bluuebunny/crossref_metadata_2025 huggingface dataset:
Critical behavior of the ferromagnetic-paramagnetic phase transition in Fe90−xNixZr10 alloy ribbons
Authors: Thanh Tran Dang , Huy Dan Nguyen , Phan The-Long , Kumarakuru Haridas , Olivier Ezra J. , Neethling Johannes H. , Yu Seong-Cho
Published: January 2014

This work presents a detailed study on the critical behavior of the ferromagnetic-paramagnetic (FM-PM) phase transition in Fe90−xNixZr10 (x = 0 and 5) alloy ribbons. Basing on field dependences of magnetization (M-H), M2 versus H/M plots prove the alloys exhibiting a second-order magnetic phase transition. To investigate the nature of the FM-PM phase transition at TC = 245 and 306 K for x = 0 and 5, respectively, we performed a critical-exponent study. The values of critical components β, γ, and δ determined by using the modified Arrott plots, Kouvel-Fisher (KF), and critical isotherm analyses agree with each other. For x = 0, the critical parameters β = 0.365 ± 0.013 and γ = 1.615 ± 0.033 are obtained by modified Arrott plots while β = 0.368 ± 0.008 and γ = 1.612 ± 0.016 are obtained by the KF method. These values are close to those expected for the 3D-Heisenberg model, revealing short-range FM interactions in Fe90Zr10. Meanwhile, for x = 5, the values of the critical parameters β = 0.423 ± 0.008 and γ = 1.325 ± 0.036 are obtained by modified Arrott plots, and β = 0.425 ± 0.006 and γ = 1.323 ± 0.012 are obtained by the KF method. The falling of the β value in between the values of the mean-field theory (β = 0.5) and the 3D-Heisenberg model (β = 0.365) indicates an existence of FM short-range order and magnetic inhomogeneity in Fe85Ni5Zr10. With a partial replacement of Ni for Fe in Fe90−xNixZr10, the value of the critical exponent β trends to shift towards that of the mean-field theory. Such the result proves the presence of Ni favors establishing FM long-range order. The nature of this phenomenon is carefully discussed.
Damage growth and recollection in aluminum under axisymmetric convergence using a helical flux compression generator
Authors: Kaul A. M. , Ivanovsky A. V. , Atchison W. L. , Petrukhin A. A. , Duday P. V. , Griego J. R. , Salazar M. , Nadezhin S. S. , Tyupanova O. A. , Oro D. M. , Holtkamp D. B. , Rodriguez G. , Tabaka L. J. , Kraev A. I. , Skobelev A. N. , Westley D. T. , Anderson B. G. , Ivanov V. A. , Glybin A. M. , Kuzyaev A. I. , Stone J. B. , Payton J. R. , Goodwin P. M. , McCulloch Q. , Montoya R. R. , Dudin V. I. , Zimenkov A. A. , Randolph R. B. , Fierro F. , Reinovsky R. E. , Rousculp C. L. , Balandina A. N. , Podurets A. M.
Published: January 2014

Damage initiation and evolution, failure, and recollection processes under axisymmetric convergence were studied in the Russian-Damage experimental series, a joint effort between the Los Alamos National Laboratory and the All-Russian Institute of Experimental Physics. A helical explosive magnetic generator was used to drive a cylindrical liner shell to produce shock wave loading of a concentric cylindrical target shell. Shock wave amplitude was controlled by the liner-to-target spacing and by the magnetic field amplitude. Variation of the current pulse duration produced either a single impact, to study damage initiation through failure, or a double impact, to study failure with recollection. Both full and partial recollection of the main crack was obtained. By fielding high-precision diagnostics to measure the dynamic drive conditions and material response and by employing post-shot metallographic analysis, this project produced well-characterized experimental data across a range of damage and recollection levels for the chosen material, aluminum. We present selected experimental results to illustrate the methodology and utility of this experimental technique.
Ga and Al doped zinc oxide thin films for transparent conducting oxide applications: Structure-property correlations
Authors: Temizer Namik K. , Nori Sudhakar , Narayan Jagdish
Published: January 2014

We report a detailed investigation on the structure-property correlations in Ga and Al codoped ZnO films on c-sapphire substrates where the thin film microstructure varies from nanocrystalline to single crystal. We have achieved highly epitaxial films with very high optical transmittance (close to 90%) and low resistivity (∼110 μΩ-cm) values. The films grown in an ambient oxygen partial pressure (PO2) of 5 × 10−2 Torr and at growth temperatures from room temperature to 600 °C show semiconducting behavior, whereas samples grown at a PO2 of 1 × 10−3 Torr show metallic nature. The most striking feature is the occurrence of resistivity minima at relatively high temperatures around 110 K in films deposited at high temperatures. The measured optical and transport properties were found to be a strong function of growth conditions implying that the drastic changes are brought about essentially by native point defects. The structure-property correlations reveal that point defects play an important role in modifying the structural, optical, electrical, and magnetic properties and such changes in physical properties are controlled predominantly by the defect content.
Stochastic, real-space, imaginary-time evaluation of third-order Feynman–Goldstone diagrams
Authors: Willow Soohaeng Yoo , Hirata So
Published: January 2014

