Phospholipase activities associated with the tonoplast from Acer pseudoplatanus cells: identification of a phospholipase A1 activity

AbstractThe study of phospholipase activities associated with the tonoplast of Acer pseudoplatanus was performed in vitro with sn-2[14C]acylphosphatidylcholine (PC) as a substrate. The hydrolysis of radiolabelled PC into [14C]phosphatidic acid and [14C]lyso-PC demonstrated the presence of phospholipase D and A1 activities, respectively, associated with the tonoplast of Acer pseudoplatanus. The vacuolar sap did not show any significant phospholipase activity. In a second step, the properties of the phospholipase A1, activity was studied using tonoplast endogenous PC labelled in vivo with [l4C]choline as a substrate. The phospholipase A1 showed an optimal activity at pH about 6–6.5, did not necessarily require divalent cations, but was stimulated by Mg2+ and particularly by Ca2+. This work presents the first evidence for the presence of phospholipases A1 in plant cells

Spatial distribution of pelagic fish off Adélie and George V Land, East Antarctica in the austral summer 2008

AbstractPelagic fish assemblages and community structure were examined along longitudinal and meridian transects off Adélie and George V Land, East Antarctica, in the austral summer 2008. Fish were sampled with an RMT 8 net principally from six discrete depth layers (0–50–100–200–500–1000–2000 m) in the oceanic zone and from three depth layers (0–50–100–200 m) over the continental shelf zone. A total of 20,281 individuals from 27 species were collected. Pleuragramma antarcticum was the most dominant species by number (18,710 inds), followed by Chionodraco hamatus (768), Trematomus newnesi (375), Cyclothone microdon (101), Electrona antarctica (92), Bathylagus antarcticus (51) and Notolepis coatsi (54). Cluster analysis revealed that the fish community was clearly divided at the Antarctic Slope Front into separate oceanic and shelf assemblages, being dominated by mesopelagic fish and notothenioids, respectively. The Southern Boundary of Antarctic Circumpolar Current likely restricted a more northern distribution of notothenioids in the upper 200 m. Mesopelagic fish dominated the large biomass below 500 m and notothenioids dominated that in the upper 100 m. It is considered that mesopelagic fish in the oceanic zone would unlikely be eaten by seabirds because no distinctive diel vertical migration to the surface layer was observed. In the neritic zone, notothenioids (C. hamatus, T. newnesi and P. antarcticum) possibly play an important role as prey items for flying seabirds, penguins and other notothenioids fish especially in the shallow depth stratum (0–100 m)

Lipid peroxidation in tobacco leaves treated with the elicitor cryptogein: evaluation by high-temperature thermoluminescence emission and chlorophyll fluorescence

AbstractTreatment of excised tobacco leaves with the fungal elicitor cryptogein progressively induced lipid peroxidation. In a first step, evidence was provided by the accumulation of thiobarbituric acid reactive substances (TBARS) and in a second step, the process was monitored for a 26 h period by high-temperature thermoluminescence (TL) emission, showing a close correlationship with the TBARS data. Differences in the temperature-associated F0 rise (constant fluorescence) and in fluorescence emission spectra point to a progressive destabilization of the thylakoid membrane, especially affecting Photosystem II (PS II). In parallel, the PS II quantum efficiency ΔF / Fm and the Fv / Fm ratio of chlorophyll fluorescence induction decreased significantly over the 24 h period

Activated protein C increases sensitivity to vasoconstriction in rabbit Escherichia coli endotoxin-induced shock

INTRODUCTION: The aim of this study was to investigate the effects of activated protein C (aPC) on vascular function, endothelial injury, and haemostasis in a rabbit endotoxin-induced shock model. METHOD: This study included 22 male New Zealand rabbits weighing 2.5 to 3 kg each. In vitro vascular reactivity, endothelium CD31-PECAM1 immunohistochemistry, plasma coagulation factors and monocyte tissue factor (TF) expression were performed 5 days (D5) after onset of endotoxic shock (initiated by 0.5 mg/kg intravenous bolus of Escherichia coli lipopolysaccharide (LPS)) with or without treatment with aPC injected as an intravenous 2 mg/kg bolus 1 hour after LPS (LPS+aPC group and LPS group, respectively). RESULTS: LPS decreased the sensitivity to phenylephrine (PE) in aortic rings without endothelium (E-) when compared to E- rings from the control group (p < 0.05). This was abolished by N(G)-nitro-L-arginine methyl ester and not observed in E- rings from aPC-treated rabbits. Although aPC failed to decrease monocyte TF expression in endotoxinic animals at D5, aPC treatment restored the endothelium-dependent sensitivity in response to PE (2.0 ± 0.2 μM in rings with endothelium (E+) versus 1.0 ± 0.2 μM in E- rings (p < 0.05) in the LPS+aPC group versus 2.4 ± 0.3 μM in E+ rings versus 2.2 ± 0.2 μM in E- rings (p value not significant), in the LPS group). Endotoxin-induced de-endothelialisation was reduced by aPC at D5 (28.5 ± 2.3% in the LPS+aPC group versus 40.4 ± 2.4% in the LPS group, p < 0.05). CONCLUSION: These data indicate that aPC increased the sensitivity to a vasoconstrictor agent (PE) associated with restoration of endothelial modulation, and protected against endothelial histological injury in endotoxin-induced shock. It failed to inhibit TF expression at D5 after LPS injection

The ubiquitin-editing enzyme A20 controls NK cell homeostasis through regulation of mTOR activity and TNF

