Biology subjects

Duval, R.

Publications and source records attributed to Duval, R..

4 recordsLinked to original sources

bioRxiv2026

Light-dependent cell fixing with DNA-targeting fluorophores

Light has become of paramount importance for the spatiotemporal control of cell labeling, activity and death. We found that palmatine, a DNA-binding alkaloid, mediates the fixation of live cells upon visible light irradiation. Fixation takes a few seconds or minutes depending on the power used, is accompanied by nuclear fluorescent labeling in target cells, exhibits a high degree of control from cell islets to single cells, yielding cells with intact nucleus and membrane boundaries. 'Optofixation' relies on palmatine-DNA interaction, singlet oxygen photogeneration and lipid peroxidation, producing fixing levels of endogenous aldehydes. We also establish that many commonly used nuclear dyes exhibit optofixation properties across the UV-far red spectrum. Comprising the straightforward inactivation and labeling of native target cells by small fluorophores, this unprecedented, comparatively simple technology has the potential for major applications in biological research.

cell biology↗

bioRxiv2025

DNAi: an open-source AI tool for unbiased DNA fiber analysis

DNA fiber assays are powerful tools for investigating replication dynamics at the single-molecule level. However, their application and widespread adoption has been hampered by the labor-intensive and tedious nature of manual analysis of large numbers of images. Quantification of labeled DNA fibers typically depends on subjective examination, selection, and annotation of individual fibers from fluorescence microscopy images reducing inter-user consistency, reproducibility, and experimental throughput. To address these issues, we developed DNAi, a computer vision tool based on deep learning allowing automated detection and quantification of labeled DNA fiber length. DNAi was trained on a large and diverse dataset of manually annotated images of DNA fibers and matches human performance and accuracy in segmentation and length measurement across a wide range of experimental conditions. The open-source tool includes a user-friendly interface, which permits visual validation and manual selection of segmented fibers. Overall, DNAi enables robust, rapid, and reproducible DNA fiber analysis, and is freely available. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=113 SRC="FIGDIR/small/679603v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@1c8fd78org.highwire.dtl.DTLVardef@78f40corg.highwire.dtl.DTLVardef@de60e5org.highwire.dtl.DTLVardef@1ab7db5_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2021

Artemisinin-independent inhibitory activity of Artemisia sp. infusions against different Plasmodium stages including relapse-causing hypnozoites

Artemisinin-based combination therapies (ACT) are the frontline treatments against malaria worldwide. Recently the use of traditional infusions from Artemisia annua (from which artemisinin is obtained) or A. afra (lacking artemisinin) has been controversially advocated. Such unregulated plant-based remedies are strongly discouraged as they might constitute sub-optimal therapies and promote drug resistance. Here, we conducted the first comparative study of the anti-malarial effects of both plant infusions in vitro against the asexual erythrocytic stages of P. falciparum and the pre-erythrocytic (i. e., liver) stages of various Plasmodium species. Low concentrations of either infusion accounted for significant inhibitory activities across every parasite species and stage studied. We show that these antiplasmodial effects were essentially artemisinin-independent and were additionally monitored by observations of the parasite apicoplast and mitochondrion. In particular, the infusions significantly incapacitated sporozoites, and for P. vivax and P. cynomolgi, disrupted the hypnozoites. This provides the first indication that compounds other than 8-aminoquinolines could be effective antimalarials against relapsing parasites. These observations advocate for further screening to uncover urgently needed novel antimalarial lead compounds.

microbiology↗

bioRxiv2020

Plasmodium falciparum sexual parasites regulate infected erythrocyte permeability

To ensure the transport of nutrients necessary for their survival, Plasmodium falciparum parasites increase erythrocyte permeability to diverse solutes. These New Permeation Pathways (NPP) have been extensively characterized in the pathogenic asexual parasite stages, however the existence of NPP has never been investigated in gametocytes, the sexual stages responsible for transmission to mosquitoes. Here, we show that NPP are still active in erythrocytes infected with immature gametocytes and that this activity declines along gametocyte maturation. Our results indicate that NPP are regulated by cyclic AMP (cAMP) signaling cascade during sexual parasite stages, and that the decrease in cAMP levels in mature stages results in a slowdown of NPP activity. We also show that NPP facilitate the uptake of artemisinin derivatives and that phosphodiesterase (PDE) inhibitors can reactivate NPP and increase drug uptake in mature gametocyte-infected erythrocytes. These processes are predicted to play a key role in P. falciparum gametocyte biology and susceptibility to antimalarials.

microbiology↗