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Observed rapid bedrock uplift in Amundsen Sea Embayment promotes ice-sheet stability

ScienceNOW Daily News Feed - Jue, 06/21/2018 - 11:38

The marine portion of the West Antarctic Ice Sheet (WAIS) in the Amundsen Sea Embayment (ASE) accounts for one-fourth of the cryospheric contribution to global sea-level rise and is vulnerable to catastrophic collapse. The bedrock response to ice mass loss, glacial isostatic adjustment (GIA), was thought to occur on a time scale of 10,000 years. We used new GPS measurements, which show a rapid (41 millimeters per year) uplift of the ASE, to estimate the viscosity of the mantle underneath. We found a much lower viscosity (4 x 1018 pascal-second) than global average, and this shortens the GIA response time scale from tens to hundreds of years. Our finding requires an upward revision of ice mass loss from gravity data of 10% and increases the potential stability of the WAIS against catastrophic collapse.

Anomalously low dielectric constant of confined water

ScienceNOW Daily News Feed - Jue, 06/21/2018 - 11:38

The dielectric constant of interfacial water has been predicted to be smaller than that of bulk water ( 80) because the rotational freedom of water dipoles is expected to decrease near surfaces, yet experimental evidence is lacking. We report local capacitance measurements for water confined between two atomically flat walls separated by various distances down to 1 nanometer. Our experiments reveal the presence of an interfacial layer with vanishingly small polarization such that its out-of-plane is only ~2. The electrically dead layer is found to be two to three molecules thick. These results provide much-needed feedback for theories describing water-mediated surface interactions and the behavior of interfacial water, and show a way to investigate the dielectric properties of other fluids and solids under extreme confinement.

A precise extragalactic test of General Relativity

ScienceNOW Daily News Feed - Jue, 06/21/2018 - 11:38

Einstein’s theory of gravity, General Relativity, has been precisely tested on Solar System scales, but the long-range nature of gravity is still poorly constrained. The nearby strong gravitational lens ESO 325-G004 provides a laboratory to probe the weak-field regime of gravity and measure the spatial curvature generated per unit mass, . By reconstructing the observed light profile of the lensed arcs and the observed spatially resolved stellar kinematics with a single self-consistent model, we conclude that = 0.97 ± 0.09 at 68% confidence. Our result is consistent with the prediction of 1 from General Relativity and provides a strong extragalactic constraint on the weak-field metric of gravity.

New genus of extinct Holocene gibbon associated with humans in Imperial China

ScienceNOW Daily News Feed - Jue, 06/21/2018 - 11:38

Although all extant apes are threatened with extinction, there is no evidence for human-caused extinctions of apes or other primates in postglacial continental ecosystems, despite intensive anthropogenic pressures associated with biodiversity loss for millennia in many regions. Here, we report a new, globally extinct genus and species of gibbon, Junzi imperialis, described from a partial cranium and mandible from a ~2200- to 2300-year-old tomb from Shaanxi, China. Junzi can be differentiated from extant hylobatid genera and the extinct Quaternary gibbon Bunopithecus by using univariate and multivariate analyses of craniodental morphometric data. Primates are poorly represented in the Chinese Quaternary fossil record, but historical accounts suggest that China may have contained an endemic ape radiation that has only recently disappeared.

Locally coordinated synaptic plasticity of visual cortex neurons in vivo

ScienceNOW Daily News Feed - Jue, 06/21/2018 - 11:38

Plasticity of cortical responses in vivo involves activity-dependent changes at synapses, but the manner in which different forms of synaptic plasticity act together to create functional changes in neurons remains unknown. We found that spike timing–induced receptive field plasticity of visual cortex neurons in mice is anchored by increases in the synaptic strength of identified spines. This is accompanied by a decrease in the strength of adjacent spines on a slower time scale. The locally coordinated potentiation and depression of spines involves prominent AMPA receptor redistribution via targeted expression of the immediate early gene product Arc. Hebbian strengthening of activated synapses and heterosynaptic weakening of adjacent synapses thus cooperatively orchestrate cell-wide plasticity of functional neuronal responses.

Adaptive introgression underlies polymorphic seasonal camouflage in snowshoe hares

ScienceNOW Daily News Feed - Jue, 06/21/2018 - 11:38

Snowshoe hares (Lepus americanus) maintain seasonal camouflage by molting to a white winter coat, but some hares remain brown during the winter in regions with low snow cover. We show that cis-regulatory variation controlling seasonal expression of the Agouti gene underlies this adaptive winter camouflage polymorphism. Genetic variation at Agouti clustered by winter coat color across multiple hare and jackrabbit species, revealing a history of recurrent interspecific gene flow. Brown winter coats in snowshoe hares likely originated from an introgressed black-tailed jackrabbit allele that has swept to high frequency in mild winter environments. These discoveries show that introgression of genetic variants that underlie key ecological traits can seed past and ongoing adaptation to rapidly changing environments.

Antihomotypic affinity maturation improves human B cell responses against a repetitive epitope

ScienceNOW Daily News Feed - Jue, 06/21/2018 - 11:38

Affinity maturation selects B cells expressing somatically mutated antibody variants with improved antigen-binding properties to protect from invading pathogens. We determined the molecular mechanism underlying the clonal selection and affinity maturation of human B cells expressing protective antibodies against the circumsporozoite protein of the malaria parasite Plasmodium falciparum (PfCSP). We show in molecular detail that the repetitive nature of PfCSP facilitates direct homotypic interactions between two PfCSP repeat-bound monoclonal antibodies, thereby improving antigen affinity and B cell activation. These data provide a mechanistic explanation for the strong selection of somatic mutations that mediate homotypic antibody interactions after repeated parasite exposure in humans. Our findings demonstrate a different mode of antigen-mediated affinity maturation to improve antibody responses to PfCSP and presumably other repetitive antigens.

