Levels of Cadmium, Lead, Mercury and 137caesium in Caribou (Rangifer tarandus) Tissues from Northern Québec

Levels of cadmium (Cd), lead (Pb) and total mercury (Hg) were assessed in samples of muscle, kidney, and liver from caribou (Rangifer tarandus; n = 317) harvested in two regions of northern Québec between 1994 and 1996. Levels of 137caesium (137Cs) were also examined in muscle samples. Log concentration of the three metals varied significantly among tissues and was lowest in diaphragm muscle and highest in kidneys and liver. Mean Cd (wet weight, w.w.) concentration was 0.01 µg/g in muscle, 7.69 µg/g in kidneys and 1.13 µg/g in liver. Levels of Cd exceeded tolerance thresholds for human consumption in nearly all kidney samples and in nearly half the liver samples. Mean Pb concentration (w.w.) was 0.05 µg/g in muscle, 0.26 µg/g in kidneys and 0.95 µg/g in liver, with few samples exceeding consumption thresholds. Mean total Hg concentration (w.w.) in muscle was 0.03 µg/g, 1.26 µg/g in kidneys and 0.67 µg/g in liver, with concentrations exceeding consumption thresholds in most kidney samples and nearly half the liver samples. Regional differences occurred in log concentration of the three metals for most tissues, with the western region consistently showing higher values. Mean log Cd and Pb concentrations increased with age in kidneys, but log Pb decreased with age in muscle samples. Interactions between month of collection and sex and region also occurred for some metals in some tissues. Mean level of 137Cs in muscle samples was 94.7 Bq/kg, never exceeding the acceptable limit for human consumption.On a mesuré les niveaux de cadmium (Cd), de plomb (Pb) et de mercure total (Hg) dans des échantillons de muscle, de rein et de foie de caribous (Rangifer tarandus; n = 317) prélevés dans deux régions du Québec nordique entre 1994 et 1996. On a en outre étudié les niveaux de césium 137 (137Cs) dans des échantillons musculaires. Les concentrations enregistrées des trois métaux montraient d'importantes variations parmi les divers tissus et étaient les plus faibles dans le muscle du diaphragme et les plus élevées dans le rein et le foie. La concentration moyenne de Cd (poids frais, p.f.) était de 0,01 µg/g dans le muscle, de 7,69 µg/g dans le rein et de 1,13 µg/g dans le foie. Les niveaux de Cd dépassaient les seuils de tolérance pour la consommation humaine dans presque tous les échantillons de rein et dans près de la moitié des échantillons de foie. La concentration moyenne (p.f.) de Pb était de 0,05 µg/g dans le muscle, de 0,26 µg/g dans le rein et de 0,95 µg/g dans le foie, avec peu d'échantillons dépassant les seuils de consommation. La concentration moyenne de Hg total (p.f.) dans le muscle était de 0,03 µg/g, de 1,26 µg/g dans le rein et de 0,67 µg/g dans le foie, avec des concentrations qui dépassaient les seuils de consommation dans la plupart des échantillons de rein et presque la moitié des échantillons de foie. Des différences régionales sont apparues dans les concentrations enregistrées des trois métaux pour la plupart des tissus, la zone occidentale montrant constamment des valeurs plus élevées. Avec l'âge, les concentrations moyennes enregistrées pour le Cd et le Pb augmentaient dans le rein, alors que celles de Pb diminuaient dans le muscle. Des interactions entre le mois des prélèvements, le sexe et la région se produisaient aussi avec certains métaux et certains tissus. Le niveau moyen de 137Cs dans les échantillons musculaires était de 94,7 Bq/kg, ne dépassant jamais la limite acceptable pour la consommation humaine

MICU1 Interacts with the D-Ring of the MCU Pore to Control Its Ca2+ Flux and Sensitivity to Ru360

Proper control of the mitochondrial Ca2+ uniporter's pore (MCU) is required to allow Ca2+-dependent activation of oxidative metabolism and to avoid mitochondrial Ca2+ overload and cell death. The MCU's gatekeeping and cooperative activation is mediated by the Ca2+-sensing MICU1 protein, which has been proposed to form dimeric complexes anchored to the EMRE scaffold of MCU. We unexpectedly find that MICU1 suppresses inhibition of MCU by ruthenium red/Ru360, which bind to MCU's DIME motif, the selectivity filter. This led us to recognize in MICU1's sequence a putative DIME interacting domain (DID), which is required for both gatekeeping and cooperative activation of MCU and for cell survival. Thus, we propose that MICU1 has to interact with the D-ring formed by the DIME domains in MCU to control the uniporter. Copyright © 2018 Elsevier Inc. All rights reserved

