Journal Articles

[This Week in Science] Zeroing in on essential human genes

Science - Fri, 11/27/2015 - 00:00
Author: L. Bryan Ray
Categories: Journal Articles

[This Week in Science] Antidepressants suppress DNA methylation

Science - Fri, 11/27/2015 - 00:00
Author: Leslie K. Ferrarelli
Categories: Journal Articles

[Editors' Choice] More neurons mean less need for sleep

Science - Fri, 11/27/2015 - 00:00
Author: Peter Stern
Categories: Journal Articles

[Editors' Choice] Diversity through ADVANCEment

Science - Fri, 11/27/2015 - 00:00
Author: Melissa McCartney
Categories: Journal Articles

[Editors' Choice] Cell size matters to meristems

Science - Fri, 11/27/2015 - 00:00
Author: Pamela J. Hines
Categories: Journal Articles

[Editors' Choice] A shifting wet girdle around the tropics

Science - Fri, 11/27/2015 - 00:00
Author: H. Jesse Smith
Categories: Journal Articles

[Editors' Choice] Committing to memory

Science - Fri, 11/27/2015 - 00:00
Author: Lisa D. Chong
Categories: Journal Articles

[Editors' Choice] Mitochondrial quality control

Science - Fri, 11/27/2015 - 00:00
Author: Stella M. Hurtley
Categories: Journal Articles

[Editors' Choice] Crystal structure of a rhodium carbene

Science - Fri, 11/27/2015 - 00:00
Author: Jake Yeston
Categories: Journal Articles

[Review] Vibrational spectroscopic imaging of living systems: An emerging platform for biology and medicine

Science - Fri, 11/27/2015 - 00:00
Vibrational spectroscopy has been extensively applied to the study of molecules in gas phase, in condensed phase, and at interfaces. The transition from spectroscopy to spectroscopic imaging of living systems, which allows the spectrum of biomolecules to act as natural contrast, is opening new opportunities to reveal cellular machinery and to enable molecule-based diagnosis. Such a transition, however, involves more than a simple combination of spectrometry and microscopy. We review recent efforts that have pushed the boundary of the vibrational spectroscopic imaging field in terms of spectral acquisition speed, detection sensitivity, spatial resolution, and imaging depth. We further highlight recent applications in functional analysis of single cells and in label-free detection of diseases. Authors: Ji-Xin Cheng, X. Sunney Xie
Categories: Journal Articles

[Research Article] Principles of connectivity among morphologically defined cell types in adult neocortex

Science - Fri, 11/27/2015 - 00:00
Since the work of Ramón y Cajal in the late 19th and early 20th centuries, neuroscientists have speculated that a complete understanding of neuronal cell types and their connections is key to explaining complex brain functions. However, a complete census of the constituent cell types and their wiring diagram in mature neocortex remains elusive. By combining octuple whole-cell recordings with an optimized avidin-biotin-peroxidase staining technique, we carried out a morphological and electrophysiological census of neuronal types in layers 1, 2/3, and 5 of mature neocortex and mapped the connectivity between more than 11,000 pairs of identified neurons. We categorized 15 types of interneurons, and each exhibited a characteristic pattern of connectivity with other interneuron types and pyramidal cells. The essential connectivity structure of the neocortical microcircuit could be captured by only a few connectivity motifs. Authors: Xiaolong Jiang, Shan Shen, Cathryn R. Cadwell, Philipp Berens, Fabian Sinz, Alexander S. Ecker, Saumil Patel, Andreas S. Tolias
Categories: Journal Articles

[Research Article] A continent-wide assessment of the form and intensity of large mammal herbivory in Africa

Science - Fri, 11/27/2015 - 00:00
Megafaunal extinctions and a lack of suitable remote sensing technology impede our understanding of both the ecological legacy and current impacts of large mammal herbivores in the Earth system. To address this, we reconstructed the form and intensity of herbivory pressure across sub-Saharan Africa ~1000 years ago. Specifically, we modeled and mapped species-level biomass for 92 large mammal herbivores using census data, species distributions, and environmental covariates. Trait-based classifications of these species into herbivore functional types, and analyses of their biomass surfaces, reveal four ecologically distinct continental-scale herbivory regimes, characterized by internally similar forms and intensities of herbivory pressure. Associations between herbivory regimes, fire prevalence, soil nutrient status, and rainfall provide important insights into African ecology and pave the way for integrating herbivores into global-scale studies. Authors: Gareth P. Hempson, Sally Archibald, William J. Bond
Categories: Journal Articles

[Report] Semiconductor interfacial carrier dynamics via photoinduced electric fields

