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Phytoplankton diversity and ocean phosphate uptake [Environmental Sciences]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
We have a limited understanding of the consequences of variations in microbial biodiversity on ocean ecosystem functioning and global biogeochemical cycles. A core process is macronutrient uptake by microorganisms, as the uptake of nutrients controls ocean CO2 fixation rates in many regions. Here, we ask whether variations in ocean phytoplankton...

Optimal resource allocation in cellular sensing [Physics]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
Living cells deploy many resources to sense their environments, including receptors, downstream signaling molecules, time, and fuel. However, it is not known which resources fundamentally limit the precision of sensing, like weak links in a chain, and which can compensate each other, leading to trade-offs between them. We present a...

Remote-controlled therapy with resorbable devices [Engineering]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
A paradigm shift for implantable medical devices lies at the confluence between regenerative medicine, where materials remodel and integrate in the biological milieu, and technology, through the use of recently developed material platforms based on biomaterials and bioresorbable technologies such as optics and electronics. The union of materials and technology...

Chorismate mutase catalysis revisited [Biophysics and Computational Biology]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
For more than half a century, transition state theory has provided a useful framework for understanding the origins of enzyme catalysis. As proposed by Pauling, enzymes accelerate chemical reactions by binding transition states tighter than substrates, thereby lowering the activation energy compared with that of the corresponding uncatalyzed process. This...

Substrate specificity of DHHC5 [Cell Biology]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
The cardiac phosphoprotein phospholemman (PLM) regulates the cardiac sodium pump, activating the pump when phosphorylated and inhibiting it when palmitoylated. Protein palmitoylation, the reversible attachment of a 16 carbon fatty acid to a cysteine thiol, is catalyzed by the Asp-His-His-Cys (DHHC) motif-containing palmitoyl acyltransferases. The cell surface palmitoyl acyltransferase DHHC5...

Energetics and stability of metastudtite [Chemistry]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
Metastudtite, (UO2)O2(H2O)2, is one of two known natural peroxide minerals, but little is established about its thermodynamic stability. In this work, its standard enthalpy of formation, −1,779.6 ± 1.9 kJ/mol, was obtained by high temperature oxide melt drop solution calorimetry. Decomposition of synthetic metastudtite was characterized by thermogravimetry and differential...

Peripheral CB1R blockade and diabetic nephropathy [Medical Sciences]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
Diabetic nephropathy is a major cause of end-stage kidney disease, and overactivity of the endocannabinoid/cannabinoid 1 receptor (CB1R) system contributes to diabetes and its complications. Zucker diabetic fatty (ZDF) rats develop type 2 diabetic nephropathy with albuminuria, reduced glomerular filtration, activation of the renin-angiotensin system (RAS), oxidative/nitrative stress, podocyte loss,...

FAT10-MAD2 binding is important for cancer growth [Medical Sciences]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
FAT10 (HLA-F-adjacent transcript 10) is a ubiquitin-like modifier that is commonly overexpressed in various tumors. It was found to play a role in mitotic regulation through its interaction with mitotic arrest-deficient 2 (MAD2). Overexpression of FAT10 promotes tumor growth and malignancy. Here, we identified the MAD2-binding interface of FAT10 to...

Oscillatory Knk1 maintains straight growth [Cell Biology]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
Cellular morphogenesis relies partly on cell polarization by the cytoskeleton. In the fission yeast Schizosaccharomyces pombe, it is well established that microtubules (MTs) deliver the spatial cue Tea1, a kelch repeat protein, to the tip regions to direct the growth machinery at the cell tips driving the linear extension of...

Trajectories of the ribosome as a nanomachine [Biophysics and Computational Biology]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
A Brownian machine, a tiny device buffeted by the random motions of molecules in the environment, is capable of exploiting these thermal motions for many of the conformational changes in its work cycle. Such machines are now thought to be ubiquitous, with the ribosome, a molecular machine responsible for protein...

HTRA2 in essential tremor and Parkinson disease [Genetics]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
Essential tremor is one of the most frequent movement disorders of humans and can be associated with substantial disability. Some but not all persons with essential tremor develop signs of Parkinson disease, and the relationship between the conditions has not been clear. In a six-generation consanguineous Turkish kindred with both...

Evolution of Bantu kinship [Anthropology]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
Kinship provides the fundamental structure of human society: descent determines the inheritance pattern between generations, whereas residence rules govern the location a couple moves to after they marry. In turn, descent and residence patterns determine other key relationships such as alliance, trade, and marriage partners. Hunter-gatherer kinship patterns are viewed...

Haze in China [Environmental Sciences]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
As the world’s second largest economy, China has experienced severe haze pollution, with fine particulate matter (PM) recently reaching unprecedentedly high levels across many cities, and an understanding of the PM formation mechanism is critical in the development of efficient mediation policies to minimize its regional to global impacts. We...

Missing heritability: The role of common variants [Genetics]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
Genome-wide association studies (GWASs), also called common variant association studies (CVASs), have uncovered thousands of genetic variants associated with hundreds of diseases. However, the variants that reach statistical significance typically explain only a small fraction of the heritability. One explanation for the “missing heritability” is that there are many additional...

GABA{rho} in cerebellar GFAP+ cells [Cell Biology]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
GABA-A receptors mediating synaptic or extrasynaptic transmission are molecularly and functionally distinct, and glial cells are known to express a plethora of GABA-A subunits. Here we demonstrate that GFAP+ cells of the granular layer of cerebellum express GABAρ subunits during early postnatal development, thereby conferring peculiar pharmacologic characteristics to GABA...

UbcH7 regulates 53BP1 stability [Biochemistry]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
DNA double-strand break (DSB) repair is not only key to genome stability but is also an important anticancer target. Through an shRNA library-based screening, we identified ubiquitin-conjugating enzyme H7 (UbcH7, also known as Ube2L3), a ubiquitin E2 enzyme, as a critical player in DSB repair. UbcH7 regulates both the steady-state...

BG505 SOSIP selects HIV neutralizing antibodies [Microbiology]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
Broadly neutralizing antibodies (bnAbs) targeting the trimer apex of HIV envelope are favored candidates for vaccine design and immunotherapy because of their great neutralization breadth and potency. However, methods of isolating bnAbs against this site have been limited by the quaternary nature of the epitope region. Here we report the...

Splice site correction by engineered U2AF65 [Applied Biological Sciences]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
Purine interruptions of polypyrimidine (Py) tract splice site signals contribute to human genetic diseases. The essential splicing factor U2AF65 normally recognizes a Py tract consensus sequence preceding the major class of 3′ splice sites. We found that neurofibromatosis- or retinitis pigmentosa-causing mutations in the 5′ regions of Py tracts severely...

Elevated hippocampal resting-state connectivity [Neuroscience]

PNAS Early Edition Articles - Mon, 11/24/2014 - 14:07
The brain is not idle during rest. Functional MRI (fMRI) studies have identified several resting-state networks, including the default mode network (DMN), which contains a set of cortical regions that interact with a hippocampus (HC) subsystem. Age-related alterations in the functional architecture of the DMN and HC may influence memory...
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