El agotamiento de la reserva orgánica del suelo y su relación con el secuestro de carbono atmosférico

Peer reviewe

Dial variations in temperature, salinity and dissolved oxygen from the neritic waters off Cochin during April (peak summer)

Dial variations of important hydrographic parameters were studied continuously for 7 days at a 100 m depth station off Cochin. The frequency of observations varied from 1-3 hourly intervals. In surface waters, the ranges in temperature, salinity and dissolved oxygen values recorded during 10-17 April were 30.64°-32.36°C, 34.56- 34.68 X lO''' and 4.06-4.65 ml/1 respectively. Tlie STD profiles in the diurnal study revealed clearly the premonsoon warming (30°-31°C) in the upper 0-30 m depth zone. In the water column up to 50 m depth, mean salinity values ranged from 34.6 to 35 X 10 while dissolved oxygen values were above 4 mI/1. Time series observations on the production and utilisation of dissolved oxygen revealed wide fluctuation from hour to hour. Vertical gradients in the diurnal study indicated the existence of thermocline around 60 m depth with sharp decline in temperature and dissolved oxygen and increase in salinity below 60 m. The diurnal variation on the distribution of temperature and dissolved oxygen exhibited significant rhythmic tidal impulse of a semi-diurnal wave pattern which was more prominent in the bottom layer below 60 m

Single-Cell Imaging of Bioenergetic Responses to Neuronal Excitotoxicity and Oxygen and Glucose Deprivation

Excitotoxicity is a condition occurring during cerebral ischemia, seizures, and chronic neurodegeneration. It is characterized by overactivation of glutamate receptors, leading to excessive Ca2+/Na+ influx into neurons, energetic stress, and subsequent neuronal injury.We and others have previously investigated neuronal populations to study how bioenergetic parameters determine neuronal injury; however, such experiments are often confounded by population-based heterogeneity and the contribution of effects of non-neuronal cells. Hence, we here characterized bioenergetics during transient excitotoxicity in rat and mouse primary neurons at the single-cell level using fluorescent sensors for intracellular glucose, ATP, and activation of the energy sensor AMP-activated protein kinase (AMPK). We identified ATP depletion and recovery to energetic homeostasis, along withAMPKactivation, as surprisingly rapid and plastic responses in two excitotoxic injury paradigms. We observed rapid recovery of neuronal ATP levels also in the absence of extracellular glucose, or when glycolytic ATP production was inhibited, but found mitochondria to be critical for fast and complete energetic recovery. Using an injury model of oxygen and glucose deprivation, we identified a similarly rapid bioenergetics response, yet with incompleteATPrecovery and decreasedAMPKactivity. Interestingly, excitotoxicity also induced an accumulation of intracellular glucose, providing an additional source of energy during and after excitotoxicity-induced energy depletion. We identified this to originate from extracellular, AMPKdependent glucose uptake and from intracellular glucose mobilization. Surprisingly, cells recovering their elevated glucose levels faster to baseline survived longer, indicating that the plasticity of neurons to adapt to bioenergetic challenges is a key indicator of neuronal viability

Post-tsunami oceanographic conditions in southern Arabian Sea and Bay of Bengal

Physical oceanographic conditions along the east and west coasts of India immediately after the recent devastating tsunami are presented here. The thermocline in the southeast coast exhibited trivial downward tilt towards north. A mixed layer deepening (>50 m) associated with low-salinity ( 36.0 psu) was identified as the Arabian Sea high salinity water mass along the west coast of India around 100 m depth up to 10°N. The heat content changes closely followed similar changes in the depth of the 20°C isotherm. Turbidity measurements using light scattering sensor showed the existence of two layers of high-scattering, one around 40 m and the other around 250 m. The shallow high-scattering layer is associated with high chlorophyll a concentration, but the deeper high-scattering layer noticed at shallow stations off the west and east coasts of India may be due to the resuspension of the sea-floor sediments due to turbulence generated by the tsunami

Anti-cancer activity of novel dibenzo[b,f]azepine tethered isoxazoline derivatives

10.1186/1472-6769-12-5BMC Chemical Biology12

Latrepirdine is a potent activator of AMP-activated protein kinase and reduces neuronal excitability.

