Biology subjects

Duvernois-Berthet, E.

Publications and source records attributed to Duvernois-Berthet, E..

7 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↗

bioRxiv2025

Interplay between petal identity and cell layer identity in petunia flowers

In flowering plants, floral organ identity is specified by the combinatorial action of homeotic genes. While the role of these genes in the early specification of organ identity is well established, their late function throughout floral organ development and in specific cell types is much less characterized. In particular, since plant organs are structured in clonally-independent cell layers, whether and how homeotic identity interacts with cell layer identity is unknown. We have previously identified cell layer-specific mutants for the petal identity gene PhDEF in petunia flowers, resulting in drastically different petal phenotypes whether PhDEF is expressed in the petal epidermis or in the mesophyll. In this study, using a combination of single-cell RNA-Seq and chromatin immunoprecipitation on phdef cell layer-specific mutants, we find that PhDEF regulates a different set of target genes in the petal epidermis and mesophyll, with a major regulatory action in the epidermis. We uncover a high diversity of binding profiles in PhDEF target genes, with a complex combination of layer-specific or non-specific binding sites, and a much more prominent binding of PhDEF in the epidermis than in the mesophyll. Our study highlights that floral homeotic genes like PhDEF can have different regulatory actions in different cell contexts, here different cell layers, demonstrating that cell layer identity indeed influences the regulatory processes underlying homeotic identity.

developmental biology↗

bioRxiv2023

Comparative transcriptomics reveal a novel tardigrade specific DNA binding protein induced in response to ionizing radiation

Tardigrades, microscopic animals found in virtually all ecosystems, are renowned for their remarkable ability to withstand extreme conditions. Recent studies have identified novel tardigrade specific protein families that aid in resistance to desiccation and ionizing radiation (IR). Notably, a tardigrade specific DNA binding protein called Dsup (for DNA damage suppressor) has been found to protect from X-ray damage in human cells and from hydroxyl radicals in vitro. However, Dsup has only been found in two species within the Hypsibioidea superfamily. To better understand mechanisms underlying radio-resistance in the Tardigrada phylum, we first characterized DNA damage and repair in response to IR in the model species Hypsibius exemplaris. By analysis of phosphorylated H2AX, we demonstrated the induction and repair of DNA double-strand breaks after IR exposure. Importantly, the rate of single-strand breaks induced was roughly equivalent to that in human cells, suggesting that DNA repair plays a predominant role in the remarkable radio-resistance of tardigrades. In order to identify novel tardigrade specific genes involved, we next conducted a comparative transcriptomics across three species, H. exemplaris, Acutuncus antarcticus and Paramacrobiotus fairbanksi, the latter belonging to the Macrobiotoidea superfamily known to lack Dsup homologs. In all three species, many genes of DNA repair were among the most strongly overexpressed genes alongside a novel tardigrade specific gene, named Tardigrade DNA damage Response protein 1 (TDR1). We found that TDR1 protein interacts with DNA and forms aggregates at high concentration suggesting it may condensate DNA and act by preserving chromosome organization until DNA repair is accomplished. Remarkably, when expressed in human cells, TDR1 improved resistance to Bleomycin, a radiomimetic drug. Based on these findings, we propose that TDR1 is a novel tardigrade specific gene responsible for conferring resistance to IR. Our study sheds light on mechanisms of DNA repair helping to cope with high levels of DNA damage. Furthermore, it suggests that at least two tardigrade specific genes, respectively for Dsup and TDR1, have independently evolved DNA-binding functions that contribute to radio-resistance in the Tardigrada phylum.

molecular biology↗

bioRxiv2021

Nucleosome positioning on large tandem DNA repeats of the '601' sequence engineered in Saccharomyces cerevisiae