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ScienceNOW Daily News Feed - Jue, 06/21/2018 - 11:38

In vivo brain GPCR signaling elucidated by phosphoproteomics

ScienceNOW Daily News Feed - Jue, 06/21/2018 - 11:38

A systems view of G protein–coupled receptor (GPCR) signaling in its native environment is central to the development of GPCR therapeutics with fewer side effects. Using the kappa opioid receptor (KOR) as a model, we employed high-throughput phosphoproteomics to investigate signaling induced by structurally diverse agonists in five mouse brain regions. Quantification of 50,000 different phosphosites provided a systems view of KOR in vivo signaling, revealing novel mechanisms of drug action. Thus, we discovered enrichment of the mechanistic target of rapamycin (mTOR) pathway by U-50,488H, an agonist causing aversion, which is a typical KOR-mediated side effect. Consequently, mTOR inhibition during KOR activation abolished aversion while preserving beneficial antinociceptive and anticonvulsant effects. Our results establish high-throughput phosphoproteomics as a general strategy to investigate GPCR in vivo signaling, enabling prediction and modulation of behavioral outcomes.

Comment on "Sterilizing immunity in the lung relies on targeting fungal apoptosis-like programmed cell death"

ScienceNOW Daily News Feed - Jue, 06/21/2018 - 11:38

Shlezinger et al. (Reports, 8 September 2017, p. 1037) report that the common fungus Aspergillus fumigatus, a cause of aspergillosis, undergoes caspase-dependent apoptosis-like cell death triggered by lung neutrophils. However, the technologies they used do not provide reliable evidence that fungal cells die via a protease signaling cascade thwarted by a fungal caspase inhibitor homologous to human survivin.

Analysis of shared heritability in common disorders of the brain

ScienceNOW Daily News Feed - Jue, 06/21/2018 - 11:38

Disorders of the brain can exhibit considerable epidemiological comorbidity and often share symptoms, provoking debate about their etiologic overlap. We quantified the genetic sharing of 25 brain disorders from genome-wide association studies of 265,218 patients and 784,643 control participants and assessed their relationship to 17 phenotypes from 1,191,588 individuals. Psychiatric disorders share common variant risk, whereas neurological disorders appear more distinct from one another and from the psychiatric disorders. We also identified significant sharing between disorders and a number of brain phenotypes, including cognitive measures. Further, we conducted simulations to explore how statistical power, diagnostic misclassification, and phenotypic heterogeneity affect genetic correlations. These results highlight the importance of common genetic variation as a risk factor for brain disorders and the value of heritability-based methods in understanding their etiology.

Response to Comment on "Sterilizing immunity in the lung relies on targeting fungal apoptosis-like programmed cell death"

ScienceNOW Daily News Feed - Jue, 06/21/2018 - 11:38

Aouacheria et al. question the interpretation of contemporary assays to monitor programmed cell death with apoptosis-like features (A-PCD) in Aspergillus fumigatus. Although our study focuses on fungal A-PCD for host immune surveillance and infectious outcomes, the experimental approach incorporates multiple independent A-PCD markers and genetic manipulations based on fungal rather than mammalian orthologs to circumvent the limitations associated with any single approach.

An emerging drug discovery approach to combat cancer

EurekAlert! - Mié, 06/20/2018 - 22:00
This review paper will cover recent advances in the development of chemotherapeutic agents against several metabolic targets for cancer therapy, including glucose transporters, hexokinase, pyruvate kinase M2, glutaminase, and isocitrate dehydrogenase.

New evidence brief shows long-term effects of child-family separation

EurekAlert! - Mié, 06/20/2018 - 22:00
Parent-child separation has long-term effects on child well-being, even if there is subsequent reunification. After being separated, reunited children can experience lasting difficulty with emotional attachment to their parents, self-esteem, and physical and psychological health, according to a new brief released by the Society for Research in Child Development (SRCD). The brief, written by scholars of SRCD's Latino Caucus, emphasizes that for some children, time does not appear to fully heal these psychological wounds.

Starving fungi could save millions of lives each year

EurekAlert! - Mié, 06/20/2018 - 22:00
Researchers have identified a potentially new approach to treating lethal fungal infections that claim more than 1.6 million lives each year: starving the fungi of key nutrients, preventing their growth and spread.

Accurate measurements of sodium intake confirm relationship with mortality

EurekAlert! - Mié, 06/20/2018 - 22:00
Eating foods high in salt is known to contribute to high blood pressure, but does that linear relationship extend to increased risk of cardiovascular disease and death? Recent cohort studies have contested that relationship, but a new study published in the International Journal of Epidemiology by investigators from Brigham and Women's Hospital and their colleagues using multiple measurements confirms it.

Study suggests bias for sons remains among second-generation women of South Asian descent

EurekAlert! - Mié, 06/20/2018 - 22:00
A preference for male children persists among second-generation mothers of South Asian descent, according to new study that found a skewed ratio of male-to-female babies born to these women in Ontario.

Princeton chemists teach an enzyme a new trick, with potential for building new molecules

EurekAlert! - Mié, 06/20/2018 - 22:00
Princeton chemists led by Prof. Todd Hyster have found a way to make a naturally occurring enzyme take on a new, artificial role, which has significant implications for modern chemistry, including pharmaceutical production.

Our intestinal microbiome influences metabolism -- through the immune system

EurekAlert! - Mié, 06/20/2018 - 22:00
The innate immune system, our first line of defense against bacterial infection, has a side job that's equally important: fine-tuning our metabolism.

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