Large scale quantum simulations: C_60 impacts on a semiconducting surface

We present tight binding molecular dynamics simulations of C_60 collisions on the reconstructed diamond(111) surface, carried out with an O(N) method and with cells containing 1140 atoms. The results of our simulations are in very good agreement with experiments performed under the same impact conditions. Furthermore our calculations provide a detailed characterization of the microscopic processes occuring during the collision, and allow the identification of three impact regimes, as a function of the fullerene incident energy. Finally, the study of the reactivity between the cluster and the surface gives insight into the deposition mechanisms of C_60 on semiconducting substrates

Present and LGM permafrost from climate simulations : contribution of statistical downscaling

We quantify the agreement between permafrost distributions from PMIP2 (Paleoclimate Modeling Intercomparison Project) climate models and permafrost data. We evaluate the ability of several climate models to represent permafrost and assess the variability between their results. <br><br> Studying a heterogeneous variable such as permafrost implies conducting analysis at a smaller spatial scale compared with climate models resolution. Our approach consists of applying statistical downscaling methods (SDMs) on large- or regional-scale atmospheric variables provided by climate models, leading to local-scale permafrost modelling. Among the SDMs, we first choose a transfer function approach based on Generalized Additive Models (GAMs) to produce high-resolution climatology of air temperature at the surface. Then we define permafrost distribution over Eurasia by air temperature conditions. In a first validation step on present climate (CTRL period), this method shows some limitations with non-systematic improvements in comparison with the large-scale fields. <br><br> So, we develop an alternative method of statistical downscaling based on a Multinomial Logistic GAM (ML-GAM), which directly predicts the occurrence probabilities of local-scale permafrost. The obtained permafrost distributions appear in a better agreement with CTRL data. In average for the nine PMIP2 models, we measure a global agreement with CTRL permafrost data that is better when using ML-GAM than when applying the GAM method with air temperature conditions. In both cases, the provided local information reduces the variability between climate models results. This also confirms that a simple relationship between permafrost and the air temperature only is not always sufficient to represent local-scale permafrost. <br><br> Finally, we apply each method on a very different climate, the Last Glacial Maximum (LGM) time period, in order to quantify the ability of climate models to represent LGM permafrost. The prediction of the SDMs (GAM and ML-GAM) is not significantly in better agreement with LGM permafrost data than large-scale fields. At the LGM, both methods do not reduce the variability between climate models results. We show that LGM permafrost distribution from climate models strongly depends on large-scale air temperature at the surface. LGM simulations from climate models lead to larger differences with LGM data than in the CTRL period. These differences reduce the contribution of downscaling

QTL analysis of resistance to Fusarium head blight in Swiss winter wheat ( Triticum aestivum L.)

Fusarium head blight (FHB) of wheat is a widespread and destructive disease which occurs in humid and semi-humid areas. FHB epidemics can cause serious yield and quality losses under favorable climatic conditions, but the major concern is the contamination of grains with mycotoxins. Resistance to FHB is quantitatively inherited and greatly influenced by the environment. Its evaluation is costly and time-consuming. The genetic basis of FHB resistance has mainly been studied in spring wheat. The objective of this study was to map quantitative trait loci (QTLs) for resistance to FHB in a population of 240 recombinant inbred lines (RILs) derived from a cross between the two Swiss winter wheat cultivars Arina (resistant) and Forno (susceptible). The RILs were genotyped with microsatellite and RFLP markers. The resulting genetic map comprises 380 loci and spans 3,086cM. The 240 RILs were evaluated for resistance to FHB in six field trials over 3 years. Composite interval mapping (CIM) analyses carried out on FHB AUDPC (i.e. mean values across six environments) revealed eight QTLs which altogether explained 47% of the phenotypic variance. The three main QTLs were mapped on the long arms of chromosomes 6D (R 2=22%), 5B (R 2=14%) and 4A (R 2=10%). The QTL detected on 5B originated from the susceptible parent Forno. Other QTLs with smaller effects on FHB resistance were detected on chromosomes 2AL, 3AL, 3BL, 3DS and 5A

