Feed aggregator

Tet proteins influence the balance between neuroectodermal and mesodermal fate choice by inhibiting Wnt signaling [Developmental Biology]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
TET-family dioxygenases catalyze conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) and oxidized methylcytosines in DNA. Here, we show that mouse embryonic stem cells (mESCs), either lacking Tet3 alone or with triple deficiency of Tet1/2/3, displayed impaired adoption of neural cell fate and concomitantly skewed toward cardiac mesodermal fate. Conversely, ectopic...

Analysis of 138 pathogenic mutations in presenilin-1 on the in vitro production of A{beta}42 and A{beta}40 peptides by {gamma}-secretase [Biochemistry]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
A hallmark of Alzheimer’s disease (AD) is the aggregation of β-amyloid peptides (Aβ) into amyloid plaques in patient brain. Cleavage of amyloid precursor protein (APP) by the intramembrane protease γ-secretase produces Aβ of varying lengths, of which longer peptides such as Aβ42 are thought to be more harmful. Increased ratios...

Ideal charge-density-wave order in the high-field state of superconducting YBCO [Physics]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
The existence of charge-density-wave (CDW) correlations in cuprate superconductors has now been established. However, the nature of the CDW ground state has remained uncertain because disorder and the presence of superconductivity typically limit the CDW correlation lengths to only a dozen unit cells or less. Here we explore the field-induced...

Cliff-edge model of obstetric selection in humans [Anthropology]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
The strikingly high incidence of obstructed labor due to the disproportion of fetal size and the mother’s pelvic dimensions has puzzled evolutionary scientists for decades. Here we propose that these high rates are a direct consequence of the distinct characteristics of human obstetric selection. Neonatal size relative to the birth-relevant...

Experimental evolution reveals hyperparasitic interactions among transposable elements [Evolution]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
Transposable elements (TEs) are repeated DNA sequences that can constitute a substantial part of genomes. Studying TEs’ activity, interactions, and accumulation dynamics is thus of major interest to understand genome evolution. Here, we describe the transposition dynamics of cut-and-paste mariner elements during experimental (short- and longer-term) evolution in Drosophila melanogaster....

CO synthesized from the central one-carbon pool as source for the iron carbonyl in O2-tolerant [NiFe]-hydrogenase [Biochemistry]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
Hydrogenases are nature’s key catalysts involved in both microbial consumption and production of molecular hydrogen. H2 exhibits a strongly bonded, almost inert electron pair and requires transition metals for activation. Consequently, all hydrogenases are metalloenzymes that contain at least one iron atom in the catalytic center. For appropriate interaction with...

Emergent oscillations assist obstacle negotiation during ant cooperative transport [Biophysics and Computational Biology]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
Collective motion by animal groups is affected by internal interactions, external constraints, and the influx of information. A quantitative understanding of how these different factors give rise to different modes of collective motion is, at present, lacking. Here, we study how ants that cooperatively transport a large food item react...

State estimation and prediction using clustered particle filters [Applied Mathematics]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
Particle filtering is an essential tool to improve uncertain model predictions by incorporating noisy observational data from complex systems including non-Gaussian features. A class of particle filters, clustered particle filters, is introduced for high-dimensional nonlinear systems, which uses relatively few particles compared with the standard particle filter. The clustered particle...

Transcription factor Zeb2 regulates commitment to plasmacytoid dendritic cell and monocyte fate [Immunology and Inflammation]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
Dendritic cells (DCs) and monocytes develop from a series of bone-marrow–resident progenitors in which lineage potential is regulated by distinct transcription factors. Zeb2 is an E-box–binding protein associated with epithelial–mesenchymal transition and is widely expressed among hematopoietic lineages. Previously, we observed that Zeb2 expression is differentially regulated in progenitors committed...

Correction for Jabed et al., Targeted microRNA expression in dairy cattle directs production of {beta}-lactoglobulin-free, high-casein milk [Corrections]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
AGRICULTURAL SCIENCES Correction for “Targeted microRNA expression in dairy cattle directs production of β-lactoglobulin-free, high-casein milk,” by Anower Jabed, Stefan Wagner, Judi McCracken, David N. Wells, and Goetz Laible, which appeared in issue 42, October 16, 2012, of Proc Natl Acad Sci USA (109:16811–16816; first published October 1, 2012; 10.1073/pnas.1210057109)....

