Do pH changes in the leaf apoplast contribute to rapid inhibition of leaf elongation rate by water stress? Comparison of stress responses induced by polyethylene glycol and down-regulation of root hydraulic conductivity

International audienceWe have dissected the influences of apoplastic pH and cell turgor on short-term responses of leaf growth to plant water status, by using a combination of a double-barrelled pH-selective microelectrodes and a cell pressure probe. These techniques were used, together with continuous measurements of leaf elongation rate (LER), in the (hidden) elongating zone of the leaves of intact maize plants while exposing roots to various treatments. Polyethylene glycol (PEG) reduced water availability to roots, while acid load and anoxia decreased root hydraulic conductivity. During the first 30 min, acid load and anoxia induced moderate reductions in leaf growth and turgor, with no effect on leaf apoplastic pH. PEG stopped leaf growth, while turgor was only partially reduced. Rapid alkalinization of the apoplast, from pH 4.9 ± 0.3 to pH 5.8 ± 0.2 within 30 min, may have participated to this rapid growth reduction. After 60 min, leaf growth inhibition correlated well with turgor reduction across all treatments, supporting a growth limitation by hydraulics. We conclude that apoplastic alkalinization may transiently impair the control of leaf growth by cell turgor upon abrupt water stress, whereas direct hydraulic control of growth predominates under moderate conditions and after a 30-60 min delay following imposition of water stress

Compte-rendu de fin de projet, ANR-11-BSV7-015 01, UNLOCKP – Mobilisation des réserves de Phytate du sol : quelles sont les clefs nécessaires pour accéder au phosphore de ce trésor ? Programme blanc

Compte-rendu de fin de projet, ANR-11-BSV7-015 01, UNLOCKP – Mobilisation des réserves de Phytate du sol : quelles sont les clefs nécessaires pour accéder au phosphore de ce trésor ? Programme blan

Ectomycorrhizal fungi and mobilisation of organic phosphorus from forest soil: Novel data and actual role

International audienceIt has been demonstrated that forest soils contain a high proportion of phosphorus (P) in organic form (Po) that is represented by phosphomonoesters (such as glucose1-P, ATP, phytic acid, ...) or phosphodiesters (such as nucleic acids or phospholipids). To be used by trees, the phosphate group (Pi) must be released by the hydrolysis of the strong ester bond by enzymes that are phosphatases (Pases). We are currently working on the hypothesis that phosphatases released by ectomycorrhizal (ECM) fungi play an important role in the recycling of P in forest soil, thus contributing to plant P nutrition. We addressed this question in the context of spodosoils of "Landes de Gascogne" as these soils, ensuring around 40% of conifer wood production in France, are very poor in Pi and high in Po contents relative to total P contents, making P limiting for maritime pine (Pinus pinaster) growth. We worked on (i) Hebeloma cylindrosporum, a model fungal ECM species able to release huge amounts of Pase activity when grown in vitro in P-starved conditions, and (ii) on native ECM species. We found that H. cylindrosporum released 4 acid Pase isoforms able to hydrolyse a broad range of phosphate monoesters and to a low extent, the phosphodiester bis-pNPP. However, the efficiency of each isoform to release Pi from Po extracted from spodosoils was low. The role of native species was studied by cultivating P. pinaster seedlings in intact soil samples from plots of different ages or fertilisation design.. Despite a high pNPPAse activity in ECM tips, P mobilisation from soil Po, measured by plant P accumulation, was very low in those soils with the lowest mineral P availability and the highest Po concentrations. Surprisingly, we found a significant decrease in Po fractions in soils that were annually fertilised and irrigated. Finally, based on our findings, we will propose a novel scheme of the possible role of ECM fungal Pase in Po mobilisation from forest soil

Le projet du developpement local dans la mutation economique et culturelle des societes industrialisees

SIGLECNRS AR 12981 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Ectomycorrhizal fungi and mobilisation of organic phosphorus from forest soil: myth or reality?

