Expression Profile of Nuclear Receptors along Male Mouse Nephron Segments Reveals a Link between ERRβ and Thick Ascending Limb Function

The nuclear receptor family orchestrates many functions related to reproduction, development, metabolism, and adaptation to the circadian cycle. The majority of these receptors are expressed in the kidney, but their exact quantitative localization in this ultrastructured organ remains poorly described, making it difficult to elucidate the renal function of these receptors. In this report, using quantitative PCR on microdissected mouse renal tubules, we established a detailed quantitative expression map of nuclear receptors along the nephron. This map can serve to identify nuclear receptors with specific localization. Thus, we unexpectedly found that the estrogen-related receptor β (ERRβ) is expressed predominantly in the thick ascending limb (TAL) and, to a much lesser extent, in the distal convoluted tubules. In vivo treatment with an ERR inverse agonist (diethylstilbestrol) showed a link between this receptor family and the expression of the Na+,K+-2Cl− cotransporter type 2 (NKCC2), and resulted in phenotype presenting some similarities with the Bartter syndrom (hypokalemia, urinary Na+ loss and volume contraction). Conversely, stimulation of ERRβ with a selective agonist (GSK4716) in a TAL cell line stimulated NKCC2 expression. All together, these results provide broad information regarding the renal expression of all members of the nuclear receptor family and have allowed us to identify a new regulator of ion transport in the TAL segments

Upstream ORF affects MYCN translation depending on exon 1b alternative splicing

<p>Abstract</p> <p>Background</p> <p>The <it>MYCN </it>gene is transcribed into two major mRNAs: one full-length (<it>MYCN) </it>and one exon 1b-spliced (<it>MYCN</it>^{Δ1<it>b</it>}) mRNA. But nothing is known about their respective ability to translate the MYCN protein.</p> <p>Methods</p> <p>Plasmids were prepared to enable translation from the upstream (uORF) and major ORF of the two <it>MYCN </it>transcripts. Translation was studied after transfection in neuroblastoma SH-EP cell line. Impact of the upstream AUG on translation was evaluated after directed mutagenesis. Functional study with the two <it>MYCN </it>mRNAs was conducted by a cell viability assay. Existence of a new protein encoded by the <it>MYCN</it>^{Δ1<it>b </it>}uORF was explored by designing a rabbit polyclonal antibody against a specific epitope of this protein.</p> <p>Results</p> <p>Both are translated, but higher levels of protein were seen with <it>MYCN</it>^{Δ1<it>b </it>}mRNA. An upstream ORF was shown to have positive cis-regulatory activity on translation from <it>MYCN </it>but not from <it>MYCN</it>^{Δ1<it>b </it>}mRNA. In transfected SH-EP neuroblastoma cells, high MYCN dosage obtained with <it>MYCN</it>^{Δ1<it>b </it>}mRNA translation induces an antiapoptotic effect after serum deprivation that was not observed with low MYCN expression obtained with <it>MYCN </it>mRNA. Here, we showed that MYCNOT: <it>MYCN </it>Overlap Transcript, a new protein of unknown function is translated from the upstream AUG of <it>MYCN</it>^{Δ1<it>b </it>}mRNA.</p> <p>Conclusions</p> <p>Existence of upstream ORF in <it>MYCN </it>transcripts leads to a new level of MYCN regulation. The resulting MYCN dosage has a weak but significant anti-apoptotic activity after intrinsic apoptosis induction.</p

Etudes structurales et dynamiques d'un composite d'inclusion incommensurable sous pression hydrostatique

Les changements de phase et les propriétés dynamiques du nonadécane-urée ont été étudiés par différentes techniques sous pression (P 4kbars) une nouvelle phase orthorhombique gardant la métrique hexagonale apparaît. A 300 K, par diffraction neutronique, le paramètre d'incommensurabilité varie sous l'effet de la pression et une déformation différente des sous-réseaux d'alcane et d'urée est constatée au dessus de 1 kbar. Les défauts de conformation des chaînes étudiés par différentes spectroscopies montrent une variation de leur concentration qui offre d'étonnantes similarités avec la périodicité du sous-réseau d'alcane. Ils expliquent en grande partie, la translation anormalement grande des alcanes le long des canaux.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Ionic liquids to monitor the nano-structuration and the surface functionalization of material electrodes: a proof of concept applied to cobalt oxyhydroxide

