bluuebunny/crossref_metadata_2025 huggingface dataset:
A carpet cloak for static magnetic field
Authors: Wang Rongfeng , Lei Mei Zhong , Jun Cui Tie
Published: May 2013

We present a two-dimensional carpet cloak for static magnetic field, a design that renders the magnetic response of a given volume invisible from its exterior, without altering the external magnetic fields. The device is designed using transformation optics method and can be implemented with alternating superconducting and magnetic material layers. Through the proper design of the constitutive tensors and relative thicknesses of each slab, we achieve the perfect performance of invisibility. Full wave numerical simulations confirm our design.
Measurement of elastic constants of monoclinic nickel-titanium and validation of first principles calculations
Authors: Stebner A. P. , Brown D. W. , Brinson L. C.
Published: May 2013

Polycrystalline, monoclinic nickel-titanium specimens were subjected to tensile and compressive deformations while neutron diffraction spectra were recorded in situ. Using these data, orientation-specific and macroscopic Young's moduli are determined from analysis of linear-elastic deformation exhibited by 13 unique orientations of monoclinic lattices and their relationships to each macroscopic stress and strain. Five of 13 elastic compliance constants are also identified: s11 = 1.15, s15 = −1.10, s22 = 1.34, s33 = 1.06, s35 = −1.54, all × 10−2 GPa−1. Through these results, recent atomistic calculations of monoclinic nickel-titanium elastic constants are validated.
Communication: Photoelectron angular distributions of CH− reveal a temporary anion state
Authors: Bandyopadhyay Biswajit , Pruitt Carrie Jo M. , Goebbert Daniel J.
Published: May 2013

Photoelectron imaging has broadened the scope of traditional photoelectron spectroscopy by combining a simultaneous photoelectron angular distribution, PAD, measurement with kinetic energy analysis. A fundamental understanding of PADs has been largely limited to simple atomic systems. However, a new model has recently been developed that predicts PADs as a function of electron kinetic energy for a simple linear combination of s and p atomic orbitals. We used CH− to test this model by acquiring PADs in a photoelectron imaging spectrometer at wavelengths from 600 to 355 nm. The PADs for electron detachment from the HOMO (1π) of CH− fit model predictions. However, the PADs associated with detachment from the HOMO-1 (3σ) orbital exhibit anomalous behavior at low electron kinetic energies because of a resonant process that arises from a previously undetected excited state of CH−.
Thermoelectric property enhancement by Cu nanoparticles in nanostructured FeSb2
Authors: Koirala Machhindra , Zhao Huaizhou , Pokharel Mani , Chen Shuo , Dahal Tulashi , Opeil Cyril , Chen Gang , Ren Zhifeng
Published: May 2013

We present the thermoelectric figure-of-merit (ZT) improvement in nanostructured FeSb2 by Cu nanoparticles of ∼5 nm as a modulation dopant. Because of the similar work functions between FeSb2 and Cu and the high electrical conductivity of Cu, the Kondo insulator-like electrical resistivity of FeSb2 at low temperatures was dramatically reduced. Both carrier concentration and mobility of the nanocomposites were improved over pure FeSb2 without degrading the Seebeck coefficient. Overall, an improvement of ∼90% in power factor was achieved for the optimized nanocomposite FeSb2Cu0.045. Combined with the reduced thermal conductivity by Cu/FeSb2 interfaces, ZT was improved by ∼110%. These results clearly demonstrate the potential of modulation doping to enhance the thermoelectric performance of FeSb2. A similar approach could be applied to other Kondo insulators or previously known thermoelectric materials to improve ZT.
Epitaxial growth of γ-CoV2O6 thin films: Structure, morphology, and magnetic properties
Authors: Lenertz M. , Colis S. , Ulhaq-Bouillet C. , Dinia A.
Published: May 2013