A new, alternative set of interpretation rules of Feynman–Goldstone diagrams for many-body perturbation theory is proposed, which translates diagrams into algebraic expressions suitable for direct Monte Carlo integrations. A vertex of a diagram is associated with a Coulomb interaction (rather than a two-electron integral) and an edge with the trace of a Green's function in real space and imaginary time. With these, 12 diagrams of third-order many-body perturbation (MP3) theory are converted into 20-dimensional integrals, which are then evaluated by a Monte Carlo method. It uses redundant walkers for convergence acceleration and a weight function for importance sampling in conjunction with the Metropolis algorithm. The resulting Monte Carlo MP3 method has low-rank polynomial size dependence of the operation cost, a negligible memory cost, and a naturally parallel computational kernel, while reproducing the correct correlation energies of small molecules within a few mEh after 106 Monte Carlo steps.
Graphene electron cannon: High-current edge emission from aligned graphene sheets
Authors: Liu Jianlong , Zeng Baoqing , Wang Wenzhong , Li Nannan , Guo Jing , Fang Yong , Deng Jiang , Li Jiangnan , Hao Chenchun
Published: January 2014

High-current field emitters are made by graphene paper consist of aligned graphene sheets. Field emission luminance pattern shows that their electron beams can be controlled by rolling the graphene paper from sheet to cylinder. These specific electron beams would be useful to vacuum devices and electron beam lithograph. To get high-current emission, the graphene paper is rolled to array and form graphene cannon. Due to aligned emission array, graphene cannon have high emission current. Besides high emission current, the graphene cannon is also tolerable with excellent emission stability. With good field emission properties, these aligned graphene emitters bring application insight.
Reflection terahertz time-domain spectroscopy of RDX and HMX explosives
Authors: Choi Kyujin , Hong Taeyoon , Ik Sim Kyung , Ha Taewoo , Cheol Park Byung , Hyuk Chung Jin , Gyeong Cho Soo , Hoon Kim Jae
Published: January 2014

We report on our study of RDX and HMX, two of the most commonly used explosive materials, in bulk pellets with reflection terahertz time-domain spectroscopy in the frequency range of 0.3–3 THz. The maximum entropy method was utilized to correct our raw reflection data against the phase error due to the relative displacement between the sample and the reference. Both the refractive index n and the extinction coefficient k in the terahertz region were acquired for these two explosives without a Kramers-Kronig analysis. Both RDX and HMX exhibit a series of distinct peaks not quite detectable in the more conventional transmission-type measurements due to their high terahertz absorptivity. Our results are compared with the literature data on powder samples.
Multistep metal insulator transition in VO2 nanowires on Al2O3 (0001) substrates
Authors: Takami Hidefumi , Kanki Teruo , Tanaka Hidekazu
Published: January 2014

We observed a temperature- and voltage-induced multistep metal-insulator transition (MIT) in vanadium dioxide nanowires fabricated on Al2O3 (0001) substrates. Nanowires with a width of 200 nm showed a multistep MIT that exhibited a resistivity change of nearly two orders of magnitude in a 0.5 K temperature step. These multistep resistivity jumps can be understood as a transition of a single domain, whose size is estimated to be around 50–70 nm from numerical calculation. We found that the temperature-induced isotropic conductive behavior of the nanowires becomes similar to the voltage-induced anisotropic one as their width decreases.
Merged vector gratings recorded in a photocrosslinkable polymer liquid crystal film for polarimetry
Authors: Sasaki Tomoyuki , Wada Takumi , Noda Kohei , Kawatsuki Nobuhiro , Ono Hiroshi
Published: January 2014

A merged vector grating, which is holographically fabricated in an anisotropic medium by irradiation with interference light with intensity modulation and polarization modulation, was designed to detect the polarization of light. The merged vector grating is recorded by the interference of two elliptically polarized beams with equal intensities, parallel azimuths, equal ellipticities, and different directions of rotation. We clarified theoretically that the Stokes parameters of the incident light beam are described by the diffraction efficiency of the merged vector grating. Also, to apply this property to formation of a polarimeter without any moving parts or mechanisms, two merged vector gratings with different grating vectors were recorded in a photocrosslinkable polymer liquid crystal film by angle-multiplexed holography. By investigation of the diffraction properties of the gratings obtained, we demonstrated the applicability of the merged vector gratings for use in polarimetry.
Unusual thermopower of inhomogeneous graphene grown by chemical vapor deposition
Authors: Nam Youngwoo , Sun Jie , Lindvall Niclas , Jae Yang Seung , Rae Park Chong , Woo Park Yung , Yurgens August
Published: January 2014

We report on thermopower (TEP) and resistance measurements of inhomogeneous graphene grown by chemical vapor deposition (CVD). Unlike the conventional resistance of pristine graphene, the gate-dependent TEP shows a large electron-hole asymmetry. This can be accounted for by inhomogeneity of the CVD-graphene where individual graphene regions contribute with different TEPs. At the high magnetic field and low temperature, the TEP has large fluctuations near the Dirac point associated with the disorder in the CVD-graphene. TEP measurements reveal additional characteristics of CVD-graphene, which are difficult to obtain from the measurement of resistance alone.
Electrically tunable refractive index in the dark conglomerate phase of a bent-core liquid crystal
Authors: Nagaraj M. , Görtz V. , Goodby J. W. , Gleeson H. F.
Published: January 2014

Here we report an electrically tunable refractive index observed in an isotropic liquid crystal phase known as the dark conglomerate (DC) phase. This unusual change in the refractive index which has not been reported before in the DC phase of other bent-core liquid crystals occurs because of a series of electric-field-driven transformations that take place in the DC phase of the studied bent-core liquid crystal. These transformations give rise to a decrease in the refractive index of the system, when an electric field is applied across the device, and no change in the birefringence is seen during such behavior. The electro-optic phenomenon is described in detail and the possibility of exploiting this for a number of liquid crystal based device applications is discussed.
Room temperature ferromagnetism in CuO/Cu2O microspheres: Towards interface effect
Authors: Gao Daqiang , zhang Zhipeng , Xu Qiang , Zhang Jing , Yan Zhongjie , Yao Jinli , Xue Desheng
Published: January 2014