Science - Fri, 11/27/2015 - 00:00
Solar photoconversion in semiconductors is driven by charge separation at the interface of the semiconductor and contacting layers. Here we demonstrate that time-resolved photoinduced reflectance from a semiconductor captures interfacial carrier dynamics. We applied this transient photoreflectance method to study charge transfer at p-type gallium-indium phosphide (p-GaInP2) interfaces critically important to solar-driven water splitting. We monitored the formation and decay of transient electric fields that form upon photoexcitation within bare p-GaInP2, p-GaInP2/platinum (Pt), and p-GaInP2/amorphous titania (TiO2) interfaces. The data show that a field at both the p-GaInP2/Pt and p-GaInP2/TiO2 interfaces drives charge separation. Additionally, the charge recombination rate at the p-GaInP2/TiO2 interface is greatly reduced owing to its p-n nature, compared with the Schottky nature of the p-GaInP2/Pt interface. Authors: Ye Yang, Jing Gu, James L. Young, Elisa M. Miller, John A. Turner, Nathan R. Neale, Matthew C. Beard
Categories: Journal Articles

[Report] Near-unity photoluminescence quantum yield in MoS2

Science - Fri, 11/27/2015 - 00:00
Two-dimensional (2D) transition metal dichalcogenides have emerged as a promising material system for optoelectronic applications, but their primary figure of merit, the room-temperature photoluminescence quantum yield (QY), is extremely low. The prototypical 2D material molybdenum disulfide (MoS2) is reported to have a maximum QY of 0.6%, which indicates a considerable defect density. Here we report on an air-stable, solution-based chemical treatment by an organic superacid, which uniformly enhances the photoluminescence and minority carrier lifetime of MoS2 monolayers by more than two orders of magnitude. The treatment eliminates defect-mediated nonradiative recombination, thus resulting in a final QY of more than 95%, with a longest-observed lifetime of 10.8 ± 0.6 nanoseconds. Our ability to obtain optoelectronic monolayers with near-perfect properties opens the door for the development of highly efficient light-emitting diodes, lasers, and solar cells based on 2D materials. Authors: Matin Amani, Der-Hsien Lien, Daisuke Kiriya, Jun Xiao, Angelica Azcatl, Jiyoung Noh, Surabhi R. Madhvapathy, Rafik Addou, Santosh KC, Madan Dubey, Kyeongjae Cho, Robert M. Wallace, Si-Chen Lee, Jr-Hau He, Joel W. Ager, Xiang Zhang, Eli Yablonovitch, Ali Javey
Categories: Journal Articles

[Report] Deformation-assisted fluid percolation in rock salt

Science - Fri, 11/27/2015 - 00:00
Deep geological storage sites for nuclear waste are commonly located in rock salt to ensure hydrological isolation from groundwater. The low permeability of static rock salt is due to a percolation threshold. However, deformation may be able to overcome this threshold and allow fluid flow. We confirm the percolation threshold in static experiments on synthetic salt samples with x-ray microtomography. We then analyze wells penetrating salt deposits in the Gulf of Mexico. The observed hydrocarbon distributions in rock salt require that percolation occurred at porosities considerably below the static threshold due to deformation-assisted percolation. Therefore, the design of nuclear waste repositories in salt should guard against deformation-driven fluid percolation. In general, static percolation thresholds may not always limit fluid flow in deforming environments. Authors: Soheil Ghanbarzadeh, Marc A. Hesse, Maša Prodanović, James E. Gardner
Categories: Journal Articles

[Report] Predicting poverty and wealth from mobile phone metadata

Science - Fri, 11/27/2015 - 00:00
Accurate and timely estimates of population characteristics are a critical input to social and economic research and policy. In industrialized economies, novel sources of data are enabling new approaches to demographic profiling, but in developing countries, fewer sources of big data exist. We show that an individual’s past history of mobile phone use can be used to infer his or her socioeconomic status. Furthermore, we demonstrate that the predicted attributes of millions of individuals can, in turn, accurately reconstruct the distribution of wealth of an entire nation or to infer the asset distribution of microregions composed of just a few households. In resource-constrained environments where censuses and household surveys are rare, this approach creates an option for gathering localized and timely information at a fraction of the cost of traditional methods. Authors: Joshua Blumenstock, Gabriel Cadamuro, Robert On
Categories: Journal Articles

[Report] A pharyngeal jaw evolutionary innovation facilitated extinction in Lake Victoria cichlids

Science - Fri, 11/27/2015 - 00:00
Evolutionary innovations, traits that give species access to previously unoccupied niches, may promote speciation and adaptive radiation. Here, we show that such innovations can also result in competitive inferiority and extinction. We present evidence that the modified pharyngeal jaws of cichlid fishes and several marine fish lineages, a classic example of evolutionary innovation, are not universally beneficial. A large-scale analysis of dietary evolution across marine fish lineages reveals that the innovation compromises access to energy-rich predator niches. We show that this competitive inferiority shaped the adaptive radiation of cichlids in Lake Tanganyika and played a pivotal and previously unrecognized role in the mass extinction of cichlid fishes in Lake Victoria after Nile perch invasion. Authors: Matthew D. McGee, Samuel R. Borstein, Russell Y. Neches, Heinz H. Buescher, Ole Seehausen, Peter C. Wainwright
Categories: Journal Articles