We report on the epitaxial growth of 100 nm thick triclinic γ-CoV2O6 thin films deposited by pulsed laser deposition on TiO2(100) substrate. The layers were grown in narrow experimental conditions, at 600 °C and 0.1 millibar oxygen pressure. X-ray diffraction and transmission electron microscopy evidenced the presence of two variants and the following epitaxial relation between the layers and the substrate: [001]TiO2(100)∥[0±10]γ-CoV2O6(100). Besides the magnetization steps expected in γ-CoV2O6, low temperature magnetic measurements performed along different crystalline axes show the existence of a strong anisotropy compatible with that expected from a one dimensional system, with the easy magnetization axis lying along the b direction (i.e., the Co chains).
Note: Thermal analysis of the long line source electron gun
Authors: Iqbal M. , Wasy A. , Lodhi M. A. K.
Published: May 2013

We performed thermal analysis for our previously reported [M. Iqbal, K. Masood, M. Rafiq, M. A. Chaudhry, and F. Aleem, Rev. Sci. Instrum. 74, 4616 (2003)10.1063/1.1614852], long linear filament electron gun assembly using ANSYS software. The source was set under a thermal load of 3000 °C, to evaluate temperature distribution, thermal strain, and heat flux at various components of the gun. We calculated the maximum heat flux (9.0 W/mm2) that produced a thermal strain of 0.05 at the focusing electrodes. However, the minimum value of the heat flux (0.3 W/mm2) was at the anode electrodes which correspond to a negligible thermal strain. The gun was validated experimentally showing a uniform cross section of the beam at the molybdenum work plate comparable to the size of the filament. Our experimental and theoretical results are in agreement. The gun had been in continuous operation for several hours at high temperatures without any thermal run-out.
Spherical magnetic nanoparticles fabricated by laser target evaporation
Authors: Safronov A. P. , Beketov I. V. , Komogortsev S. V. , Kurlyandskaya G. V. , Medvedev A. I. , Leiman D. V. , Larrañaga A. , Bhagat S. M.
Published: May 2013

Magnetic nanoparticles of iron oxide (MNPs) were prepared by the laser target evaporation technique (LTE). The main focus was on the fabrication of de-aggregated spherical maghemite MNPs with a narrow size distribution and enhanced effective magnetization. X-ray diffraction, transmission electron microscopy, magnetization and microwave absorption measurements were comparatively analyzed. The shape of the MNPs (mean diameter of 9 nm) was very close to being spherical. The lattice constant of the crystalline phase was substantially smaller than that of stoichiometric magnetite but larger than the lattice constant of maghemite. High value of Ms up to 300 K was established. The 300 K ferromagnetic resonance signal is a single line located at a field expected from spherical magnetic particles with negligible magnetic anisotropy. The maximum obtained concentration of water based ferrofluid was as high as 10g/l of magnetic material. In order to understand the temperature and field dependence of MNPs magnetization, we invoke the core-shell model. The nanoparticles is said to have a ferrimagnetic core (roughly 70 percent of the caliper size) while the shell consists of surface layers in which the spins are frozen having no long range magnetic order. The core-shell interactions were estimated in frame of random anisotropy model. The obtained assembly of de-aggregated nanoparticles is an example of magnetic nanofluid stable under ambient conditions even without an electrostatic stabilizer.
A Model of Conflict Resolution in Public Participation GIS for Land-Use Planning
Authors: Zhang Yongjun , Fung Tung
Published: May 2013

On the basis of the principle of sustainable development, land-use planning often requires a compromise between economic development and environmental conservation with social justice advocated. Given that values, perceptions, and ideas vary among stakeholders, land-use planning often involves a variety of conflicts with advocating public participation. In this paper we focus on extending the decision-support capabilities of public participation GIS (PPGIS) to facilitate conflict resolution. In the proposed model, conflicts are designated to be investigated and resolved from two levels, namely the value level and the specifics level. From the value level, a consensus-building process is proposed to help participants promote mutual understanding and achieve group agreement. At the specifics level, participants are asked to search for compromise space through discussions over particular concerns. The ultimate goal of the model is to help participants to work out the most acceptable land-use plan. Moreover, a PPGIS prototype with the conflict-resolution model was designed and implemented in the context of Lantau Island, Hong Kong. The study could contribute to PPGIS research and land-use planning by developing the methodology of conflict resolution. The challenges that we encountered and some future directions are also covered in the paper.
Neighborhood Contexts, Health, and Behavior: Understanding the Role of Scale and Residential Sorting
Authors: Spielman Seth E , Yoo Eun-Hye , Linkletter Crystal
Published: May 2013