The room temperature ferromagnetism at the interface between CuO and Cu2O microspheres is reported in this letter. Magnetic measurement results indicate that the interface-based ferromagnetism can be tuned by changing the phase rations of the CuO/Cu2O compounds synthesized by one-step hydrothermal method at different reaction times. The indirect double-exchange model was employed to explain the observed ferromagnetism. This finding suggests that tailoring the interfaces is an effective route to engineer architecture with enhanced magnetic properties and establish a striking example of emergent phenomena at oxide interfaces.
A comparison of deterministic and stochastic models for predicting the impacts of different sheep body lice (Bovicola ovis) management practices
Authors: Horton Brian J. , Carew Anna L.
Published: January 2014

A deterministic model for predicting the prevalence of lice in sheep flocks was compared with a stochastic model. The stochastic model was based on data from 100 000 simulated farms and encompassed: a range of lice detection levels at shearing, whether or not treatment was applied where no lice were detected, the efficacy of treatments used, and the adequacy of quarantine measures against entering sheep. The deterministic model generated more extreme estimates of the effects of lice management changes, and was judged unsatisfactory for long-term decision making. Predictions based on the stochastic model were consistent with reported survey values, suggesting the stochastic model could be used to predict benefits and costs associated with changes in louse-control methods. According to the stochastic model, the two factors that could provide the greatest reduction in dollar costs were improvement of quarantine by limiting the incidence of lice entering the flock, and improvement of eradication methods. The deterministic model suggested that there would be large benefits from improvement in detection, but the stochastic model only found small dollar benefits with improved detection in the absence of changes such as more effective treatments. Changing the proportion of flocks that were treated when no lice were detected had little effect on the predicted incidence of lousy flocks.
Discrete mechanisms of mTOR and cell cycle regulation by AMPK agonists independent of AMPK
Authors: Liu Xiaona , Chhipa Rishi Raj , Pooya Shabnam , Wortman Matthew , Yachyshin Sara , Chow Lionel M. L. , Kumar Ashish , Zhou Xuan , Sun Ying , Quinn Brian , McPherson Christopher , Warnick Ronald E. , Kendler Ady , Giri Shailendra , Poels Jeroen , Norga Koenraad , Viollet Benoit , Grabowski Gregory A. , Dasgupta Biplab
Published: January 2014

Significance

Cancer cells reprogram their metabolism for optimal growth and survival. AMPK-activated protein kinase (AMPK) is a key energy sensor that controls many metabolic pathways including metabolic reprogramming. However, its role in cancer is poorly understood. Some studies claim that it has a tumor suppressor role while others show its protumor role. Two AMPK-activating compounds (including metformin, now in many clinical trials) are widely used to suppress cancer cell proliferation. We found that AMPK is abundantly expressed in high-grade gliomas and, in contrast to popular belief, these two AMPK activators suppressed glioma cell proliferation through unique AMPK-independent mechanisms.
Reducing virulence of the human pathogen
Burkholderia
by altering the substrate specificity of the quorum-quenching acylase PvdQ
Authors: Koch Gudrun , Nadal-Jimenez Pol , Reis Carlos R. , Muntendam Remco , Bokhove Marcel , Melillo Elena , Dijkstra Bauke W. , Cool Robbert H. , Quax Wim J.
Published: January 2014

Significance

Resistance toward commonly used antibiotics is becoming a serious issue in the fight against bacterial pathogens. One promising strategy lies in the interference of bacterial quorum sensing by the hydrolysis of the signaling molecules. In this study, we present a structure-aided computational design approach to alter the substrate specificity of the quorum-quenching acylase PvdQ. Introduction of two point mutations in residues lining the active site led to a switch in substrate specificity, rendering the enzyme highly active toward C8-HSL and thereby reducing virulence caused by
Burkholderia cenocepacia
. Thus, this work not only provides a structural insight into the substrate specificity of quorum-quenching acylases but also indicates their potential in the fight against specific bacterial pathogens.
Evaluative and hedonic wellbeing among those with and without children at home
Authors: Deaton Angus , Stone Arthur A.
Published: January 2014

Significance

Most people think of their children as making their lives better. Yet many studies have found that those without children value their lives more than those with children. We also find a (small) negative effect, but only once we take into account that people with children have more favorable circumstances that predispose them to have better lives. Parents also experience more daily joy and more daily stress than nonparents. Interpreting such results requires that we think about who chooses to be a parent. If parents choose to be parents, and nonparents choose to be nonparents, there is no reason to expect that one group will be better or worse off than the other once other circumstances are controlled.
Detection of sweet tastants by a conserved group of insect gustatory receptors
Authors: Freeman Erica Gene , Wisotsky Zev , Dahanukar Anupama
Published: January 2014

Significance

Insects have gustatory receptors with which they taste chemicals and make important choices about foods, mates, and egg deposition sites. Gustatory receptors are novel proteins, and understanding how they recognize diverse chemicals is an unmet challenge. We developed a method to examine taste receptor function using a
Drosophila
olfactory neuron as a host for expressing taste receptors. We individually tested all sweet receptors of the fly, which resulted in specific sugar responses in the olfactory neuron. We also successfully expressed a bitter receptor and a mosquito taste receptor. Our study describes a systematic view of how the fly’s taste receptors detect sweet substances and holds promise for uncovering functions of taste receptors from insects that transmit diseases or damage crops.
Cyclin D2 is a GATA4 cofactor in cardiogenesis
Authors: Yamak Abir , Latinkić Branko V. , Dali Rola , Temsah Rana , Nemer Mona
Published: January 2014

