Differential requirements for the chemokine receptor CCR7 in T cell activation during Listeria monocytogenes infection

Effective priming of T cell responses depends on cognate interactions between naive T cells and professional antigen-presenting cells (APCs). This contact is the result of highly coordinated migration processes, in which the chemokine receptor CCR7 and its ligands, CCL19 and CCL21, play a central role. We used the murine Listeria monocytogenes infection model to characterize the role of the CCR7/CCR7 ligand system in the generation of T cell responses during bacterial infection. We demonstrate that efficient priming of naive major histocompatibility complex (MHC) class Ia–restricted CD8+ T cells requires CCR7. In contrast, MHC class Ib–restricted CD8+ T cells and MHC class II–restricted CD4+ T cells seem to be less dependent on CCR7; memory T cell responses are independent of CCR7. Infection experiments with bone marrow chimeras or mice reconstituted with purified T cell populations indicate that CCR7 has to be expressed on CD8+ T cells and professional APCs to promote efficient MHC class Ia–restricted T cell priming. Thus, different T cell subtypes and maturation stages have discrete requirements for CCR7

Uncertainties in projections of the baltic sea ecosystem driven by an ensemble of global climate models

Many coastal seas worldwide are affected by human impacts such as eutrophication causing, inter alia, oxygen depletion, and extensive areas of hypoxia. Depending on the region, global warming may reinforce these environmental changes by reducing air-sea oxygen fluxes, intensifying internal nutrient cycling, and increasing river-borne nutrient loads. The development of appropriate management plans to effectively protect the marine environment requires projections of future marine ecosystem states. However, projections with regional climate models commonly suffer from shortcomings in the driving global General Circulation Models (GCMs). The differing sensitivities of GCMs to increased greenhouse gas concentrations affect regional projections considerably. In this study, we focused on one of the most threatened coastal seas, the Baltic Sea, and estimated uncertainties in projections due to climate model deficiencies and due to unknown future greenhouse gas concentration, nutrient load and sea level rise scenarios. To address the latter, simulations of the period 1975–2098 were performed using the initial conditions from an earlier reconstruction with the same Baltic Sea model (starting in 1850). To estimate the impacts of climate model uncertainties, dynamical downscaling experiments with four driving global models were carried out for two greenhouse gas concentration scenarios and for three nutrient load scenarios, covering the plausible range between low and high loads. The results suggest that changes in nutrient supply, in particular phosphorus, control the long-term (centennial) response of eutrophication, biogeochemical fluxes and oxygen conditions in the deep water. The analysis of simulated primary production, nitrogen fixation, and hypoxic areas shows that uncertainties caused by the various nutrient load scenarios are greater than the uncertainties due to climate model uncertainties and future greenhouse gas concentrations. In all scenario simulations, a proposed nutrient load abatement strategy, i.e., the Baltic Sea Action Plan, will lead to a significant improvement in the overall environmental state. However, the projections cannot provide detailed information on the timing and the reductions of future hypoxic areas, due to uncertainties in salinity projections caused by uncertainties in projections of the regional water cycle and of the mean sea level outside the model domain.publishedVersio

Impacts of changing society and climate on nutrient loading to the Baltic Sea

This paper studies the relative importance of societal drivers and changing climate on anthropogenic nutrient inputs to the Baltic Sea. Shared Socioeconomic Pathways and Representative Concentration Pathways are extended at temporal and spatial scales relevant for the most contributing sectors. Extended socioeconomic and climate scenarios are then used as inputs for spatially and temporally detailed models for population and land use change, and their subsequent impact on nutrient loading is computed. According to the model simulations, several factors of varying influence may either increase or decrease total nutrient loads. In general, societal drivers outweigh the impacts of changing climate. Food demand is the most impactful driver, strongly affecting land use and nutrient loads from agricultural lands in the long run. In order to reach the good environmental status of the Baltic Sea, additional nutrient abatement efforts should focus on phosphorus rather than nitrogen. Agriculture is the most important sector to be addressed under the conditions of gradually increasing precipitation in the region and increasing global demand for food. (C) 2020 The Authors. Published by Elsevier B.V.Peer reviewe

Local densities, distribution functions, and wave function correlations for spatially resolved shot noise at nanocontacts

We consider a current-carrying, phase-coherent multi-probe conductor to which a small tunneling contact is attached. We treat the conductor and the tunneling contact as a phase-coherent entity and use a Green's function formulation of the scattering approach. We show that the average current and the current fluctuations at the tunneling contact are determined by an effective local non-equilibrium distribution function. This function characterizes the distribution of charge-carriers (or quasi-particles) inside the conductor. It is an exact quantum-mechanical expression and contains the phase-coherence of the particles via local partial densities of states, called injectivities. The distribution function is analyzed for different systems in the zero-temperature limit as well as at finite temperature. Furthermore, we investigate in detail the correlations of the currents measured at two different contacts of a four-probe sample, where two of the probes are only weakly coupled contacts. In particular, we show that the correlations of the currents are at zero-temperature given by spatially non-diagonal injectivities and emissivities. These non-diagonal densities are sensitive to correlations of wave functions and the phase of the wave functions. We consider ballistic conductors and metallic diffusive conductors. We also analyze the Aharonov-Bohm oscillations in the shot noise correlations of a conductor which in the absence of the nano-contacts exhibits no flux-sensitivity in the conductance.Comment: 17 pages, 8 figure

