Persistence of microcystin production by Planktothrix agardhii (Cyanobacteria) exposed to different salinities

International audienceRecent reports predict increases in harmful cyanobacteria in water systems worldwide due to climatic and environmental changes, which would compromise water quality and public health. Among abiotic changes, higher salinities are expected to promote the growth of certain harmful species, such as Planktothrix agardhii, which forms blooms in brackish waters. Since P. agardhii is a common producer of cyanotoxin, we investigated the growth and tolerance of this species when exposed in vitro to a range of salinities, while assessing variations in its microcystin diversity and production in batch cultures during a time-frame experiment spanning 18 days. The study revealed salt acclimation of the brackish P. agardhii, which continued to produce microcystins in salty cultures, while maintaining its growth capacity at low to medium NaCl (ranging from 0 to 7.5 g l−1). With higher concentrations (10 to 15 g l−1) significantly less growth occurred, corresponding to the shortening of cyanobacterial filaments, which nevertheless maintained their metabolic functions, as revealed by the high intensity of chlorophyll auto-fluorescence and persistent microcystin production. These findings showed that moderate to high salt levels do not inhibit microcystin production by P. agardhii, at least for several weeks. This raises questions concerning the persistence of harmful cyanobacteria in shallow water systems more exposed to evaporation and consequently to an increase in salinity in the future, as predicted by various climate models

Mutation of FOP/FGFR1OP in mice recapitulates human short rib-polydactyly ciliopathy

Skeletal dysplasias are a clinically and genetically heterogeneous group of bone and cartilage disorders. A total of 436 skeletal dysplasias are listed in the 2015 revised version of the nosology and classification of genetic skeletal disorders, of which nearly 20% are still genetically and molecularly uncharacterized. We report the clinical and molecular characterization of a lethal skeletal dysplasia of the short-rib group caused by mutation of the mouse Fop gene. Fop encodes a centrosomal and centriolar satellite (CS) protein. We show that Fop mutation perturbs ciliogenesis in vivo and that this leads to the alteration of the Hedgehog signaling pathway. Fop mutation reduces CSs movements and affects pericentriolar material composition, which probably participates to the ciliogenesis defect. This study highlights the role of a centrosome and CSs protein producing phenotypes in mice that recapitulate a short rib-polydactyly syndrome when mutated

Rural and urban distribution of wild and domestic carnivore stools in the context of Echinococcus multilocularis environmental exposure

International audienceIn zoonotic infections, the relationships between animals and humans lead to parasitic disease with severity that ranges from mild symptoms to life-threatening conditions. In cities and their surrounding areas, this statement is truer with the overcrowding of the protagonists of the parasites' life cycle. The present study aims to investigate the distribution of a parasite, Echinococcus multilocularis, which is the causative agent of alveolar echinococcosis, using copro-sampling in historically endemic rural settlements of the eastern part of France and in newly endemic areas including urban parks and settlements surrounding Paris. Based on 2741 morphologically identified and geolocalized copro-samples, the density of fox faeces was generally higher in the surrounding settlements, except for one rural area where the faeces were at larger density downtown in the winter. Fox faeces are rare but present in urban parks. Dog faeces are concentrated in the park entrances and in the centre of the settlements. DNA was extracted for 1530 samples that were collected and identified from fox, dog, cat, stone marten and badger carnivore hosts. Echinococcus multilocularis diagnosis and host faecal tests were performed using real-time PCR. We failed to detect the parasite in the surroundings of Paris, but the parasite was found in the foxes, dogs and cats in the rural settlements and their surroundings in the historically endemic area. A spatial structuring of the carnivore stool distribution was highlighted in the present study with high densities of carnivore stools among human occupied areas within some potentially high-risk locations

Bacteria cells in the surface water of the Mackenzie Delta Region during 4 expeditions from spring to fall in 2019

Samples for bacterial abundance (1.5 mL) were preserved with glutaraldehyde (1% final concentration) and stored at -80°C. Samples were stained with SYBRTM Green I (Thermofisher Scientific) and analyzed on a flow cytometer (FACSCanto, BD Biosciences) as previously described (Gasol & Del Giorgio, 2000; doi:10.3989/scimar.2000.64n2197)

Phytoplankton pigment concentrations measured by HPLC in the surface water of the Mackenzie Delta Region during 4 expeditions from spring to fall in 2019

