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Breeding and gene flow in animal domestication [Social Sciences]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
For the last 150 y scholars have focused upon the roles of intentional breeding and genetic isolation as fundamental to understanding the process of animal domestication. This analysis of ethnoarchaeological, archaeological, and genetic data suggests that long-term gene flow between wild and domestic stocks was much more common than previously...

Structural analysis of EndoS [Immunology]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
To evade host immune mechanisms, many bacteria secrete immunomodulatory enzymes. Streptococcus pyogenes, one of the most common human pathogens, secretes a large endoglycosidase, EndoS, which removes carbohydrates in a highly specific manner from IgG antibodies. This modification renders antibodies incapable of eliciting host effector functions through either complement or Fc...

Symbol addition by monkeys [Neuroscience]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
Weber’s law can be explained either by a compressive scaling of sensory response with stimulus magnitude or by a proportional scaling of response variability. These two mechanisms can be distinguished by asking how quantities are added or subtracted. We trained Rhesus monkeys to associate 26 distinct symbols with 0–25 drops...

Lead in ancient Rome's city waters [Anthropology]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
It is now universally accepted that utilization of lead for domestic purposes and water distribution presents a major health hazard. The ancient Roman world was unaware of these risks. How far the gigantic network of lead pipes used in ancient Rome compromised public health in the city is unknown. Lead...

Structure of the SAM-I/IV variant riboswitch [Biochemistry]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
In bacteria, sulfur metabolism is regulated in part by seven known families of riboswitches that bind S-adenosyl-l-methionine (SAM). Direct binding of SAM to these mRNA regulatory elements governs a downstream secondary structural switch that communicates with the transcriptional and/or translational expression machinery. The most widely distributed SAM-binding riboswitches belong to...

Dystroglycan regulation of inhibitory plasticity [Neuroscience]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
Dystroglycan (DG), a cell adhesion molecule well known to be essential for skeletal muscle integrity and formation of neuromuscular synapses, is also present at inhibitory synapses in the central nervous system. Mutations that affect DG function not only result in muscular dystrophies, but also in severe cognitive deficits and epilepsy....

Gut-associated leukocyte trafficking [Immunology]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
Given mounting evidence of the importance of gut-microbiota/immune-cell interactions in immune homeostasis and responsiveness, surprisingly little is known about leukocyte movements to, and especially from, the gut. We address this topic in a minimally perturbant manner using Kaede transgenic mice, which universally express a photoconvertible fluorescent reporter. Transcutaneous exposure of...

Origin of domesticated chili pepper in Mexico [Anthropology]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
The study of crop origins has traditionally involved identifying geographic areas of high morphological diversity, sampling populations of wild progenitor species, and the archaeological retrieval of macroremains. Recent investigations have added identification of plant microremains (phytoliths, pollen, and starch grains), biochemical and molecular genetic approaches, and dating through 14C accelerator...

Interepithelial signaling in kidney development [Developmental Biology]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
In most organs of the body, epithelial tissues are supported by their own basement membrane and underlying stroma, the latter being regarded as a complex of amorphous cells, extracellular matrices, and soluble factors. We demonstrate here that an epithelial tube can serve as a component of stroma that supports the...

Robust cortical representation of speech [Neuroscience]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
Humans and animals can reliably perceive behaviorally relevant sounds in noisy and reverberant environments, yet the neural mechanisms behind this phenomenon are largely unknown. To understand how neural circuits represent degraded auditory stimuli with additive and reverberant distortions, we compared single-neuron responses in ferret primary auditory cortex to speech and...

aPKC{zeta}/{iota} control MT1-MMP traffic in tumor invasion [Cell Biology]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
Dissemination of carcinoma cells requires the pericellular degradation of the extracellular matrix, which is mediated by membrane type 1-matrix metalloproteinase (MT1-MMP). In this article, we report a co–up-regulation and colocalization of MT1-MMP and atypical protein kinase C iota (aPKCι) in hormone receptor-negative breast tumors in association with a higher risk...

Modulation of a sodium channel by sevoflurane [Medical Sciences]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
Halogenated inhaled general anesthetic agents modulate voltage-gated ion channels, but the underlying molecular mechanisms are not understood. Many general anesthetic agents regulate voltage-gated Na+ (NaV) channels, including the commonly used drug sevoflurane. Here, we investigated the putative binding sites and molecular mechanisms of sevoflurane action on the bacterial NaV channel...

Convergent evolution in plant domestication [Anthropology]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
Recent increases in archaeobotanical evidence offer insights into the processes of plant domestication and agricultural origins, which evolved in parallel in several world regions. Many different crop species underwent convergent evolution and acquired domestication syndrome traits. For a growing number of seed crop species, these traits can be quantified by...

Multiple out-of-Africa modern human dispersals [Anthropology]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
Despite broad consensus on Africa as the main place of origin for anatomically modern humans, their dispersal pattern out of the continent continues to be intensely debated. In extant human populations, the observation of decreasing genetic and phenotypic diversity at increasing distances from sub-Saharan Africa has been interpreted as evidence...

Millisecond dynamics of RNA polymerase II [Biophysics and Computational Biology]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
Transcription is a central step in gene expression, in which the DNA template is processively read by RNA polymerase II (Pol II), synthesizing a complementary messenger RNA transcript. At each cycle, Pol II moves exactly one register along the DNA, a process known as translocation. Although X-ray crystal structures have...

Amyloid burst monitored by calorimetry [Biophysics and Computational Biology]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
Amyloid fibrils form in supersaturated solutions via a nucleation and growth mechanism. Although the structural features of amyloid fibrils have become increasingly clearer, knowledge on the thermodynamics of fibrillation is limited. Furthermore, protein aggregation is not a target of calorimetry, one of the most powerful approaches used to study proteins....

SAMHD1 activation [Biochemistry]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
The HIV-1 restriction factor sterile α-motif/histidine-aspartate domain-containing protein 1 (SAMHD1) is a tetrameric protein that catalyzes the hydrolysis of all dNTPs to the deoxynucleoside and tripolyphosphate, which effectively depletes the dNTP substrates of HIV reverse transcriptase. Here, we establish that SAMHD1 is activated by GTP binding to guanine-specific activator sites...

Rice domestication [Biological Sciences]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
Rice (Oryza sativa) is one of the most important cereal grains in the world today and serves as a staple food source for more than half of the world’s population. Research into when, where, and how rice was brought into cultivation and eventually domesticated, along with its development into a...

Modeling domestication history [Evolution]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
The domestication of plants and animals marks one of the most significant transitions in human, and indeed global, history. Traditionally, study of the domestication process was the exclusive domain of archaeologists and agricultural scientists; today it is an increasingly multidisciplinary enterprise that has come to involve the skills of evolutionary...

Network analysis of streamwater chemistry [Environmental Sciences]

PNAS Early Edition Articles - Mon, 04/21/2014 - 13:25
By coupling synoptic data from a basin-wide assessment of streamwater chemistry with network-based geostatistical analysis, we show that spatial processes differentially affect biogeochemical condition and pattern across a headwater stream network. We analyzed a high-resolution dataset consisting of 664 water samples collected every 100 m throughout 32 tributaries in an...
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