The Molecular Genetic Architecture of Self-Employment

Economic variables such as income, education, and occupation are known to affect mortality and morbidity, such as cardiovascular disease, and have also been shown to be partly heritable. However, very little is known about which genes influence economic variables, although these genes may have both a direct and an indirect effect on health. We report results from the first large-scale collaboration that studies the molecular genetic architecture of an economic variable-entrepreneurship-that was operationalized using self-employment, a widely-available proxy. Our results suggest that common SNPs when considered jointly explain about half of the narrow-sense heritability of self-employment estimated in twin data (σg2/σP2= 25%, h2= 55%). However, a meta-analysis of genome-wide association studies across sixteen studies comprising 50,627 participants did not identify genome-wide significant SNPs. 58 SNPs with p<10-5were tested in a replication sample (n = 3,271), but none replicated. Furthermore, a gene-based test shows that none of the genes that were previously suggested in the literature to influence entrepreneurship reveal significant associations. Finally, SNP-based genetic scores that use results from the meta-analysis capture less than 0.2% of the variance in self-employment in an independent sample (p≥0.039). Our results are consistent with a highly polygenic molecular genetic architecture of self-employment, with many genetic variants of small effect. Although self-employment is a multi-faceted, heavily environmentally influenced, and biologically distal trait, our results are similar to those for other genetically complex and biologically more proximate outcomes, such as height, intelligence, personality, and several diseases

The influence of increasing water turbidity on the sea surface temperature in the Baltic Sea: A model sensitivity study

The aim of the present study is to investigate the influence of enhanced absorption of sunlight at the sea surface due to increasing water turbidity and its effect on the sea surface temperatures (SST) in the Baltic Sea. The major question behind our investigations is, whether this effect needs to be included in Baltic Sea circulation models or can be neglected. Our investigations cover both, mean state and SST trends during the recent decades. To quantify the impact of water turbidity on the mean state different sensitivity ocean hind-cast experiments are performed. The state-of-the art ocean model RCO (Rossby Centre Ocean model) is used to simulate the period from 1962 to 2007. In the first simulation, a spatially and temporally constant value for the attenuation depth is used, while in the second experiment a climatological monthly mean, spatially varying attenuation coefficient is derived from satellite observations of the diffuse attenuation coefficient at 490 nm. The inclusion of a spatially varying light attenuation leads to significant SST changes during summer. Maximum values of + 0.5 K are reached in the Gulf of Finland and close to the eastern coasts, when compared to a fixed attenuation of visible light of 0.2 m− 1. The temperature anomalies basically match the pattern of increased light attenuation with strongest effects in shallow waters. Secondary effects due to changes in the current system are of minor importance. Similar results are obtained when considering trends. In the absence of long-term basin wide observations of attenuation coefficients, some idealizations have to be applied when investigating the possible influence of long-term changes in water turbidity on the SST. Two additional sensitivity experiments are based on a combination of long-term Secchi depth station observations and the present day pattern of water turbidity, as observed by satellite. We show the potential of increased water turbidity to affect the summer SST trends in the Baltic Sea significantly, while the estimated effect is apparently too small to explain the overall extreme summer trends observed in the Baltic Sea. Highlights ► Investigation of the modeled influence of water turbidity on the sea surface temperature (SST) of the Baltic Sea. ► Hind-cast simulations (1962–2007) with different attenuation depths, using the regional ocean model RCO. ► The inclusion of an observed spatially varying light leads regionally to significant SST changes during summer. ► Secondary effects due to changes in the current system are of minor importance. ► The influence of increasing water turbidity on SST trends is regionally statistically significant while the effect is rather small

On the dynamics of oxygen, phosphorus and cyanobacteria in the Baltic Sea; A model study

Oxygen and phosphorus dynamics and cyanobacterial blooms in the Baltic Sea are discussed using results from the Swedish Coastal and Ocean Biogeochemical model (SCOBI) coupled to the Rossby Centre Ocean model (RCO). The high-resolution circulation model is used to simulate the time period from 1902 to 1998 using reconstructed physical forcing and climatological nutrient loads of the late 20th century. The analysis of the results covers the last 30 years of the simulation period. The results emphasize the importance of internal phosphorus and oxygen dynamics, the variability of physical conditions and the natural long-term variability of phosphorus supplies from land on the phosphorus content in the Baltic Sea. These mechanisms play an important role on the variability of available surface layer phosphorus in late winter in the Baltic Sea. The content of cyanobacteria increases with the availability of phosphorus in the surface layers of the Baltic proper and the probability for large cyanobacteria blooms in the model is rapidly increased at higher concentrations of excess dissolved inorganic phosphorus in late winter. The natural increase of phosphorus supplies from land due to increased river runoff since the early 1970s may to a large degree explain the increased phosphorus content in the Baltic proper. Another significant fraction of the increase is explained by the release of phosphorus from increased anoxic areas during the period. These results refer to the long-term variability of the phosphorus cycle. In accordance to earlier publications is the short-term (i.e. interannual) variability of the phosphorus content in the Baltic proper mainly explained by oxygen dependent sediment fluxes