Rapid assembly of a polar network architecture drives efficient actomyosin contractility

Actin network architecture and dynamics play a central role in cell contractility and tissue morphogenesis. RhoA-driven pulsed contractions are a generic mode of actomyosin contractility, but the mechanisms under- lying how their specific architecture emerges and how this architecture supports the contractile function of the network remain unclear. Here we show that, during pulsed contractions, the actin network is assembled by two subpopulations of formins: a functionally inactive population (recruited) and formins actively partici- pating in actin filament elongation (elongating). We then show that elongating formins assemble a polar actin network, with barbed ends pointing out of the pulse. Numerical simulations demonstrate that this geometry favors rapid network contraction. Our results show that formins convert a local RhoA activity gradient into a polar network architecture, causing efficient network contractility, underlying the key function of kinetic con- trols in the assembly and mechanics of cortical network architectures

Predictors of Aged Residential Care Placement in Patients Newly Diagnosed with Dementia at a New Zealand Memory Service

Background: Aged residential care (ARC) is a significant cost of dementia care. However, little is known about the predictors of ARC placement in New Zealand (NZ), which is important for service planning and funding. The aim of this study was to investigate the sociodemographic and clinical characteristics that predict future ARC placement among people who received a new diagnosis of dementia at a NZ memory service. Methods: Routinely collected baseline sociodemographic and clinical data in a memory service from 14/06/13 and 14/12/19 were linked with administrative LTC admission data up to 24/1/2020. Survival analysis was carried out using multivariate Cox regression models to determine significant risk factors and their association with ARC placement. Results: A total of 657 NZ European, Māori and Pacific Islander patients were included in the analyses. There were significant differences by ethnicity including age, living situation, comorbidity and ARC placement. Adjusted analyses showed that risk of ARC placement was increased by older age (HR 1.02 per year, 95%CI:1.00–1.05), moderate dementia (HR 1.45, 95%CI:1.05–1.99), severe dementia (HR 2.25, 95%CI:1.33–3.81), and antipsychotics (HR 1.55, 95%CI:1.04–2.32); while risk was reduced in Māori (HR 0.35, 95%CI:0.18–0.68) and Pacific Islanders (HR 0.32, 95%CI:0.20–0.51). Conclusions: Despite having more severe dementia and higher comorbidity, Māori and Pacific Islanders had reduced risks of ARC placement. There is an urgent need to better understand dementia care issues and to ensure culturally safe and responsive dementia services are accessible by Māori and Pacific Islanders living in the community

Altimetry for the future: Building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the ‘‘Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

Altimetry for the future: building on 25 years of progress

In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the “Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

Covid-19 : l’université à l’épreuve du télétravail. Une organisation fragmentée

International audienceCet article restitue les résultats d’une enquête collective et pluridisciplinaire qui a porté sur les effets du télétravail soudain et massif imposé à l’Université en raison de la crise sanitaire. Des questionnaires évaluant les incidences sur la vie familiale, les tms, les rps et comportant des questions ouvertes ont été administrés en juin 2020. Les résultats indiquent une dégradation des conditions de travail sur toutes les catégories de personnel, administratif, enseignement et recherche. Le télétravail a fait l’objet de régulations organisationnelles locales révélatrices de procédures de coordination incomplètes et de mises en œuvre contrastées et contingentes

Xylem Sap Metabolite Profile Changes During Phytostimulation of Maize by the Plant Growth-Promoting Rhizobacterium, Azospirillum lipoferum CRT1

Plant Growth-Promoting Rhizobacteria (PGPR) enhances host plant growth and tolerance to biotic and abiotic stresses. Despite increased knowledge of their functional activities, reports of their impact on host metabolism and signalling networks are rare. In this study, small organic substances were analysed in the ascending xylem sap of maize plantlets that were inoculated with the PGPR Azospirillum lipoferum. In this feasibility study, xylem sap collection using a Scholander chamber was combined with metabolome analysis by Gas Chromatography-Mass Spectrometry (GC-MS) based profiling. Two genotypes of maize were investigated. Cultivar Seiddi displayed A. lipoferum-mediated increases in lateral root growth and enhanced photosynthetic potential unlike non-responsive cultivar FuturiXX. A total of 119 small organic substances were annotated in maize xylem sap. The content of 17 substances, including primary metabolites, such as sucrose, maltose, glucose, TCA cycle intermediates, amino acids, GABA and shikimate pathway metabolites, decreased in both cultivars after A. lipoferum inoculation and may thus reflect general effects of the maize-A. lipoferum interaction. The content of 28 additional substances, namely glucose, lactic acid, acidic intermediates of the pentose phosphate and ascorbate/aldarate pathways and defense-related hydroxycinnamic acids, specifically changed in the xylem sap of the A. lipoferum-phytostimulated cultivar Seiddi, therefore, suggesting that phytostimulation of maize by A. lipoferum may involve xylem-transported metabolic signalling. Glucose or other metabolites that are retrograde transported through the xylem to the shoot by transpirational pull may act as feedback signals of the root status. Such signals may stimulate leaves to enhance photosynthesis-mediated C-assimilation that is needed to sustain A. lipoferum-triggered root growth. The untargeted metabolome analysis of the xylem, i.e., the xylenome, indicates that the differential interactions of the two maize cultivars Seiddi and FuturiXX with Azospirillum lipoferum could represent a feasible system for the study of the role of xylem transported signals in plant/ PGPR interactions