The determination of phytoplankton using high performance liquid chromatography (HPLC) is detailed in Hooker et al. (2005; doi:10.1364/AO.44.000553) and Ras et al. (2008; doi:10.5194/bg-5-353-2008). Briefly, the pigments of particles retained on GF/F (0.7 µm) filters were extracted at -20°C with 3 mL methanol (100%). The filter samples were then disrupted using a sonicator and clarified one hour later by vacuum filtration through GF/F filters. The extracts were rapidly analyzed within 24h by HPLC with a complete Agilent Technologies system (comprising LC Chemstation software, a degasser, a binary pump, a refrigerated autosampler, a column thermostat and a diode array detector)

Enseigner et apprendre à l'ère de l'intelligence artificielle

International audienceAs part of the Digital Working Group (GTnum) #Scol_IA “Renewal of digital practices and creative uses of digital and AI” we are pleased to present the white paper “Teaching and learning in the era of Artificial Intelligence, Acculturation , integration and creative uses of AI in education”. The white paper edited by Margarida Romero, Laurent Heiser and Alexandre Lepage aims to provide the various educational actors with a diversified perspective both on the issues of acculturation and training in AI and on the resources and feedback from the various research teams and organisations. of scientific culture in the French-speaking countries. A multidisciplinary approach makes it possible to consider the perspectives of researchers in computer science as well as those of education and training sciences, information and communication sciences and the expertise of teaching professionals. and scientific mediation.Dans le cadre du Groupe de Travail numérique (GTnum) #Scol_IA “Renouvellement des pratiques numériques et usages créatifs du numérique et IA” nous sommes heureux de vous présenter le livre blanc “Enseigner et apprendre à l’ère de l’Intelligence Artificielle, Acculturation, intégration et usages créatifs de l’IA en éducation”. Le livre blanc édité par Margarida Romero, Laurent Heiser et Alexandre Lepage vise apporter aux différents acteurs éducatifs un éclairage diversifié tant des enjeux de l’acculturation et formation à l’IA que des ressources et retours d’expérience des différentes équipes de recherche et organismes de culture scientifique de la francophonie. Une approche pluridisciplinaire permet de considérer tant les perspectives des chercheurs en sciences de l’informatique, que celles des sciences de l’éducation et de la formation, les sciences de l’information et la communication et l’expertise des professionnels de l’enseignement et de la médiation scientifique

Nunataryuk field campaigns: Understanding the origin and fate of terrestrial organic matter in the coastal waters of the Mackenzie Delta region

International audienceAbstract. Climate warming and related drivers of soil thermal change in the Arctic are expected to modify the distribution and dynamics of carbon contained in perennially frozen grounds. Thawing of permafrost in the Mackenzie Delta region of northwestern Canada, coupled with increases in river discharge and coastal erosion, trigger the release of terrestrial organic matter (OMt) from the largest Arctic drainage basin in North America into the Arctic Ocean. While this process is ongoing, well-established, and its rate is accelerating, the fate of the newly-mobilized organic matter, as it transits from the watershed through the delta and into the marine system, remains poorly understood. In the framework of the European Horizon 2020 Nunataryuk programme, and as part of the Work Package 4 (WP4) Coastal Waters theme, four field expeditions were conducted in the Mackenzie Delta region and southern Beaufort Sea from April to September 2019. The temporal sampling design allowed the survey of ambient conditions in the coastal waters under full ice cover prior to the spring freshet, during ice break-up in summer, as well as anterior to the freeze-up period in fall. To capture the fluvial-marine transition zone, and with distinct challenges related to shallow waters and changing seasonal and meteorological conditions, the field sampling was conducted in close partnership with members of the communities of Aklavik, Inuvik and Tuktoyaktuk, using several platforms: helicopters, snowmobiles and small boats. Water column profiles of physical and optical variables were measured in situ, while surface water, groundwater and sediment samples were collected and preserved for the determination of the composition and sources of OMt, including particulate and dissolved organic carbon (POC, DOC), and chromophoric dissolved organic matter (CDOM), as well as a suite of physical, chemical and biological variables. Here we present an overview of the standardized datasets, including hydrographic profiles, remote sensing reflectance, temperature and salinity, particle absorption, nutrients, dissolved organic carbon, particulate organic carbon, particulate organic nitrogen, colored dissolved organic matter absorption, fluorescent dissolved organic matter intensity, suspended particulate matter, total particulate carbon, total particulate nitrogen, stable water isotopes, radon in water, bacterial abundance, and a string of phytoplankton pigments including total chlorophyll. Datasets and related metadata can be found in Juhls et al. 2021. https://doi.pangaea.de/10.1594/PANGAEA.937587