Proceedings of the Natural Academy of Sciences

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Eukaryotes: Being and becoming [Biological Sciences]

Tue, 09/01/2015 - 13:38
In their letter, Lane and Martin (1) take us to task for our treatment (2) of their earlier paper (3). In that paper (3), there is much about genes, albeit mostly about the cost of their expression, not their replication. The focus is on how many additional genes mitochondria allow...
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Defusing redox bombs? [Biophysics and Computational Biology]

Tue, 09/01/2015 - 13:38
Proteins catalyze crucial reactions via unstable, high-energy chemical intermediates. In the absence of physiological substrates, activated redox cofactors become ticking time bombs, capable of producing oxidative damage to the protein. In PNAS, Gray and Winkler (1) propose that chains of tryptophan (Trp) and tyrosine (Tyr) residues may serve as escape...
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Shifting patterns in climate and salmon survival [Ecology]

Tue, 09/01/2015 - 13:38
Although Pacific salmon never swim within 2,000 km of the equatorial Pacific Ocean, this does not mean they are beyond the reach of El Niño and the Southern Oscillation (ENSO). Pacific salmon habitats are subject to robust long-distance climate linkages; tropical ENSO indicators are well correlated with the dominant pattern...
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Fossil aquatic plants [Evolution]

Tue, 09/01/2015 - 13:38
The world of 120 million years ago was one of dynamic biological processes. During that time the flowering plants emerged as the dominant global floristic element, a transformative event that ultimately altered the character of the entire planet. Understandably, the rapid rise of angiosperms has intrigued paleoecologists and evolutionary biologists,...
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The art of bacterial war [Microbiology]

Tue, 09/01/2015 - 13:38
“He will win who knows when to fight and when not to fight.” ― Sun Tzu, The Art of War, circa 500 BC (1) Microbes are remarkably social. They live in complex, interdependent communities where they share and exchange a variety of beneficial compounds ranging from cell−cell signals to iron-scavenging...
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Functional metagenomics and the human microbiome [Chemistry]

Tue, 09/01/2015 - 13:38
The trillions of bacteria that make up the human microbiome are believed to encode functions that are important to human health; however, little is known about the specific effectors that commensal bacteria use to interact with the human host. Functional metagenomics provides a systematic means of surveying commensal DNA for...
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Neural microgenesis of face recognition [Psychological and Cognitive Sciences]

Tue, 09/01/2015 - 13:38
Despite a wealth of information provided by neuroimaging research, the neural basis of familiar face recognition in humans remains largely unknown. Here, we isolated the discriminative neural responses to unfamiliar and familiar faces by slowly increasing visual information (i.e., high-spatial frequencies) to progressively reveal faces of unfamiliar or personally familiar...
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Metabolic fate of DNA-derived base propenals [Applied Biological Sciences]

Tue, 09/01/2015 - 13:38
Although mechanistically linked to disease, cellular molecules damaged by endogenous processes have not emerged as significant biomarkers of inflammation and disease risk, due in part to poor understanding of their pharmacokinetic fate from tissue to excretion. Here, we use systematic metabolite profiling to define the fate of a common DNA...
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Multi-SUMO-binding proteins [Biochemistry]

Tue, 09/01/2015 - 13:38
Protein SUMOylation has emerged as an important regulatory event, particularly in nuclear processes such as transcriptional control and DNA repair. In this context, small ubiquitin-like modifier (SUMO) often provides a binding platform for the recruitment of proteins via their SUMO-interacting motifs (SIMs). Recent discoveries point to an important role for...
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Sustainability of the research enterprise [Medical Sciences]

Tue, 09/01/2015 - 13:38
The US research enterprise is under significant strain due to stagnant funding, an expanding workforce, and complex regulations that increase costs and slow the pace of research. In response, a number of groups have analyzed the problems and offered recommendations for resolving these issues. However, many of these recommendations lacked...
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Human monoclonal antibody effective against H7N9 [Applied Biological Sciences]

