Biology subjects

Devime, F.

Publications and source records attributed to Devime, F..

6 recordsLinked to original sources

bioRxiv2026

Integrated cellular and molecular responses to uranium chemotoxicity in the metal-tolerant microalga Coelastrella sp. PCV

Understanding the toxicity of hazardous metals in microalgae is critical for environmental risk assessment and sustainable phycoremediation. Metal-tolerant organisms provide powerful models for dissecting the mechanisms that mitigate metal toxicity. Here, we investigated the cellular and molecular responses to uranium (U) chemotoxicity in the metal-tolerant microalga Coelastrella sp. PCV. We used an integrated multi-omics and high-resolution imaging approach, combined with physiological analyses, to elucidate the mechanisms underlying U tolerance in Coelastrella. Using TEM-EDX, U was localized to the cell wall, polyphosphate bodies within acidocalcisomes, and vacuoles. Three-dimensional cell reconstruction and morphometric analysis using FIB-SEM showed that U-challenged cells displayed increased vacuolization, reflecting sequestration of uranyl ions and autophagy-mediated detoxification. Transcriptome responses were rapid and extensive, characterized by repression of cell division and photosynthesis, and pronounced imbalance in protein turnover and trafficking. Uranium also disrupted the homeostasis of essential elements, with marked rewiring of gene networks governing molybdenum, manganese, phosphate, iron and calcium homeostasis, notably affecting transporters and metal-binding proteins. Coelastrella sp. PCV efficiently sequestered U in acidocalcisomes and vacuoles, while rapidly excluding U from the cell. These coordinated detoxification responses are likely mediated by calcium, iron, ABC, and MATE transporters among the strongly deregulated genes under U stress.

plant biology↗

bioRxiv2025

Effects of manganese dioxide on macrophages under different exposure schemes

Manganese dioxide is a material that is more and more used in its particular form, for many industrial applications such as chemical catalysis or for batteries. Thus, workers can be exposed to this particulate chemical. It is known that overexposure to manganese leads to a brain disease called manganism. However, manganese is also known to impact the pulmonary function, which is important as pulmonary exposure is of prime importance for workers. We thus investigated the effects of manganese dioxide on macrophages, i.e. the scavenger cells that take particulates in charge in our bodies. To this purpose, we used a combination of proteomic and targeted approaches, in order to obtain a wide view of the cellular responses to manganese dioxide. We also used a repeated exposure mode, in order to better mimic occupational exposure. Our results point out the fact that manganese oxide nanoparticles are rather toxic for macrophages and induce mitochondrial dysfunction, oxidative stress and a pro-inflammatory response. Environmental significanceManganese dioxide is more and more used in batteries, so that workers in batteries factories are exposed to this metallic oxide. As always for particulate materials, macrophages are the first line of defense of the organism. We thus investigated the effects of manganese dioxide on macrophages, using a repeated exposure scheme to mimic occupational exposure, and the effects were documented by a combination of proteomic and targeted approaches. The functional effects include mitochondrial dysfunction, oxidative stress and inflammation.

pharmacology and toxicology↗

bioRxiv2025

The devil lies in the details: small structural and chemical changes in iron oxide pigments largely alter the biological outcomes in macrophages

Because of their technical qualities, such as resistance to fading and to high temperatures, mineral pigments are still widely used nowadays. Among the diversity of mineral pigments, iron oxide pigments represent a widely-used class, because of their technical qualities, diversity of shades (from yellow to red to brown to black) and low toxicity compared to heavy metals-based pigments. However, a low toxicity does not mean the absence of adverse effects. We thus investigated the effects on macrophages of two different subtypes of Pigment Red 101, i.e. hematite, produced by two different processes, namely a wet precipitation process and a calcination process. Macrophages were chosen as a target cell type because they represent the main scavenger cell type that is in charge of handling particulate materials in the body. During this comparison, we realized that the calcined pigment was contaminated from the start by bacterial endotoxins, which induced intense inflammatory responses and biased the comparison. After depyrogenation, the calcined pigment proved to dissolve to a higher extent in macrophages, but to show less important adverse effects (e.g. alteration of the mitochondrial transmembrane potential, oxidative stress and inflammatory responses) than the precipitated pigment in a recovery exposure mode, allowing to investigate delayed effects of the pigments. Thus, despite their identical pigment number, pigments differing in their structure and in their synthesis induce different responses from living cells, even if administrated in equivalent amount. This should be taken into account for some applications, such as tattooing. Moreover, endotoxin contamination should also be checked to increase workers and users safety

pharmacology and toxicology↗

bioRxiv2025

Beyond the ink: cellular and molecular effects of iron-based pigments on macrophages

