The preservation of atmospheric nitrate in snow at Summit, Greenland

There is great interest in using nitrate NO3 isotopic composition in ice cores to track the history of precursor nitrogen oxides (NOx = NO + NO2) in the atmosphere. Nitrate NO3 however can be lost from the snow by surface processes, such as photolysis back to NOx upon exposure to sunlight, making it difficult to interpret records of NO3 as a tracer of atmospheric NOx loading. In a campaign consisting of two field seasons (May–June) at Summit, Greenland, high temporal frequency surface snow samples were collected and analyzed for the oxygen isotopic composition of NO3. The strong, linear relationship observed between the oxygen isotopes of NO3 in both 2010 and 2011, is difficult to explain in the presence of significant post depositional processing of NO3 unless several unrelated variables change in concert. Therefore, the isotopic signature of NO3 in the snow at Summit is most feasibly explained as preserved atmospheric NO3 deposition

A Contraction Stress Model of Hypertrophic Cardiomyopathy due to Sarcomere Mutations.

Thick-filament sarcomere mutations are a common cause of hypertrophic cardiomyopathy (HCM), a disorder of heart muscle thickening associated with sudden cardiac death and heart failure, with unclear mechanisms. We engineered four isogenic induced pluripotent stem cell (iPSC) models of β-myosin heavy chain and myosin-binding protein C3 mutations, and studied iPSC-derived cardiomyocytes in cardiac microtissue assays that resemble cardiac architecture and biomechanics. All HCM mutations resulted in hypercontractility with prolonged relaxation kinetics in proportion to mutation pathogenicity, but not changes in calcium handling. RNA sequencing and expression studies of HCM models identified p53 activation, oxidative stress, and cytotoxicity induced by metabolic stress that can be reversed by p53 genetic ablation. Our findings implicate hypercontractility as a direct consequence of thick-filament mutations, irrespective of mutation localization, and the p53 pathway as a molecular marker of contraction stress and candidate therapeutic target for HCM patients

Ecoregional Analysis of Nearshore Sea-Surface Temperature in the North Pacific

The quantification and description of sea surface temperature (SST) is critically important because it can influence the distribution, migration, and invasion of marine species; furthermore, SSTs are expected to be affected by climate change. To better understand present temperature regimes, we assembled a 29-year nearshore time series of mean monthly SSTs along the North Pacific coastline using remotely-sensed satellite data collected with the Advanced Very High Resolution Radiometer (AVHRR) instrument. We then used the dataset to describe nearshore (<20 km offshore) SST patterns of 16 North Pacific ecoregions delineated by the Marine Ecoregions of the World (MEOW) hierarchical schema. Annual mean temperature varied from 3.8°C along the Kamchatka ecoregion to 24.8°C in the Cortezian ecoregion. There are smaller annual ranges and less variability in SST in the Northeast Pacific relative to the Northwest Pacific. Within the 16 ecoregions, 31–94% of the variance in SST is explained by the annual cycle, with the annual cycle explaining the least variation in the Northern California ecoregion and the most variation in the Yellow Sea ecoregion. Clustering on mean monthly SSTs of each ecoregion showed a clear break between the ecoregions within the Warm and Cold Temperate provinces of the MEOW schema, though several of the ecoregions contained within the provinces did not show a significant difference in mean seasonal temperature patterns. Comparison of these temperature patterns shared some similarities and differences with previous biogeographic classifications and the Large Marine Ecosystems (LMEs). Finally, we provide a web link to the processed data for use by other researchers

Deprivation, importation, and prison suicide: Combined effects of institutional conditions and inmate composition

Previous research on suicide in United States prisons focused on the characteristics of inmates who commit suicide while largely ignoring the prison context surrounding these suicides. The following analyses used national data on 1,082 state prisons in the United States to examine how prison conditions (deprivation) and inmate composition (importation) predict prison suicide. Results of a negative binomial regression model showed that the number of suicides was significantly increased in supermaximum and maximum security prisons (relative to minimum), under conditions of overcrowding and violence, and in prisons where a greater proportion of inmates received mental health services. Although deprivation variables were overwhelmingly predictive of suicide, the results pointed to the combined effects of institutional conditions and inmate composition on prison suicide.