Significance

Cyclin D2 is a cell cycle regulator with spatially restricted expression. Loss and gain of function in animal models also revealed a role in cell differentiation, but the mechanisms underlying this are incompletely understood. The cardiogenic transcription factor GATA4 is an upstream regulator of cyclin D2. We show that GATA4 and cyclinD2 are part of a forward reinforcing loop in which cyclin D2 feeds back to enhance GATA4 activity through direct interaction. Mutations in GATA4 that abrogate cyclin D2 interactions are associated with human congenital heart disease. The results unravel a unique transcriptional role of cyclin D2 that may underlie its cell specificity. The finding that cyclin D2 is a cardiogenic GATA4 cofactor may be exploitable therapeutically for heart repair.
Lateral organ boundaries 1
is a disease susceptibility gene for citrus bacterial canker disease
Authors: Hu Yang , Zhang Junli , Jia Hongge , Sosso Davide , Li Ting , Frommer Wolf B. , Yang Bing , White Frank F. , Wang Nian , Jones Jeffrey B.
Published: January 2014

Significance

Citrus bacterial canker, which is caused by several species in the genus
Xanthomonas
, is a severe disease with worldwide distribution affecting all the commercially important citrus species and cultivars. The mechanisms of canker development, involving erumpent pustule formation and bacterial growth, are not known. Our findings suggest that virulence determinants in several pathogens activate a single host disease susceptibility (S) gene that has a critical contribution to bacterial growth and host pustule development. The S gene represents an excellent candidate for control measures for the citrus bacterial canker.
Unveiling the mechanism by which microsporidian parasites prevent locust swarm behavior
Authors: Shi Wangpeng , Guo Yang , Xu Chuan , Tan Shuqian , Miao Jing , Feng Yanjie , Zhao Hong , St. Leger Raymond J. , Fang Weiguo
Published: January 2014

Significance

The ability of parasites to modify the behavior of their hosts is a widespread phenomenon, but the underlying mechanisms remain to be deciphered. Locusts such as
Locusta migratoria manilensis
are infamous for their ability to aggregate into gregarious migratory swarms that pose a major threat to food security. The microsporidian parasite
Paranosema locustae
can disrupt swarm formation by migratory locusts, but the underlying mechanisms of this action remain unexplored. In this study, we found that
P. locustae
and the native gut bacteria that produce the aggregation pheromone are mutually refractory. The reduction in aggregation pheromone reduces the production of the neurotransmitter serotonin (which initiates gregarization) and dopamine (which induces and maintains gregarization), preventing swarm behavior of migratory locusts.
Tetrapyrrole biosynthetic enzyme protoporphyrinogen IX oxidase 1 is required for plastid RNA editing
Authors: Zhang Fan , Tang Weijiang , Hedtke Boris , Zhong Linlin , Liu Lin , Peng Lianwei , Lu Congming , Grimm Bernhard , Lin Rongcheng
Published: January 2014

Significance

Both posttranscriptional RNA editing and tetrapyrrole metabolism are important processes in land plants and animals. A direct link between these two distinct programs had hitherto not been established. This study reveals an unexpected function for protoporphyrinogen IX oxidase 1 from model plant
Arabidopsis thaliana
in regulating plastid RNA editing through interacting with and modulating the stability of multiple organellar RNA editing factors. In addition to furthering our knowledge of the composition of the plant organellar editing apparatus, this research provides insight into both the conserved and divergent roles of enzymes in the tetrapyrrole metabolism during evolution.
Strain-specific innate immune signaling pathways determine malaria parasitemia dynamics and host mortality
Authors: Wu Jian , Tian Linjie , Yu Xiao , Pattaradilokrat Sittiporn , Li Jian , Wang Mingjun , Yu Weishi , Qi Yanwei , Zeituni Amir E. , Nair Sethu C. , Crampton Steve P. , Orandle Marlene S. , Bolland Silvia M. , Qi Chen-Feng , Long Carole A. , Myers Timothy G. , Coligan John E. , Wang Rongfu , Su Xin-zhuan
Published: January 2014

Significance

Malaria infection causes a severe disease with diverse symptoms. The molecular mechanisms underlying the differences of malaria pathology remain unknown or controversial. Here we infected mice with two closely related strains of rodent malaria parasite
Plasmodium yoelii
and characterized host genome-wide responses to the infections. We found that in mice infected with parasite N67, type I interferon was produced to a high level, leading to suppression of parasitemia. We further characterized the molecular mechanisms and identified host receptors in recognizing parasite ligands. In contrast, mice infected with N67C parasite mounted a strong inflammatory response, leading to severe pathology and host death. This study reveals previously unrecognized mechanisms associated with strain-specific malaria infection and provides important information for studying human malaria pathogenesis.
Longitudinal four-dimensional mapping of subcortical anatomy in human development
Authors: Raznahan Armin , Shaw Phillip W. , Lerch Jason P. , Clasen Liv S. , Greenstein Deanna , Berman Rebecca , Pipitone Jon , Chakravarty Mallar M. , Giedd Jay N.
Published: January 2014