Recent reviews in sociology, public health, and urban planning suggest small-scale geographic variations in urban environments are associated with an individual's health, behavior, and well-being. However, estimation of these ‘neighborhood effects' are complicated. One complicating factor is residential sorting: Individual characteristics such as race, age, and socioeconomic status are associated with behavior and health and these same individual-level factors are often geographically clustered within neighborhoods. This residential sorting leads to a correlation between individual and environmental determinants of behavior and health and poses problems for statistical inference. A second complicating factor is uncertainty about the geographic dimensions of a person's neighborhood. We explore these two potential confounders through a simulation experiment that generates synthetic cityscapes and synthetic behaviors for geolocated individuals. The simulation is used to develop a model of how residential sorting, urban structure, and the geographic definition of an individual's neighborhood affect our understanding of the association between the urban environment and behavior. We find that residential sorting does not systematically affect the magnitude of neighborhood effect estimates, however, the misrepresentation of the geographic dimensions of an individual's neighborhood leads to systematic bias in estimates of neighborhood effects. Unlike previous research on the modifiable areal unit problem we find a systematic relationship between the definition of geographic units of analysis and the magnitude of regression coefficients.
Mistletoe flora (Loranthaceae and Santalaceae) of the Kimberley, a tropical region in Western Australia, with particular reference to fire
Authors: Start A. N.
Published: May 2013

The mistletoe flora of the tropical Kimberley region of Western Australia was studied over a 30-year period, with a particular emphasis on distributions, use of hosts and effects of fire. The results were compared with those of a similar study undertaken in the Pilbara, a more arid tropical region in the same State. The flora consisted of one genus with three species in the Santalaceae and five genera with 22 species (one with two varieties) in the Loranthaceae. Amyema was the largest genus in both regions. Four species are regarded as Kimberley endemics but two of them may also occur in the Northern Territory. Most species occurred in three or more of five Kimberley bioregions. However, six species were recorded only from the North Kimberley where they were all rare. Host records included 165 species from 33 families. Fabaceae (particularly Acacia) and Myrtaceae (particularly Eucalyptus and Corymbia) were the most important. The perfect dichotomy between species using fabaceous and myrtaceous hosts in the Pilbara was strong but imperfect in the Kimberley. Fire responses of two species were not observed. Two (perhaps three) taxa were able to resprout, whereas the remaining taxa were killed if scorched. Most species occurred, at least occasionally, in relatively fire-safe refugia. Nevertheless, fire is eroding distributions of many species and may be threatening some, particularly the rare North Kimberley species.
Facile Domino Access to Unexpected Alkyl 3-Substituted-2-hydroxy-3,4-dihydro-2H-1,4-benzoxazine-2-carboxylates
Authors: Zhang Ya-Ru , Huang Xiao , Xu Dong-Cheng , Xie Jian-Wu
Published: May 2013

A new domino alkylation–cyclization–air-oxidation of 2-halo-1,3-dicarbonyl compounds with 2-aminophenols promoted by caesium salts under aerobic conditions has been developed. Unexpected alkyl 3-substituted-2-hydroxy-3,4-dihydro-2H-1,4-benzoxazine-2-carboxylates, rather than normal ethyl 3,4-dihydro-2H-1,4-benzoxazine-2-carboxylate, were exclusively obtained under mild conditions. A plausible mechanism for this unprecedented reaction is also given.
Survival and growth of perennial halophytes on saltland in a Mediterranean environment is affected by depth to watertable in summer as well as subsoil salinity
Authors: Barrett-Lennard E. G. , Bennett Sarita Jane , Altman M.
Published: May 2013

