Skeletal muscle Akt activity stimulates muscle growth and imparts resistance to obesity, glucose intolerance and fatty liver disease. We recently found that ursolic acid increases skeletal muscle Akt ...activity and stimulates muscle growth in non-obese mice. Here, we tested the hypothesis that ursolic acid might increase skeletal muscle Akt activity in a mouse model of diet-induced obesity. We studied mice that consumed a high fat diet lacking or containing ursolic acid. In skeletal muscle, ursolic acid increased Akt activity, as well as downstream mRNAs that promote glucose utilization (hexokinase-II), blood vessel recruitment (Vegfa) and autocrine/paracrine IGF-I signaling (Igf1). As a result, ursolic acid increased skeletal muscle mass, fast and slow muscle fiber size, grip strength and exercise capacity. Interestingly, ursolic acid also increased brown fat, a tissue that shares developmental origins with skeletal muscle. Consistent with increased skeletal muscle and brown fat, ursolic acid increased energy expenditure, leading to reduced obesity, improved glucose tolerance and decreased hepatic steatosis. These data support a model in which ursolic acid reduces obesity, glucose intolerance and fatty liver disease by increasing skeletal muscle and brown fat, and suggest ursolic acid as a potential therapeutic approach for obesity and obesity-related illness.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In the tropopause region turbulence exhibits a common feature with posing a threat for aviation as well as presenting a pathway for cross tropopause exchange. However, current numerical weather ...prediction and in particular climate models still struggle to resolve a large part of the dynamics responsible for turbulence generation. This renders high resolution observations of turbulence to be very valuable to identify the spatio‐temporal distribution of turbulence. In this study we use aircraft observations along with reanalysis data over the North Atlantic during winter season to analyze turbulence occurrence. Using a tropopause‐based coordinate system, we found that turbulence occurs within a sharp unimodal distribution which maximizes just below the tropopause. Turbulence also significantly affects the first 2 km above the tropopause which highlights its potential impact on the formation of the so called extratropical mixing layer around the tropopause.
Plain Language Summary
Besides its importance for aviation safety atmospheric turbulence is of general interest in atmospheric sciences. It is of fundamental importance due its capability to mix air masses of different origin, fluid dynamical properties, and chemical composition. The mixing of trace gases can significantly influence the atmospheric chemistry as well as the overall radiative budget. Particularly at the tropopause, a conceptual transport barrier which separates the troposphere from the stratosphere where turbulence may play a key role to overcome this barrier. Turbulence occurs intermittently and on scales below the resolution of numerical weather prediction models. Therefore it is important to compare turbulence measurements with resolved flow characteristics in the model, to identify turbulence and diagnose its effect on the atmosphere. This study approaches this issue by comparing a comprehensive data set of turbulence measurements with a contemporary model derived representation of the atmospheric state. The analysis highlights the significance of the tropopause location to identify turbulence, diagnose the underlaying processes, and assess the viability of common turbulence diagnostics. First, our results provide insight into the degree of separation between the troposphere and the stratosphere. Second they could help to improve numerical model diagnostics to identify and forecast atmospheric turbulence.
Key Points
Atmospheric turbulence over the winter North Atlantic exhibits a pronounced tropopause‐following behavior
Tropopause‐based mapping sorts turbulence diagnostics by atmospheric layer and reveals distinct features in the vertical distribution
Turbulence occurs comparatively frequently in the layer which is colocated to the chemical transition between troposphere and stratosphere
Skeletal muscle atrophy is a common and debilitating condition that lacks a pharmacologic therapy. To develop a potential therapy, we identified 63 mRNAs that were regulated by fasting in both human ...and mouse muscle, and 29 mRNAs that were regulated by both fasting and spinal cord injury in human muscle. We used these two unbiased mRNA expression signatures of muscle atrophy to query the Connectivity Map, which singled out ursolic acid as a compound whose signature was opposite to those of atrophy-inducing stresses. A natural compound enriched in apples, ursolic acid reduced muscle atrophy and stimulated muscle hypertrophy in mice. It did so by enhancing skeletal muscle insulin/IGF-I signaling and inhibiting atrophy-associated skeletal muscle mRNA expression. Importantly, ursolic acid's effects on muscle were accompanied by reductions in adiposity, fasting blood glucose, and plasma cholesterol and triglycerides. These findings identify a potential therapy for muscle atrophy and perhaps other metabolic diseases.
