ROLE OF CUTANEOUS AFFERENTS IN THE CONTROL OF FINE MOVEMENTS

An increase in the quantity of afferents has been observed to be less useful to normal individual, therefore to patients suffering from neurological problems. To determine the effect of reduction of cutaneous afferents in the control of fine movements.Sixty healthy individuals, age between 20 and 25 years, were randomized into 2 groups.Main outcome measures: The speed of movements was measured with a specific device constructed specially to this study, related to digital chronometer that detects 1/100 of the second. T-test was performed for outcome measure and to evaluate individual difference within groups in the presence of significance. The position at the edge of the support show an increase in the speed of the fine movement by 82% than the position completely on the support

ROLE OF CUTANEOUS AFFERENTS IN THE CONTROL OF FINE MOVEMENTS

An increase in the quantity of afferents has been observed to be less useful to normal individual, therefore to patients suffering from neurological problems. To determine the effect of reduction of cutaneous afferents in the control of fine movements.Sixty healthy individuals, age between 20 and 25 years, were randomized into 2 groups.Main outcome measures: The speed of movements was measured with a specific device constructed specially to this study, related to digital chronometer that detects 1/100 of the second. T-test was performed for outcome measure and to evaluate individual difference within groups in the presence of significance. The position at the edge of the support show an increase in the speed of the fine movement by 82% than the position completely on the support

Metabolic responses to waterlogging differ between roots and shoots and reflect phloem transport alteration in medicago truncatula

Root oxygen deficiency that is induced by flooding (waterlogging) is a common situation in many agricultural areas, causing considerable loss in yield and productivity. Physiological and metabolic acclimation to hypoxia has mostly been studied on roots or whole seedlings under full submergence. The metabolic difference between shoots and roots during waterlogging, and how roots and shoots communicate in such a situation is much less known. In particular, the metabolic acclimation in shoots and how this, in turn, impacts on roots metabolism is not well documented. Here, we monitored changes in the metabolome of roots and shoots of barrel clover (Medicago truncatula), growth, and gas-exchange, and analyzed phloem sap exudate composition. Roots exhibited a typical response to hypoxia, such as γ-aminobutyrate and alanine accumulation, as well as a strong decline in raffinose, sucrose, hexoses, and pentoses. Leaves exhibited a strong increase in starch, sugars, sugar derivatives, and phenolics (tyrosine, tryptophan, phenylalanine, benzoate, ferulate), suggesting an inhibition of sugar export and their alternative utilization by aromatic compounds production via pentose phosphates and phosphoenolpyruvate. Accordingly, there was an enrichment in sugars and a decline in organic acids in phloem sap exudates under waterlogging. Mass-balance calculations further suggest an increased imbalance between loading by shoots and unloading by roots under waterlogging. Taken as a whole, our results are consistent with the inhibition of sugar import by waterlogged roots, leading to an increase in phloem sugar pool, which, in turn, exert negative feedback on sugar metabolism and utilization in shoots.This research was funded by the Région Pays de la Loire and Angers Loire Métropole, via the grant Connect Talent Isosee