Farmers need methods for assessing the capability of saltland for productive use based on characteristics that are readily measurable at the paddock scale. We conducted experiments on saltland transects with gradients of salinity and depth to watertable at three sites in south-western Australia. Each was planted with five perennial species with at least some salt tolerance: samphire (Tecticornia mellaria K.A.Sheph.), river saltbush (Atriplex amnicola Paul G.Wilson), small leaf bluebush (Maireana brevifolia (R.Br.) Paul G.Wilson), saltwater couch (Paspalum vaginatum Sw.), and Rhodes grass (Chloris gayana Kunth). Survival and growth of species was related to depth to watertable in summer and average subsoil (0.25–0.50 m depth) electrical conductivity of the saturation extract (ECe). It has been hypothesised that plant zonation on land affected by dryland salinity is affected by the level of salinity and waterlogging on sites. While plant survival ≥60% could be associated with particular ranges of depth to watertable and soil salinity, our data suggest that the most important factor affecting survival and growth was the presence of shallow groundwater in summer. The range of depths to watertable in summer associated with ‘good survival’ (≥60%) was 0.7–1.0 m with samphire, 0.7–1.6 m with saltwater couch, 0.8–1.5 m with Rhodes grass, 0.7–2.4 m with river saltbush, and 0.9–2.4 m with small leaf bluebush. The subsoil ECe (95% confidence interval) associated with ‘good survival’ was 5–14 dS/m for Rhodes grass, 6–11 dS/m for small leaf bluebush, 7–11 dS/m for river saltbush, 6–16 dS/m for saltwater couch, and 27–65 dS/m for samphire. Growth of the perennial grasses was strongly affected by the presence of a shallow watertable in summer; the size of saltwater couch and Rhodes grass increased many-fold as watertable depths decreased from ~1.3 to 0.9 m from the soil surface.
Estimation of the steady-state cyclic electron flux around PSI in spinach leaf discs in white light, CO2-enriched air and other varied conditions
Authors: Kou Jiancun , Takahashi Shunichi , Oguchi Riichi , Fan Da-Yong , Badger Murray R. , Chow Wah Soon
Published: May 2013

Cyclic electron flux (CEF) around PSI is essential for efficient photosynthesis and aids photoprotection, especially in stressful conditions, but the difficulty in quantifying CEF is non-trivial. The total electron flux through PSI (ETR1) and the linear electron flux (LEFO2) through both photosystems in spinach leaf discs were estimated from the photochemical yield of PSI and the gross oxygen evolution rate, respectively, in CO2-enriched air. ΔFlux = ETR1 – LEFO2 is an upper estimate of CEF. Infiltration of leaf discs with 150 μM antimycin A did not affect LEFO2, but decreased ΔFlux 10-fold. ΔFlux was practically negligible below 350 μmol photons m−2 s−1, but increased linearly above it. The following results were obtained at 980 μmol photons m−2 s−1. ΔFlux increased 3-fold as the temperature increased from 5°C to 40°C. It did not decline at high temperature, even when LEFO2 decreased. ΔFlux increased by 80% as the relative water content of leaf discs decreased from 100 to 40%, when LEFO2 decreased 2-fold. The method of using ΔFlux as a non-intrusive upper estimate of steady-state CEF in leaf tissue appears reasonable when photorespiration is suppressed.
Impact of embryo donor adiposity, birthweight and gender on early postnatal growth, glucose metabolism and body composition in the young lamb
Authors: Wallace Jacqueline M. , Milne John S. , Aitken Raymond P. , Adam Clare L.
Published: May 2013

Intrauterine growth restriction (IUGR) is a risk factor for metabolic syndrome, notably when associated with rapid postnatal catch-up growth. A sheep paradigm was used to assess relationships between prenatal and early postnatal growth trajectories, metabolism and body composition. Singletons (single-sire embryo transfer from obese and control donors) were gestated and suckled by overnourished adolescent dams and categorised by birthweight as IUGR or normal (N). Gestation length was equivalent in both categories and all lambs were delivered spontaneously preterm (PT; mean (± s.e.m.) 139.8 ± 1.7 days; term = 145–147 days). The IUGR lambs were smaller at birth, but fractional growth rates (FGR) for eight anthropometry parameters were higher and independent of gender (except thorax girth; males (M) < females (F)). At Day 48, fasting glucose (IUGR > N; M > F) and first-phase insulin response (to 20 min; IUGR < N; M < F) after glucose were influenced by prenatal growth and gender. Embryo donor adiposity influenced glucose tolerance only. Plasma insulin, insulin-like growth factor-1 (M > F) and leptin (M < F) were influenced by gender but not prenatal growth. At necropsy (Day 77), IUGR plus PT lambs had decreased carcass and visceral organ weights, but carcass composition was not different from N plus PT. In contrast, M were heavier, with lower internal fat mass, carcass fat percentage and perirenal fat leptin mRNA than F. Therefore, IUGR was associated with increased postnatal FGR and altered glucose handling, but, without absolute catch-up growth, gender had the predominant influence on postnatal leptinaemia and adiposity.
Sex-specific epigenetic disruption and behavioral changes following low-dose in utero bisphenol A exposure
Authors: Kundakovic Marija , Gudsnuk Kathryn , Franks Becca , Madrid Jesus , Miller Rachel L. , Perera Frederica P. , Champagne Frances A.
Published: May 2013

