Combining optical and radar satellite image time series to map natural vegetation: savannas as an example

Up-to-date land cover maps are important for biodiversity monitoring as they are central to habitat and ecosystem distribution assessments. Satellite remote sensing is a key technology for generating these maps. Until recently, land cover mapping has been limited to static approaches, which have primarily led to the production of either global maps at coarse spatial resolutions or geographically restricted maps at high spatial resolutions. The recent availability of optical (Sentinel-2) and radar (Sentinel-1) satellite image time series (SITS) which provide access to high spatial and very high temporal resolutions, is a game changer, offering opportunities to map land cover using both temporal and spatial information. These data moreover open interesting perspectives for land cover mapping based on data combination approach. However, the usefulness of combining dense time series (more than 30 images per year) and data combination approaches to map natural vegetation has so far not been assessed. To address this gap, this contribution tests the idea that the combined consideration of optical and radar data combination and time series analyses can significantly improve natural vegetation mapping in the Pendjari National Park, a Sahelian savanna protected area in Benin. Results highlight that the combination of Sentinel-1 and Sentinel-2 SITS performs as well as Sentinel-2 SITS alone in terms of classification accuracy. Land cover maps are however qualitatively better when considering the data combination approach. Our results also clearly show that the use of dense/hypertemporal optical time series significantly improves classification outcomes compared to using multitemporal only a few images per year) or monotemporal data. Altogether, this work thus demonstrates the ability of dense SITS to improve discrimination of natural vegetation types using information on their phenology, leading to more detailed and more reliable maps for environmental management

Versicolorin A, a precursor in aflatoxins biosynthesis, is a food contaminant toxic for human intestinal cells

Aflatoxin B1 (AFB1) is the most potent carcinogen among mycotoxins. Its biosynthesis involves the formation of versicolorin A (VerA), whose chemical structure shares many features with AFB1. Our data revealed significant levels of VerA in foodstuff from Central Asia and Africa. Given this emerging food risk, it was of prime interest to compare the toxic effects of the two mycotoxins against cells originating from the intestinal tract. We used human colon cell lines (Caco-2, HCT116) to investigate the cytotoxic process induced by the two mycotoxins. Contrary to AFB1, a low dose of VerA (1 μM) disturbed the expression level of thousands of genes (18 002 genes). We show that the cytotoxic effects of low doses of VerA (1–20 μM) were stronger than the same low doses of AFB1 in both Caco-2 and HCT116 cell lines. In Caco-2 cells, VerA induced DNA strand breaks that led to apoptosis and reduced DNA replication of dividing cells, consequently inhibiting cell proliferation. Although VerA was able to induce the p53 signaling pathway in p53 wild-type HCT116 cells, its toxicity process did not mainly rely on p53 expression since similar cytotoxic effects were also observed in HCT116 cells that do not express p53. In conclusion, this study provides evidence of the risk of food contamination by VerA and shed light on its toxicological effect on human colon cells

Un siècle de recherche sur les bactériophages

Les bactériophages tiennent une place prépondérante dans le monde vivant. Du point de vue épistémologique, ils participent à la compréhension du vivant via trois aspects fondamentaux : (i) les mécanismes moléculaires les plus intimes du fonctionnement des infections virales et de celui des cellules elles-mêmes (biologie moléculaire) ; (ii) le fonctionnement des écosystèmes (écologie) ; et (iii) la dynamique adaptative des populations virales et bactériennes (évolution). À travers une présentation historique de la découverte des bactériophages et de leurs fascinantes propriétés, cette revue relate la genèse des découvertes fondamentales associées à l’étude des bactériophages et présente une vision synthétique des champs de recherche actuels.Bacteriophages have a prominent place in the living world. They participate to our understanding of the living world through three main aspects : (i) the dissection of the most intimist aspects of viral infection molecular mechanisms (molecular biology), (ii) the description and functioning mechanisms of ecosystems (ecology), and (iii) the adaptive dynamics of integrated viral and host-cell populations (evolution). This review looks back at the genesis of these fundamental findings and draws a picture of the most active fields of current research

Mycoplasma pneumoniae infections, 11 countries in Europe and Israel, 2011 to 2016