The so-called 601 DNA sequence is often used to constrain the position of nucleosomes on a DNA molecule in vitro. Although the ability of the 147 base pair sequence to precisely position a nucleosome in vitro is well documented, in vivo application of this property has been explored only in a few studies and yielded contradictory conclusions. Our goal in the present study was to test the ability of the 601 sequence to dictate nucleosome positioning in Saccharomyces cerevisiae in the context of a long tandem repeat array inserted in a yeast chromosome. We engineered such arrays with three different repeat size, namely 167, 197 and 237 base pairs. Although our arrays are able to position nucleosomes in vitro as expected, analysis of nucleosome occupancy on these arrays in vivo revealed that nucleosomes are not preferentially positioned as expected on the 601-core sequence along the repeats and that the measured nucleosome repeat length does not correspond to the one expected by design. Altogether our results demonstrate that the rules defining nucleosome positions on this DNA sequence in vitro are not valid in vivo, at least in this chromosomal context, questioning the relevance of using the 601 sequence in vivo to achieve precise nucleosome positioning on designer synthetic DNA sequences.

synthetic biology↗

bioRxiv2021

Marine gregarine genomes illuminate current understanding of apicomplexan glideosome

Our current view of the evolutionary history, coding and adaptive capacities of Apicomplexa, protozoan parasites of a wide range of metazoan, is currently strongly biased toward species infecting humans, as data on early diverging apicomplexan lineages infecting invertebrates is extremely limited. Here, we characterized the genome of the marine eugregarine Porospora gigantea, intestinal parasite of Lobsters, remarkable for the macroscopic size of its vegetative feeding forms (trophozoites) and its gliding speed, the fastest so far recorded for Apicomplexa. Two highly syntenic genomes named A and B were assembled. Similar in size (~9 Mb) and coding capacity (~5300 genes), A and B genomes are 10.8% divergent at the nucleotide level, corresponding to 16-38 My in divergent time. Orthogroup analysis across 25 (proto)Apicomplexa species, including Gregarina niphandrodes, showed that A and B are highly divergent from all other known apicomplexan species, revealing an unexpected breadth of diversity. Phylogenetically these two species branch sister to Cephaloidophoroidea, and thus expand the known crustacean gregarine superfamily. The genomes were mined for genes encoding proteins necessary for gliding, a key feature of apicomplexans parasites, currently studied through the molecular model called glideosome. Sequence analysis shows that actin-related proteins and regulatory factors are strongly conserved within apicomplexans. In contrast, the predicted protein sequences of core glideosome proteins and adhesion proteins are highly variable among apicomplexan lineages, especially in gregarines. These results confirm the importance of studying gregarines to widen our biological and evolutionary view of apicomplexan species diversity, and to deepen our understanding of the molecular bases of key functions enabling parasitism, such as the glideosome.

genomics↗

bioRxiv2018

Reduced central and peripheral inflammatory responses and increased mitochondrial activity contribute to diet-induced obesity resistance in WSB/EiJ mice.

