Biology subjects

Courel, M.

Publications and source records attributed to Courel, M..

3 recordsLinked to original sources

bioRxiv2026

Metabolic reorganization shapes the dynamics of a water kefir microbial community

Microbial fermentations emerge from the collective activity of interacting species whose relative abundances, metabolic functions, and environmental constraints continuously change over time. Water kefir provides a tractable model to investigate how multispecies communities coordinate their metabolic activities during fermentation. Here, we combined time-resolved community profiling, physicochemical measurements, metabolite quantification, and controlled co-culture assays to characterize the dynamics of a water kefir consortium comprising 19 detected microbial species. Our results reveal that water kefir fermentation is not adequately described as a simple succession of independently acting microbial groups. Instead, the community undergoes a reproducible reorganization of its collective metabolism around 20 h of fermentation. This transition marks a shift from an early regime characterized by the accumulation of soluble sugars and ethanol to a later regime dominated by enhanced sugar consumption and lactate production. Controlled interaction assays further showed that bacterial partners can alter carbon-use behaviour in Saccharomyces cerevisiae, highlighting the capacity of interspecies interactions to reshape metabolic phenotypes within the consortium. Together, these results support an ecological view of water kefir fermentation in which community-wide metabolic reorganization emerges from the interplay between microbial interactions, resource availability, and environmental change.

microbiology↗

bioRxiv2024

Cell cycle-dependent mRNA localization in P-bodies

Understanding the dynamics of RNA targeting to membraneless organelles is essential to disentangle their functions. Here, we investigate how P-bodies (PBs) evolve during cell cycle progression. PB purification across the cell cycle uncovers widespread changes in their RNA content, which are partly uncoupled from cell cycle-dependent changes in RNA expression. Single molecule FISH shows various mRNA localization patterns in PBs peaking in G1, S, or G2, with examples illustrating the timely capture of mRNAs in PBs when their encoded protein becomes dispensable. Yet, rather than directly reflecting absence of translation, cyclic mRNA localization in PBs can be controlled by RBPs, such as HuR in G2, and by RNA features. Indeed, while PB mRNAs are AU-rich at all cell cycle phases, they are specifically longer in G1, possibly related to post-mitotic PB reassembly. Altogether, our study supports a model where PBs are more than a default location for excess untranslated mRNAs.

cell biology↗

bioRxiv2018

GC content shapes mRNA decay and storage in human cells

Control of protein expression results from the fine tuning of mRNA synthesis, decay and translation. These processes, which are controlled by a large number of RNA-binding proteins and by localization in RNP granules such as P-bodies, appear often intimately linked although the rules of this interplay are not well understood. In this study, we combined our recent P-body transcriptome with various transcriptomes obtained following silencing of broadly acting mRNA decay and repression factors. This analysis revealed the central role of GC content in mRNA fate, in terms of P-body localization, mRNA translation and mRNA decay. It also rationalized why PBs mRNAs have a strikingly low protein yield. We report too the existence of distinct mRNA decay pathways with preference for AU-rich or GC-rich transcripts. Compared to this impact of the GC content, sequence-specific RBPs and miRNAs appeared to have only modest additional effects on their bulk targets. Altogether, these results lead to an integrated view of post-transcriptional control in human cells where most regulation at the level of translation is dedicated to AU-rich mRNAs, which have a limiting protein yield, whereas regulation at the level of 5 decay applies to GC-rich mRNAs, whose translation is optimal.

molecular biology↗