Latrepirdine/Dimebon is a small-molecule compound with attributed neurocognitive-enhancing activities, which has recently been tested in clinical trials for the treatment of Alzheimer\u27s and Huntington\u27s disease. Latrepirdine has been suggested to be a neuroprotective agent that increases mitochondrial function, however the molecular mechanisms underlying these activities have remained elusive. We here demonstrate that latrepirdine, at (sub)nanomolar concentrations (0.1 nM), activates the energy sensor AMP-activated protein kinase (AMPK). Treatment of primary neurons with latrepirdine increased intracellular ATP levels and glucose transporter 3 translocation to the plasma membrane. Latrepirdine also increased mitochondrial uptake of the voltage-sensitive probe TMRM. Gene silencing of AMPKα or its upstream kinases, LKB1 and CaMKKβ, inhibited this effect. However, studies using the plasma membrane potential indicator DisBAC2(3) demonstrated that the effects of latrepirdine on TMRM uptake were largely mediated by plasma membrane hyperpolarization, precluding a purely \u27mitochondrial\u27 mechanism of action. In line with a stabilizing effect of latrepirdine on plasma membrane potential, pretreatment with latrepirdine reduced spontaneous Ca(2+) oscillations as well as glutamate-induced Ca(2+) increases in primary neurons, and protected neurons against glutamate toxicity. In conclusion, our experiments demonstrate that latrepirdine is a potent activator of AMPK, and suggest that one of the main pharmacological activities of latrepirdine is a reduction in neuronal excitability

भवानीप्रसाद मिश्र : व्यक्तित्व एवं कृतित्व

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NOX4-dependent Hydrogen peroxide promotes shear stress-induced SHP2 sulfenylation and eNOS activation

© 2015 Elsevier Inc.All rights reserved. Laminar shear stress (LSS) triggers signals that ultimately result in atheroprotection and vasodilatation. Early responses are related to the activation of specific signaling cascades. We investigated the participation of redox-mediated modifications and in particular the role of hydrogen peroxide (H2O2) in the sulfenylation of redox-sensitive phosphatases. Exposure of vascular endothelial cells to short periods of LSS (12 dyn/cm2) resulted in the generation of superoxide radical anion as detected by the formation of 2-hydroxyethidium by HPLC and its subsequent conversion to H2O2, which was corroborated by the increase in the fluorescence of the specific peroxide sensor HyPer. By using biotinylated dimedone we detected increased total protein sulfenylation in the bovine proteome, which was dependent on NADPH oxidase 4 (NOX4)-mediated generation of peroxide. Mass spectrometry analysis allowed us to identify the phosphatase SHP2 as a protein susceptible to sulfenylation under LSS. Given the dependence of FAK activity on SHP2 function, we explored the role of FAK under LSS conditions. FAK activation and subsequent endothelial NO synthase (eNOS) phosphorylation were promoted by LSS and both processes were dependent on NOX4, as demonstrated in lung endothelial cells isolated from NOX4-null mice. These results support the idea that LSS elicits redox-sensitive signal transduction responses involving NOX4-dependent generation of hydrogen peroxide, SHP2 sulfenylation, and ulterior FAK-mediated eNOS activation.Ministerio deEconomía y Competitividad, SAF2012-31338(S.L.),CSD2007-00020(S. L.), SAF2010-37926(J.V.); Instituto de Salud CarlosIII, REDinREN RD12/0021/0009(S.L.), ProteoRed-PT13/0001/0017(J.V.), RETIC-RD12/0042/0056(J.V.); Deutsche Forschungsgemeinschaft (SFB815/TP1toK.S.andR.P.B.andSCHR1241/1-1toK.S.); German Center for Cardiovascular Research; ComunidaddeMadrid “Fi-broteam” S2010/BMD-2321(S.L.);and Fundación Renal “Iñigo Alvarez deToledo” (S.L.). This work was also supported by European Cooperationin Science and Technology actionsBM-1203(EU-ROS) and BM-1005(ENOGAS) (S.L.).A.M.S.is supported by the British Heart Foundation.TheCBMSO receives institutional support from Fundación Ramón ArecesPeer Reviewe

Thermomagnetic history effects in SmMn2_2Ge2_2

The intermetallic compound SmMn$_2$Ge$_2$, displaying multiple magnetic phase transitions, is being investigated in detail for its magnetization behavior near the 145 K first order ferromagnetic to antiferromagnetic transition occuring on cooling, in particular for thermomagnetic history effects in the magnetization data. The most unusual finding is that the thermomagnetic irreversibility, [= M$^{FCW}$(T)-M$^{ZFC}$(T)] at 135 K is higher in intermediate magnetic field strengths. By studying the response of the sample (i.e., thermomagnetic irreversibility and thermal hysteresis) to different histories of application of magnetic field and temperature, we demonstrate how the supercooling and superheating of the metastable magnetic phases across the first order transition at 145 K contribute to overall thermomagnetic irreversibility.Comment: 15 pages, 5 figures, to appear in Physical Review