Background: Mycoplasma pneumoniae is a leading cause of community-acquired pneumonia, with large epidemics previously described to occur every 4 to 7 years. Aim: To better understand the diagnostic methods used to detect M. pneumoniae; to better understand M. pneumoniae testing and surveillance in use; to identify epidemics; to determine detection number per age group, age demographics for positive detections, concurrence of epidemics and annual peaks across geographical areas; and to determine the effect of geographical location on the timing of epidemics. Methods: A questionnaire was sent in May 2016 to Mycoplasma experts with national or regional responsibility within the ESCMID Study Group for Mycoplasma and Chlamydia Infections in 17 countries across Europe and Israel, retrospectively requesting details on M. pneumoniae-positive samples from January 2011 to April 2016. The Moving Epidemic Method was used to determine epidemic periods and effect of country latitude across the countries for the five periods under investigation. Results: Representatives from 12 countries provided data on M. pneumoniae infections, accounting for 95,666 positive samples. Two laboratories initiated routine macrolide resistance testing since 2013. Between 2011 and 2016, three epidemics were identified: 2011/12, 2014/15 and 2015/16. The distribution of patient ages for M. pneumoniae-positive samples showed three patterns. During epidemic years, an association between country latitude and calendar week when epidemic periods began was noted. Conclusions: An association between epidemics and latitude was observed. Differences were noted in the age distribution of positive cases and detection methods used and practice. A lack of macrolide resistance monitoring was noted

Avian pathogenic Escherichia coli (APEC) strain-dependent immunomodulation of respiratory granulocytes and mononuclear phagocytes in CSF1R-reporter transgenic chickens

Avian pathogenic Escherichia coli (APEC) cause severe respiratory and systemic disease in chickens, commonly termed colibacillosis. Early immune responses after initial infection are highly important for the outcome of the infection. In this study, the early interactions between GFP-expressing APEC strains of serotypes O1:K1:H7 and O2:K1:H5 and phagocytic cells in the lung of CSF1R-reporter transgenic chickens were investigated. CSF1R-reporter transgenic chickens express fluorescent protein under the control of elements of the CSF1R promoter and enhancer, such that cells of the myeloid lineage can be visualized in situ and sorted. Chickens were separately inoculated with APEC strains expressing GFP and culled 6 h post-infection. Flow cytometric analysis was performed to phenotype and sort the cells that harbored bacteria in the lung, and the response of the sorted cells was defined by transcriptomic analysis. Both APEC strains were mainly detected in CSF1R-transgeneneg (CSF1R-tgneg) and CSF1R-tglow MHC IIneg MRC1L-Bneg cells and low numbers of APEC were detected in CSF1R-tghigh MHC IIpos MRC1L-Bpos cells. Transcriptomic and flow cytometric analysis identified the APECpos CSF1R-tgneg and CSF1R-tglow cells as heterophils and the APECpos CSF1R-tghigh cells as macrophages and dendritic cells. Both APEC strains induced strong inflammatory responses, however in both CSF1R-tgneg/low and CSF1R-tghigh cells, many immune related pathways were repressed to a greater extent or less activated in birds inoculated with APEC O2-GFP compared to APEC O1-GFP inoculated birds. Comparison of the immune pathways revealed the aryl hydrocarbon receptor (AhR) pathway, IL17 and STAT3 signaling, heterophil recruitment pathways and the acute phase response, are modulated particularly post-APEC O2-GFP inoculation. In contrast to in vivo data, APEC O2-GFP was more invasive in CSF1R-tghigh cells in vitro than APEC O1-GFP and had higher survival rates for up to 6 h post-infection. Our data indicate significant differences in the responses induced by APEC strains of prevalent serotypes, with important implications for the design and interpretation of future studies. Moreover, we show that bacterial invasion and survival in phagocyte populations in vitro is not predictive of events in the chicken lung

Exposition des travailleurs en élevages de porcs et de volailles de chair à l’ammoniac et aux particules

