Biology subjects

Courville, R.

Publications and source records attributed to Courville, R..

3 recordsLinked to original sources

bioRxiv2025

The Microbiotas Response to Host Adaptive Evolution

Over the past two decades, experimental evolution has significantly advanced our understanding of evolutionary patterns and mechanisms of genomic change. One critically underexplored dimension is the role of microbiota in host adaptive evolution. In this research we investigate the microbiota from forty laboratory-selected Drosophila melanogaster populations exhibiting four distinct aging trajectories, ranging from extremely-short lifespans to -long lifespans. Using metagenomic sequencing and colony forming unit (CFU) counts in both conventional and gnotobiotic conditions, we uncover substantial microbiota differentiation among these populations. The most striking pattern is the consistent loss of Wolbachia in populations selected for rapid aging, in contrast to its near complete dominance in long-lived populations. This suggests a positive association between relative abundance of Wolbachia and lifespan, alongside a negative correlation between Wolbachia and Acetic Acid Bacteria (AAB) titres. These findings position the microbiota, and particularly Wolbachia, as a potentially integral component in host life history evolution, with implications for understanding the microbial contributions to aging and adaptation. SignificanceFruit flies bred for short lifespans consistently lose the bacterial symbiote Wolbachia, while the microbiota of long-lived flies are almost entirely dominated by it. There is a stable, recurring link between this microbe and lifespan, and traits associated with lifespan. This persistent pattern suggests that microbiota, Wolbachia in particular, may play a direct role in shaping the evolution of lifespan.

microbiology↗

bioRxiv2022

Immune defense in Drosophila melanogaster depends on diet, sex, and mating status

Post-mating immunosuppression has been widely accepted as a female trait in Drosophila melanogaster. Our results challenge this notion by presenting a mating-immunity trade-off in males as well as in females. When inoculated with the fungal pathogen, Beauveria bassiana, both males and females die faster compared to inoculated virgins, and survival is lower when inoculated flies are continuously mated compared to a single day of mating. Past studies with Beauveria bassiana have shown females to be more susceptible to infection than males. Our results challenge this finding as well, showing that the direction of sexual dimorphism in immune defense depends on mating status, specific Beauveria bassiana strain, and fly genotype. Moreover, we show that survival after fungal infection is largely influenced by diet, and that post-infection dietary improvements can help enhance survival. Post-mating suppression in Drosophila survival of B. bassiana infection presents study opportunities with potential applications for biological control of insect vectors of human disease and insect crop pests.

physiology↗

bioRxiv2020

Cerebrospinal fluid (CSF) boosts metabolism and virulence expression factors in Acinetobacter baumannii

In a recent report by the Centers for Disease Control and Prevention (CDC), multidrug resistant (MDR) Acinetobacter baumannii is a pathogen described as an "urgent threat". Infection with this bacterium manifests as different diseases such as community and nosocomial pneumonia, bloodstream infections, endocarditis, urinary tract, wound infections, burn infections, skin and soft tissue infections, and meningitis. In particular, nosocomial meningitis, a common complication of neurosurgery caused by extensively-drug resistant (XDR) A. baumannii, is extremely challenging to manage. Therefore, it is necessary to identify signals, such as exposure to cerebrospinal fluid (CSF), that trigger expression of virulence factors that are associated with the successful establishment and progress of this infection. While a hypervirulent A. baumannii strain did not show changes in its transcriptome when incubated in the presence of CSF, a low-virulence isolate showed significant differences in gene expression and phenotypic traits. Exposure to 4% CSF caused increased expression of virulence factors such as fimbriae, pilins, and iron chelators, and virulence as determined in various model systems. Furthermore, although CSFs presence did not enhance bacterial growth, it was associated with an increase of expression of genes encoding transcription, translation, and the ATP synthesis machinery. Experiments to identify the active CSF component pointed to human serum albumin (HSA). ImportanceAcinetobacter baumannii, notorious for its multidrug resistant phenotype, overcomes nutrient deprived and desiccated conditions through its metabolic flexibility, pathogenic and physiological adaptability. Although this pathogen is commonly associated with respiratory infections, there have been a considerable amount of cases of A. baumannii bacterial meningitis. These infections are usually post-neurological surgery complications associated with high mortality rates ranging from 40 to 70%. This work describes interactions that may occur during A. baumannii infection of human cerebrospinal fluid (CSF). A. baumanniis displays capabilities to persist and thrive in a nutrient-limited environment, which also triggers the expression of virulence factors. This work also further explores A. baumanniis utilization of an essential component within CSF to trigger enhanced expression of genes associated with its pathoadaptibility in this environment.

microbiology↗