Analysis of nitrate in the snow and atmosphere at Summit, Greenland: Chemistry and transport

International audienceAs a major sink of atmospheric nitrogen oxides (NOx = NO + NO2), nitrate (NO3-) in polar snow can reflect the long-range transport of NOx and related species (e.g., PAN). On the other hand, because NO3- in snow can be photolyzed, potentially producing gas-phase NOx locally, NO3- in snow (and thus, ice) may reflect local processes. Here we investigate the relationship between local atmospheric composition at Summit, Greenland (72°35’N, 38°25’W) and the isotopic composition of NO3- to determine the degree to which local processes influence atmospheric and snow NO3-. Based on snow and atmospheric observations during May-June 2010 and 2011, we find no connection between the local atmospheric concentrations of a suite of gases (BrO, NO, NOy, HNO3 and nitrite (NO2-)) and the NO3- isotopic composition or concentration in snow. This suggests that 1) the snow NO3- at Summit is primarily derived from long-range transport and 2) this NO3- is largely preserved in the snow. Additionally, three isotopically distinct NO3- sources were found to be contributing to the NO3- in the snow at Summit during both 2010 and 2011. Through the complete isotopic composition of NO3-, we suggest that these sources are local anthropogenic particulate NO3- from station activities (δ15N = 16‰, Δ17O = 4‰ and δ18O = 23‰), NO3- formed from mid-latitude NOx (δ15N = -10‰, Δ17O = 29‰, δ18O = 78‰) and a NO3- source that is possibly influenced or derived from stratospheric ozone NO3- (δ15N = 5‰, Δ17O = 39‰, δ18O = 100‰)

A Contraction Stress Model of Hypertrophic Cardiomyopathy due to Sarcomere Mutations

Summary: Thick-filament sarcomere mutations are a common cause of hypertrophic cardiomyopathy (HCM), a disorder of heart muscle thickening associated with sudden cardiac death and heart failure, with unclear mechanisms. We engineered four isogenic induced pluripotent stem cell (iPSC) models of β-myosin heavy chain and myosin-binding protein C3 mutations, and studied iPSC-derived cardiomyocytes in cardiac microtissue assays that resemble cardiac architecture and biomechanics. All HCM mutations resulted in hypercontractility with prolonged relaxation kinetics in proportion to mutation pathogenicity, but not changes in calcium handling. RNA sequencing and expression studies of HCM models identified p53 activation, oxidative stress, and cytotoxicity induced by metabolic stress that can be reversed by p53 genetic ablation. Our findings implicate hypercontractility as a direct consequence of thick-filament mutations, irrespective of mutation localization, and the p53 pathway as a molecular marker of contraction stress and candidate therapeutic target for HCM patients. : Cohn et al. show that thick-filament sarcomere mutations that cause hypertrophic cardiomyopathy result in hypercontractility in human cardiac microtissues engineered from isogenic iPSCs. These findings illustrate that hypercontractility is independent from changes in calcium handling and mutation location, but results in oxidative stress, p53 activation, and increased p53-dependent cell death with metabolic stress. Keywords: induced pluripotent stem cells, cardiomyopathy, heart failure, tissue engineering, sarcomere function, hypertrophyp53 signalin

Molecular phylogeny, biogeography, and habitat preference evolution of Marsupials

Marsupials exhibit great diversity in ecology and morphology. However, compared to their sister group, the placental mammals, our understanding of many aspects of marsupial evolution remains limited. We use 101 mitochondrial genomes and data from 26 nuclear loci to reconstruct a dated phylogeny including 97% of extant genera and 58% of modern marsupial species. This tree allows us to analyze the evolution of habitat preference and geographic distributions of marsupial species through time. We found a pattern of mesic-adapted lineages evolving to use more arid and open habitats, which is broadly consistent with regional climate and environmental change. However, contrary to the general trend, several lineages subsequently appear to have reverted from drier to more mesic habitats. Biogeographic reconstructions suggest that current views on the connectivity between Australia and New Guinea/Wallacea during the Miocene and Pliocene need to be revised. The antiquity of several endemic New Guinean clades strongly suggests a substantially older period of connection stretching back to the Middle Miocene, and implies that New Guinea was colonized by multiple clades almost immediately after its principal formation