This paper reports on an innovative and efficient approach based on the use of ionic liquids to govern the nano-structuration of HCoO2, in order to optimize the porosity and enhance the ionic diffusion through the electrode materials. In this work, we show that (1-pentyl-3-methyl-imidazolium bromide (PMIMBr) and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4)) ionic liquids (ILs) used as templates during the synthesis orientate the nanoparticle aggregation which leads to increase of the porosity and the average pore size of the electrode material. It is also demonstrated that the ILs are strongly bonded to the HCoO2 surface, leading to surface functionalized HCoO2 materials, also called nanohybrids. This surface tailoring stabilizes the material upon cycling and shifts the oxidation potential linked to the Co(III)/Co(IV) redox couple to lower voltage in an alkaline 5 M KOH electrolyte. The surface and porosity optimizations facilitate the ionic diffusion through the material, improve the electron transfer ability within the electrode and lead to greatly enhanced specific capacity in both alkaline 5 M-KOH and neutral 0.5 M-K2SO4 aqueous electrolytes (66.7 mA h g−1 and 47.5 mA h g−1 respectively for HCoO2–PMIMBr and HCoO2–EMIMBF4 compared to 18.1 mA h g−1 for bare HCoO2 in 5 M-KOH at 1 A g−1).Laboratory of excellency for electrochemical energy storag

Promising nanometric spinel cobalt oxides for electrochemical energy storage : investigation of Li and H environments by NMR

Spinel-type cobalt oxides with formula HxLiyCo3−δO4 exhibit interesting properties for various electrochemical energy storage applications thanks to their attractive electronic properties, due to the presence of H and Li ions in their structure as well as their nanometric dimensions. The effect of temperature on the H and Li environments is studied by investigating materials heat-treated at temperatures ranging from 25 to 650 °C by means of NMR spectroscopy. Two types of proton are evidenced: one bonded to oxygen atoms belonging to the network (hydroxyl group) and the other one involved in the H2O molecule. This configuration is in agreement with IR spectroscopy measurements, revealing the absence of free −OH groups, which mean that protons in the structure are involved in hydrogen bonds. After heat treatments at increasing temperature, NMR confirms that hydrogen is released, which induces first the migration of Li ions beyond 200 °C (probably from the 8a to the 16c sites), followed by a progressive reorganization of the structure with formation of HT-LiCoO2 beyond 400 °C

P2-NaxMn1/2Fe1/2O2 Phase Used as Positive Electrode in Na Batteries: Structural Changes Induced by the Electrochemical (De)intercalation Process.

The electrochemical properties of the P2-type NaxMn1/2Fe1/2O2 (x = 0.62) phase used as a positive electrode in Na batteries were tested in various voltage ranges at C/20. We show that, even if the highest capacity is obtained for the first cycles between 1.5 and 4.3 V, the best capacity after 50 cycles is obtained while cycling between 1.5 and 4.0 V (120 mAh g(-1)). The structural changes occurring in the material during the (de)intercalation were studied by operando in situ X-ray powder diffraction (XRPD) and ex situ synchrotron XRPD. We show that a phase with an orthorhombic P'2-type structure is formed for x ≈ 1, due to the cooperative Jahn-Teller effect of the Mn(3+) ions. P2 structure type stacking is observed for 0.35 < x < 0.82, while above 4.0 V, a new phase appears. A full indexation of the XRPD pattern of this latter phase was not possible because of the broadening of the diffraction peaks. However, a much shorter interslab distance was found that may imply a gliding of the MO2 slab occurring at high voltage. Raman spectroscopy was used as a local probe and showed that in this new phase the MO2 layers are maintained, but the phase exhibits a strong degree of disorder.Oxydes lamellaires de sodium et de métaux de transition : relation structure - propriété

Delamination of nickel–cobalt oxyhydroxides for electrochemical energy storage applications

