Éditeur(s) : HAL CCSD
Résumé : International audience
The search for safe antimalarial compounds acting against asexual symptom-responsible stages and sexual transmission-responsible forms of Plasmodium species is one of the major challenges in malaria elimination programs. So far, among current drugs approved for human use, only primaquine has transmission-blocking activity. The discovery of small molecules targeting different Plasmodium falcip-arum life stages remains a priority in antimalarial drug research. In this context, several independent studies have recently reported antiplasmodial and transmission-blocking activities of commonly used stains, dyes and fluorescent probes against P. falciparum including chloroquine-resistant isolates. Herein we have studied the antimalarial activities of dyes with different scaffold and we report that the triar-ylmethane dye (TRAM) Brilliant green inhibits the growth of asexual stages (IC 50 2 mM) and has exflagellation-blocking activity (IC 50 800 nM) against P. falciparum reference strains (3D7, 7G8) and chloroquine-resistant clinical isolate (Q206). In a second step we have investigated the antiplasmodial activities of two polysulfonated triarylmethane food dyes. Green S (E142) is weakly active against P. falciparum asexual stage (IC 50 x 17 mM) whereas Patent Blue V (E131) is inactive in both antimalarial assays. By applying liquid chromatography techniques for the culture supernatant analysis after cell washings and lysis, we report the detection of Brilliant green in erythrocytes, the selective uptake of Green S (E142) by infected erythrocytes, whereas Patent Blue V (E131) could not be detected within non-infected and 3D7-infected erythrocytes. Overall, our results suggest that two polysulfonated food dyes might display different affinity with transporters or channels on infected RBC membrane.
International journal for parasitology. Drugs and drug resistance

Droits : http://creativecommons.org/licenses/by-nc-sa/
pasteur-01614675
https://hal-pasteur.archives-ouvertes.fr/pasteur-01614675
https://hal-pasteur.archives-ouvertes.fr/pasteur-01614675/document
https://hal-pasteur.archives-ouvertes.fr/pasteur-01614675/file/Leba%20LJ-article%20colorant-version%20publiee.pdf
DOI : 10.1016/j.ijpddr.2017.07.002

Éditeur(s) : HAL CCSD American Society of Tropical Medicine and Hygiene
Résumé : International audience
Anti-leishmaniasis drug resistance is a common problem worldwide. The aim of this study was to inventory the general in vitro level of sensitivity of Leishmania isolates circulating in French Guiana and to highlight potential in vitro pentamidine-resistant isolates. This sensitivity study was conducted on 36 patient-promastigote isolates for seven drugs (amphotericin B, azithromycin, fluconazole, meglumine antimoniate, miltefosine, paromomycin, and pentamidine) using the Cell Counting Kit-8 viability test. The IC50 values obtained were heterogeneous. One isolate exhibited high IC50 values for almost all drugs tested. Pentamidine, which is the first-line treatment in French Guiana, showed efficacy at very low doses (mean of 0.0038 μg/mL). The concordance of the in vitro pentamidine results with the patients' clinical outcomes was 94% (K = 0.82).
ISSN: 0002-9637

inserm-01481512
http://www.hal.inserm.fr/inserm-01481512
http://www.hal.inserm.fr/inserm-01481512/document
http://www.hal.inserm.fr/inserm-01481512/file/2017%2C%20Ginouves%20-%20In%20vitro%20sensitivity%20of%20cutaneous%20leishmania.pdf
DOI : 10.4269/ajtmh.16-0373