National audienceForest soils contain a high proportion of phosphorus (P) in organic form (Po) represented by phosphomonoesters (such as glucose 1-P, ATP, phytate, …) or phosphodiesters (such as nucleic acids or phospholipids). To be used by trees, the phosphate group (Pi) must be released by the hydrolysis of the ester bond by phosphatases (Pases). It has been hypothesized that ectomycorrhizal (ECM) fungi, able to release phosphatases in their environment, could play an important role in the recycling of P in forest soil, thus contributing to plant P nutrition. We addressed this question in the context of the maritime pine (Pinus pinaster) forest representing the first planted area in France. This forest is established on sandy podzol very poor in available Pi but high in Po contents relative to total P contents, making P limiting for tree growth. Field studies showed a high degree of mycorrhizal symbiosis. To assess the efficiency of fungal Pases on organic P hydrolysis, we used Hebeloma cylindrosporum, a fungal ECM species isolated from maritime pine plots, able to release significant amounts of Pase activity when grown in vitro in P-starved conditions. Using cation-exchange chromatography, we separated four fractions with AcPase activity. Each AcPase active fraction displayed strong ability in vitro to hydrolyse a wide range of phosphate monoesters, but none of them efficiently hydrolysed phytate. In vitro measurements showed that up to 11% of the NaHCO3-extractable Po from intact soil was phosphatase reactive. This value reached 50% in soils autoclaved previously (Louche et al. 2010, FEMS 73: 323-335). Taken together, these data suggest that AcPases secreted from H. cylindrosporum could be much more efficient in recycling microbial organic P pools that may be delivered by soil autoclaving than other soil organic P

Pratiques de chercheurs et outils de bibliothécaires : quelle(s) convergence(s) en vue de la production de données FAIR ?: Table-ronde JABES 2022

National audienceSi l’utilisation de référentiels partagés est une évidence pour les bibliothécaires puisque nécessaire au bon fonctionnement des catalogues, cela n’est pas complètement le cas au sein des communautés de recherche. Or, l’exposition des données sur le web et l’exigence d’interopérabilité invitent à affirmer et étendre le rôle des référentiels dans ce contexte, avec pour effet de tisser des liens de coopération et de dialogue riches et fructueux entre chercheurs et professionnels de la documentation.Les invités de cette table ronde évoqueront concrètement la façon dont, en coopération avec l’Abes, ils ont pu intégrer la dimension « données » à leurs projets de recherche respectifs

Retrospective de la prospective La prospective dans le domaine des transports, recherche critique

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : RL 592 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Unstable TTTTA/TTTCA expansions in MARCH6 are associated with Familial Adult Myoclonic Epilepsy type 3

Familial Adult Myoclonic Epilepsy (FAME) is a genetically heterogeneous disorder characterized by cortical tremor and seizures. Intronic TTTTA/TTTCA repeat expansions in SAMD12 (FAME1) are the main cause of FAME in Asia. Using genome sequencing and repeat-primed PCR, we identify another site of this repeat expansion, in MARCH6 (FAME3) in four European families. Analysis of single DNA molecules with nanopore sequencing and molecular combing show that expansions range from 3.3 to 14 kb on average. However, we observe considerable variability in expansion length and structure, supporting the existence of multiple expansion configurations in blood cells and fibroblasts of the same individual. Moreover, the largest expansions are associated with micro-rearrangements occurring near the expansion in 20% of cells. This study provides further evidence that FAME is caused by intronic TTTTA/TTTCA expansions in distinct genes and reveals that expansions exhibit an unexpectedly high somatic instability that can ultimately result in genomic rearrangements

Severity of COVID-19 and survival in patients with rheumatic and inflammatory diseases: data from the French RMD COVID-19 cohort of 694 patients