This work is dedicated to the memory of Patrizia Paradiso.International audienceNickel–cobalt oxyhydroxide has been delaminated by tetrabutylammonium (TBA+) intercalation in aqueous media. The electrochemical performance of the different materials obtained during delamination has been evaluated, with special emphasis on the effect of the intercalated species and their influence on the behavior of the delaminated material, toward electrochemical energy storage applications. Delamination in TBAOH, reported for the first time for nickel–cobalt oxyhydroxide in aqueous media, is an excellent route to increase the number of electrochemically active sites and to enhance the capacity of nickel–cobalt oxyhydroxide. Results show an increase in capacity from 112 mA·h·g–1 in 1 M LiOH at 1 A·g–1 for the nondelaminated precursor to 165 mA·h·g–1 after exfoliation and restacking. Thus, carefully designed exfoliation is a promising route to enhance the performance of electrode materials for electrochemical energy storage

Contribution of multi-method geophysics to the understanding of a high-temperature geothermal province: The Bouillante area (Guadeloupe, Lesser Antilles)

International audienceThe Bouillante high-temperature geothermal field (Guadeloupe, French Lesser Antilles) is located on the west coast of Basse-Terre Island, about 15 km from the currently active Soufrière volcano. We have studied the shallow structure of the geothermal zone using a compilation of all available gravity, magnetic and resistivity data, both subaerial and marine, acquired during the last 30 years. Geophysical models have been developed based on geological constraints and previous geophysical interpretations. The resistivity distribution from electromagnetic surveys is interpreted in terms of water saturation of rocks, hydrothermal alteration and presence of hydrated minerals. Gravity is used to distinguish and characterize the denser formations from the low density areas. Finally, we are able to differentiate structures which pre- and post-date various recent magnetic inversions using the polarity of the magnetic anomalies. By integrating these results the previous conceptual model for the geothermal province has been improved, with the layering of the geological formations as defined by geophysical parameters now being taken into account, in agreement with the classical scheme of geothermal reservoirs. The shallow resistive layer is explained in terms of recent massive formations. The conductive intermediate layer marks the low density, demagnetized clay cover of the altered geothermal system. The deep resistive layer is associated with dense formations increasing in age with depth, and corresponds to the deep geothermal reservoir. Based on our geophysical data, the geothermal activity could be more developed towards the east and north compared to the previously proposed area. A volcano-structural control seems to affect the internal structure of the province, and consequently the development of geothermal activity. This current work could be used as a basis for future surveys of the Bouillante province in order to improve constraints, and to increase our knowledge of the island's overall evolution

Incorporation of Fe3+ into MnO2 birnessite for enhanced energy storage: Impact on the structure and the charge storage mechanisms

Birnessite δ-MnO2, with its low cost, high theoretical capacity, and stable cycling performance in aqueous electrolytes, holds promise as an electrode material for high-power and cost-effective electrochemical energy storage devices. To address its poor electronic conductivity, we incorporated environmentally friendly iron into birnessite and conducted a comprehensive study on its influence on crystal structure, electrochemical reaction mechanisms, and energy storage performance. In this study, a series of birnessite samples with varying iron content (δ-Mn1-xFexO2 with 0 ≤ x ≤ 0.20) were synthesized using solid-state reactions, resulting in well-crystallized particles with micrometric platelet morphology. Through X-ray absorption and Mössbauer spectroscopies, we clearly demonstrated that Fe replaces Mn in the metal oxide layer, while X-ray diffraction revealed that iron content significantly affects interlayer site symmetry and the resulting polytype. The sample with the lowest iron content (δ-Mn0.96Fe0.04O2) exhibits a monoclinic birnessite structure with an O-type interlayer site, while increasing iron content leads to hexagonal symmetry with P-type interlayer sites. Electrochemical investigations indicated that these P-type sites facilitate the diffusion of partially hydrated alkaline ions and exhibit superior rate capabilities compared to the O-type phase. Furthermore, operando XAS revealed that Fe is electrochemically inactive and that the charge storage in birnessite-type phases in a 0.5M K2SO4 electrolyte primarily relies on the redox reaction of Mn. Finally, we determined that P-type δ-Mn0.87Fe0.13O2 achieved the best compromise between enhancing electrical conductivity and maintaining a maximum content of electrochemically active Mn cations