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Mental models of sustainable agriculture [Sustainability Science]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
Linking knowledge to action requires understanding how decision-makers conceptualize sustainability. This paper empirically analyzes farmer “mental models” of sustainability from three winegrape-growing regions of California where local extension programs have focused on sustainable agriculture. The mental models are represented as networks where sustainability concepts are nodes, and links are established...

Ghrelin and hepatic lipogenesis [Medical Sciences]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
Although ghrelin has been demonstrated to stimulate energy intake and storage through a central mechanism, its effect on hepatic lipid metabolism remains largely uncharacterized. Ghrelin receptor antagonism or gene deletion significantly decreased obesity-associated hepatic steatosis by suppression of de novo lipogenesis, whereas exogenous ghrelin stimulated lipogenesis, leading to hepatic lipid...

Commensals protect against food allergy [Immunology and Inflammation]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
Environmentally induced alterations in the commensal microbiota have been implicated in the increasing prevalence of food allergy. We show here that sensitization to a food allergen is increased in mice that have been treated with antibiotics or are devoid of a commensal microbiota. By selectively colonizing gnotobiotic mice, we demonstrate...

Dynamic hydration shells of hydrocarbons in water [Biophysics and Computational Biology]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
Kauzmann's explanation of how the hydrophobic factor drives protein folding is reexamined. His explanation said that hydrocarbon hydration shells are formed, possibly of clathrate water, and they explain why hydrocarbons have uniquely low solubilities in water. His explanation was not universally accepted because of skepticism about the clathrate hydration shell....

Missense variants in PPARG increase type 2 diabetes risk [Genetics]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
Peroxisome proliferator-activated receptor gamma (PPARG) is a master transcriptional regulator of adipocyte differentiation and a canonical target of antidiabetic thiazolidinedione medications. In rare families, loss-of-function (LOF) mutations in PPARG are known to cosegregate with lipodystrophy and insulin resistance; in the general population, the common P12A variant is associated with a...

Ultrafast tissue staining with chemical tags [Neuroscience]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
Genetically encoded fluorescent proteins and immunostaining are widely used to detect cellular and subcellular structures in fixed biological samples. However, for thick or whole-mount tissue, each approach suffers from limitations, including limited spectral flexibility and lower signal or slow speed, poor penetration, and high background labeling, respectively. We have overcome...

Inhibition of BDV replication by a squirrel EBLN [Microbiology]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
Animal genomes contain endogenous viral sequences, such as endogenous retroviruses and retrotransposons. Recently, we and others discovered that nonretroviral viruses also have been endogenized in many vertebrate genomes. Bornaviruses belong to the Mononegavirales and have left endogenous fragments, called “endogenous bornavirus-like elements” (EBLs), in the genomes of many mammals. The...

N. bacilliformis NrdD can use Trx as a reductant [Biochemistry]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
The class III anaerobic ribonucleotide reductases (RNRs) studied to date couple the reduction of ribonucleotides to deoxynucleotides with the oxidation of formate to CO2. Here we report the cloning and heterologous expression of the Neisseria bacilliformis class III RNR and show that it can catalyze nucleotide reduction using the ubiquitous...

Analysis of pseudogenes across three phyla [Biophysics and Computational Biology]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
Pseudogenes are degraded fossil copies of genes. Here, we report a comparison of pseudogenes spanning three phyla, leveraging the completed annotations of the human, worm, and fly genomes, which we make available as an online resource. We find that pseudogenes are lineage specific, much more so than protein-coding genes, reflecting...

Cell separation using tilted-angle acoustic waves [Cell Biology]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
Separation of cells is a critical process for studying cell properties, disease diagnostics, and therapeutics. Cell sorting by acoustic waves offers a means to separate cells on the basis of their size and physical properties in a label-free, contactless, and biocompatible manner. The separation sensitivity and efficiency of currently available...

Metabolic costs of human brain development [Neuroscience]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
The high energetic costs of human brain development have been hypothesized to explain distinctive human traits, including exceptionally slow and protracted preadult growth. Although widely assumed to constrain life-history evolution, the metabolic requirements of the growing human brain are unknown. We combined previously collected PET and MRI data to calculate...

E. coli formate hydrogenlyase [Biochemistry]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
Under anaerobic conditions, Escherichia coli can carry out a mixed-acid fermentation that ultimately produces molecular hydrogen. The enzyme directly responsible for hydrogen production is the membrane-bound formate hydrogenlyase (FHL) complex, which links formate oxidation to proton reduction and has evolutionary links to Complex I, the NADH:quinone oxidoreductase. Although the genetics,...

Neutralization of latent HIV by potent antibodies [Medical Sciences]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
Several highly potent and broadly neutralizing monoclonal antibodies against HIV have recently been isolated from B cells of infected individuals. However, the effects of these antibodies on the persistent viral reservoirs in HIV-infected individuals receiving antiretroviral therapy (ART) are unknown. We show that several HIV-specific monoclonal antibodies—in particular, PGT121, VRC01,...

Unconventional secretion of nonenveloped virus [Cell Biology]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
The cell-to-cell spread of cytoplasmic constituents such as nonenveloped viruses and aggregated proteins is usually thought to require cell lysis. However, mechanisms of unconventional secretion have been described that bypass the secretory pathway for the extracellular delivery of cytoplasmic molecules. Components of the autophagy pathway, an intracellular recycling process, have...

A critical reanalysis of genomics and well-being [Genetics]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
Fredrickson et al. [Fredrickson BL, et al. (2013) Proc Natl Acad Sci USA 110(33):13684–13689] claimed to have observed significant differences in gene expression related to hedonic and eudaimonic dimensions of well-being. Having closely examined both their claims and their data, we draw substantially different conclusions. After identifying some important conceptual...

Paramyxovirus fusion without full 6HB zippering [Microbiology]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
Enveloped viruses such as HIV and members of the paramyxovirus family use metastable, proteinaceous fusion machineries to merge the viral envelope with cellular membranes for infection. A hallmark of the fusogenic glycoproteins of these pathogens is refolding into a thermodynamically highly stable fusion core structure composed of six antiparallel α-helices,...

MC4Rs in PVH regulate food intake [Neuroscience]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
Activation of melanocortin-4 receptors (MC4Rs) restrains feeding and prevents obesity; however, the identity, location, and axonal projections of the neurons bearing MC4Rs that control feeding remain unknown. Reexpression of MC4Rs on single-minded 1 (SIM1)+ neurons in mice otherwise lacking MC4Rs is sufficient to abolish hyperphagia. Thus, MC4Rs on SIM1+ neurons,...

TPC interactome [Cell Biology]

PNAS Early Edition Articles - Mon, 08/25/2014 - 13:38
The two-pore channels (TPC1 and TPC2) belong to an ancient family of intracellular ion channels expressed in the endolysosomal system. Little is known about how regulatory inputs converge to modulate TPC activity, and proposed activation mechanisms are controversial. Here, we compiled a proteomic characterization of the human TPC interactome, which...
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