HAL-Université de Bretagne Occidentale
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Tracing the origin and evolution of specialized biosynthetic pathways in marine organisms
No full textInternational audienceABSTRACT Harmful algal blooms (HABs) pose public health and ecological risks in aquatic environments. HABs drive the bioaccumulation of a specific family of specialized metabolites known as “kainoids.” Kainoid derivatives, such as kainic acid (KA) and domoic acid (DA), are among the most toxic marine-derived metabolites produced by a limited number of algal species. While recent studies have provided insights into the molecular basis of KA and DA production in red algae and diatoms, knowledge of the biosynthesis of kainoids remains insufficient. In a new report published in mBio , Wood-Rocca et al. decode the DA biosynthetic route in the widespread Western Pacific benthic diatom Nitzschia navis-varingica (S. M. Wood-Rocca, N. Allsing, Y. Ashida, M. Mochizuki, et al., mBio 16:e02079-25, 2025, https://doi.org/10.1128/mbio.02079-25 ). We discuss how evolutionary genomics studies bridge the gap between fundamental biology and applied environmental and biotechnological research, enhancing our ability to understand, predict, and harness marine natural products
Non-farm entrepreneurship and children's schooling: Panel data evidence from rural Côte d'Ivoire
No full textInternational audienceThis paper investigates the impact of household participation in non-farm enterprises on children’s school enrolment in Côte d’Ivoire, focusing on children aged 3 to 12—the formative years for early learning and cognitive development. Using household-level panel data and two rigorous empirical strategies, we examine whether engaging in non-agricultural income-generating activities improves educational outcomes. Our findings indicate that participation in rural non-farm enterprises significantly reduces the number of out-of-school children, suggesting a positive link between income diversification and educational investment. Disaggregating results by location and gender reveals important differences. Non-farm entrepreneurship is positively associated with boys’ school enrolment in both rural and urban areas, whereas the positive effect for girls is observed only in urban settings. This highlights a persistent gender gap in rural education access that non-farm income alone may not fully address. These results have clear policy implications. Promoting non-farm enterprise development—particularly in rural areas—can improve school participation rates, especially for boys. However, complementary interventions may be needed to ensure girls benefit equally. Overall, the study underscores the role of rural non-farm entrepreneurship in advancing human capital through enhanced educational outcomes
Rare earth element abundances and gadolinium contamination in tap water worldwide
No full textInternational audienceGadolinium-based contrast agents (GBCAs) are widely used in magnetic resonance imaging (MRI) and have emerged as persistent contaminants in surface and drinking water since the 1990s. We present a method based on the coprecipitation of rare earth elements (REEs) with iron hydroxides to estimate the amount of macrocyclic GBCAs in water, and apply it here for the first time to investigate the degree of Gd contamination in tap water worldwide. Our results indicate that Gd contamination is widespread in drinking water distribution systems. Tap water in big European cities such as Berlin, Amsterdam, Paris, and Lyon is more contaminated in Gd than tap water from Asian (Beijing, Guangzhou, Wuhan, Shanghai, Seoul, Tokyo) or American megacities (Los Angeles, New York, and Rio de Janeiro). Furthermore, our data suggest that drinking water treatment processes degrade Gd complexes to varying extent, which can increase the bioavailability of free Gd ions
Optimal Formalin-Fixed Paraffin Embedded Sample Preservation for Efficient Staining in Multiplex Imaging
No full textInternational audienceThe accuracy of immunohistochemical techniques depends critically on the preservation of antigenic integrity in tissue samples. Although formalin-fixed paraffin-embedded tissues are commonly used for long-term storage, several studies reported signal degradation over time. However, the extent of this degradation and the influence of storage conditions on a wide range of markers remain poorly characterized. In this study, tissue blocks collected over an eight-year period and tissue sections stored under different conditions (room temperature, 4°C, -20°C, -80°C) were analyzed. Twenty-five antibodies targeting immune, stromal, and structural markers were used to stain four different tissue sections. Samples were acquired using imaging mass cytometry (IMC). Signal intensities were first quantified, then the data were analyzed, before and after normalization using imcRtools pipeline. A gradual loss of signal intensity was observed in blocks stored at room temperature for more than six years, affecting the detection of certain markers regardless of tissue type. For some sections, significant signal degradation was observed after only one week at room temperature and for others after one month of storage. Markers such as CD20, CD45, and CD45RA proved to be particularly sensitive. Storage at -20°C or -80°C preserved the quality of the staining, whereas storage at 4°C only allowed partial preservation. Normalization corrected some variations but did not enable the recovery of signals that were severely altered or absent. Commonly used room temperature storage causes gradual reduction in IMC-detected immunoreactivity, which may affect scientific interpretation and diagnosis. Storing sections at -20°C is, therefore, an effective and accessible solution. For retrospective studies, we recommend using blocks that are less than six years old. Overall, these results highlight the importance of pre-established standardized preservation protocols to ensure the reproducibility of analyses
