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Photophysiological performance of zooxanthellate endosymbionts (Symbiodiniaceae) in the golden jellyfish Mastigias papua across a natural environmental gradient in marine lakes of Palau (Micronesia)
No full textInternational audienceIntroduction: Understanding how organisms adapt to complex and variable environments requires in situ analysis of ecological performance in different environments.Methods: In this multi-year study, we investigate the photophysiological performance of dinoflagellate endosymbionts (Symbiodiniaceae) of the golden jellyfish Mastigias papua across a natural environmental gradient of marine lakes and semienclosed coves in the Palau Archipelago (Western Caroline Islands, Pacific Ocean).Results: These sites vary in terms of age, distance from the nearby ocean (lagoon) and underwater light conditions, all of which influence the ecology of the host and that of its symbionts. Jellyfish endosymbionts from isolated lakes ‐ remote from the ocean and characterized by more turbid conditions – were found to exhibit significantly lower photosynthetic performance (quantum yield and PSII performance index) than endosymbionts from sites more connected to the nearby ocean and with clearer waters. The pigment composition of endosymbionts varied little between those collected from inland lakes and ocean-connected coves, and showed little sign of adaptation to light spectra dominated by reddish wavelengths.Discussion: This suggests a mismatch between the optical characteristics of waters in more turbid lake environments and those of pigments that appear to remain optimized for blue light use in marine dinoflagellates. While published studies show evidence of morphological and behavioral adaptations in Mastigias jellyfish living in Palau’s marine lakes, this study suggests that their symbionts are limited by reduced pigment plasticity and lower photosynthetic performance. These results highlight the importance of symbiont characteristics and physiological compatibility in driving host adaptation, and the potential for evolutionary mismatch in tightly integrated symbioses, under novel environmental conditions
Correction: Beyond single nanomaterial exposure: investigating the fate of a TiO 2 and CeO 2 nanomaterial mixture in freshwater mesocosms
No full textInternational audienceCorrection for ‘Beyond single nanomaterial exposure: investigating the fate of a TiO 2 and CeO 2 nanomaterial mixture in freshwater mesocosms’ by Amazigh Ouaksel et al. , Environ. Sci.: Nano , 2026, https://doi.org/10.1039/d5en00871a
Epifitismo a través de una pteridoflora megadiversa: helechos y licófitos como epífitos en Perú
No full textInternational audienceFerns and lycophytes represent the second largest epiphytic group of vascular plants. Here we examined herbaria collection and literature to provide an account of epiphytes for Peru’s pteridoflora. We assessed compositional differences related to geography, altitudinal distribution, and vegetation type, along with observations on endemism and conservation. We report in total 521 species of epiphytes, of which 86 are new epiphyte records. These epiphytic ferns and lycophytes represent 35.4% of the total pteridoflora of Peru. We found 32 endemic species among these plants, most of them growing in humid montane forests. We also found regional differences in the composition of this flora, with compositional richness higher in the Eastern Andean slopes, followed by the Lowlands of the Amazon basin. Populations of epiphytic ferns and lycophytes are mostly known from protected areas (82% of all epiphytes), and most of them were recorded from 10 National Parks, whereas 97 species of which 15 are endemics occur in non-protected areas. There are still many challenges for those interested in epiphytism. These challenges include the correct use of the term epiphyte and habit details, incorporating the gametophytic phase of the life cycle of these plants, the biology of interactions, genetics and population studies. All are challenges associated with the continued need to address geographical gaps in knowledge of the epiphytic flora outside of protected sites, and in regions threatened by land-use and landscape changes.Los helechos y licófitos representan el segundo grupo más grande de plantas epífitas vasculares. Aquí examinamos colecciones de herbarios y la literatura para proveer un registro de los epífitos en la pteridoflora de Perú. Evaluamos diferencias en la composición relacionadas a la geografía, distribución altitudinal y tipo de vegetación, además de observaciones sobre endemismo y