L'air des bâtiments porcins et avicoles contient de l’ammoniac et des particules. Pour caractériser l'exposition des travailleurs à ces polluants, des données ont été collectées dans des exploitations agricoles. Les mesures ont été effectuées dans 20 exploitations porcines pendant des tâches considérées comme exposantes : les soins aux porcelets, le sevrage, l'alimentation des porcelets et le tri des porcs. 21 exploitations avicoles ont également été suivies pendant la surveillance en fin de bande, le ramassage, le curage du fumier et le paillage du bâtiment. En général, les particules et l'ammoniac ne sont pas considérés comme des risques professionnels par les travailleurs. Le risque est souvent minimisé mais les mesures montrent que l'exposition aux particules et à l'ammoniac impacte leur santé (augmentation des symptômes respiratoires et diminution de la capacité respiratoire). En outre, 15% des exploitations porcines ont une teneur en ammoniac supérieure à la limite d'exposition professionnelle (20 ppm pendant 15 minutes) pour au moins une des tâches contrôlées. En aviculture, 17% des mesures d'ammoniac au cours des tâches suivies sans paillage et 3% de toutes les mesures de particules effectuées dépassent la valeur maximale recommandée (5 mg/m3 de particules alvéolaires). Il est nécessaire de sensibiliser les acteurs du terrain aux risques respiratoires. À cette fin, une chaîne YouTube AIR Eleveur a été créée, ainsi que 2 brochures (équipement de protection et résultats AIR Eleveur).The air of pig and poultry farms contains ammonia and dust. To characterize the exposure of workers to these pollutants, data were collected on farms. Measurements were carried out in 20 pig farms during piglet care, weaning, feeding of piglets and sorting pigs and in 21 poultry farms during inspection of animals, catching birds, the manure disposal and litter distribution in the building. In general, particulate matter and ammonia are not considered as occupational hazards by workers. The risk is often minimized but measurements showed that exposure to particulate matter and ammonia poses a risk to their health (increased respiratory symptoms and decreased respiratory capacity). In addition, 15% of pig farms had an ammonia content above the occupational exposure limit (20 ppm for 15 minutes) on at least one of the tasks monitored. In poultry farming, 17% of the ammonia measurements during the tasks followed without mulching, and 3% of all the measurements of particles carried out exceeded the maximum recommended value (5 mg / m3 of cellular particles). It is necessary to sensitize the actors of the field on the respiratory risks. For this purpose, an AIR Eleveur YouTube channel was created as well as 2 brochures (protection equipment and AIR Eleveur results)

The IL-15 / sIL-15Rα complex modulates immunity without effect on asthma features in mouse

Background Interleukin 15 (IL-15) is a growth and modulating factor for B, T lymphocytes and natural killer cells (NK). Its action on innate and adaptive immunity is modulated by its alpha chain receptor (IL-15Rα). The IL-15/sIL-15Rα complex (IL-15Cx) increases the bioavailability and activity of the cytokine in vivo. IL-15Cx has been used in diseases to dampen IL-15 inflammation by the use of soluble IL-15Ralpha specificity. Here, we aim to evaluate the interest of IL-15Cx in a mouse model of asthma. Methods Using a mouse model of asthma consisting in percutaneous sensitization and intranasal challenge with total house dust mite extract, we evaluated the effect of IL-15Cx injected intraperitoneally four times after a first nasal challenge. Respiratory function was assessed by the technique of forced oscillations (Flexivent®). The effect on bronchial remodeling was evaluated by lung histology. The inflammatory status was analyzed by flow cytometry. Results We observed that the IL-15Cx modulates lung and systemic inflammation by increasing NK cells, CD8+ memory T cells and regulatory cells. However, IL-15Cx displays no effect on bronchial hyperreactivity, bronchial remodeling nor cellular bronchial infiltrate, but limits the secretion of bronchial mucus and modulates only inflammatory response in a HDM-allergic asthma murine model. Conclusions IL-15Cx has a limited effect on immune response in asthma and has no effect on lung function in mice. Thus, it limits its therapeutic potential but might suggest a combinatory potential with other therapeutics

Bdellovibrio and like organisms in lake geneva: An unseen elephant in the room?

When considering microbial biotic interactions, viruses as well as eukaryotic grazers are known to be important components of aquatic microbial food webs. It might be the same for bacterivorous bacteria but these groups have been comparatively less studied. This is typically the case of the Bdellovibrio and like organisms (BALOs), which are obligate bacterial predators of other bacteria. Recently, the abundance and distribution of three families of this functional group were investigated in perialpine lakes, revealing their presence and quantitative importance. Here, a more in-depth analysis is provided for Lake Geneva regarding the diversity of these bacterial predators at different seasons, sites and depths. We reveal a seasonal and spatial (vertical) pattern for BALOs. They were also found to be relatively diverse (especially Bdellovibrionaceae) and assigned to both known and unknown phylogenetic clusters. At last we found that most BALOs were positively correlated to other bacterial groups, mainly Gram-negative, in particular Myxococcales (among which many are predators of other microbes). This study is the first shedding light on this potentially important bacterial killing group in a large and deep lake