densities of both microbial populations and VLPs challenge traditional explanations of top-down control exerted by viruses. At close to saturation salinities, prokaryotic populations are dominated by Archaea and the bacterial clade Salinibacter. In this work we examine the episomal maintenance of a virus within a Salinibacter ruber host. We found that infected cultures of Sal. ruber M1 developed a population-level resistance and underwent systematic and reproducible recovery post infection that was counter-intuitively dependent on the multiplicity of infection (MOI), where higher MOI led to better host outcomes. Furthermore, we developed a nonlinear population dynamics model that successfully reproduced the qualitative features of the recovery. This suggests that the maintenance of the virus episomally, often referred to as pseudolysogeny, and lysis inhibition allow for host-virus co-existence under high MOI infections. Our results emphasize the ecological importance of exploring a spectrum of viral infection strategies beyond the conventional binary of lysis or lysogeny.

microbiology↗

bioRxiv2021

Nasopharyngeal Microbiota as an early severity biomarker in COVID-19 hospitalised patients: a retrospective cohort study in a Mediterranean area.

BackgroundThere is mounting evidence suggesting that the microbiome composition could be different in COVID-19 patients. However, the relationship between microbiota and COVID-19 severity progression is still being assessed. This study aimed to analyse the diversity and taxonomic composition of the nasopharyngeal microbiota, to determine its association with COVID-19 clinical outcome. Methods and FindingsSamples came from a retrospective cohort of adult patients with COVID-19, hospitalised in a tertiary centre. To study the nasopharyngeal microbiota, we utilized 16S rRNA sequencing. Raw sequences were processed by QIIME2. The associations between the microbiota, invasive mechanical ventilation (IMV), and all-cause mortality were analysed by multiple logistic regression (OR; 95%CI), adjusted for age, gender, and comorbidity. 177 patients were included: median age 68.0 years, 57.6% males, 59.3% had a Charlson comorbidity index [≥]3, and 89.2% with pneumonia. The microbiota diversity indexes were lower in patients with a fatal outcome, and this association persisted after adjustment for the main confounders; whereas the {beta} diversity analysis showed a significant clustering, grouping the patients with a fatal outcome. After multivariate adjustment, the presence of Selenomonas spp., Filifactor spp., Actinobacillus spp., or Chroococcidiopsis spp., was associated with a reduced risk of IMV (adjusted OR 0.06[95%CI 0.01-0.0.47], p = 0.007). ConclusionsThe microbiota diversity and taxonomic composition are related to COVID-19 severity. Higher diversity and the presence of certain genera in the nasopharyngeal microbiota seem to be early biomarkers of a favourable clinical evolution in hospitalised patients with moderate to severe SARS-CoV-2 infections.

microbiology↗

bioRxiv2018

A more physiological approach to lipid metabolism alterations in cancer: CRC-like organoids assessment

Precision medicine might be the response to the recent questioning of the use of metformin as an anticancer drug in colorectal cancer (CRC). Thus, in order to establish properly its benefits, its application need to be assayed on the different progression stages of CRC. In this way, organoids imply a more physiological tool, representing a new therapeutic opportunity for CRC personalized treatment to assay tumor stage-dependent drugs effects. Since the lipid metabolism-related axis, ACSL/SCD, stimulates colon cancer progression and Metformin is able to rescuing the invasive and migratory phenotype conferred to cancer cells upon this axis overexpression; we checked ACSL/SCD status, its regulatory miRNAs and the effect of Metformin treatment in organoids as a model for specific and personalized treatment. Despite ACSL4 expression is upregulated in CRC-like organoids, Metformin is able to downregulate it, especially in the first stages. Besides, organoids are clearly more sensitive in this first stage (Apc mutated) to Metformin than current chemotherapeutic drugs such as fluorouracil (5-FU). Metformin performs an independent \"Warburg effect\" blockade to cancer progression and is able to reduce crypt stem cell markers expression such as Lgr5+. These results suggest a putative increased efficiency of the use of Metformin in the first stages of CRC than in advanced disease.

cancer biology↗