Significance

Our spatiotemporal understanding of subcortical development in humans lags far behind that of the cortical sheet. This disparity ignores that developmental refinements and disruptions of complex behavior involve systems spanning both components of the brain. We begin redressing this imbalance by applying new techniques for striatal, pallidal and thalamic morphometry to large-scale longitudinal neuroimaging data extending from childhood through early adulthood. This work (
i
) establishes the curvilinear, sexual dimorphic and often protracted nature of global volume change within each structure, (
ii
) reveals profound spatiotemporal complexities in striatal, pallidal and thalamic maturation that are organized by the known topography of primate cortico-subcortical connectivity, and (
iii
) identifies focal sex differences in subcortical maturation that strike regions implicated in psychopathologies with an adolescent-emergent sex-bias.
Primate energy expenditure and life history
Authors: Pontzer Herman , Raichlen David A. , Gordon Adam D. , Schroepfer-Walker Kara K. , Hare Brian , O’Neill Matthew C. , Muldoon Kathleen M. , Dunsworth Holly M. , Wood Brian M. , Isler Karin , Burkart Judith , Irwin Mitchell , Shumaker Robert W. , Lonsdorf Elizabeth V. , Ross Stephen R.
Published: January 2014

Significance

Measurements of daily energy expenditure indicate that primates, including humans, expend only half of the calories expected for mammals of similar body size. As energy expenditure is central to organismal biology, these results hold important implications for life history, evolutionary biology, and foraging ecology for primates and other mammals. Specifically, we show that primates’ remarkably low metabolic rates account for their distinctively slow rates of growth, reproduction, and aging.
Prestimulus oscillatory power and connectivity patterns predispose conscious somatosensory perception
Authors: Weisz Nathan , Wühle Anja , Monittola Gianpiero , Demarchi Gianpaolo , Frey Julia , Popov Tzvetan , Braun Christoph
Published: January 2014

Significance

Experimental use of near-threshold stimuli is regarded as an important approach to study neural processes leading to conscious access (defined in operational terms as “reportability”). Looking to what extent prestimulus periods contribute to the variability of perceptual states has become increasingly popular, frequently pointing to an increased excitability of relevant sensory regions. Here, we aim to extend this “local” perspective by a network approach. A framework called “Windows to Consciousness” is introduced. We postulate that along with an enhanced excitability, preestablished pathways of information flow are a crucial ingredient, determining whether an upcoming near-threshold stimulus will be consciously perceived. Using magnetoencephalography combined with state-of-the-art source-imaging approaches, we are able to report supportive evidence.
In situ sum-frequency vibrational spectroscopy of electrochemical interfaces with surface plasmon resonance
Authors: Liu Wei-Tao , Shen Y. Ron
Published: January 2014

Significance

Electrochemical (EC) reactions play vital roles in many disciplines of modern science and technology, but their molecular-level understanding is still very poor. This is due to a lack of analytical tools that can access interfaces between metals and liquids, and identify unknown surface species. By exploiting surface plasmon resonant enhancement at EC interfaces, we demonstrate, with relevant examples at gold electrodes, the feasibility of using surface-specific sum-frequency spectroscopy to measure in situ and real-time vibrational spectra during EC reactions. The success of this approach is significant as it could bring us more insight and better understanding of EC reactions at the molecular level.
Leukocyte immunoglobulin-like receptor B1 is critical for antibody-dependent dengue
Authors: Chan Kuan Rong , Ong Eugenia Z. , Tan Hwee Cheng , Zhang Summer Li-Xin , Zhang Qian , Tang Kin Fai , Kaliaperumal Nivashini , Lim Angeline Pei Chiew , Hibberd Martin L. , Chan Soh Ha , Connolly John E. , Krishnan Manoj N. , Lok Shee Mei , Hanson Brendon J. , Lin Chao-Nan , Ooi Eng Eong
Published: January 2014

Significance

Dengue virus (DENV) infects almost 400 million people annually and some of these infections result in life threatening disease. An incomplete understanding of pathogenesis, particularly on how non- or subneutralizing levels of antibody augments DENV infection of cells expressing Fc-gamma receptors (FcγRs), has hampered vaccine development. Here, we show that, to overcome the activating FcγR-dependent expression of type-I interferon stimulated genes (ISGs), DENV binds and activates the inhibitory receptor, leukocyte immunoglobulin-like receptor-B1 (LILRB1). LILRB1 signals through its immunoreceptor tyrosine-based inhibition motif cytoplasmic tail to inhibit the expression of ISGs required for successful antibody-dependent DENV infection. Inhibition of DENV activation of LILRB1 could hence be a strategy for vaccine or therapeutic design.
Germ-line activation of the luteinizing hormone receptor directly drives spermiogenesis in a nonmammalian vertebrate
Authors: Chauvigné François , Zapater Cinta , Gasol Josep M. , Cerdà Joan
Published: January 2014

Significance

In vertebrates, the transition of postmeiotic spermatids into spermatozoa (spermiogenesis) is believed to occur indirectly in response to androgens released by the somatic Leydig cells after activation of the luteinizing hormone/choriogonadotropin receptor (LHCGR). In contrast to this indirect model, here we show that distantly related fishes express the homolog of the tetrapod LHCGR (Lhcgrba) also in germ cells, which directly drives spermiogenesis in response to the luteinizing hormone. Our findings reveal a nonsteroidal role of the Lhcgrba pathway in vertebrate germ cells with potential implications for the causes of male infertility.
Efficient and directed peptide bond formation in the gas phase via ion/ion reactions
Authors: McGee William M. , McLuckey Scott A.
Published: January 2014