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : In French Guiana, the population growth will result in an increase in demand for agricultural products and thus, will lead to an increase in the amount of tropical forests converted into cropland or pasture. Impacts of different agricultural systems on greenhouse gas (GHG) fluxes have not been studied in French Guiana. In this context, the fire-free chop-and-mulch method was used to convert a tropical forest site to agriculture. This study focused on soil nitrous oxide (N2O) emissions and we compared four land uses: (1) the undisturbed tropical forest, (2) recently converted grassland and recently converted croplands (fertilized soybean/maize rotation) with either (3) disk tillage or (4) no tillage.N2O measurements were obtained through the chamber technique and conducted over a 1-year period (measurements began 19 months after the forest was cleared). N2O fluxes were related to soil parameters measured at each sampling date: nitrate and ammonium contents, gravimetric water content (GWC) and temperature.Through the entire period, the mean (±standard error) and median N2O fluxes were 3.8 ± 0.5 and 2.7 g N ha−1 day−1, respectively for undisturbed tropical forest and 2.4 ± 0.9 and 0.8 g N ha−1 day−1, respectively for grassland (mowed Brachiaria ruziziensis). For croplands, no significant difference was found for N2O emissions between both agricultural practices. The mean (±standard error) and median N2O fluxes were 8.5 ± 1.2 and 4.0 g N ha−1 day−1, respectively for disk tillage plots and 8.5 ± 1.3 and 3.6 g N ha−1 day−1, respectively for no tillage plots. Nitrogen inputs (due to the application of fertilizer or due to the mineralization of crop residues) led to higher N2O fluxes, resulting in significantly higher mean N2O emissions from croplands compared to the forest, when only considering land use effect on N2O fluxes in a statistical model. The soil nitrate content, GWC and temperature had a significant positive effect on N2O fluxes. Taking into account these soil parameters in another statistical model, N2O emissions from croplands were not higher than the natural N2O emissions from tropical forest soils. Our results suggest that, if more forest will have to be converted in the course of the expected population growth in French Guiana, it could have low impact on the soil N2O fluxes (similar to natural fluxes from forest) with the improving of farming techniques (for example modification of the splitting of N-fertilizer) in the cropping plots.
ISSN: 0167-8809

hal-01204228
https://hal.archives-ouvertes.fr/hal-01204228
DOI : 10.1016/j.agee.2015.04.004
PRODINRA : 307607

Éditeur(s) : HAL CCSD
Résumé : One critical challenge for plants is to maintain an adequate nutrient supply under fluctuating environmental conditions. This is particularly true for epiphytic species that have limited or no access to the pedosphere and often live in harsh climates. Bromeliads have evolved key innovations such as epiphytism, water-absorbing leaf trichomes, tank habit and Crassulacean acid metabolism (CAM) photosynthesis that enable them to survive under various environmental conditions. Bromeliads encompass diverse ecological types that live on different substrates (they can be terrestrial, epilithic or epiphytic) and vary in their ability to retain water (they can be tank-forming or tankless) and photosynthetic pathway (i.e. C3 or CAM). In this review, we outline the nutritional modes and specializations that enable bromeliads to thrive in a wide range of nutrient-poor (mostly nitrogen-depleted) environments.Important FindingsBromeliads have evolved a great diversity of morphologies and functional adaptations leading to the existence of numerous nutritional modes. Focusing on species that have absorptive foliar trichomes, we review evidence that bromeliads have evolved multi-faceted nutritional strategies to respond to fluctuations in the supply of natural nitrogen (N). These plants have developed mutualistic associations with many different and functionally diverse terrestrial and aquatic microorganisms and metazoans that contribute substantially to their mineral nutrition and, thus, their fitness and survival. Bacterial and fungal microbiota-assisted N provisioning, protocarnivory, digestive mutualisms and myrmecotrophic pathways are the main strategies used by bromeliads to acquire nitrogen. The combination of different nutritional pathways in bromeliads represents an important adaptation enabling them to exploit nutrient-poor habitats. Nonetheless, as has been shown for several other vascular plants, multiple partners are involved in nutrient acquisition indicating that there have been convergent adaptations to nutrient scarcity. Finally, we point out some gaps in the current knowledge of bromeliad nutrition that offer fascinating research opportunities.
ISSN: 1752-9921

hal-01532637
https://hal.archives-ouvertes.fr/hal-01532637
DOI : 10.1093/jpe/rtv052
PRODINRA : 384521