[Report] Anticancer immunotherapy by CTLA-4 blockade relies on the gut microbiota

Science - Fri, 11/27/2015 - 00:00
Antibodies targeting CTLA-4 have been successfully used as cancer immunotherapy. We find that the antitumor effects of CTLA-4 blockade depend on distinct Bacteroides species. In mice and patients, T cell responses specific for B. thetaiotaomicron or B. fragilis were associated with the efficacy of CTLA-4 blockade. Tumors in antibiotic-treated or germ-free mice did not respond to CTLA blockade. This defect was overcome by gavage with B. fragilis, by immunization with B. fragilis polysaccharides, or by adoptive transfer of B. fragilis–specific T cells. Fecal microbial transplantation from humans to mice confirmed that treatment of melanoma patients with antibodies against CTLA-4 favored the outgrowth of B. fragilis with anticancer properties. This study reveals a key role for Bacteroidales in the immunostimulatory effects of CTLA-4 blockade. Authors: Marie Vétizou, Jonathan M. Pitt, Romain Daillère, Patricia Lepage, Nadine Waldschmitt, Caroline Flament, Sylvie Rusakiewicz, Bertrand Routy, Maria P. Roberti, Connie P. M. Duong, Vichnou Poirier-Colame, Antoine Roux, Sonia Becharef, Silvia Formenti, Encouse Golden, Sascha Cording, Gerard Eberl, Andreas Schlitzer, Florent Ginhoux, Sridhar Mani, Takahiro Yamazaki, Nicolas Jacquelot, David P. Enot, Marion Bérard, Jérôme Nigou, Paule Opolon, Alexander Eggermont, Paul-Louis Woerther, Elisabeth Chachaty, Nathalie Chaput, Caroline Robert, Christina Mateus, Guido Kroemer, Didier Raoult, Ivo Gomperts Boneca, Franck Carbonnel, Mathias Chamaillard, Laurence Zitvogel
Categories: Journal Articles

[Report] Commensal Bifidobacterium promotes antitumor immunity and facilitates anti–PD-L1 efficacy

Science - Fri, 11/27/2015 - 00:00
T cell infiltration of solid tumors is associated with favorable patient outcomes, yet the mechanisms underlying variable immune responses between individuals are not well understood. One possible modulator could be the intestinal microbiota. We compared melanoma growth in mice harboring distinct commensal microbiota and observed differences in spontaneous antitumor immunity, which were eliminated upon cohousing or after fecal transfer. Sequencing of the 16S ribosomal RNA identified Bifidobacterium as associated with the antitumor effects. Oral administration of Bifidobacterium alone improved tumor control to the same degree as programmed cell death protein 1 ligand 1 (PD-L1)–specific antibody therapy (checkpoint blockade), and combination treatment nearly abolished tumor outgrowth. Augmented dendritic cell function leading to enhanced CD8+ T cell priming and accumulation in the tumor microenvironment mediated the effect. Our data suggest that manipulating the microbiota may modulate cancer immunotherapy. Authors: Ayelet Sivan, Leticia Corrales, Nathaniel Hubert, Jason B. Williams, Keston Aquino-Michaels, Zachary M. Earley, Franco W. Benyamin, Yuk Man Lei, Bana Jabri, Maria-Luisa Alegre, Eugene B. Chang, Thomas F. Gajewski
Categories: Journal Articles

[Report] Malaria parasites target the hepatocyte receptor EphA2 for successful host infection

Science - Fri, 11/27/2015 - 00:00
The invasion of a suitable host hepatocyte by mosquito-transmitted Plasmodium sporozoites is an essential early step in successful malaria parasite infection. Yet precisely how sporozoites target their host cell and facilitate productive infection remains largely unknown. We found that the hepatocyte EphA2 receptor was critical for establishing a permissive intracellular replication compartment, the parasitophorous vacuole. Sporozoites productively infected hepatocytes with high EphA2 expression, and the deletion of EphA2 protected mice from liver infection. Lack of host EphA2 phenocopied the lack of the sporozoite proteins P52 and P36. Our data suggest that P36 engages EphA2, which is likely to be a key step in establishing the permissive replication compartment. Authors: Alexis Kaushansky, Alyse N. Douglass, Nadia Arang, Vladimir Vigdorovich, Nicholas Dambrauskas, Heather S. Kain, Laura S. Austin, D. Noah Sather, Stefan H.I. Kappe
Categories: Journal Articles
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