conservación. Reportamos 521 especies de epífitos, de los cuales 86 representan nuevos registros. Los helechos y licófitos epífitos representan el 35.4% del total de la pteridoflora peruana. Encontramos entre estas epífitas, 32 especies endémicas, la mayoría de ellas ocupan el bosque húmedo montano. Hallamos también diferencias regionales en la composición de esta flora, con la riqueza más alta en las laderas de los andes orientales, seguido por la de llanura de la cuenca amazónica. Poblaciones de helechos y licófitos epífitos se conocen mayormente de áreas protegidas (82% de todas las epífitas), y estas provenientes principalmente de 10 Parques Nacionales, mientras que 97 especies incluyendo 15 endemismos se hallan en áreas no protegidas. Reconocemos la persistencia de numerosos retos a los interesados en epifitismo. Estos retos incluyen el empleo correcto del término epífito y detalles del hábito, la incorporación de la fase gametofítica de estas plantas, el examen de la biología de interacciones de los helechos y licófitos epífitos con otros organismos, la inclusión de estudios genéticos y poblacionales. Todos estos retos asociados a la aún necesidad de resolver los vacíos de información geográfica de la flora epífita fuera de áreas protegidas y en regiones amenazadas por cambios tanto en el uso de la tierra como en el paisaje
Supports d'écriture et les sources conservées ou disparues dans les mondes chinois et grec
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Optimal transport unlocks end-to-end learning for single-molecule localization
No full textInternational audienceSingle-molecule localization microscopy (SMLM) allows reconstructing biology-relevant structures beyond the diffraction limit by detecting and localizing individual fluorophores --- fluorescent molecules stained onto the observed specimen --- over time to reconstruct super-resolved images.Currently, efficient SMLM requires non-overlapping emitting fluorophores, leading to long acquisition times that hinders live-cell imaging.Recent deep-learning approaches can handle denser emissions, but they rely on variants of non-maximum suppression (NMS) layers, which are unfortunately non-differentiable and may discard true positives with their local fusion strategy.In this presentation, we reformulate the SMLM training objective as a set-matching problem, deriving an optimal-transport loss that eliminates the need for NMS during inference and enables end-to-end training.Additionally, we propose an iterative neural network that integrates knowledge of the microscope's optical system inside our model.Experiments on synthetic benchmarks and real biological data show that both our new loss function and architecture surpass the state of the art at moderate and high emitter densities.Code is available at https://github.com/RSLLES/SHOT
ClimarisQ: What can we learn from playing a game for climate education?
No full textInternational audienceClimarisQ is both a web and mobile game developed by the Institut Pierre-Simon Laplace to support climate change communication through interactive decision-making. This paper presents an exploratory evaluation of the game based on a post-play questionnaire completed by 77 users. Respondents rated ClimarisQ positively in terms of usability and scientific credibility. Self-reported outcomes indicate that the game supported reflection on the complexity, trade-offs, and uncertainty of climate-related decision-making, rather than the acquisition of factual knowledge, particularly among users with prior expertise. The respondent group was predominantly composed of educated and climate-aware adults, which limits generalization to other audiences. Beyond the questionnaire, the game has been tested in dozens of facilitated sessions with thousands of non-specialist participants, with consistently positive feedback. These results suggest that ClimarisQ can function as a complementary tool for climate education and outreach, especially when used in facilitated settings that encourage discussion and interpretation
Correctly rounded vector implementation of the exponential function in binary64 arithmetic
No full textWe present a vectorized implementation of the exponential function that is correctly rounded in rounded-to-nearest binary64 floating-point arithmetic, demonstrating the feasibility of vectorized correctly rounded implementations. The vectorization is done automatically by the compiler
Validation of EarthCARE CPR reflectivity using the ACTRIS cloud radar network