ObjectivesEnergy balance disruption due to excess of calorie-rich food is considered to be one of the major players in the current worldwide obesity pandemic. In rodents, a high fat diet (HFD) induces not only obesity, but also inflammation and mitochondrial dysfunctions. To identify factors underlying diet-induced obesity (DIO) resistance we compared the wild-derived mouse strain WSB/EiJ, characterized by a striking resistance to DIO, with the more DIO-sensitive C57BL/6J strain.\n\nMethodsWe analysed circulating levels of lipids, cytokines and adipokines as well as hypothalamic markers of inflammatory status and mitochondrial activity in both strains exposed to HFD for three days (3d) or eight weeks (8wk). To identify hypothalamic genes potentially involved in these differential regulations, we selected 86 genes related to inflammation and mitochondrial pathways. We analysed their expression levels by high throughput microfluidic qPCR on RNA extracted from laser micro-dissected arcuate (ARC) and paraventricular (PVN) hypothalamic nuclei of the two strains of mice, under the different HFD treatments.\n\nResultsAfter 3d and 8wk HFD, C57BL/6J mice, in contrast to WSB/EiJ, displayed significantly increased body weight gain, and also increased circulating levels of leptin, cholesterol, HDL and LDL. WSB/EiJ mice displayed a lower inflammatory status, both peripherally (lower levels of circulating cytokines) and centrally (less activated microglia in the hypothalamus) as well as more reactive mitochondria in the hypothalamus. Principal Component Analysis and gene ontology analysis of gene expression data showed, first, that datasets segregated as a function of strain and second, allowed to identify the metabolic pathways involved. These results were reinforced by the identification of strain-specific differential expression of several individual hypothalamic genes as well as differential effects of HFD between strains.\n\nConclusionsAdaptation to metabolic stress in the DIO-resistant WSB/EiJ strain implicates enhanced lipid metabolism, lower peripheral and hypothalamic inflammatory status and higher mitochondrial activity than in the C57BL/6J strain. These results point to the implication of the hypothalamic inflammatory and mitochondrial pathways as key factors in the control of energy homeostasis and the resistance to DIO.\n\nDeclarations of interest: none\n\nHighlightsO_LIDiet-induced-obesity resistance of WSB/EiJ implicates enhanced lipid metabolism\nC_LIO_LIWSB/EiJ mice are protected from HFD-induced peripheral and central inflammation\nC_LIO_LIEnhanced hypothalamic transport and signalling of endocrine molecules in WSB/EiJ\nC_LIO_LIWSB/EiJ hypothalamic mitochondria dynamics differ from C57BL/6J\nC_LIO_LIDifferential regulation of hypothalamic inflammatory/mitochondria genes in WSB/EiJ\nC_LI

physiology↗

bioRxiv2018

Comparative analysis of molecular signatures suggests the use of gabapentin for the management of endometriosis-associated pain

CapsuleComparative analysis of gene expression signatures from endometriosis and mouse models shows that CACNA2{delta}s calcium-channel components involved in nociception are targets for the treatment of endometriosis-associated pain.\n\nContextDifferential gene expression analyses comparing endometriotic lesions to eutopic endometrium have shown that the transcription factors DLX5 and DLX6 are drastically down-regulated in the ectopic implants. These finding suggests that regulatory cascades involving DLX5/6 might be involved in the origin of endometriosis symptoms such as chronic pelvic pain. We have shown that mice in which Dlx5 and Dlx6 are selectively inactivated in the uterus present an endometrial phenotype reminiscent of endometriosis implants.\n\nObjectiveIdentify new targets for the treatment of endometriosis.\n\nDesignTo better focus the search for endometriosis targets we have compared the profile of genes deregulated in normal and ectopic women endometrium to those deregulated in the uterus of normal and Dlx5/Dlx6-null mice.\n\nSettingsAcademic research unit and University Hospital research laboratory\n\nAnimalsMice carrying a uterus-specific deletion of Dlx5/Dlx6.\n\nInterventionsAnalysis of archive sections from normal endometrium and endometriosis implants.\n\nMain OutcomeA novel endometriosis signature suggests that 2{delta}s subunits of voltage-gated calcium channel are targets for the management of endometriosis-associated pain.\n\nResultsWe identify a signature of 30 genes similarly deregulated in human endometriosis implants and in Dlx5/6-null mouse uteri reinforcing the notion that the down-regulation of Dlx5/6 is an early event in the progress of endometriosis. CACNA2D3, a component of the voltage-dependent calcium channel complex is strongly overexpressed both in endometriosis implants and in mutant mouse uteri; other members of the alfa2delta family, CACNA2D1 and CACNA2D2, are also overexpressed in endometriosis.\n\nConclusionCACNA2D1, CACNA2D2 and CACNA2D3 are directly involved in pain perception. In particular, CACNA2D3 has been associated to pain sensitization and heat nociception in animal models while, in patients, variants of this gene are associated to reduced sensitivity to acute noxious stimuli. As CACNA2Ds are targets of gabapentinoids analgesics, our results suggest to consider the use of these drugs for the treatment of endometriosis-associated pain. Indeed, recent small-scale clinical studies have shown that gabapentin can be effective in the treatment of women chronic pelvic pain. Our findings reinforce the need for a large definitive trial.

pharmacology and toxicology↗