Modulation du métabolisme azoté sous hypoxie racinaire, chez Medicago truncatula

Plants grow in a dynamic environment, which often, imposes constraints on growth and development. Among the adverse environmental factors commonly encountered by land plants, flooding or waterlogging which imposes a temporary root hypoxia (1-2% oxygen). Hypoxia stress jeopardizes plant survival, and therefore induces tremendous damage on the agricultural production and natural ecosystem. Most previous studies of biological and biochemical alterations in plants, due to hypoxic stress, have focused on sugar metabolism. However, few data, regarding the effect of root hypoxia on nitrogen (N) metabolism have recently become available. The aim of our work is to study the impact of root hypoxia on nitrogen metabolism in the model plant "Medicago truncatula." Our results showed that root hypoxia leads to a significant increase in shoot biomass (MF and MS) with increased stem elongation and number of leaves during a transitional period of almost 5 weeks before inducing plant death. Effects on primary metabolism were followed by metabolomic analysis (GC-MS), labeling of nitrogen (15N) and expression of genes involved in nitrogen metabolism. Root hypoxia induced the expected rearrangement of carbon and nitrogen in the root but interestingly it induced significant changes in C and N metabolisms in the aerated shoot. Hypoxia-induced changes in shoot biomass and metabolism were obtained in split-root experiment where only part of the root system was submitted to hypoxia. The response of the aerated shoot to root hypoxia suggests a communication between root and shoot upon hypoxia aiming at a coherent adaptive response at the whole plant level. The nature of this communication deserves to be more thoroughly investigated.Les plantes se développent dans un environnement dynamique, ce qui impose souvent des contraintes sur la croissance et le développement. Parmi les facteurs environnementaux adverses, fréquemment rencontrés par les plantes terrestres, l'inondation ou submersion temporaire qui impose une hypoxie racinaire (1-2% d'oxygène). La submersion du sol peut avoir un très fort impact sur la survie des plantes, et donc sur la production agricole ainsi que les écosystèmes naturels. La plupart des études antérieures sur les altérations biologiques et biochimiques chez les plantes, dues au stress hypoxique, ont porté sur le métabolisme des sucres. Toutefois, quelques données concernant les effets de l'hypoxie racinaire sur le métabolisme azoté (N) sont récemment devenues disponibles. Le but de notre travail est d'étudier les effets de l'hypoxie racinaire sur le métabolisme azoté chez la plante modèle "Medicago truncatula". Les résultats obtenus ont montré que l'hypoxie racinaire entraine une augmentation significative de la biomasse aérienne (MF et MS) avec allongement des tiges et augmentation du nombre de feuilles pendant une période transitoire allant jusqu'à 5 semaines avant d'engendrer la mort des plantes. Les effets sur le métabolisme primaire ont été suivis par des analyses métabolomiques (GC-MS), marquage à l'azote (15N) et expression de gènes impliqués dans le métabolisme azoté. Nos résultats montrent que si l'hypoxie racinaire entraine des modifications sommes toute attendues des métabolismes de l'azote et du carbone, elle entraine également des réarrangements de ces métabolismes dans la partie aérienne non soumise à l'hypoxie. La réponse des parties aériennes en termes de croissance et de modification métabolique a été obtenue même quand une partie minoritaire seulement du système racinaire a été soumise à l'hypoxie suggérant une communication racine - partie aérienne qui mériterait d'être plus étudiée dans l'avenir