Tue, 09/01/2015 - 13:38
Emerging strains of influenza represent a significant public health threat with potential pandemic consequences. Of particular concern are the recently emerged H7N9 strains which cause pneumonia with acute respiratory distress syndrome. Estimates are that nearly 80% of hospitalized patients with H7N9 have received intensive care unit support. VIS410, a human...
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Color in spherical colloidal assemblies [Applied Physical Sciences]

Tue, 09/01/2015 - 13:38
Materials in nature are characterized by structural order over multiple length scales have evolved for maximum performance and multifunctionality, and are often produced by self-assembly processes. A striking example of this design principle is structural coloration, where interference, diffraction, and absorption effects result in vivid colors. Mimicking this emergence of...
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Homeostasis and aerobic glycolysis in yeast [Biochemistry]

Tue, 09/01/2015 - 13:38
Aerobic glycolysis in yeast and cancer cells produces pyruvate beyond oxidative needs, a paradox noted by Warburg almost a century ago. To address this question, we reanalyzed extensive measurements from 13C magnetic resonance spectroscopy of yeast glycolysis and the coupled pathways of futile cycling and glycogen and trehalose synthesis (which...
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Poxvirus DNA replication origin [Biochemistry]

Tue, 09/01/2015 - 13:38
Poxviruses reproduce in the host cytoplasm and encode most or all of the enzymes and factors needed for expression and synthesis of their double-stranded DNA genomes. Nevertheless, the mode of poxvirus DNA replication and the nature and location of the replication origins remain unknown. A current but unsubstantiated model posits...
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MutL traps MutS at a DNA mismatch [Biochemistry]

Tue, 09/01/2015 - 13:38
DNA mismatch repair (MMR) identifies and corrects errors made during replication. In all organisms except those expressing MutH, interactions between a DNA mismatch, MutS, MutL, and the replication processivity factor (β-clamp or PCNA) activate the latent MutL endonuclease to nick the error-containing daughter strand. This nick provides an entry point...
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In vitro reconstitution of E-cadherin junction [Biophysics and Computational Biology]

Tue, 09/01/2015 - 13:38
Epithelial (E)-cadherin-mediated cell−cell junctions play important roles in the development and maintenance of tissue structure in multicellular organisms. E-cadherin adhesion is thus a key element of the cellular microenvironment that provides both mechanical and biochemical signaling inputs. Here, we report in vitro reconstitution of junction-like structures between native E-cadherin in...
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Mechanobiological oscillators control lymph flow [Biophysics and Computational Biology]

Tue, 09/01/2015 - 13:38
The ability of cells to sense and respond to physical forces has been recognized for decades, but researchers are only beginning to appreciate the fundamental importance of mechanical signals in biology. At the larger scale, there has been increased interest in the collective organization of cells and their ability to...
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Structure of isolated and ribosome-bound BipA [Biophysics and Computational Biology]

Tue, 09/01/2015 - 13:38
BPI-inducible protein A (BipA) is a member of the family of ribosome-dependent translational GTPase (trGTPase) factors along with elongation factors G and 4 (EF-G and EF4). Despite being highly conserved in bacteria and playing a critical role in coordinating cellular responses to environmental changes, its structures (isolated and ribosome bound)...
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Small-molecule enhanced RPE generation from hPSC [Cell Biology]

Tue, 09/01/2015 - 13:38
Age-related macular degeneration (AMD) is associated with dysfunction and death of retinal pigment epithelial (RPE) cells. Cell-based approaches using RPE-like cells derived from human pluripotent stem cells (hPSCs) are being developed for AMD treatment. However, most efficient RPE differentiation protocols rely on complex, stepwise treatments and addition of growth factors,...
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Regulated proteolysis of a peptidoglycan hydrolase [Cell Biology]

Tue, 09/01/2015 - 13:38
Bacterial growth and morphogenesis are intimately coupled to expansion of peptidoglycan (PG), an extensively cross-linked macromolecule that forms a protective mesh-like sacculus around the cytoplasmic membrane. Growth of the PG sacculus is a dynamic event requiring the concerted action of hydrolases that cleave the cross-links for insertion of new material...
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