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► We determined mRNA expression signatures of skeletal muscle atrophy in humans ► Muscle atrophy signatures negatively correlated with the signature of ursolic acid ► Ursolic acid reduced muscle atrophy and induced muscle hypertrophy in mice ► Although ursolic acid increased skeletal muscle mass, it reduced adiposity
Recent studies on the formation of a quasi-permanent layer of enhanced static stability above the thermal tropopause revealed the contributions of dynamical and radiative processes. Dry dynamics ...leads to the evolution of a tropopause inversion layer (TIL), which is, however, too weak compared to observations and thus diabatic contributions are required. In this study we aim to assess the importance of diabatic processes in the understanding of TIL formation at midlatitudes. The non-hydrostatic model COSMO (COnsortium for Small-scale MOdelling) is applied in an idealized midlatitude channel configuration to simulate baroclinic life cycles. The effect of individual diabatic processes related to humidity, radiation, and turbulence is studied first to estimate the contribution of each of these processes to the TIL formation in addition to dry dynamics. In a second step these processes are stepwise included in the model to increase the complexity and finally estimate the relative importance of each process. The results suggest that including turbulence leads to a weaker TIL than in a dry reference simulation. In contrast, the TIL evolves stronger when radiation is included but the temporal evolution is still comparable to the reference. Using various cloud schemes in the model shows that latent heat release and consecutive increased vertical motions foster an earlier and stronger appearance of the TIL than in all other life cycles. Furthermore, updrafts moisten the upper troposphere and as such increase the radiative effect from water vapor. Particularly, this process becomes more relevant for maintaining the TIL during later stages of the life cycles. Increased convergence of the vertical wind induced by updrafts and by propagating inertia-gravity waves, which potentially dissipate, further contributes to the enhanced stability of the lower stratosphere. Finally, radiative feedback of ice clouds reaching up to the tropopause is identified to potentially further affect the strength of the TIL in the region of the clouds.
Major reactor accidents of nuclear power plants are rare, yet the consequences are catastrophic. But what is meant by "rare"? And what can be learned from the Chernobyl and Fukushima incidents? Here ...we assess the cumulative, global risk of exposure to radioactivity due to atmospheric dispersion of gases and particles following severe nuclear accidents (the most severe ones on the International Nuclear Event Scale, INES 7), using particulate 137Cs and gaseous 131I as proxies for the fallout. Our results indicate that previously the occurrence of INES 7 major accidents and the risks of radioactive contamination have been underestimated. Using a global model of the atmosphere we compute that on average, in the event of a major reactor accident of any nuclear power plant worldwide, more than 90% of emitted 137Cs would be transported beyond 50 km and about 50% beyond 1000 km distance before being deposited. This corroborates that such accidents have large-scale and trans-boundary impacts. Although the emission strengths and atmospheric removal processes of 137Cs and 131I are quite different, the radioactive contamination patterns over land and the human exposure due to deposition are computed to be similar. High human exposure risks occur around reactors in densely populated regions, notably in West Europe and South Asia, where a major reactor accident can subject around 30 million people to radioactive contamination. The recent decision by Germany to phase out its nuclear reactors will reduce the national risk, though a large risk will still remain from the reactors in neighbouring countries.