No full textInternational audienceThe Earth Cloud, Aerosol, and Radiation Explorer (EarthCARE) satellite carries a cloud profiling radar (CPR) designed to observe global cloud properties. In this study, we assess the calibration of CPR reflectivity profiles by comparing them with seven calibrated ground-based cloud radars from the European Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS).We compare the statistics of ice cloud reflectivities observed from space and from each ground site. The CPR dataset includes all observations within a 200 km radius of each site, while the ground-based dataset comprises vertical profiles collected during the same time period. By analysing the differences in reflectivity statistics, we estimate the calibration bias between CPR and each site. To ensure robustness, we implement a method to select height bins with comparable reflectivity statistics, excluding uncorrelated observations that could contaminate the results. The reliability of our bias estimates is validated through closure: each ground radar has been calibrated using the same reference, and the independently derived space-versus-ground biases obtained across sites are consistent. Our methodology also provides uncertainty estimates for the reflectivity biases and explores the time sampling required for reliable comparisons.Based on the comparisons from the seven ground-sites, we find that the bias in the EarthCARE L2a reflectivity product is of -0.2 ± 0.4 dB, confirming the high quality of the satellite's calibration. This robust statistical approach, validated with calibrated radars, establishes EarthCARE as a potential reference for calibrating ACTRIS and other ground-based sites in the future
Refined cellular activity expression signatures provide a targeted framework to quantify phenotypic intra-tumor heterogeneity in single-cell data
No full textSingle cell RNA-seq (scRNA-seq) now allows deeper insight into cellular biology at both the individual and population level. Measuring cell-to-cell variations in the population enables quantification of phenotypic heterogeneity in populations in which cell states and identities deviate from healthy transcriptomic profiles. Cellular activities quantifiable using gene set enrichment analyses can provide useful grounds to quantify phenotypic heterogeneity, but the specificity and adequacy of existing molecular signatures for scRNA-seq data is still insufficient. Here we induced 6 activities in vitro, for which we refined existing expression signatures to enhance specificity and detection in scRNA-seq data: epithelial-mesenchymal transition (EMT), DNA repair, responses to interferons α and γ (IFNα and IFNγ, respectively), glycolysis, oxidative phosphorylation (OxPhos). We report new signatures, with much lower redundancy between IFNα and IFNγ, and glycolysis and OxPhos signatures, achieving average AUCs of 0.85 across bootstrapped datasets for each activity. We could use these signatures to quantify phenotypic intra-tumor heterogeneity (ITH) in 20 patient samples and 14 cell lines, observing high correlation with diversity indices in classified healthy cells (p<0.001). Focusing on cancer cells only, we furthermore report higher phenotypic ITH in patients than in cell lines (p<0.001), and in basal tumors (p=0.028)
An atypical case of equine eosinophilic keratoconjunctivitis
No full textInternational audienceThis case report describes an unusual presentation of eosinophilic keratoconjunctivitis (EK) in a horse. A 6‐year‐old Warmblood gelding was presented for acute blepharospasm and pruritus of the left eye. Topical antibiotics and/or corticoid treatments had been applied without success. The ophthalmic examination revealed a large granulomatous mass at the central part of the dorsal corneal limbus. This mass had a haemorrhagic appearance, and multiple caseous deposits were visible on the surface. Cytology and culture exams were performed under topical anaesthesia. Cytology revealed significant eosinophilic and neutrophilic inflammatory infiltrates. Bacteriology and mycology cultures were negative. A keratoconjunctivectomy was performed under sedation and topical anaesthesia, and the sample was submitted for histology. A rapid improvement in clinical signs was observed. The histopathological analysis revealed abundant degenerative and necrotic tissue, strongly eosinophilic, also extending into the corneal stroma with adjacent areas of collagenous necrosis. The proliferative nature of the lesion was linked to the intensity of the inflammatory reaction. There were no visible pathogens. One year later, no signs of recurrence were observed. This case report describes a necrotic and proliferative form of EK in a horse with a successful surgical outcome