Significance

The generation of peptide bonds is of longstanding interest both from the standpoints of the origin of life and for synthesis. We describe here a general approach for forming peptide linkages in the gas phase via ion/ion reactions. Examples of the addition of a single amino acid to the N terminus of a peptide and the addition of a polypeptide to the N terminus of a peptide are demonstrated. This work constitutes a unique means for generating peptide linkages that are fast (<1 s), efficient (tens of percent), and flexible. Possible application areas include the generation of peptide libraries for the generation of tandem MS data and for the soft landing of peptide products for microarrays.
Dynamics of axonal regeneration in adult and aging zebrafish reveal the promoting effect of a first lesion
Authors: Graciarena Mariana , Dambly-Chaudière Christine , Ghysen Alain
Published: January 2014

Significance

The posterior lateral line of zebrafish is a suitable system to study axonal regeneration in vivo because of the superficial location of neurons and targets, allowing one to follow reinnervation in live fish on a daily basis. Here we demonstrate the effectiveness and fidelity of regeneration throughout adulthood. We show that the latency before the nerve regenerates increases with age but is reduced after a second nerve cut at all ages, suggesting that a regeneration-promoting factor induced by the first cut facilitates regeneration on a second cut. We provide evidence that this factor remains present at the site of the first lesion for several days and is intrinsic to the neurons themselves.
GRK3 is essential for metastatic cells and promotes prostate tumor progression
Authors: Li Wenliang , Ai Nanping , Wang Suming , Bhattacharya Nandita , Vrbanac Vladimir , Collins Michael , Signoretti Sabina , Hu Yanhui , Boyce Frederick M. , Gravdal Karsten , Halvorsen Ole J. , Nalwoga Hawa , Akslen Lars A. , Harlow Ed , Watnick Randolph S.
Published: January 2014

Significance

Although the majority of cancer-related deaths are consequences of metastatic dissemination, the molecular and cellular forces that drive tumor cell dispersion are still poorly understood. To help identify new regulators that play critical roles in these processes, we screened for human kinases that are important for continued survival of metastatic cells. One kinase identified from these screens, the G-protein–coupled receptor kinase 3 (GRK3; or β-adrenergic receptor kinase 2), was found to have a key role in promoting prostate tumor growth and metastasis in mouse models through enhancing angiogenesis. Notably, GRK3 is overexpressed in human prostate metastatic tumors. Further studies on GRK3 and its pathways promise to expand our knowledge of cancer metastasis and also yield new cancer therapeutic targets.
Structures of yeast mitochondrial ADP/ATP carriers support a domain-based alternating-access transport mechanism
Authors: Ruprecht Jonathan J. , Hellawell Alex M. , Harding Marilyn , Crichton Paul G. , McCoy Airlie J. , Kunji Edmund R. S.
Published: January 2014

Significance

ADP/ATP carriers are archetypal members of the mitochondrial carrier family of transport proteins, which are thought to operate by a common but unresolved mechanism. Members of this family play key roles in many aspects of cell physiology and are implicated in several severe human diseases. Here, we present the structures of Aac2p and Aac3p, ADP/ATP carriers from
Saccharomyces cerevisiae
, determined by X-ray crystallography. Together with mutagenesis and functional assays, the structures support an alternating-access transport mechanism involving domain-based motions, where salt-bridge networks act as gates, providing access to a central substrate-binding site.
Increasing socioeconomic disparities in adolescent obesity
Authors: Frederick Carl B. , Snellman Kaisa , Putnam Robert D.
Published: January 2014

Significance

Childhood and youth obesity represent significant US public health challenges. Recent findings that the childhood obesity ‘‘epidemic’’ may have slightly abated have been met with relief from health professionals and popular media. However, we document that the overall trend in youth obesity rates masks a significant and growing class gap between youth from upper and lower socioeconomic status (SES) backgrounds. Until 2002, obesity rates increased at similar rates for all adolescents, but since then, obesity has begun to decline among higher SES youth but continued to increase among lower SES youth. These results underscore the need to target public health interventions to disadvantaged youth who remain at risk, as well as to examine how health information circulates through class-biased channels.
Living liquid crystals
Authors: Zhou Shuang , Sokolov Andrey , Lavrentovich Oleg D. , Aranson Igor S.
Published: January 2014

Significance

We propose a class of active matter, the living liquid crystal (LLC), representing motile rod-shaped bacteria placed in water-based nontoxic liquid crystal. Long-range orientational order of the liquid crystal and the swimming activity of bacteria demonstrate a strong coupling that dramatically alters individual and collective bacterial dynamics. For example, swimming bacteria perturb the orientational order of the liquid crystal or even cause its local melting, making the flagella motion optically visible. Second, self-organized textures emerge from the initial uniform LLC alignment with a characteristic length controlled by a balance between bacteria activity and anisotropic viscoelasticity of liquid crystal. Third, the local liquid crystal orientation controls the direction of motion of bacteria. LLC can lead to valuable biosensoring and biomedical applications.
Timing of cyber conflict
Authors: Axelrod Robert , Iliev Rumen
Published: January 2014