As ochre, iron oxide is among the most ancient pigments used by mankind for different purposes, including tattooing as demonstrated on tattoed mummies. Iron oxides are still used in tattooing nowadays and especially in dermopigmentation, an area of medical tattoing aiming at restoring the color of skin. This ancient use of iron oxide does not mean that it has no effect on cells, and especially on macrophages, the cells that maintain pigments particles on site in tattoos. We thus investigated in vitro the delayed/sustained effects of iron oxide pigments on macrophages, i.e. the effects occurring a few days after the exposure to pigments, on pigments-loaded macrophages but in a pigment-free medium, mimicking the status of tattooed skin after all the pigment particles have been captured. By combining proteomic and targeted approaches, we determined that red iron oxide (but not black iron oxide) induces perturbations in mitochondria, altering the mitochondrial transmembrane potential. Red iron oxide also induces oxidative stress and the secretion of pro-inflammatory cytokines such as interleukin 6 and tumor necrosis factor. Thus, red iron oxide induces adverse effects on macrophages that may persist over time, owing to its low intracellular dissolution.

immunology↗

bioRxiv2023

Characterization of a uranium-tolerant green microalga of the genus Coelastrella with high potential for the remediation of metal-polluted waters

Uranium (U) pollution of terrestrial and aquatic ecosystems poses a significant threat to the environment and human health because this radionuclide is chemotoxic. Characterization of organisms that tolerate and accumulate U is critical to decipher the mechanisms evolved to cope with the radionuclide and to propose new effective strategies for bioremediation of U-contaminated environments. Here, we isolated a unicellular green microalga of the genus Coelastrella from U-contaminated wastewater. We showed that Coelastrella sp. PCV is much more tolerant to U than Chlamydomonas reinhardtii and Chlorella vulgaris. Coelastrella is able to accumulate U very rapidly, then gradually release it into the medium, behaving as an excluder to limit the toxic effects of U. The ability of Coelastrella to accumulate U is remarkably high, with up to 600 mg U sorbed per g dry biomass. Coelastrella is able to grow and maintain high photosynthesis in natural metal-contaminated waters from a wetland near a reclaimed U mine. Over a single one-week growth cycle, Coelastrella is able to capture 25-55% of U from contaminated waters and demonstrates lipid droplet accumulation. Coelastrella sp. PCV is a very promising microalga for the remediation of polluted waters with valorization of algal biomass that accumulates lipids. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=176 SRC="FIGDIR/small/546994v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@1ff356corg.highwire.dtl.DTLVardef@c53d0org.highwire.dtl.DTLVardef@15284eborg.highwire.dtl.DTLVardef@946d49_HPS_FORMAT_FIGEXP M_FIG C_FIG

plant biology↗

bioRxiv2021

Calcium-permeable cation channels are involved in uranium uptake in Arabidopsis thaliana

Uranium (U) is a non-essential and toxic element that is taken up by plants from the environment. The assimilation pathway of U is still unknown in plants and any other organism. In this study, we provide several evidences that U is taken up by the roots of Arabidopsis thaliana through Ca2+-permeable cation channels. First, we showed that deprivation of Arabidopsis plants with calcium induced a 1.5-fold increase in the capacity of roots to accumulate U, suggesting that calcium deficiency promoted the radionuclide import pathway. Second, we showed that external calcium inhibits U accumulation in roots, suggesting a common route for the uptake of both cations. Third, we found that gadolinium, nifedipine and verapamil inhibit the absorption of U, suggesting that different types of Ca2+-permeable channels serve as a route for U uptake. Last, we showed that U bioaccumulation in Arabidopsis mutants deficient for the Ca2+-permeable channels MCA1 and ANN1 was decreased by 40%. This suggests that MCA1 and ANN1 contribute to the absorption of U in different zones and cell layers of the root. Together, our results describe for the first time the involvement of Ca2+-permeable cation channels in the cellular uptake of U.

plant biology↗