Fxyd2 regulates Aδ- and C-fiber mechanosensitivity and is required for the maintenance of neuropathic pain

Identification of the molecular mechanisms governing sensory neuron subtype excitability is a key requisite for the development of treatments for somatic sensory disorders. Here, we show that the Na,K-ATPase modulator Fxyd2 is specifically required for setting the mechanosensitivity of Aδ-fiber low-threshold mechanoreceptors and sub-populations of C-fiber nociceptors, a role consistent with its restricted expression profile in the spinal somatosensory system. We also establish using the spared nerve injury model of neuropathic pain, that loss of Fxyd2 function, either constitutively in Fxyd2(-/-) mice or acutely in neuropathic rats, efficiently alleviates mechanical hypersensitivity induced by peripheral nerve lesions. The role of Fxyd2 in modulating Aδ- and C-fibers mechanosensitivity likely accounts for the anti-allodynic effect of Fxyd2 knockdown. Finally, we uncover the evolutionarily conserved restricted expression pattern of FXYD2 in human dorsal root ganglia, thus identifying this molecule as a potentially promising therapeutic target for peripheral neuropathic pain management

Differential Regulation of GABABReceptor Trafficking by Different Modes ofN-methyl-d-aspartate (NMDA) Receptor Signaling

Inhibitory GABAB receptors (GABABRs) can down-regulate most excitatory synapses in the CNS by reducing postsynaptic excitability. Functional GABABRs are heterodimers of GABAB1 and GABAB2 subunits and here we show that the trafficking and surface expression of GABABRs is differentially regulated by synaptic or pathophysiological activation of NMDA receptors (NMDARs). Activation of synaptic NMDARs using a chemLTP protocol increases GABABR recycling and surface expression. In contrast, excitotoxic global activation of synaptic and extrasynaptic NMDARs by bath application of NMDA causes the loss of surface GABABRs. Intriguingly, exposing neurons to extreme metabolic stress using oxygen/glucose deprivation (OGD) increases GABAB1 but decreases GABAB2 surface expression. The increase in surface GABAB1 involves enhanced recycling and is blocked by the NMDAR antagonist AP5. The decrease in surface GABAB2 is also blocked by AP5 and by inhibiting degradation pathways. These results indicate that NMDAR activity is critical in GABABR trafficking and function and that the individual subunits can be separately controlled to regulate neuronal responsiveness and survival

Adaptive Movement Compensation for In Vivo Imaging of Fast Cellular Dynamics within a Moving Tissue

In vivo non-linear optical microscopy has been essential to advance our knowledge of how intact biological systems work. It has been particularly enabling to decipher fast spatiotemporal cellular dynamics in neural networks. The power of the technique stems from its optical sectioning capability that in turn also limits its application to essentially immobile tissue. Only tissue not affected by movement or in which movement can be physically constrained can be imaged fast enough to conduct functional studies at high temporal resolution. Here, we show dynamic two-photon Ca2+ imaging in the spinal cord of a living rat at millisecond time scale, free of motion artifacts using an optical stabilization system. We describe a fast, non-contact adaptive movement compensation approach, applicable to rough and weakly reflective surfaces, allowing real-time functional imaging from intrinsically moving tissue in live animals. The strategy involves enslaving the position of the microscope objective to that of the tissue surface in real-time through optical monitoring and a closed feedback loop. The performance of the system allows for efficient image locking even in conditions of random or irregular movements

Arc Valley atmospheric pollution study (Maurienne, Savoie) : New and improved methods for air quality biomonitoring survey using plants