Significance

The world’s economy and international security have come to depend upon a secure Internet. International rivalries and conflicts have already provided challenges to Internet security in the form of espionage, sabotage, and denial of service. New vulnerabilities in computer systems are constantly being discovered. When an individual, group, or nation has access to means of exploiting such vulnerabilities in a rival’s computer systems, it faces a decision of whether to exploit its capacity immediately or wait for a more propitious time. This paper introduces a simple mathematical model applied to four case studies to promote the understanding of the new domain of cyber conflict.
Human natural killer cells control
Plasmodium falciparum
infection by eliminating infected red blood cells
Authors: Chen Qingfeng , Amaladoss Anburaj , Ye Weijian , Liu Min , Dummler Sara , Kong Fang , Wong Lan Hiong , Loo Hooi Linn , Loh Eva , Tan Shu Qi , Tan Thiam Chye , Chang Kenneth T. E. , Dao Ming , Suresh Subra , Preiser Peter R. , Chen Jianzhu
Published: January 2014

Significance

Study of human immune responses to malaria parasite infection has been hampered by a lack of small animal models. Although immunodeficient mice supplemented with human RBCs support human parasite infection, these animals lack a human immune system. We have overcome this obstacle by developing mice that possess both human RBCs and immune system and that support multiple cycles of
Plasmodium falciparum
infection. We further show that human natural killer cells preferentially interact with and kill infected RBCs in a contact-dependent manner. The small animal model reported here likely will facilitate the dissection of human immune responses to malaria parasite infection and the evaluation of therapeutics and vaccines.
Integrated description of protein dynamics from room-temperature X-ray crystallography and NMR
Authors: Fenwick R. Bryn , van den Bedem Henry , Fraser James S. , Wright Peter E.
Published: January 2014

Significance

Most proteins are inherently flexible and their dynamics play a central role in their biological functions. A molecular level understanding of protein function and mechanism requires an accurate description of the atomic coordinates in both time and space. Here we show, through studies of the enzyme dihydrofolate reductase, that multiconformer models derived from room-temperature X-ray crystallographic data can be used synergistically with nuclear magnetic resonance relaxation measurements to provide a detailed description of both the amplitude and timescale of fluctuations in atomic coordinates. This hybrid approach provides a more complete description of protein dynamics than can be obtained from either method alone. The room-temperature crystallographic ensemble accurately reflects the picosecond–nanosecond motions of the protein backbone and side chains.
The WNT receptor FZD7 is required for maintenance of the pluripotent state in human embryonic stem cells
Authors: Fernandez Antonio , Huggins Ian J. , Perna Luca , Brafman David , Lu Desheng , Yao Shiyin , Gaasterland Terry , Carson Dennis A. , Willert Karl
Published: January 2014

Significance

Embryonic stem cells (ESCs) are unique in their ability to expand and self-renew indefinitely while retaining the potential to give rise to all mature cell types. The molecular mechanisms underlying these properties remain poorly understood. We investigated the role of the highly conserved WNT signaling pathway in controlling self-renewal and found that the WNT receptor encoded by the frizzled family receptor 7 (FZD7) gene is essential for maintaining human ESCs in an undifferentiated and pluripotent state. Using an FZD7-specific fragment antigen binding protein, as well as knockdown of FZD7 expression, we showed that the FZD7 receptor transduces a WNT/β-catenin signal in human ESCs. These data demonstrate that an endogenous WNT signaling loop is essential for the maintenance of human ESCs in an undifferentiated state.
Reproducible selection of high avidity CD8
+
T-cell clones following secondary acute virus infection
Authors: Cukalac Tania , Chadderton Jesseka , Handel Andreas , Doherty Peter C. , Turner Stephen J. , Thomas Paul G. , La Gruta Nicole L.
Published: January 2014

Significance

Exactly how memory cells are selected into a recall response to acute viral infection (stochastic or deterministic) remains unresolved. This paper demonstrates definitively that selection of virus-specific CD8
+
T cells from memory occurs via active selection of particular T-cell clones after secondary virus infection and that this selection appears to be based on the avidity of the T-cell receptor (TCR) for the virus-derived peptide (p) + major histocompatibility complex class I molecule. We also show that despite clear clonal preferences, there is no global narrowing of epitope-specific TCR diversity in the recall response. We propose that the immune system has evolved such a strategy to optimize cytotoxic T-lymphocyte responses while safeguarding TCR repertoire diversity.
Pih1d3 is required for cytoplasmic preassembly of axonemal dynein in mouse sperm
Authors: Dong Fenglan , Shinohara Kyosuke , Botilde Yanick , Nabeshima Ryo , Asai Yasuko , Fukumoto Akemi , Hasegawa Toshiaki , Matsuo Moe , Takeda Hiroyuki , Shiratori Hidetaka , Nakamura Tetsuya , Hamada Hiroshi
Published: January 2014

Axonemal dynein complexes are preassembled in the cytoplasm before their transport to cilia, but the mechanism of this process remains unclear. We now show that mice lacking Pih1d3, a PIH1 domain–containing protein, develop normally but manifest male sterility. Pih1d3−/− sperm were immotile and fragile, with the axoneme of the flagellum lacking outer dynein arms (ODAs) and inner dynein arms (IDAs) and showing a disturbed 9+2 microtubule organization. Pih1d3 was expressed specifically in spermatogenic cells, with the mRNA being most abundant in pachytene spermatocytes. Pih1d3 localized to the cytoplasm of spermatogenic cells but was not detected in spermatids or mature sperm. The levels of ODA and IDA proteins were reduced in the mutant testis and sperm, and Pih1d3 was found to interact with an intermediate chain of ODA as well as with Hsp70 and Hsp90. Our results suggest that Pih1d3 contributes to cytoplasmic preassembly of dynein complexes in spermatogenic cells by stabilizing and promoting complex formation by ODA and IDA proteins.
The CP110-interacting proteins Talpid3 and Cep290 play overlapping and distinct roles in cilia assembly
Authors: Kobayashi Tetsuo , Kim Sehyun , Lin Yu-Chun , Inoue Takanari , Dynlacht Brian David
Published: January 2014