Multi-objective evolutionary algorithms and integer programming for the optimization of underwater acoustic sensor network design
No full textInternational audienceA modelling of the design of UWASN as a Multi Objective optimization problem.• 4 different optimization criteria, 2 exact methods, 2 ad-hoc heuristics and 2 meta-heuristics for solving the problem.• 4 experiments to compare exact and reference methods to approximate approaches.• 16 test cases used and a mixed approach for efficiently extending an existing real-life network.</div
Participatory democracy in question: The case of “the sea in debate”
No full textInternational audienceWhile participatory democracy invites all citizens to take part directly in the decision-making process, the selection of participants in public debates is a critical issue for the legitimacy of the resulting public choices. This paper examines this question in the context of the national public debate on offshore wind energy held in France in the first quarter of 2024. We study an original survey measuring spatial preferences for offshore wind energy in which both participants in the public debate and respondents from the general population were simultaneously surveyed. We find large differences between the two groups of respondents in terms of gender, age, and education, as well as in their spatial preferences for wind farm locations. Using an entropy balancing approach, we reject the hypothesis that these differences in spatial preferences are due to composition effects. These findings underscore the need for policymakers to exercise caution when interpreting the outcomes of public debates
Resolving false positive Eu anomaly in seep carbonates with high Ba/Sm ratio using DGA resin separation
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Exploration of Engagement and Interaction Patterns with Virtual vs Human Influencers: A 24-Month Comparison of Two Breton Personalities
No full textInternational audienceVirtual influencers, defined as computer-generated personas operated by creative teams, are reshaping influencer marketing, yet their reception compared to human influencers remains uncertain. While studies conducted in several countries suggest that novelty may stimulate engagement, evidence from the breton context, where authenticity and proximity are central evaluative criteria, remains limited. This exploratory study compares, over a 24month period, the performance of a virtual influencer and a human influencer with comparable audience size and thematic focus. Results show no statistically significant difference in engagement, including likes, comments and interaction rate. However, user interactions with the virtual influencer display slightly more polarized reactions, although negative comments remain extremely rare overall. These findings suggest that virtual influencers may integrate into the Breton digital landscape without clearly outperforming or underperforming human influencers. The study contributes to contextualizing virtual influencer effects in Europe and highlights the need for controlled experimental research to further examine the roles of authenticity and technological innovation.</div
An intense peak of paraglacial dismantlement of mountain slopes: Insights from dating and volume quantification of rock-slope failure deposits in the Icelandic Westfjords (Dýrafjörður and Önundarfjörður)
No full textInternational audienceParaglacial rock slope failures (RSFs) are prominent processes of landscape evolution in deglaciated terrains, such as the Westfjords of Iceland. This study aims to provide chronological and volumetric data on RSF deposits in the Dýrafjörður and Önundarfjörður fjords, in order to document the magnitude, duration, and geomorphic impact of the intense peak of Early and Middle Holocene paraglacial denudation. By refining the timing of a paraglacial signal, this work contributes to a better understanding of sedimentary production and landscape evolution during the Holocene.A total of 17 RSFs was studied, described and mapped using the Schmidt-hammer exposure-age dating method, calibrated with radiocarbon dating. Surficial block morphometry and volumetric estimates of RSF deposits were derived from field measurements, orthophotography, and high-resolution digital elevation models.RSF ages are concentrated in the Early to Middle Holocene. The vast majority of this activity occurred between 12 and 6 cal. ka BP. During this 6000-year interval, ~83 million m3 of debris were deposited, which accounts for approximately 90% of the total volume (~92.5 M m3) from all 17 RSF sites. This indicates a primary paraglacial adjustment phase characterized by high sediment delivery efficiency. Slope reactivations occurred over periods up to 3400 years, with superimpositions of deposits: these are multi-phased RSFs.Finally, a significant lag of approximately 3000 years is observed between the deglaciation (~10.2 cal. ka BP) and the peak in rock-slope failure activity (8–6 cal. ka BP), which coincides with the Holocene Thermal Maximum climax in Iceland (8.6–5.2 cal. ka BP). The subsequent cessation of major RSFs activity after ~4 cal. ka BP marks the transition to a stable, non-glacial equilibrium