International audienceObjectives: There is little known about the impact of SARS-CoV-2 on patients with inflammatory rheumatic and musculoskeletal diseases (iRMD). We examined epidemiological characteristics associated with severe disease, then with death. We also compared mortality between patients hospitalised for COVID-19 with and without iRMD.Methods: Individuals with suspected iRMD-COVID-19 were included in this French cohort. Logistic regression models adjusted for age and sex were used to estimate adjusted ORs and 95% CIs of severe COVID-19. The most significant clinically relevant factors were analysed by multivariable penalised logistic regression models, using a forward selection method. The death rate of hospitalised patients with iRMD-COVID-19 (moderate-severe) was compared with a subset of patients with non-iRMD-COVID-19 from a French hospital matched for age, sex, and comorbidities.Results: Of 694 adults, 438 (63%) developed mild (not hospitalised), 169 (24%) moderate (hospitalised out of the intensive care unit (ICU) and 87 (13%) severe (patients in ICU/deceased) disease. In multivariable imputed analyses, the variables associated with severe infection were age (OR=1.08, 95% CI: 1.05-1.10), female gender (OR=0.45, 95% CI: 0.25-0.80), body mass index (OR=1.07, 95% CI: 1.02-1.12), hypertension (OR=1.86, 95% CI: 1.01-3.42), and use of corticosteroids (OR=1.97, 95% CI: 1.09-3.54), mycophenolate mofetil (OR=6.6, 95% CI: 1.47-29.62) and rituximab (OR=4.21, 95% CI: 1.61-10.98). Fifty-eight patients died (8% (total) and 23% (hospitalised)). Compared with 175 matched hospitalised patients with non-iRMD-COVID-19, the OR of mortality associated with hospitalised patients with iRMD-COVID-19 was 1.45 (95% CI: 0.87-2.42) (n=175 each group).Conclusions: In the French RMD COVID-19 cohort, as already identified in the general population, older age, male gender, obesity, and hypertension were found to be associated with severe COVID-19. Patients with iRMD on corticosteroids, but not methotrexate, or tumour necrosis factor alpha and interleukin-6 inhibitors, should be considered as more likely to develop severe COVID-19. Unlike common comorbidities such as obesity, and cardiovascular or lung diseases, the risk of death is not significantly increased in patients with iRMD

Severity of COVID-19 and survival in patients with rheumatic and inflammatory diseases: data from the French RMD COVID-19 cohort of 694 patients

International audienceObjectives: There is little known about the impact of SARS-CoV-2 on patients with inflammatory rheumatic and musculoskeletal diseases (iRMD). We examined epidemiological characteristics associated with severe disease, then with death. We also compared mortality between patients hospitalised for COVID-19 with and without iRMD.Methods: Individuals with suspected iRMD-COVID-19 were included in this French cohort. Logistic regression models adjusted for age and sex were used to estimate adjusted ORs and 95% CIs of severe COVID-19. The most significant clinically relevant factors were analysed by multivariable penalised logistic regression models, using a forward selection method. The death rate of hospitalised patients with iRMD-COVID-19 (moderate-severe) was compared with a subset of patients with non-iRMD-COVID-19 from a French hospital matched for age, sex, and comorbidities.Results: Of 694 adults, 438 (63%) developed mild (not hospitalised), 169 (24%) moderate (hospitalised out of the intensive care unit (ICU) and 87 (13%) severe (patients in ICU/deceased) disease. In multivariable imputed analyses, the variables associated with severe infection were age (OR=1.08, 95% CI: 1.05-1.10), female gender (OR=0.45, 95% CI: 0.25-0.80), body mass index (OR=1.07, 95% CI: 1.02-1.12), hypertension (OR=1.86, 95% CI: 1.01-3.42), and use of corticosteroids (OR=1.97, 95% CI: 1.09-3.54), mycophenolate mofetil (OR=6.6, 95% CI: 1.47-29.62) and rituximab (OR=4.21, 95% CI: 1.61-10.98). Fifty-eight patients died (8% (total) and 23% (hospitalised)). Compared with 175 matched hospitalised patients with non-iRMD-COVID-19, the OR of mortality associated with hospitalised patients with iRMD-COVID-19 was 1.45 (95% CI: 0.87-2.42) (n=175 each group).Conclusions: In the French RMD COVID-19 cohort, as already identified in the general population, older age, male gender, obesity, and hypertension were found to be associated with severe COVID-19. Patients with iRMD on corticosteroids, but not methotrexate, or tumour necrosis factor alpha and interleukin-6 inhibitors, should be considered as more likely to develop severe COVID-19. Unlike common comorbidities such as obesity, and cardiovascular or lung diseases, the risk of death is not significantly increased in patients with iRMD