Soybean (Glycine max L.) Nuclear DNA Contains Four tufA Genes Coding for the Chloroplast-specific Translation Elongation Factor EF-Tu

The chloroplast tufA gene codes for the translation elongation factor EF-Tu. In algae like e.g. Euglena tufA is part of the chloroplast DNA but in land plants the equivalent gene is transposed to the nuclear DNA. Using a previously sequenced Euglena gracilis tufA DNA probe a cDNA library from soybean was screened. Two cDNA clones (cDNA1 and cDNA2) were sequenced (ca. 500 nucleotides) and shown to contain parts of the chloroplast tufA gene. A cDNA1 fragment was used to screen a genomic library and one complete tufA gene was sequenced including 640 nucleotides of the region upstream of the transcription start site which was identified by S1 endonuclease protection experiments. The soybean genome contains four tufA genes which belong to two subfamilies with two members each. TufA mRNA is absent in dark grown seedlings but light grown seedlings contain a stable tufA mRNA of ca. 1.6 -1.7 kb. The open reading frame codes for a chloroplast transit peptide (71 amino acids) and a very conservative chloroplast EF-Tu protein

Modulation of the c-Jun N-terminal kinase activity in the embryonic heart in response to anoxia-reoxygenation: involvement of the Ca2+ and mitoKATP channels

Whether the response of the fetal heart to ischemia-reperfusion is associated with activation of the c-Jun N-terminal kinase (JNK) pathway is not known. In contrast, involvement of the sarcolemmal L-type Ca2+ channel (LCC) and the mitochondrial KATP (mitoKATP) channel has been established. This work aimed at investigating the profile of JNK activity during anoxia-reoxygenation and its modulation by LCC and mitoKATP channel. Hearts isolated from 4-day-old chick embryos were submitted to anoxia (30min) and reoxygenation (60min). Using the kinase assay method, the profile of JNK activity in the ventricle was determined every 10min throughout anoxia-reoxygenation. Effects on JNK activity of the LCC blocker verapamil (10nM), the mitoKATP channel opener diazoxide (50μM) and the blocker 5-hydroxydecanoate (5-HD, 500μM), the mitochondrial Ca2+ uniporter (MCU) inhibitor Ru360 (10μM), and the antioxidant N-(2-mercaptopropionyl) glycine (MPG, 1mM) were determined. In untreated hearts, JNK activity was increased by 40% during anoxia and peaked fivefold relative to basal level after 30-40min reoxygenation. This peak value was reduced by half by diazoxide and was tripled by 5-HD. Furthermore, the 5-HD-mediated stimulation of JNK activity during reoxygenation was abolished by diazoxide, verapamil or Ru360. MPG had no effect on JNK activity, whatever the conditions. None of the tested pharmacological agents altered JNK activity under basal normoxic conditions. Thus, in the embryonic heart, JNK activity exhibits a characteristic pattern during anoxia and reoxygenation and the respective open-state of LCC, MCU and mitoKATP channel can be a major determinant of JNK activity in a ROS-independent manne

Brief reoxygenation episodes during chronic hypoxia enhance posthypoxic recovery of LV function: Role of mitogen-activated protein kinase signaling pathways

Children with congenital cyanotic heart defects have worse outcomes after surgical repair of their heart defects compared with noncyanotic ones. Institution of extracorporeal circulation in these children exposes the cyanotic heart to reoxygenation injury. Mitogen-activated protein kinase (MAPK) signaling cascades are major regulators of cardiomyocyte function in acute hypoxia and reoxygenation. However, their roles in chronic hypoxia are incompletely understood. We determined myocardial activation of the three major MAPKs, c-Jun NH2-terminal kinase (JNK), extracellular signal-regulated kinase-1/2 (ERK1/2), and p38-MAPK in adult rats exposed to hypoxia (FIO2=0.10) for varying periods of time. Myocardial function was analyzed in isolated perfused hearts. Acute hypoxia stimulated JNK and p38-MAPK activation. Chronic hypoxia (2weeks) was associated with increased p38-MAPK (but not JNK) activation, increased apoptosis, and impaired posthypoxic recovery of LV function. Brief normoxic episodes (1h/day) during chronic hypoxia abolished p38-MAPK activation, stimulated MEK-ERK1/2 activation modestly, and restored posthypoxic LV function. In vivo p38-MAPK inhibition by SB203580 or SB202190 in chronically hypoxic rats restored posthypoxic LV function. These results indicate that sustained hypoxemia maintains p38-MAPK in a chronically activated state that predisposes to myocardial impairment upon reoxygenation. Brief normoxic episodes during chronic hypoxia prevent p38-MAPK activation and restore posthypoxic recovery of myocardial functio

Regulation of the JNK3 signaling pathway during islet isolation: JNK3 and c-fos as new markers of islet quality for transplantation.