Immobilization causes skeletal muscle atrophy via complex signaling pathways that are not well understood. To better understand these pathways, we investigated the roles of p53 and ATF4, two ...transcription factors that mediate adaptations to a variety of cellular stresses. Using mouse models, we demonstrate that 3 days of muscle immobilization induces muscle atrophy and increases expression of p53 and ATF4. Furthermore, muscle fibers lacking p53 or ATF4 are partially resistant to immobilization-induced muscle atrophy, and forced expression of p53 or ATF4 induces muscle fiber atrophy in the absence of immobilization. Importantly, however, p53 and ATF4 do not require each other to promote atrophy, and coexpression of p53 and ATF4 induces more atrophy than either transcription factor alone. Moreover, muscle fibers lacking both p53 and ATF4 are more resistant to immobilization-induced atrophy than fibers lacking only p53 or ATF4. Interestingly, the independent and additive nature of the p53 and ATF4 pathways allows for combinatorial control of at least one downstream effector, p21. Using genome-wide mRNA expression arrays, we identified p21 mRNA as a skeletal muscle transcript that is highly induced in immobilized muscle via the combined actions of p53 and ATF4. Additionally, in mouse muscle, p21 induces atrophy in a manner that does not require immobilization, p53 or ATF4, and p21 is required for atrophy induced by immobilization, p53, and ATF4. Collectively, these results identify p53 and ATF4 as essential and complementary mediators of immobilization-induced muscle atrophy and discover p21 as a critical downstream effector of the p53 and ATF4 pathways.
The ancestor of Gloeobacter violaceus PCC 7421(T) is believed to have diverged from that of all known cyanobacteria before the evolution of thylakoid membranes and plant plastids. The long and ...largely independent evolutionary history of G. violaceus presents an organism retaining ancestral features of early oxygenic photoautotrophs, and in whom cyanobacteria evolution can be investigated. No other Gloeobacter species has been described since the genus was established in 1974 (Rippka et al., Arch Microbiol 100:435). Gloeobacter affiliated ribosomal gene sequences have been reported in environmental DNA libraries, but only the type strain's genome has been sequenced. However, we report here the cultivation of a new Gloeobacter species, G. kilaueensis JS1(T), from an epilithic biofilm in a lava cave in Kīlauea Caldera, Hawai'i. The strain's genome was sequenced from an enriched culture resembling a low-complexity metagenomic sample, using 9 kb paired-end 454 pyrosequences and 400 bp paired-end Illumina reads. The JS1(T) and G. violaceus PCC 7421(T) genomes have little gene synteny despite sharing 2842 orthologous genes; comparing the genomes shows they do not belong to the same species. Our results support establishing a new species to accommodate JS1(T), for which we propose the name Gloeobacter kilaueensis sp. nov. Strain JS1(T) has been deposited in the American Type Culture Collection (BAA-2537), the Scottish Marine Institute's Culture Collection of Algae and Protozoa (CCAP 1431/1), and the Belgian Coordinated Collections of Microorganisms (ULC0316). The G. kilaueensis holotype has been deposited in the Algal Collection of the US National Herbarium (US# 217948). The JS1(T) genome sequence has been deposited in GenBank under accession number CP003587. The G+C content of the genome is 60.54 mol%. The complete genome sequence of G. kilaueensis JS1(T) may further understanding of cyanobacteria evolution, and the shift from anoxygenic to oxygenic photosynthesis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this study we examine the simulated downward transport and mixing of stratospheric air into the upper tropical troposphere as observed on a research flight during the SCOUT-O3 campaign in ...connection with a deep convective system. We use the Advanced Research Weather and Research Forecasting (WRF-ARW) model with a horizontal resolution of 333 m to examine this downward transport. The simulation reproduces the deep convective system, its timing and overshooting altitudes reasonably well compared to radar and aircraft observations. Passive tracers initialised at pre-storm times indicate the downward transport of air from the stratosphere to the upper troposphere as well as upward transport from the boundary layer into the cloud anvils and overshooting tops. For example, a passive ozone tracer (i.e. a tracer not undergoing chemical processing) shows an enhancement in the upper troposphere of up to about 30 ppbv locally in the cloud, while the in situ measurements show an increase of 50 ppbv. However, the passive carbon monoxide tracer exhibits an increase, while the observations show a decrease of about 10 ppbv, indicative of an erroneous model representation of the transport processes in the tropical tropopause layer. Furthermore, it could point to insufficient entrainment and detrainment in the model. The simulation shows a general moistening of air in the lower stratosphere, but it also exhibits local dehydration features. Here we use the model to explain the processes causing the transport and also expose areas of inconsistencies between the model and observations.