Bisphenol A (BPA) is an estrogenic endocrine disruptor widely used in the production of plastics. Increasing evidence indicates that in utero BPA exposure affects sexual differentiation and behavior; however, the mechanisms underlying these effects are unknown. We hypothesized that BPA may disrupt epigenetic programming of gene expression in the brain. Here, we provide evidence that maternal exposure during pregnancy to environmentally relevant doses of BPA (2, 20, and 200 µg/kg/d) in mice induces sex-specific, dose-dependent (linear and curvilinear), and brain region-specific changes in expression of genes encoding estrogen receptors (ERs; ERα and ERβ) and estrogen-related receptor-γ in juvenile offspring. Concomitantly, BPA altered mRNA levels of epigenetic regulators DNA methyltransferase (DNMT) 1 and DNMT3A in the juvenile cortex and hypothalamus, paralleling changes in estrogen-related receptors. Importantly, changes in ERα and DNMT expression in the cortex (males) and hypothalamus (females) were associated with DNA methylation changes in the ERα gene. BPA exposure induced persistent, largely sex-specific effects on social and anxiety-like behavior, leading to disruption of sexually dimorphic behaviors. Although postnatal maternal care was altered in mothers treated with BPA during pregnancy, the effects of in utero BPA were not found to be mediated by maternal care. However, our data suggest that increased maternal care may partially attenuate the effects of in utero BPA on DNA methylation. Overall, we demonstrate that low-dose prenatal BPA exposure induces lasting epigenetic disruption in the brain that possibly underlie enduring effects of BPA on brain function and behavior, especially regarding sexually dimorphic phenotypes.
How vinculin regulates force transmission
Authors: Dumbauld David W. , Lee Ted T. , Singh Ankur , Scrimgeour Jan , Gersbach Charles A. , Zamir Evan A. , Fu Jianping , Chen Christopher S. , Curtis Jennifer E. , Craig Susan W. , García Andrés J.
Published: May 2013

Focal adhesions mediate force transfer between ECM-integrin complexes and the cytoskeleton. Although vinculin has been implicated in force transmission, few direct measurements have been made, and there is little mechanistic insight. Using vinculin-null cells expressing vinculin mutants, we demonstrate that vinculin is not required for transmission of adhesive and traction forces but is necessary for myosin contractility-dependent adhesion strength and traction force and for the coupling of cell area and traction force. Adhesion strength and traction forces depend differentially on vinculin head (VH) and tail domains. VHenhances adhesion strength by increasing ECM-bound integrin–talin complexes, independently from interactions with vinculin tail ligands and contractility. A full-length, autoinhibition-deficient mutant (T12) increases adhesion strength compared with VH, implying roles for both vinculin activation and the actin-binding tail. In contrast to adhesion strength, vinculin-dependent traction forces absolutely require a full-length and activated molecule; VHhas no effect. Physical linkage of the head and tail domains is required for maximal force responses. Residence times of vinculin in focal adhesions, but not T12 or VH, correlate with applied force, supporting a mechanosensitive model for vinculin activation in which forces stabilize vinculin’s active conformation to promote force transfer.
Deficits in human trisomy 21 iPSCs and neurons
Authors: Weick Jason P. , Held Dustie L. , Bonadurer George F. , Doers Matthew E. , Liu Yan , Maguire Chelsie , Clark Aaron , Knackert Joshua A. , Molinarolo Katharine , Musser Michael , Yao Lin , Yin Yingnan , Lu Jianfeng , Zhang Xiaoqing , Zhang Su-Chun , Bhattacharyya Anita
Published: May 2013