La Maurienne est soumise à un trafic routier et autoroutier intense qui traverse les Alpes par le tunnel du Fréjus. La pollution atmosphérique associée a été étudiée, au niveau local, à l’aide d’un maillage reposant sur deux approches complémentaires, biologique et chimique. Les propriétés de rétention des particules des aiguilles de Pinus sylvestris, Pinus nigra et Picea abies ont été utilisées pour réaliser un suivi spatio-temporel des émissions. Les dépôts ont été analysés par microscopie électronique à balayage couplée à la spectrométrie de rayons X. L’analyse a porté sur le Phosphore et les traceurs de pollution routière (Al, Ti, Fe). Il a pu être montré que les distances de dispersion particulaires dépassaient 300 m pour les axes routiers et plusieurs kilomètres pour le Phosphore. La pollution primaire azotée émise par les véhicules en circulation a été étudiée avec Molinia caerulea, poacée bioaccumulateur nitrophile. Sa capacité de croissance et d’accumulation de l’azote est liée aux émissions et à la densité du trafic. De plus, la composition isotopique de la Molinie (d15N) dépendant des oxydes d’azote véhiculaires permet d’envisager son utilisation comme bioindicateur. Ces données permettent de mieux comprendre l’impact potentiel du trafic sur les écosystèmes à proximité des grands axes de circulation. L’étude des niveaux et de la répartition de l’ozone troposphérique en vallée de Maurienne a été étudiée en 2004 et 2005 selon des méthodes biologiques et chimiques. Les résultats confirment l’efficacité du matériel biologique (tabac Bel-W3) et des capteurs chimiques dans la détermination des niveaux d'ozone aux basses altitudes. En revanche, une perte de sensibilité a été identifiée dans les conditions spécifiques de montagne qui limitent son utilisation au-dessus de 1000m. Ce travail, à travers différentes approches de la biosurveillance et un maillage dense de stations d’avoir une image réaliste de la pollution atmosphérique dans une vallée de montagne et de ses impacts potentiels sur les écosystèmes forestiers.The Maurienne is subjected to a heavy traffic of lories and cars crossing the Alps through the Frejus tunnel. Atmospheric pollution depending on traffic has been studied using a dense net of biological and chemical sensors. The adhesive properties of plant cuticles of Pinus sylvestris, Pinus nigra and Picea abies were used for spatio-temporal analyses of emitted particles. Elementary composition of deposits was determined using SEM and Xray spectrometry. Analyses were focused on P and traffic tracers (Al, Ti, Fe). Results show that traffic particles can be transported as far as 300 m from the roads and highways while Phosphorus was detected at some kilometers from the factory. The poaceae Molinia caerulea was used for nitrogen pollution study. Leaf growth and nitrogen content were related to NOx levels and traffic density. Moreover, nitrogen isotopic composition (d15N) of leaves depend on exposure to traffic related nitrogen oxides. Taken altogether, results show that Molinia can be used as a nitrogen bioindicator and give information on the potential impact on mountain ecosystems in the vicinity of main roads and motorways. Both biological (tobacco Bel-W3) and chemical methods were used for determination of levels and distribution of tropospheric ozone in the Maurienne valley in 2004 and 2005. Results confirm the usefulness of both biological and chemical approachs for ozone levels determination at low altitudes. However, a sensitivity loss of ozone sensitive tobacco plants in hard mountainous conditions was characterized, limiting its use under 1000 m. This approach by the simultaneous use of several techniques and a dense network of stations give a realistic picture of the atmospheric pollution in a mountain valley and its potential impacts on forest ecosystems

Pollution atmosphérique dans la vallée de l'Arc (Maurienne, Savoie) : Nouvelles approches en biosurveillance végétale