L’objectif de cette étude est d’explorer dans notre unité de néonatologie les facteurs de risques de l’infection nosocomiale générée par Staphylococcus aureus, de déterminer la prévalence et la ...densité d’incidence de ces microorganismes, et de vérifier si ces souches sont également responsables de la formation de biofilm sur cathéters.
Deux cent cinquante-trois nouveau-nés ont été inclus dans cette étude, l’aptitude à former des biofilms a été détectée par la technique de plaque de culture de tissu, et la visualisation de ces biofilms a été faite par microscopie électronique à balayage. Les concentrations minimales inhibitrices (CMI) d’antibiotiques sur des cellules planctoniques ont été déterminées par la technique de dilutions sur microplaque à 96 puits. En parallèle, la sensibilité des cellules en mode sessile a été testée vis-à-vis de sept molécules d’antibiotiques.
La densité d’incidence de l’infection nosocomiale causée par S. aureus a été de l’ordre de 9,87 pour 1000 journées d’hospitalisation. Ces souches sont capables de former des biofilms et de résister à des concentrations 100 fois plus importantes que celles utilisées en schéma thérapeutique.
Cette étude a permis également d’identifier certains facteurs de risque de l’infection nosocomiale dans notre unité de néonatologie, à savoir la prématurité, le faible poids de naissance et la durée de séjour d’hospitalisation. Les souches responsables d’infections nosocomiales dans l’unité de néonatologie de L’EHS de Tlemcen peuvent également former des biofilms avec tout ce que cela implique comme risque en matière de résistance. Par conséquent elles peuvent constituer une véritable contrainte thérapeutique.
The objective of this study is to explore in our neonatal unit, risk factors of nosocomial infection generated by Staphylococcus aureus, to determine the prevalence and incidence density of these microorganisms and whether these strains are also responsible for biofilm formation on catheters.
Two hundred and fifty-three newborn babies were included in this study, the ability to form biofilms was detected by tissue culture plate method, and visualization of biofilms was made by Scanning Electron Microscopy “SEM”. MICs of antibiotics on planktonic cells were determined by the dilution technique in 96-well microplate. In parallel, the sensitivity of cells in sessile mode has been tested towards seven antibiotic molecules.
The incidence density of nosocomial infection caused by S. aureus was the order of 9.87 per 1000 patient days. These strains are capable of forming biofilms and resist 100 times greater than those used in regimens concentrations.
This study has also identified certain risk factors of nosocomial infection in our neonatal unit, like prematurity, low birth weight and length of hospital stay. Strains responsible for nosocomial infections in the neonatal unit of EHS Tlemcen can also form biofilms with everything that implies risk for resistance, therefore they can be a real therapeutic stress.
Phylogenetic positions, and genotypic and phenotypic characteristics of three novel methylotrophic isolates, strains 301T, 30S and SIP3-4, from sediment of Lake Washington, Seattle, USA, are ...described. The strains were restricted facultative methylotrophs capable of growth on single carbon compounds (methylamine and methanol) in addition to a limited range of multicarbon compounds. All strains used the N-methylglutamate pathway for methylamine oxidation. Strain SIP3-4 possessed the canonical (MxaFI) methanol dehydrogenase, but strains 301T and 30S did not. All three strains used the ribulose monophosphate pathway for C1 assimilation. The major fatty acids in the three strains were C16 : 0 and C16 : 1ω7c. The DNA G+C contents of strains 301T and SIP3-4 were 42.6 and 54.6 mol%, respectively. Based on 16S rRNA gene sequence phylogeny and the relevant phenotypic characteristics, strain SIP3-4 was assigned to the previously defined species Methylovorus glucosotrophus. Strains 301T and 30S were closely related to each other (100 % 16S rRNA gene sequence similarity) and shared 96.6 % 16S rRNA gene sequence similarity with a previously described isolate, Methylotenera mobilis JLW8T. Based on significant genomic and phenotypic divergence with the latter, strains 301T and 30S represent a novel species within the genus Methylotenera, for which the name Methylotenera versatilis sp. nov. is proposed; the type strain is 301T ( = VKM B-2679T = JCM 17579T). An emended description of the genus Methylotenera is provided.
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