Down syndrome (trisomy 21) is the most common genetic cause of intellectual disability, but the precise molecular mechanisms underlying impaired cognition remain unclear. Elucidation of these mechanisms has been hindered by the lack of a model system that contains full trisomy of chromosome 21 (Ts21) in a human genome that enables normal gene regulation. To overcome this limitation, we created Ts21-induced pluripotent stem cells (iPSCs) from two sets of Ts21 human fibroblasts. One of the fibroblast lines had low level mosaicism for Ts21 and yielded Ts21 iPSCs and an isogenic control that is disomic for human chromosome 21 (HSA21). Differentiation of all Ts21 iPSCs yielded similar numbers of neurons expressing markers characteristic of dorsal forebrain neurons that were functionally similar to controls. Expression profiling of Ts21 iPSCs and their neuronal derivatives revealed changes in HSA21 genes consistent with the presence of 50% more genetic material as well as changes in non-HSA21 genes that suggested compensatory responses to oxidative stress. Ts21 neurons displayed reduced synaptic activity, affecting excitatory and inhibitory synapses equally. Thus, Ts21 iPSCs and neurons display unique developmental defects that are consistent with cognitive deficits in individuals with Down syndrome and may enable discovery of the underlying causes of and treatments for this disorder.
Sulfatides are required for renal adaptation to chronic metabolic acidosis
Authors: Stettner Paula , Bourgeois Soline , Marsching Christian , Traykova-Brauch Milena , Porubsky Stefan , Nordström Viola , Hopf Carsten , Koesters Robert , Sandhoff Roger , Wiegandt Herbert , Wagner Carsten A. , Gröne Hermann-Josef , Jennemann Richard
Published: May 2013

Urinary ammonium excretion by the kidney is essential for renal excretion of sufficient amounts of protons and to maintain stable blood pH. Ammonium secretion by the collecting duct epithelia accounts for the majority of urinary ammonium; it is driven by an interstitium-to-lumen NH
3
gradient due to the accumulation of ammonium in the medullary and papillary interstitium. Here, we demonstrate that sulfatides, highly charged anionic glycosphingolipids, are important for maintaining high papillary ammonium concentration and increased urinary acid elimination during metabolic acidosis. We disrupted sulfatide synthesis by a genetic approach along the entire renal tubule. Renal sulfatide-deficient mice had lower urinary pH accompanied by lower ammonium excretion. Upon acid diet, they showed impaired ammonuria, decreased ammonium accumulation in the papilla, and chronic hyperchloremic metabolic acidosis. Expression levels of ammoniagenic enzymes and Na
+
-K
+
/NH
4
+
-2Cl
−
cotransporter 2 were higher, and transepithelial NH
3
transport, examined by in vitro microperfusion of cortical and outer medullary collecting ducts, was unaffected in mutant mice. We therefore suggest that sulfatides act as counterions for interstitial ammonium facilitating its retention in the papilla. This study points to a seminal role of sulfatides in renal ammonium handling, urinary acidification, and acid–base homeostasis.
Receptor-like kinase SOBIR1/EVR interacts with receptor-like proteins in plant immunity against fungal infection
Authors: Liebrand Thomas W. H. , van den Berg Grardy C. M. , Zhang Zhao , Smit Patrick , Cordewener Jan H. G. , America Antoine H. P. , Sklenar Jan , Jones Alexandra M. E. , Tameling Wladimir I. L. , Robatzek Silke , Thomma Bart P. H. J. , Joosten Matthieu H. A. J.
Published: May 2013