The Maurienne is subjected to a heavy traffic of lories and cars crossing the Alps through the Frejus tunnel. Atmospheric pollution depending on traffic has been studied using a dense net of biological and chemical sensors. The adhesive properties of plant cuticles of Pinus sylvestris, Pinus nigra and Picea abies were used for spatio-temporal analyses of emitted particles. Elementary composition of deposits was determined using SEM and Xray spectrometry. Analyses were focused on P and traffic tracers (Al, Ti, Fe). Results show that traffic particles can be transported as far as 300 m from the roads and highways while Phosphorus was detected at some kilometers from the factory. The poaceae Molinia caerulea was used for nitrogen pollution study. Leaf growth and nitrogen content were related to NOx levels and traffic density. Moreover, nitrogen isotopic composition (d15N) of leaves depend on exposure to traffic related nitrogen oxides. Taken altogether, results show that Molinia can be used as a nitrogen bioindicator and give information on the potential impact on mountain ecosystems in the vicinity of main roads and motorways. Both biological (tobacco Bel-W3) and chemical methods were used for determination of levels and distribution of tropospheric ozone in the Maurienne valley in 2004 and 2005. Results confirm the usefulness of both biological and chemical approachs for ozone levels determination at low altitudes. However, a sensitivity loss of ozone sensitive tobacco plants in hard mountainous conditions was characterized, limiting its use under 1000 m. This approach by the simultaneous use of several techniques and a dense network of stations give a realistic picture of the atmospheric pollution in a mountain valley and its potential impacts on forest ecosystems.La Maurienne est soumise à un trafic routier et autoroutier intense qui traverse les Alpes par le tunnel du Fréjus. La pollution atmosphérique associée a été étudiée, au niveau local, à l'aide d'un maillage reposant sur deux approches complémentaires, biologique et chimique. Les propriétés de rétention des particules des aiguilles de Pinus sylvestris, Pinus nigra et Picea abies ont été utilisées pour réaliser un suivi spatio-temporel des émissions. Les dépôts ont été analysés par microscopie électronique à balayage couplée à la spectrométrie de rayons X. L'analyse a porté sur le Phosphore et les traceurs de pollution routière (Al, Ti, Fe). Il a pu être montré que les distances de dispersion particulaires dépassaient 300 m pour les axes routiers et plusieurs kilomètres pour le Phosphore. La pollution primaire azotée émise par les véhicules en circulation a été étudiée avec Molinia caerulea, poacée bioaccumulateur nitrophile. Sa capacité de croissance et d'accumulation de l'azote est liée aux émissions et à la densité du trafic. De plus, la composition isotopique de la Molinie (d15N) dépendant des oxydes d'azote véhiculaires permet d?envisager son utilisation comme bioindicateur. Ces données permettent de mieux comprendre l'impact potentiel du trafic sur les écosystèmes à proximité des grands axes de circulation. L'étude des niveaux et de la répartition de l'ozone troposphérique en vallée de Maurienne a été étudiée en 2004 et 2005 selon des méthodes biologiques et chimiques. Les résultats confirment l'efficacité du matériel biologique (tabac Bel-W3) et des capteurs chimiques dans la détermination des niveaux d'ozone aux basses altitudes. En revanche, une perte de sensibilité a été identifiée dans les conditions spécifiques de montagne qui limitent son utilisation au-dessus de 1000m. Ce travail, à travers différentes approches de la biosurveillance et un maillage dense de stations d'avoir une image réaliste de la pollution atmosphérique dans une vallée de montagne et de ses impacts potentiels sur les écosystèmes forestiers

Drought stress in rice (Oryza sativa L.) is enhanced in the presence of the compacting earthworm Millsonia anomala

Earthworms increase growth of most plant species through a number of poorly investigated mechanisms. We tested the hypothesis that earthworm modifications of soil structure and the resulting changes in water availability to plants explain this positive effect. Addition of endogeic earthworms Millsonia anomala induced a 40% increase in shoot biomass production and a 13% increase in CO2 assimilation rate of well watered rice plants grown in pots. Conversely, when plants were subjected to water deficit, presence of earthworms had no effect on shoot biomass production and a negative impact on CO2 assimilation rate (-21%). Early stomatal closure in presence of earthworms indicated lower water availability. The hypothesis that earthworms improve plant biomass production through soil physical structure modification was thus rejected. Three hypotheses were tested to explain this decrease in water availability: (i) a decrease in soil water retention capacity, (ii) an increase in evaporation from the soil or/and (iii) an increase in plant transpiration. Results showed that earthworms significantly reduced soil water retention capacity by more than 6%, but had no effect on evaporation rate. Water losses through transpiration were greater in the presence of earthworms when the soil was maintained at field capacity, but this was not the case under drought conditions. This experiment showed that the endogeic compacting earthworm M. anomala significantly increased plant photosynthesis by an undetermined mechanism under well-watered conditions. However, photosynthesis was reduced under drought conditions due to reduced soil water retention capacity