Feed aggregator

Signal integration by PKA [Systems Biology]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
Cellular processes and homeostasis control in eukaryotic cells is achieved by the action of regulatory proteins such as protein kinase A (PKA). Although the outbound signals from PKA directed to processes such as metabolism, growth, and aging have been well charted, what regulates this conserved regulator remains to be systematically...

Jupiter's grand attack [Astronomy]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
The statistics of extrasolar planetary systems indicate that the default mode of planet formation generates planets with orbital periods shorter than 100 days and masses substantially exceeding that of the Earth. When viewed in this context, the Solar System is unusual. Here, we present simulations which show that a popular...

Rise of marine diatoms [Evolution]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
Marine diatoms are silica-precipitating microalgae that account for over half of organic carbon burial in marine sediments and thus they play a key role in the global carbon cycle. Their evolutionary expansion during the Cenozoic era (66 Ma to present) has been associated with a superior competitive ability for silicic...

Ice Age horse and camel hunting in North America [Anthropology]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
The only certain evidence for prehistoric human hunting of horse and camel in North America occurs at the Wally’s Beach site, Canada. Here, the butchered remains of seven horses and one camel are associated with 29 nondiagnostic lithic artifacts. Twenty-seven new radiocarbon ages on the bones of these animals revise...

Molecular orientation of organic semiconductors [Chemistry]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
Physical vapor deposition is commonly used to prepare organic glasses that serve as the active layers in light-emitting diodes, photovoltaics, and other devices. Recent work has shown that orienting the molecules in such organic semiconductors can significantly enhance device performance. We apply a high-throughput characterization scheme to investigate the effect...

Historical origin of semiarid vegetation bands [Ecology]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
Landscape-scale patterns of vegetation occur worldwide at interfaces between semiarid and arid climates. They are important as potential indicators of climate change and imminent regime shifts and are widely thought to arise from positive feedback between vegetation and infiltration of rainwater. On gentle slopes the typical pattern form is bands...

Sexual selection and gene expression evolution [Evolution]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
The profound and pervasive differences in gene expression observed between males and females, and the unique evolutionary properties of these genes in many species, have led to the widespread assumption that they are the product of sexual selection and sexual conflict. However, we still lack a clear understanding of the...

Development of bright cyan and orange luciferases [Cell Biology]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
Fluorescence live imaging has become an essential methodology in modern cell biology. However, fluorescence requires excitation light, which can sometimes cause potential problems, such as autofluorescence, phototoxicity, and photobleaching. Furthermore, combined with recent optogenetic tools, the light illumination can trigger their unintended activation. Because luminescence imaging does not require excitation...

DNA-templated multicomponent enzyme crystals [Chemistry]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
The ability to predictably control the coassembly of multiple nanoscale building blocks, especially those with disparate chemical and physical properties such as biomolecules and inorganic nanoparticles, has far-reaching implications in catalysis, sensing, and photonics, but a generalizable strategy for engineering specific contacts between these particles is an outstanding challenge. This...

TRAPPII regulation of RabERAB11 Golgi exit [Cell Biology]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
The oligomeric complex transport protein particle I (TRAPPI) mediates nucleotide exchange on the RAB GTPase RAB1/Ypt1. TRAPPII is composed of TRAPPI plus three additional subunits, Trs120, Trs130, and Trs65. Unclear is whether TRAPPII mediates nucleotide exchange on RAB1/Ypt1, RAB11/Ypt31, or both. In Aspergillus nidulans, RabORAB1 resides in the Golgi, RabERAB11...

Mechanisms of hematin crystallization [Chemistry]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
Hematin crystallization is the primary mechanism of heme detoxification in malaria parasites and the target of the quinoline class of antimalarials. Despite numerous studies of malaria pathophysiology, fundamental questions regarding hematin growth and inhibition remain. Among them are the identity of the crystallization medium in vivo, aqueous or organic; the...

Extreme halophilic Archaea oxidize carbon monoxide [Microbiology]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
Carbon monoxide occurs at relatively high concentrations (≥800 parts per million) in Mars’ atmosphere, where it represents a potentially significant energy source that could fuel metabolism by a localized putative surface or near-surface microbiota. However, the plausibility of CO oxidation under conditions relevant for Mars in its past or at...

Sidewinding snakes and robots turn with template [Engineering]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
Many organisms move using traveling waves of body undulation, and most work has focused on single-plane undulations in fluids. Less attention has been paid to multiplane undulations, which are particularly important in terrestrial environments where vertical undulations can regulate substrate contact. A seemingly complex mode of snake locomotion, sidewinding, can...

Mutagenesis of mating pheromone system in yeast [Genetics]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
The diversification of sex pheromones is regarded as one of the causes of prezygotic isolation that results in speciation. In the fission yeast Schizosaccharomyces pombe, the molecular recognition of a peptide pheromone by its receptor plays an essential role in sexual reproduction. We considered that molecular coevolution of a peptide-mating...

Non-native species increase floral diversity [Ecology]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
Plants are commonly listed as invasive species, presuming that they cause harm at both global and regional scales. Approximately 40% of all species listed as invasive within Britain are plants. However, invasive plants are rarely linked to the national or global extinction of native plant species. The possible explanation is...

The genome of Mycobacterium lepromatosis [Microbiology]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
Mycobacterium lepromatosis is an uncultured human pathogen associated with diffuse lepromatous leprosy and a reactional state known as Lucio's phenomenon. By using deep sequencing with and without DNA enrichment, we obtained the near-complete genome sequence of M. lepromatosis present in a skin biopsy from a Mexican patient, and compared it...

ATP synthase essential in malaria life cycle [Colloquium Paper]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
Mitochondrial ATP synthase is driven by chemiosmotic oxidation of pyruvate derived from glycolysis. Blood-stage malaria parasites eschew chemiosmosis, instead relying almost solely on glycolysis for their ATP generation, which begs the question of whether mitochondrial ATP synthase is necessary during the blood stage of the parasite life cycle. We knocked...

Evidence for indigenous nitrogen on Mars [Earth, Atmospheric, and Planetary Sciences]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
The Sample Analysis at Mars (SAM) investigation on the Mars Science Laboratory (MSL) Curiosity rover has detected oxidized nitrogen-bearing compounds during pyrolysis of scooped aeolian sediments and drilled sedimentary deposits within Gale crater. Total N concentrations ranged from 20 to 250 nmol N per sample. After subtraction of known N...

Synergistic regulation of PDE4B by PKA-C{beta} and p65 [Pharmacology]

PNAS Early Edition Articles - Mon, 03/23/2015 - 13:04
Phosphodiesterase 4B (PDE4B) plays a key role in regulating inflammation. Roflumilast, a phosphodiesterase (PDE)4-selective inhibitor, has recently been approved for treating severe chronic obstructive pulmonary disease (COPD) patients with exacerbation. However, there is also clinical evidence suggesting the development of tachyphylaxis or tolerance on repeated dosing of roflumilast and the...
Syndicate content