Modulation du métabolisme azoté sous hypoxie racinaire, chez Medicago truncatula

Plants grow in a dynamic environment, which often, imposes constraints on growth and development. Among the adverse environmental factors commonly encountered by land plants, flooding or waterlogging which imposes a temporary root hypoxia (1-2% oxygen). Hypoxia stress jeopardizes plant survival, and therefore induces tremendous damage on the agricultural production and natural ecosystem. Most previous studies of biological and biochemical alterations in plants, due to hypoxic stress, have focused on sugar metabolism. However, few data, regarding the effect of root hypoxia on nitrogen (N) metabolism have recently become available. The aim of our work is to study the impact of root hypoxia on nitrogen metabolism in the model plant "Medicago truncatula." Our results showed that root hypoxia leads to a significant increase in shoot biomass (MF and MS) with increased stem elongation and number of leaves during a transitional period of almost 5 weeks before inducing plant death. Effects on primary metabolism were followed by metabolomic analysis (GC-MS), labeling of nitrogen (15N) and expression of genes involved in nitrogen metabolism. Root hypoxia induced the expected rearrangement of carbon and nitrogen in the root but interestingly it induced significant changes in C and N metabolisms in the aerated shoot. Hypoxia-induced changes in shoot biomass and metabolism were obtained in split-root experiment where only part of the root system was submitted to hypoxia. The response of the aerated shoot to root hypoxia suggests a communication between root and shoot upon hypoxia aiming at a coherent adaptive response at the whole plant level. The nature of this communication deserves to be more thoroughly investigated.Les plantes se développent dans un environnement dynamique, ce qui impose souvent des contraintes sur la croissance et le développement. Parmi les facteurs environnementaux adverses, fréquemment rencontrés par les plantes terrestres, l'inondation ou submersion temporaire qui impose une hypoxie racinaire (1-2% d'oxygène). La submersion du sol peut avoir un très fort impact sur la survie des plantes, et donc sur la production agricole ainsi que les écosystèmes naturels. La plupart des études antérieures sur les altérations biologiques et biochimiques chez les plantes, dues au stress hypoxique, ont porté sur le métabolisme des sucres. Toutefois, quelques données concernant les effets de l'hypoxie racinaire sur le métabolisme azoté (N) sont récemment devenues disponibles. Le but de notre travail est d'étudier les effets de l'hypoxie racinaire sur le métabolisme azoté chez la plante modèle "Medicago truncatula". Les résultats obtenus ont montré que l'hypoxie racinaire entraine une augmentation significative de la biomasse aérienne (MF et MS) avec allongement des tiges et augmentation du nombre de feuilles pendant une période transitoire allant jusqu'à 5 semaines avant d'engendrer la mort des plantes. Les effets sur le métabolisme primaire ont été suivis par des analyses métabolomiques (GC-MS), marquage à l'azote (15N) et expression de gènes impliqués dans le métabolisme azoté. Nos résultats montrent que si l'hypoxie racinaire entraine des modifications sommes toute attendues des métabolismes de l'azote et du carbone, elle entraine également des réarrangements de ces métabolismes dans la partie aérienne non soumise à l'hypoxie. La réponse des parties aériennes en termes de croissance et de modification métabolique a été obtenue même quand une partie minoritaire seulement du système racinaire a été soumise à l'hypoxie suggérant une communication racine - partie aérienne qui mériterait d'être plus étudiée dans l'avenir

Modulation du métabolisme azoté sous hypoxie racinaire, chez Medicago truncatula

Plants grow in a dynamic environment, which often, imposes constraints on growth and development. Among the adverse environmental factors commonly encountered by land plants, flooding or waterlogging which imposes a temporary root hypoxia (1-2% oxygen). Hypoxia stress jeopardizes plant survival, and therefore induces tremendous damage on the agricultural production and natural ecosystem. Most previous studies of biological and biochemical alterations in plants, due to hypoxic stress, have focused on sugar metabolism. However, few data, regarding the effect of root hypoxia on nitrogen (N) metabolism have recently become available. The aim of our work is to study the impact of root hypoxia on nitrogen metabolism in the model plant "Medicago truncatula." Our results showed that root hypoxia leads to a significant increase in shoot biomass (MF and MS) with increased stem elongation and number of leaves during a transitional period of almost 5 weeks before inducing plant death. Effects on primary metabolism were followed by metabolomic analysis (GC-MS), labeling of nitrogen (15N) and expression of genes involved in nitrogen metabolism. Root hypoxia induced the expected rearrangement of carbon and nitrogen in the root but interestingly it induced significant changes in C and N metabolisms in the aerated shoot. Hypoxia-induced changes in shoot biomass and metabolism were obtained in split-root experiment where only part of the root system was submitted to hypoxia. The response of the aerated shoot to root hypoxia suggests a communication between root and shoot upon hypoxia aiming at a coherent adaptive response at the whole plant level. The nature of this communication deserves to be more thoroughly investigated.Les plantes se développent dans un environnement dynamique, ce qui impose souvent des contraintes sur la croissance et le développement. Parmi les facteurs environnementaux adverses, fréquemment rencontrés par les plantes terrestres, l'inondation ou submersion temporaire qui impose une hypoxie racinaire (1-2% d'oxygène). La submersion du sol peut avoir un très fort impact sur la survie des plantes, et donc sur la production agricole ainsi que les écosystèmes naturels. La plupart des études antérieures sur les altérations biologiques et biochimiques chez les plantes, dues au stress hypoxique, ont porté sur le métabolisme des sucres. Toutefois, quelques données concernant les effets de l'hypoxie racinaire sur le métabolisme azoté (N) sont récemment devenues disponibles. Le but de notre travail est d'étudier les effets de l'hypoxie racinaire sur le métabolisme azoté chez la plante modèle "Medicago truncatula". Les résultats obtenus ont montré que l'hypoxie racinaire entraine une augmentation significative de la biomasse aérienne (MF et MS) avec allongement des tiges et augmentation du nombre de feuilles pendant une période transitoire allant jusqu'à 5 semaines avant d'engendrer la mort des plantes. Les effets sur le métabolisme primaire ont été suivis par des analyses métabolomiques (GC-MS), marquage à l'azote (15N) et expression de gènes impliqués dans le métabolisme azoté. Nos résultats montrent que si l'hypoxie racinaire entraine des modifications sommes toute attendues des métabolismes de l'azote et du carbone, elle entraine également des réarrangements de ces métabolismes dans la partie aérienne non soumise à l'hypoxie. La réponse des parties aériennes en termes de croissance et de modification métabolique a été obtenue même quand une partie minoritaire seulement du système racinaire a été soumise à l'hypoxie suggérant une communication racine - partie aérienne qui mériterait d'être plus étudiée dans l'avenir