Rapid assembly of a polar network architecture drives efficient actomyosin contractility

S ummary Actin network architecture and dynamics play a central role in cell contractility and tissue morphogenesis. Pulsed contractions driven by RhoA represent a generic mode of actomyosin contractility, but the mechanisms underlying (1) how their specific architecture emerges, and (2) how this architecture supports the contractile function of the network, remain unclear. Here, we combine quantitative microscopy, single-molecule imaging, numerical simulations and simple mathematical modelling, to explore the dynamic network architecture underlying pulsed contraction. We show that during pulsed contractions, two subpopulations of formins are recruited by RhoA from the cytoplasm and bind to the cell surface in the early C. elegans embryo: recruited formins, a functionally inactive population, and elongating formins, which actively participate in actin filaments elongation. Focusing on formin dynamics during pulses, we show that minority elongating formins precede recruited formins, a kinetic dynamics compatible with formins capturing and rapidly saturating barbed ends available for filament elongation. We then show that these elongating formins assemble a polar network of actin, with barbed ends pointing out of the pulse, pointing to a kinetic rather than mechanical control of network architecture. Finally, our numerical simulations demonstrate that this geometry favors rapid network contraction. Our results thus show that formins saturate available actin filaments barbed ends and convert a local, biochemical gradient of RhoA activity into a polar network architecture, thereby driving rapid and efficient network contractility, an important evolutionary feature in a metazoan with a rapid embryonic cell cycles. H ighlights The formin CYK-1 drives actin network assembly during RhoA-driven pulses The process is extremely rapid, with a formin-based actin elongation rate higher than 1.3 μm·s -1 A barbed-end saturation mechanism allows for responsive F-actin assembly Rapid and responsive F-actin elongation results in the assembly of aster-like polar actin networks Numerical simulations show network polarity drives very efficient network contractilit

Multi-omics quantitative data of tomato fruit unveils regulation modes of least variable metabolites

International audienceBackground The composition of ripe fruits depends on various metabolites which content evolves greatly throughout fruit development and may be influenced by the environment. The corresponding metabolism regulations have been widely described in tomato during fruit growth and ripening. However, the regulation of other metabolites that do not show large changes in content have scarcely been studied. Results We analysed the metabolites of tomato fruits collected on different trusses during fruit development, using complementary analytical strategies. We identified the 22 least variable metabolites, based on their coefficients of variation. We first verified that they had a limited functional link with the least variable proteins and transcripts. We then posited that metabolite contents could be stabilized through complex regulations and combined their data with the quantitative proteome or transcriptome data, using sparse partial-least-square analyses. This showed shared regulations between several metabolites, which interestingly remained linked to early fruit development. We also examined regulations in specific metabolites using correlations with individual proteins and transcripts, which revealed that a stable metabolite does not always correlate with proteins and transcripts of its known related pathways. Conclusions The regulation of the least variable metabolites was then interpreted regarding their roles as hubs in metabolic pathways or as signalling molecules

Maize metabolome and proteome responses to controlled cold stress partly mimic early‐sowing effects in the field and differ from those of Arabidopsis

In Northern Europe, sowing maize one-month earlier than current agricultural practices may lead to moderate chilling damage. However, studies of the metabolic responses to low, non-freezing, temperatures remain scarce. Here, genetically-diverse maize hybrids (Zea mays, dent inbred lines crossed with a flint inbred line) were cultivated in a growth chamber at optimal temperature and then three decreasing temperatures for two days each, as well as in the field. Leaf metabolomic and proteomic profiles were determined. In the growth chamber, 50% of metabolites and 18% of proteins changed between 20 and 16°C. These maize responses, partly differing from those of Arabidopsis to short-term chilling, were mapped on genome-wide metabolic maps. Several metabolites and proteins varied similarly for all temperature decreases: seven MS-based metabolite signatures and two proteins involved in photosynthesis decreased continuously. Several metabolites or proteins increasing in the growth-chamber chilling conditions showed similar trends in the early-sowing field experiment, including trans-aconitate, three hydroxycinnamate derivatives, a benzoxazinoid, a sucrose synthase, lethal leaf-spot 1 protein, an allene oxide synthase, several glutathione transferases and peroxidases. Hybrid groups based on field biomass were used to search for the metabolite or protein responses differentiating them in growth-chamber conditions, which could be of interest for breeding. This article is protected by copyright. All rights reserved.Développement d'une infrastructure française distribuée pour la métabolomique dédiée à l'innovationCentre français de phénomique végétaleDévelopper de nouvelles variétés de maïs pour une agriculture durable: une approche intégrée de la génomique à la sélectio