Stress conditions generated throughout pancreatic islet processing initiate the activation of pro-inflammatory pathways and beta-cell destruction. Our goal is to identify relevant and preferably beta-specific markers to assess the activation of beta-cell stress and apoptotic mechanisms, and therefore the general quality of the islet preparation prior to transplantation. Protein expression and activation were analyzed by Western blotting and kinase assays. ATP measurements were performed by a luminescence-based assay. Oxygen consumption rate (OCR) was measured based on standard protocols using fiber optic sensors. Total RNA was used for gene expression analyzes. Our results indicate that pancreas digestion initiates a potent stress response in the islets by activating two stress kinases, c-Jun N-terminal Kinase (JNK) and p38. JNK1 protein levels remained unchanged between different islet preparations and following culture. In contrast, levels of JNK3 increased after islet culture, but varied markedly, with a subset of preparations bearing low JNK3 expression. The observed changes in JNK3 protein content strongly correlated with OCR measurements as determined by the Spearman's rank correlation coefficient rho [Formula: see text] in the matching islet samples, while inversely correlating with c-fos mRNA expression [Formula: see text]. In conclusion, pancreas digestion recruits JNK and p38 kinases that are known to participate to beta-cell apoptosis. Concomitantly, the islet isolation alters JNK3 and c-fos expression, both strongly correlating with OCR. Thus, a comparative analysis of JNK3 and c-fos expression before and after culture may provide for novel markers to assess islet quality prior to transplantation. JNK3 has the advantage over all other proposed markers to be islet-specific, and thus to provide for a marker independent of non-beta cell contamination

JNK3 Maintains Expression of the Insulin Receptor Substrate 2 (IRS2) in Insulin-Secreting Cells: Functional Consequences for Insulin Signaling

We have recently shown that silencing of the brain/islet specific c-Jun N-terminal Kinase3 (JNK3) isoform enhances both basal and cytokine-induced beta-cell apoptosis, whereas silencing of JNK1 or JNK2 has opposite effects. While it is known that JNK1 or JNK2 may promote apoptosis by inhibiting the activity of the pro-survival Akt pathway, the effect of JNK3 on Akt has not been documented. This study aims to determine the involvement of individual JNKs and specifically JNK3 in the regulation of the Akt signaling pathway in insulin-secreting cells. JNK3 silencing strongly decreases Insulin Receptor Substrate 2 (IRS2) protein expression, and blocks Akt2 but not Akt1 activation by insulin, while the silencing of JNK1 or JNK2 activates both Akt1 and Akt2. Concomitantly, the silencing of JNK1 or JNK2, but not of JNK3, potently phosphorylates the glycogen synthase kinase3 (GSK3β). JNK3 silencing also decreases the activity of the transcription factor Forkhead BoxO3A (FoxO3A) that is known to control IRS2 expression, in addition to increasing c-Jun levels that are known to inhibit insulin gene expression. In conclusion, we propose that JNK1/2 on one hand and JNK3 on the other hand, have opposite effects on insulin-signaling in insulin-secreting cells; JNK3 protects beta-cells from apoptosis and dysfunction mainly through maintenance of a normal IRS2 to Akt2 signaling pathway. It seems that JNK3 mediates its effects mainly at the transcriptional level, while JNK1 or JNK2 appear to mediate their pro-apoptotic effect in the cytoplasm

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer, studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory, a versatile observatory designed to address the Hot and Energetic Universe science theme, selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), it aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over an hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR, browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters. Finally we briefly discuss on the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, and touch on communication and outreach activities, the consortium organisation, and finally on the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained. (abridged).Comment: 48 pages, 29 figures, Accepted for publication in Experimental Astronomy with minor editin

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory. Athena is a versatile observatory designed to address the Hot and Energetic Universe science theme, as selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), X-IFU aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over a hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR (i.e. in the course of its preliminary definition phase, so-called B1), browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters, such as the instrument efficiency, spectral resolution, energy scale knowledge, count rate capability, non X-ray background and target of opportunity efficiency. Finally, we briefly discuss the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, touch on communication and outreach activities, the consortium organisation and the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained. The X-IFU will be provided by an international consortium led by France, The Netherlands and Italy, with ESA member state contributions from Belgium, Czech Republic, Finland, Germany, Poland, Spain, Switzerland, with additional contributions from the United States and Japan.The French contribution to X-IFU is funded by CNES, CNRS and CEA. This work has been also supported by ASI (Italian Space Agency) through the Contract 2019-27-HH.0, and by the ESA (European Space Agency) Core Technology Program (CTP) Contract No. 4000114932/15/NL/BW and the AREMBES - ESA CTP No.4000116655/16/NL/BW. This publication is part of grant RTI2018-096686-B-C21 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. This publication is part of grant RTI2018-096686-B-C21 and PID2020-115325GB-C31 funded by MCIN/AEI/10.13039/501100011033

Les cultures transgéniques permettent-elles de réduire l’usage des produits phytosanitaires ? Considérations à partir du cas du soja tolérant au glyphosate

L’article s’interroge sur l’impact des cultures transgéniques sur l’emploi des pesticides, objet de nombreux débats. Sont examinés les résultats de plusieurs études portant sur le bilan des premières années d’utilisation à grande échelle des OGM aux États-Unis, plus particulièrement du soja tolérant au glyphosate. Les travaux analysés présentent des résultats variables, surtout pour les années récentes, selon les méthodes choisies et le type d’extrapolations faites. Divers facteurs expliquant l’accroissement de l’emploi global du glyphosate sont passés en revue. Mais l’estimation des quantités d’herbicides utilisées qui dépendent de nombreux facteurs n’est pas un indicateur valide de l’impact des cultures transgéniques sur l’environnement