The plant immune system is activated by microbial patterns that are detected as nonself molecules. Such patterns are recognized by immune receptors that are cytoplasmic or localized at the plasma membrane. Cell surface receptors are represented by receptor-like kinases (RLKs) that frequently contain extracellular leucine-rich repeats and an intracellular kinase domain for activation of downstream signaling, as well as receptor-like proteins (RLPs) that lack this signaling domain. It is therefore hypothesized that RLKs are required for RLPs to activate downstream signaling. The RLPs Cf-4 and Ve1 of tomato (
Solanum lycopersicum
) mediate resistance to the fungal pathogens
Cladosporium fulvum
and
Verticillium dahliae
, respectively. Despite their importance, the mechanism by which these immune receptors mediate downstream signaling upon recognition of their matching ligand, Avr4 and Ave1, remained enigmatic. Here we show that the tomato ortholog of the
Arabidopsis thaliana
RLK Suppressor Of BIR1-1/Evershed (SOBIR1/EVR) and its close homolog
S. lycopersicum
(
Sl
)SOBIR1-like interact
in planta
with both Cf-4 and Ve1 and are required for the Cf-4– and Ve1-mediated hypersensitive response and immunity. Tomato SOBIR1/EVR interacts with most of the tested RLPs, but not with the RLKs FLS2, SERK1, SERK3a, BAK1, and CLV1. SOBIR1/EVR is required for stability of the Cf-4 and Ve1 receptors, supporting our observation that these RLPs are present in a complex with SOBIR1/EVR
in planta
. We show that SOBIR1/EVR is essential for RLP-mediated immunity and propose that the protein functions as a regulatory RLK of this type of cell-surface receptors.
Molecular mechanism and functional role of brefeldin A-mediated ADP-ribosylation of CtBP1/BARS
Authors: Colanzi Antonino , Grimaldi Giovanna , Catara Giuliana , Valente Carmen , Cericola Claudia , Liberali Prisca , Ronci Maurizio , Lalioti Vasiliki S. , Bruno Agostino , Beccari Andrea R. , Urbani Andrea , De Flora Antonio , Nardini Marco , Bolognesi Martino , Luini Alberto , Corda Daniela
Published: May 2013

ADP-ribosylation is a posttranslational modification that modulates the functions of many target proteins. We previously showed that the fungal toxin brefeldin A (BFA) induces the ADP-ribosylation of C-terminal–binding protein-1 short-form/BFA–ADP-ribosylation substrate (CtBP1-S/BARS), a bifunctional protein with roles in the nucleus as a transcription factor and in the cytosol as a regulator of membrane fission during intracellular trafficking and mitotic partitioning of the Golgi complex. Here, we report that ADP-ribosylation of CtBP1-S/BARS by BFA occurs via a nonconventional mechanism that comprises two steps: (i) synthesis of a BFA–ADP-ribose conjugate by the ADP-ribosyl cyclase CD38 and (ii) covalent binding of the BFA–ADP-ribose conjugate into the CtBP1-S/BARS NAD+-binding pocket. This results in the locking of CtBP1-S/BARS in a dimeric conformation, which prevents its binding to interactors known to be involved in membrane fission and, hence, in the inhibition of the fission machinery involved in mitotic Golgi partitioning. As this inhibition may lead to arrest of the cell cycle in G2, these findings provide a strategy for the design of pharmacological blockers of cell cycle in tumor cells that express high levels of CD38.
Innate pro–B-cell progenitors protect against type 1 diabetes by regulating autoimmune effector T cells
Authors: Montandon Ruddy , Korniotis Sarantis , Layseca-Espinosa Esther , Gras Christophe , Mégret Jérôme , Ezine Sophie , Dy Michel , Zavala Flora
Published: May 2013

Significance

Immunoregulatory poperties have been principally ascribed to various mature immune cell types, including regulatory B cells. An immature B-cell progenitor population endowed with suppressive properties per se or after differentiation into more mature regulatory B cells has not been demonstrated as yet. We now describe a pro–B-cell progenitor population that emerged upon stimulation with the Toll-like receptor-9 ligand CpG and prevented disease upon adoptive transfer into autoimmune type 1 diabetes-prone mice. Effector T cells were the target of immunoregulatory pro-B cells and of their mature progeny. Such protective pro-B cells could be instrumental for cell therapy of autoimmune diseases.
Soil biotic legacy effects of extreme weather events influence plant invasiveness
Authors: Meisner Annelein , De Deyn Gerlinde B. , de Boer Wietse , van der Putten Wim H.
Published: May 2013