Reconfiguration of N Metabolism upon Hypoxia Stress and Recovery: Roles of Alanine Aminotransferase (AlaAT) and Glutamate Dehydrogenase (GDH)

In the context of climatic change, more heavy precipitation and more frequent flooding and waterlogging events threaten the productivity of arable farmland. Furthermore, crops were not selected to cope with flooding- and waterlogging-induced oxygen limitation. In general, low oxygen stress, unlike other abiotic stresses (e.g., cold, high temperature, drought and saline stress), received little interest from the scientific community and less financial support from stakeholders. Accordingly, breeding programs should be developed and agronomical practices should be adapted in order to save plants’ growth and yield—even under conditions of low oxygen availability (e.g., submergence and waterlogging). The prerequisite to the success of such breeding programs and changes in agronomical practices is a good knowledge of how plants adapt to low oxygen stress at the cellular and the whole plant level. In the present paper, we summarized the recent knowledge on metabolic adjustment in general under low oxygen stress and highlighted thereafter the major changes pertaining to the reconfiguration of amino acids syntheses. We propose a model showing (i) how pyruvate derived from active glycolysis upon hypoxia is competitively used by the alanine aminotransferase/glutamate synthase cycle, leading to alanine accumulation and NAD+ regeneration. Carbon is then saved in a nitrogen store instead of being lost through ethanol fermentative pathway. (ii) During the post-hypoxia recovery period, the alanine aminotransferase/glutamate dehydrogenase cycle mobilizes this carbon from alanine store. Pyruvate produced by the reverse reaction of alanine aminotransferase is funneled to the TCA cycle, while deaminating glutamate dehydrogenase regenerates, reducing equivalent (NADH) and 2-oxoglutarate to maintain the cycle function

