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

Le mil en Afrique : diversité génétique et agro-physiologique : potentialités et contraintes pour l'amélioration et la culture

Deux cultivars de mil, résistant et sensible, ont été soumis à des contraintes hydriques en conditions contrôlées. Lors de la contrainte, l'activité de la phosphoénolpyruvate carboxylase (PEPC) décroît, chez les témoins arrosés, de 20 à 30 % de sa valeur initiale (effet de sénescence) et de 50 à 60 % chez les stressés. La quantité d'enzyme dosée par immunotitration décroît également. Cependant, l'activité spécifique de la PEPC rapportée à la quantité d'enzyme diminue aussi. La réhydratation est suivie d'une récupération partielle et progressive des activités et des quantités de PEPC. Le pourcentage d'inhibition de l'enzyme par le malate chute de 50 à 20 % pendant la contrainte hydrique ce qui témoigne aussi d'une modification des propriétés de l'enzyme. L'intérêt du maintien de l'activité enzymatique pour la résistance à la sécheresse en présence d'une déshydratation cellulaire est discuté en s'appuyant sur la mesure des tolérances protoplasmiques des deux cultivars et grâce à une comparaison entre le mil et le sorgho. (Résumé d'auteur

Earthworms influence the production of above- and belowground biomass and the expression of genes involved in cell proliferation and stress responses in Arabidopsis thaliana

To better understand the complex mechanisms of action of earthworms on plants, we set up an experimental system using the model plant Arabidopsis thaliana (L.) Heynh, Aporrectodea caliginosa a common temperate earthworm and two types of soil with contrasted contents in organic matter and nutrients. Changes in plant biomass, biomass allocation to roots, leaves and stems and C/N ratios were related to variations in the expression of several plant genes involved in cellular division and stress responses and with earthworm-induced alterations in soil mineral status. In the poorest soil, i.e. with low contents in mineral nutrient and organic matter, earthworms increased soil nitrate content very significantly and boosted plant aboveground biomass production. This correlated with changes in leaf transcript accumulation suggesting enhanced cell division and lesser incidence of reactive oxygen species. In the richer soil, earthworms had no significant effect on the production of aerial biomass. However, several plant responses were observed regardless of soil quality: enhanced accumulation of an auxin-responsive transcript in the leaves, a strong decrease in root length and biomass and a reduction in C/N values, particularly in the bolt stems. Although these results pointed out earthworm-induced enhancement of mineralization as a determining factor in the formidable plant growth responses, the release in the drilosphere of phytohormone-like compounds by earthworm-activated bacteria was most likely implicated as well in this process and resulted in “forced” nitrogen uptake by the plants. The herein demonstrated sensitivity of the model plant A. thaliana to earthworms shows that such new experimental set up could become a central key to the development of multidisciplinary investigations on plant–soil interactions

Heparan sulfate mimetics are neuroprotective and neuroregenerative agents for ischemic stroke.

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