The ubiquitin-editing enzyme A20 is a well-known regulator of immune cell function and homeostasis. In addition, A20 protects cells from death in an ill-defined manner. While most studies focus on its role in the TNF-receptor complex, we here identify a novel component in the A20-mediated decision between life and death. Loss of A20 in NK cells led to spontaneous NK cell death and severe NK cell lymphopenia. The few remaining NK cells showed an immature, hyperactivated phenotype, hallmarked by the basal release of cytokines and cytotoxic molecules. NK-A20(-/-) cells were hypersensitive to TNF-induced cell death and could be rescued, at least partially, by a combined deficiency with TNF. Unexpectedly, rapamycin, a well-established inhibitor of mTOR, also strongly protected NK-A20(-/-) cells from death, and further studies revealed that A20 restricts mTOR activation in NK cells. This study therefore maps A20 as a crucial regulator of mTOR signaling and underscores the need for a tightly balanced mTOR pathway in NK cell homeostasis

Unconventional Repertoire Profile Is Imprinted during Acute Chikungunya Infection for Natural Killer Cells Polarization toward Cytotoxicity

Chikungunya virus (CHIKV) is a worldwide emerging pathogen. In humans it causes a syndrome characterized by high fever, polyarthritis, and in some cases lethal encephalitis. Growing evidence indicates that the innate immune response plays a role in controlling CHIKV infection. We show here that CHIKV induces major but transient modifications in NK-cell phenotype and function soon after the onset of acute infection. We report a transient clonal expansion of NK cells that coexpress CD94/NKG2C and inhibitory receptors for HLA-C1 alleles and are correlated with the viral load. Functional tests reveal cytolytic capacity driven by NK cells in the absence of exogenous signals and severely impaired IFN-γ production. Collectively these data provide insight into the role of this unique subset of NK cells in controlling CHIKV infection by subset-specific expansion in response to acute infection, followed by a contraction phase after viral clearance

Control of anterior GRadient 2 (AGR2) dimerization links endoplasmic reticulum proteostasis to inflammation

International audienceAnterior gradient 2 (AGR2) is a dimeric protein disulfide isomerase family member involved in the regulation of protein quality control in the endoplasmic reticulum (ER). Mouse AGR2 deletion increases intestinal inflammation and promotes the development of inflammatory bowel disease (IBD). Although these biological effects are well established, the underlying molecular mechanisms of AGR2 function toward inflammation remain poorly defined. Here, using a protein-protein interaction screen to identify cellular regulators of AGR2 dimerization, we unveiled specific enhancers, including TMED2, and inhibitors of AGR2 dimerization, that control AGR2 functions. We demonstrate that modulation of AGR2 dimer formation, whether enhancing or inhibiting the process, yields pro-inflammatory phenotypes, through either autophagy-dependent processes or secretion of AGR2, respectively. We also demonstrate that in IBD and specifically in Crohn's disease, the levels of AGR2 dimerization modulators are selectively deregulated, and this correlates with severity of disease. Our study demonstrates that AGR2 dimers act as sensors of ER homeostasis which are disrupted upon ER stress and promote the secretion of AGR2 monomers. The latter might represent systemic alarm signals for pro-inflammatory responses

The ubiquitin-editing enzyme A20 controls NK cell homeostasis through regulation of mTOR activity and TNF

The ubiquitin-editing enzyme A20 is a well-known regulator of immune cell function and homeostasis. In addition, A20 protects cells from death in an ill-defined manner. While most studies focus on its role in the TNF-receptor complex, we here identify a novel component in the A20-mediated decision between life and death. Loss of A20 in NK cells led to spontaneous NK cell death and severe NK cell lymphopenia. The few remaining NK cells showed an immature, hyperactivated phenotype, hallmarked by the basal release of cytokines and cytotoxic molecules. NK-A20−/− cells were hypersensitive to TNF-induced cell death and could be rescued, at least partially, by a combined deficiency with TNF. Unexpectedly, rapamycin, a wellestablished inhibitor of mTOR, also strongly protected NK-A20−/− cells from death, and further studies revealed that A20 restricts mTOR activation in NK cells. This study therefore maps A20 as a crucial regulator of mTOR signaling and underscores the need for a tightly balanced mTOR pathway in NK cell homeostasis

Reception Test of Petals for the End Cap TEC+ of the CMS Silicon Strip Tracker

The silicon strip tracker of the CMS experiment has been completed and was inserted into the CMS detector in late 2007. The largest sub system of the tracker are its end caps, comprising two large end caps (TEC) each containing 3200 silicon strip modules. To ease construction, the end caps feature a modular design: groups of about 20 silicon modules are placed on sub-assemblies called petals and these self-contained elements are then mounted onto the TEC support structures. Each end cap consists of 144 such petals, which were built and fully qualified by several institutes across Europe. Fro

Integration of the End Cap TEC+ of the CMS Silicon Strip Tracker

The silicon strip tracker of the CMS experiment has been completed and inserted into the CMS detector in late 2007. The largest sub-system of the tracker is its end cap system, comprising two large end caps (TEC) each containing 3200 silicon strip modules. To ease construction, the end caps feature a modular design: groups of about 20 silicon modules are placed on sub-assemblies called petals and these self-contained elements are then mounted into the TEC support structures. Each end cap consists of 144 petals, and the insertion of these petals into the end cap structure is referred to as TEC integration. The two end caps were integrated independently in Aachen (TEC+) and at CERN (TEC--). This note deals with the integration of TEC+, describing procedures for end cap integration and for quality control during testing of integrated sections of the end cap and presenting results from the testing