Detection of QTLs for Stagonospora glume blotch resistance in Swiss winter wheat

Stagonospora nodorum is the causal agent of the Stagonospora glume blotch disease in hexaploid wheat. The Swiss winter bread wheat cv. 'Arina' has a highly effective, durable and quantitative glume blotch resistance. We studied 240 single seed descent (SSD)-derived lines of an 'Arina × Forno' F5:7 population to identify and map quantitative trait loci (QTLs) for glume blotch resistance under natural infestation. Using composite interval mapping (CIM) and LOD>4.5, we detected two chromosomal regions on chromosome arms 3BS and 4BL which were specifically associated with glume blotch resistance. These identified QTLs were designated QSng.sfr-3BS and QSng.sfr-4BL, respectively. QSng.sfr-3BS peaked at the locus Xgwm389 in the telomeric region of the short arm of chromosome 3B and explained 31.2% of the observed phenotypic variance for the resistance within the population. The responsible QSng.sfr-3BS allele originated from the resistant parent 'Arina'. The QTL QSng.sfr-4BL (19.1%) mapped to chromosome arm 4BL ('Forno' allele) very close to two known genes, TaMlo and a catalase (Cat). Both QTL alleles combined could enhance the resistance level by about 50%. Additionally, they showed significant epistatic effects (4.4%). We found PCR-based microsatellite markers closely linked to QSng.sfr-3BS (gwm389) and QSng.sfr-4BL (gwm251) which make marker-assisted selection (MAS) for Stagonospora glume blotch resistance feasible. We also found one resistance QTL, QSng.sfr-5BL, on the long arm of chromosome 5B which overlapped with QTLs for plant height as well as heading tim

Dissection of quantitative and durable leaf rust resistance in Swiss winter wheat reveals a major resistance QTL in the Lr34 chromosomal region

The Swiss winter bread wheat cv. ‘Forno' has a highly effective, durable and quantitative leaf rust (Puccinia triticina Eriks.) resistance which is associated with leaf tip necrosis (LTN). We studied 240 single seed descent lines of an ‘Arina×Forno' F5:7 population to identify and map quantitative trait loci (QTLs) for leaf rust resistance and LTN. Percentage of infected leaf area (%) and the response to infection (RI) were evaluated in seven field trials and were transformed to the area under the disease progress curves (AUDPC). Using composite interval mapping and LOD>4.4, we identified eight chromosomal regions specifically associated with resistance. The largest and most consistent leaf rust resistance locus was identified on the short arm of chromosome 7D (32.6% of variance explained for AUDPC_% and 42.6% for AUDPC_RI) together with the major QTL for LTN (R 2=55.6%) in the same chromosomal region as Lr34 (Xgwm295). A second major leaf rust resistance QTL (R 2=28% and 31.5%, respectively) was located on chromosome arm 1BS close to Xgwm604 and was not associated with LTN. Additional minor QTLs for LTN (2DL, 3DL, 4BS and 5AL) and leaf rust resistance were identified. These latter QTLs might correspond to the leaf rust resistance genes Lr2 or Lr22 (2DS) and Lr14a (7BL

Modeling the dynamics of glacial cycles

This article is concerned with the dynamics of glacial cycles observed in the geological record of the Pleistocene Epoch. It focuses on a conceptual model proposed by Maasch and Saltzman [J. Geophys. Res.,95, D2 (1990), pp. 1955-1963], which is based on physical arguments and emphasizes the role of atmospheric CO2 in the generation and persistence of periodic orbits (limit cycles). The model consists of three ordinary differential equations with four parameters for the anomalies of the total global ice mass, the atmospheric CO2 concentration, and the volume of the North Atlantic Deep Water (NADW). In this article, it is shown that a simplified two-dimensional symmetric version displays many of the essential features of the full model, including equilibrium states, limit cycles, their basic bifurcations, and a Bogdanov-Takens point that serves as an organizing center for the local and global dynamics. Also, symmetry breaking splits the Bogdanov-Takens point into two, with different local dynamics in their neighborhoods

Carbon superatom thin films

Assembling clusters on surfaces has emerged as a novel way to grow thin films with targeted properties. In particular, it has been proposed from experimental findings that fullerenes deposited on surfaces could give rise to thin films retaining the bonding properties of the incident clusters. However the microscopic structure of such films is still unclear. By performing quantum molecular dynamics simulations, we show that C_28 fullerenes can be deposited on a surface to form a thin film of nearly defect free molecules, which act as carbon superatoms. Our findings help clarify the structure of disordered small fullerene films and also support the recently proposed hyperdiamond model for solid C_28.Comment: 13 pages, RevTeX, 2 figures available as black and white PostScript files; color PostScript and/or gif files available upon reques