We have identified Talpid3/KIAA0586 as a component of a CP110-containing protein complex important for centrosome and cilia function. Talpid3 assembles a ring-like structure at the extreme distal end of centrioles. Ablation of Talpid3 resulted in an aberrant distribution of centriolar satellites involved in protein trafficking to centrosomes as well as cilia assembly defects, reminiscent of loss of Cep290, another CP110-associated protein. Talpid3 depletion also led to mislocalization of Rab8a, a small GTPase thought to be essential for ciliary vesicle formation. Expression of activated Rab8a suppressed cilia assembly defects provoked by Talpid3 depletion, suggesting that Talpid3 affects cilia formation through Rab8a recruitment and/or activation. Remarkably, ultrastructural analyses showed that Talpid3 is required for centriolar satellite dispersal, which precedes the formation of mature ciliary vesicles, a process requiring Cep290. These studies suggest that Talpid3 and Cep290 play overlapping and distinct roles in ciliary vesicle formation through regulation of centriolar satellite accretion and Rab8a.
DNA replication and spindle checkpoints cooperate during S phase to delay mitosis and preserve genome integrity
Authors: Magiera Maria M. , Gueydon Elisabeth , Schwob Etienne
Published: January 2014

Deoxyribonucleic acid (DNA) replication and chromosome segregation must occur in ordered sequence to maintain genome integrity during cell proliferation. Checkpoint mechanisms delay mitosis when DNA is damaged or upon replication stress, but little is known on the coupling of S and M phases in unperturbed conditions. To address this issue, we postponed replication onset in budding yeast so that DNA synthesis is still underway when cells should enter mitosis. This delayed mitotic entry and progression by transient activation of the S phase, G2/M, and spindle assembly checkpoints. Disabling both Mec1/ATR- and Mad2-dependent controls caused lethality in cells with deferred S phase, accompanied by Rad52 foci and chromosome missegregation. Thus, in contrast to acute replication stress that triggers a sustained Mec1/ATR response, multiple pathways cooperate to restrain mitosis transiently when replication forks progress unhindered. We suggest that these surveillance mechanisms arose when both S and M phases were coincidently set into motion by a unique ancestral cyclin–Cdk1 complex.
Activation of the Ano1 (TMEM16A) chloride channel by calcium is not mediated by calmodulin
Authors: Yu Kuai , Zhu Jinqiu , Qu Zhiqiang , Cui Yuan-Yuan , Hartzell H. Criss
Published: January 2014

The Ca2+-activated Cl channel anoctamin-1 (Ano1; Tmem16A) plays a variety of physiological roles, including epithelial fluid secretion. Ano1 is activated by increases in intracellular Ca2+, but there is uncertainty whether Ca2+ binds directly to Ano1 or whether phosphorylation or additional Ca2+-binding subunits like calmodulin (CaM) are required. Here we show that CaM is not necessary for activation of Ano1 by Ca2+ for the following reasons. (a) Exogenous CaM has no effect on Ano1 currents in inside-out excised patches. (b) Overexpression of Ca2+-insensitive mutants of CaM have no effect on Ano1 currents, whereas they eliminate the current mediated by the small-conductance Ca2+-activated K+ (SK2) channel. (c) Ano1 does not coimmunoprecipitate with CaM, whereas SK2 does. Furthermore, Ano1 binds very weakly to CaM in pull-down assays. (d) Ano1 is activated in excised patches by low concentrations of Ba2+, which does not activate CaM. In addition, we conclude that reversible phosphorylation/dephosphorylation is not required for current activation by Ca2+ because the current can be repeatedly activated in excised patches in the absence of ATP or other high-energy compounds. Although Ano1 is blocked by the CaM inhibitor trifluoperazine (TFP), we propose that TFP inhibits the channel in a CaM-independent manner because TFP does not inhibit Ano1 when applied to the cytoplasmic side of excised patches. These experiments lead us to conclude that CaM is not required for activation of Ano1 by Ca2+. Although CaM is not required for channel opening by Ca2+, work of other investigators suggests that CaM may have effects in modulating the biophysical properties of the channel.
Drug-induced ion channel opening tuned by the voltage sensor charge profile
Authors: Ottosson Nina E. , Liin Sara I. , Elinder Fredrik
Published: January 2014

Polyunsaturated fatty acids modulate the voltage dependence of several voltage-gated ion channels, thereby being potent modifiers of cellular excitability. Detailed knowledge of this molecular mechanism can be used in designing a new class of small-molecule compounds against hyperexcitability diseases. Here, we show that arginines on one side of the helical K-channel voltage sensor S4 increased the sensitivity to docosahexaenoic acid (DHA), whereas arginines on the opposing side decreased this sensitivity. Glutamates had opposite effects. In addition, a positively charged DHA-like molecule, arachidonyl amine, had opposite effects to the negatively charged DHA. This suggests that S4 rotates to open the channel and that DHA electrostatically affects this rotation. A channel with arginines in positions 356, 359, and 362 was extremely sensitive to DHA: 70 µM DHA at pH 9.0 increased the current >500 times at negative voltages compared with wild type (WT). The small-molecule compound pimaric acid, a novel Shaker channel opener, opened the WT channel. The 356R/359R/362R channel drastically increased this effect, suggesting it to be instrumental in future drug screening.