Differential expression of the heat shock protein Hsp70 in natural populations of the tilapia, Sarotherodon melanotheron, acclimatised to a range of environmental salinities

<p>Abstract</p> <p>Background</p> <p>The relationship between environmental variation and induction of heat shock proteins <it>(Hsps) </it>has been much documented under experimental conditions. However, very little is known about such induction in natural populations acclimatised to prevailing environmental conditions. Furthermore, while induction of stress proteins has been well documented in response to environmental contaminants and thermal stressors, little is known about whether factors, such as extreme salinity, are also potential inductors. The black-chinned tilapia <it>Sarotherodon melanotheron </it>is unusual for its ability to colonise estuarine environments in West Africa that are characterised by extremely high salinities. The relationships between mRNA levels of the 70 kDa heat shock protein (<it>Hsp70</it>) and Na⁺, K⁺-ATPase1α (<it>Naka</it>) in the gills, environmental salinity, and a life-history trait (condition factor) were investigated in wild populations of this species sampled from three locations in the Saloum estuary, at salinities ranging from 40 to 100 psu.</p> <p>Results</p> <p>The highest <it>Hsp70 </it>and <it>Naka </it>mRNA levels, and the poorest condition factors were recorded in the most saline sampling site (100 psu). The <it>Hsp70 </it>and <it>Naka </it>mRNA were correlated amongst themselves and showed a direct positive correlation with environmental salinity, and a negative correlation with fish condition factor. Thus, the <it>Hsp70 </it>is constitutively overexpressed by <it>S. melanotheron </it>acclimatised to extreme hypersalinity.</p> <p>Conclusions</p> <p>These results indicate that, although <it>S. melanotheron </it>can colonise extremely saline environments, the overexpression of <it>Hsp70 </it>combined with the higher <it>Naka </it>mRNA expression reveals that this represents a chronic stress. The induction of <it>Hsp70 </it>was, therefore, a biomarker of chronic hyper-osmotic stress which presumably can be linked to the impaired growth performance and precocious reproduction that have been demonstrated in the populations at the extremely saline sites.</p

Characterization of a 4H-SiC High Power Density Controlled Current Limiter

International audienceCritical steps for the fabrication of SiC devices are thermal annealing and metal ohmic contact formation. Metal annealing effect on the electrical characteristics of the current limiter underlines the necessity to control this device fabrication step. Measurements of contact resistivity as a function of temperature demonstrate the stability of the N type Ni/SiC contact in the range of 175 K-450 K as its value remains constant around 40 µΩ.cm 2. Post implantation annealing effect on the sheet resistance (Rsh) shows that a 1700°C/30 min annealing gives better trade off in terms of dopant activation and surface roughness. High power density has been measured up to 600 V. Current thermal stability has been measured for an applied drain to source voltage of 100 V and exhibits high power density capabilities of SiC VJFET as a controlled current limiter. Introduction

Propofol-induced unresponsiveness is associated with impaired feedforward connectivity in cortical hierarchy

peer reviewedBackground: Impaired consciousness has been associated with impaired cortical signal propagation after transcranial magnetic stimulation (TMS). We hypothesised that the reduced current propagation under propofol-induced unresponsiveness is associated with changes in both feedforward and feedback connectivity across the cortical hierarchy. Methods: Eight subjects underwent left occipital TMS coupled with high-density EEG recordings during wakefulness and propofol-induced unconsciousness. Spectral analysis was applied to responses recorded from sensors overlying six hierarchical cortical sources involved in visual processing. Dynamic causal modelling (DCM) of induced time–frequency responses and evoked response potentials were used to investigate propofol's effects on connectivity between regions. Results: Sensor space analysis demonstrated that propofol reduced both induced and evoked power after TMS in occipital, parietal, and frontal electrodes. Bayesian model selection supported a DCM with hierarchical feedforward and feedback connections. DCM of induced EEG responses revealed that the primary effect of propofol was impaired feedforward responses in cross-frequency theta/alpha–gamma coupling and within frequency theta coupling (F contrast, family-wise error corrected P<0.05). An exploratory analysis (thresholded at uncorrected P<0.001) also suggested that propofol impaired feedforward and feedback beta band coupling. Post hoc analyses showed impairments in all feedforward connections and one feedback connection from parietal to occipital cortex. DCM of the evoked response potential showed impaired feedforward connectivity between left-sided occipital and parietal cortex (T contrast P=0.004, Bonferroni corrected). Conclusions: Propofol-induced loss of consciousness is associated with impaired hierarchical feedforward connectivity assessed by EEG after occipital TMS. © 2018 British Journal of AnaesthesiaARC-06/11-34

Priors about Observables in Vector Autoregressions *

Abstract We formulate a prior about observables in a vector autoregression (VAR) and then solve the deconvolution problem for the implied prior about VAR parameters. Formulating a prior about observables is more intuitive than formulating a prior about VAR parameters directly, because VAR parameters are hard to interpret. Our numerical algorithm for approximating the implied prior about parameters works well even in high-dimensional problems and can be applied also for models other than VARs. In the empirical application we formulate a prior about growth rates of the observables in a VAR model of the United States economy. We find that this prior makes a big difference for the estimated persistence of output responses to monetary policy shocks, compared with the results of standard priors for VARs

Progressive Purkinje Cell Degeneration in tambaleante Mutant Mice Is a Consequence of a Missense Mutation in HERC1 E3 Ubiquitin Ligase

The HERC gene family encodes proteins with two characteristic domains: HECT and RCC1-like. Proteins with HECT domains have been described to function as ubiquitin ligases, and those that contain RCC1-like domains have been reported to function as GTPases regulators. These two activities are essential in a number of important cellular processes such as cell cycle, cell signaling, and membrane trafficking. Mutations affecting these domains have been found associated with retinitis pigmentosa, amyotrophic lateral sclerosis, and cancer. In humans, six HERC genes have been reported which encode two subgroups of HERC proteins: large (HERC1-2) and small (HERC3-6). The giant HERC1 protein was the first to be identified. It has been involved in membrane trafficking and cell proliferation/growth through its interactions with clathrin, M2-pyruvate kinase, and TSC2 proteins. Mutations affecting other members of the HERC family have been found to be associated with sterility and growth retardation. Here, we report the characterization of a recessive mutation named tambaleante, which causes progressive Purkinje cell degeneration leading to severe ataxia with reduced growth and lifespan in homozygous mice aged over two months. We mapped this mutation in mouse chromosome 9 and then performed positional cloning. We found a G⇔A transition at position 1448, causing a Gly to Glu substitution (Gly483Glu) in the highly conserved N-terminal RCC1-like domain of the HERC1 protein. Successful transgenic rescue, with either a mouse BAC containing the normal copy of Herc1 or with the human HERC1 cDNA, validated our findings. Histological and biochemical studies revealed extensive autophagy associated with an increase of the mutant protein level and a decrease of mTOR activity. Our observations concerning this first mutation in the Herc1 gene contribute to the functional annotation of the encoded E3 ubiquitin ligase and underline the crucial and unexpected role of this protein in Purkinje cell physiology

Géologie : Données nouvelles sur l'âge des séries rouges du golfe normano-breton

National audienc

Données nouvelles sur l'âge des séries rouges du golfe normanno-breton

National audienc