Correction to Supporting Information for Liu et al., Isoprene photochemistry over the Amazon rainforest [SI Correction]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
EARTH, ATMOSPHERIC, AND PLANETARY SCIENCES Correction to Supporting Information for “Isoprene photochemistry over the Amazon rainforest,” by Yingjun Liu, Joel Brito, Matthew R. Dorris, Jean C. Rivera-Rios, Roger Seco, Kelvin H. Bates, Paulo Artaxo, Sergio Duvoisin Jr., Frank N. Keutsch, Saewung Kim, Allen H. Goldstein, Alex B. Guenther, Antonio O....

Biconcave shape of human red-blood-cell ghosts relies on density differences between the rim and dimple of the ghost's plasma membrane [Physiology]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
The shape of the human red blood cell is known to be a biconcave disk. It is evident from a variety of theoretical work that known physical properties of the membrane, such as its bending energy and elasticity, can explain the red-blood-cell biconcave shape as well as other shapes that...

Anomalously high variation in postnatal development is ancestral for dinosaurs but lost in birds [Evolution]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
Compared with all other living reptiles, birds grow extremely fast and possess unusually low levels of intraspecific variation during postnatal development. It is now clear that birds inherited their high rates of growth from their dinosaurian ancestors, but the origin of the avian condition of low variation during development is...

Specific detection of biomolecules in physiological solutions using graphene transistor biosensors [Chemistry]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
Nanomaterial-based field-effect transistor (FET) sensors are capable of label-free real-time chemical and biological detection with high sensitivity and spatial resolution, although direct measurements in high–ionic-strength physiological solutions remain challenging due to the Debye screening effect. Recently, we demonstrated a general strategy to overcome this challenge by incorporating a biomolecule-permeable polymer...

Development of high-yield influenza B virus vaccine viruses [Microbiology]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
The burden of human infections with influenza A and B viruses is substantial, and the impact of influenza B virus infections can exceed that of influenza A virus infections in some seasons. Over the past few decades, viruses of two influenza B virus lineages (Victoria and Yamagata) have circulated in...

Long-range projections coordinate distributed brain-wide neural activity with a specific spatiotemporal profile [Neuroscience]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
One challenge in contemporary neuroscience is to achieve an integrated understanding of the large-scale brain-wide interactions, particularly the spatiotemporal patterns of neural activity that give rise to functions and behavior. At present, little is known about the spatiotemporal properties of long-range neuronal networks. We examined brain-wide neural activity patterns elicited...

Correction for Saintyves et al., Self-sustained lift and low friction via soft lubrication [Corrections]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
APPLIED PHYSICAL SCIENCES Correction for “Self-sustained lift and low friction via soft lubrication,” by Baudouin Saintyves, Theo Jules, Thomas Salez, and L. Mahadevan, which appeared in issue 21, May 24, 2016, of Proc Natl Acad Sci USA (113:5847–5849; first published May 9, 2016; 10.1073/pnas.1525462113). The authors note that Fig. 2...

Resistance mutation conserved between insects and mites unravels the benzoylurea insecticide mode of action on chitin biosynthesis [Applied Biological Sciences]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
Despite the major role of chitin biosynthesis inhibitors such as benzoylureas (BPUs) in the control of pests in agricultural and public health for almost four decades, their molecular mode of action (MoA) has in most cases remained elusive. BPUs interfere with chitin biosynthesis and were thought to interact with sulfonylurea...

Impact of the Syrian refugee crisis on land use and transboundary freshwater resources [Environmental Sciences]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
Since 2013, hundreds of thousands of refugees have migrated southward to Jordan to escape the Syrian civil war that began in mid-2011. Evaluating impacts of conflict and migration on land use and transboundary water resources in an active war zone remains a challenge. However, spatial and statistical analyses of satellite...

Spop promotes skeletal development and homeostasis by positively regulating Ihh signaling [Developmental Biology]

PNAS Early Edition Articles - Mon, 12/05/2016 - 13:59
Indian Hedgehog (Ihh) regulates chondrocyte and osteoblast differentiation through the Glioma-associated oncogene homolog (Gli) transcription factors. Previous in vitro studies suggested that Speckle-type POZ protein (Spop), part of the Cullin-3 (Cul3) ubiquitin ligase complex, targets Gli2 and Gli3 for degradation and negatively regulates Hedgehog (Hh) signaling. In this study, we...
Syndicate content