Modulation du métabolisme azoté sous hypoxie racinaire, chez Medicago truncatula

Les plantes se développent dans un environnement dynamique, ce qui impose souvent des contraintes sur la croissance et le développement. Parmi les facteurs environnementaux adverses, fréquemment rencontrés par les plantes terrestres, l'inondation ou submersion temporaire qui impose une hypoxie racinaire (1-2% d'oxygène). La submersion du sol peut avoir un très fort impact sur la survie des plantes, et donc sur la production agricole ainsi que les écosystèmes naturels. La plupart des études antérieures sur les altérations biologiques et biochimiques chez les plantes, dues au stress hypoxique, ont porté sur le métabolisme des sucres. Toutefois, quelques données concernant les effets de l'hypoxie racinaire sur le métabolisme azoté (N) sont récemment devenues disponibles. Le but de notre travail est d'étudier les effets de l'hypoxie racinaire sur le métabolisme azoté chez la plante modèle "Medicago truncatula". Les résultats obtenus ont montré que l'hypoxie racinaire entraine une augmentation significative de la biomasse aérienne (MF et MS) avec allongement des tiges et augmentation du nombre de feuilles pendant une période transitoire allant jusqu'à 5 semaines avant d'engendrer la mort des plantes. Les effets sur le métabolisme primaire ont été suivis par des analyses métabolomiques (GC-MS), marquage à l'azote (15N) et expression de gènes impliqués dans le métabolisme azoté. Nos résultats montrent que si l'hypoxie racinaire entraine des modifications sommes toute attendues des métabolismes de l'azote et du carbone, elle entraine également des réarrangements de ces métabolismes dans la partie aérienne non soumise à l'hypoxie. La réponse des parties aériennes en termes de croissance et de modification métabolique a été obtenue même quand une partie minoritaire seulement du système racinaire a été soumise à l'hypoxie suggérant une communication racine - partie aérienne qui mériterait d'être plus étudiée dans l'avenir.Plants grow in a dynamic environment, which often, imposes constraints on growth and development. Among the adverse environmental factors commonly encountered by land plants, flooding or waterlogging which imposes a temporary root hypoxia (1-2% oxygen). Hypoxia stress jeopardizes plant survival, and therefore induces tremendous damage on the agricultural production and natural ecosystem. Most previous studies of biological and biochemical alterations in plants, due to hypoxic stress, have focused on sugar metabolism. However, few data, regarding the effect of root hypoxia on nitrogen (N) metabolism have recently become available. The aim of our work is to study the impact of root hypoxia on nitrogen metabolism in the model plant "Medicago truncatula." Our results showed that root hypoxia leads to a significant increase in shoot biomass (MF and MS) with increased stem elongation and number of leaves during a transitional period of almost 5 weeks before inducing plant death. Effects on primary metabolism were followed by metabolomic analysis (GC-MS), labeling of nitrogen (15N) and expression of genes involved in nitrogen metabolism. Root hypoxia induced the expected rearrangement of carbon and nitrogen in the root but interestingly it induced significant changes in C and N metabolisms in the aerated shoot. Hypoxia-induced changes in shoot biomass and metabolism were obtained in split-root experiment where only part of the root system was submitted to hypoxia. The response of the aerated shoot to root hypoxia suggests a communication between root and shoot upon hypoxia aiming at a coherent adaptive response at the whole plant level. The nature of this communication deserves to be more thoroughly investigated.ANGERS-BU Lettres et Sciences (490072106) / SudocSudocFranceF

Impact of waterloging-induced hypoxia on nitrogen metabolism in the legume Medicago truncatula

International audienceFlooding and waterlogging due to the induced oxygen limitation in the root zone is harmful for plant development. This study examines short term modulation of nitrogen metabolism in Medicafo truncatula submitted to waterlogging. The objective was to evaluate whether and how nitrogen metabolism contributes to the mitigation of damaging effects of hypoxia. The processes that were affected early after the onset of stress were nitrate reduction and amino acids synthesis. NADH-dependent nitrate reductase activity increased dramatically in the root. It is suggested that nitrate reductase contributes to cellular acclimation to hypoxia by regenerating NAD + from NADH. The regeneration of NAD+ is a crucial issue in hypoxic cells because it is necessary for supporting increasing rates of glycolysis. Amino acids metabolism shifted from the ATP consuming pathway leading to asparagines, the most accumulated amino acid in Medicago truncatula, to pathways leading to alanine and GABA accumulation. Synthesis of alanine is not dependent on ATP and allows for storage of carbon used in glycolysis (pyruvate) in a form readily utilizable at the return to normoxic condition. GABA synthesis through the GABA shunt starts by decarboxylation of glutamate by glutamate decarboxylase (GDC) a proton consuming enzyme that helps maintaining cytosolic pH homeostasis</p