Climate change is expected to increase future abiotic stresses on ecosystems through extreme weather events leading to more extreme drought and rainfall incidences [Jentsch A, et al. (2007)
Front Ecol Environ
5(7):365–374]. These fluctuations in precipitation may affect soil biota, soil processes [Evans ST, Wallenstein MD (2012) Biogeochemistry 109:101–116], and the proportion of exotics in invaded plant communities [Jiménez MA, et al. (2011) Ecol Lett 14:1277–1235]. However, little is known about legacy effects in soil on the performance of exotics and natives in invaded plant communities. Here we report that drought and rainfall effects on soil processes and biota affect the performance of exotics and natives in plant communities. We performed two mesocosm experiments. In the first experiment, soil without plants was exposed to drought and/or rainfall, which affected soil N availability. Then the initial soil moisture conditions were restored, and a mixed community of co-occurring natives and exotics was planted and exposed to drought during growth. A single stress before or during growth decreased the biomass of natives, but did not affect exotics. A second drought stress during plant growth resetted the exotic advantage, whereas native biomass was not further reduced. In the second experiment, soil inoculation revealed that drought and/or rainfall influenced soil biotic legacies, which promoted exotics but suppressed natives. Our results demonstrate that extreme weather events can cause legacy effects in soil biota, promoting exotics and suppressing natives in invaded plant communities, depending on the type, frequency, and timing of extreme events.
Heightened emotional contagion in mild cognitive impairment and Alzheimer’s disease is associated with temporal lobe degeneration
Authors: Sturm Virginia E. , Yokoyama Jennifer S. , Seeley William W. , Kramer Joel H. , Miller Bruce L. , Rankin Katherine P.
Published: May 2013

Emotional changes are common in mild cognitive impairment (MCI) and Alzheimer’s disease (AD). Intrinsic connectivity imaging studies suggest that default mode network degradation in AD is accompanied by the release of an emotion-relevant salience network. We investigated whether emotional contagion, an evolutionarily conserved affect-sharing mechanism, is higher in MCI and AD secondary to biological alterations in neural networks that support emotion. We measured emotional contagion in 237 participants (111 healthy controls, 62 patients with MCI, and 64 patients with AD) with the Interpersonal Reactivity Index Personal Distress subscale. Depressive symptoms were evaluated with the Geriatric Depression Scale. Participants underwent structural MRI, and voxel-based morphometry was used to relate whole-brain maps to emotional contagion. Analyses of covariance found significantly higher emotional contagion at each stage of disease progression [controls < MCI (
P
< 0.01) and MCI < AD (
P
< 0.001)]. Depressive symptoms were also higher in patients compared with controls [controls < MCI (
P
< 0.01) and controls < AD (
P
< 0.0001)]. Higher emotional contagion (but not depressive symptoms) was associated with smaller volume in right inferior, middle, and superior temporal gyri (
P

FWE

< 0.05); right temporal pole, anterior hippocampus, parahippocampal gyrus; and left middle temporal gyrus (all
P
< 0.001, uncorrected). These findings suggest that in MCI and AD, neurodegeneration of temporal lobe structures important for affective signal detection and emotion inhibition are associated with up-regulation of emotion-generating mechanisms. Emotional contagion, a quantifiable index of empathic reactivity that is present in other species, may be a useful tool with which to study emotional alterations in animal models of AD.
CCT chaperonin complex is required for efficient delivery of anthrax toxin into the cytosol of host cells
Authors: Slater Louise H. , Hett Erik C. , Clatworthy Anne E. , Mark Kevin G. , Hung Deborah T.
Published: May 2013

Bacterial toxins have evolved successful strategies for coopting host proteins to access the cytosol of host cells. Anthrax lethal factor (LF) enters the cytosol through pores in the endosomal membrane formed by anthrax protective antigen. Although in vitro models using planar lipid bilayers have shown that translocation can occur in the absence of cellular factors, recent studies using intact endosomes indicate that host factors are required for translocation in the cellular environment. In this study, we describe a high-throughput shRNA screen to identify host factors required for anthrax lethal toxin-induced cell death. The cytosolic chaperonin complex chaperonin containing t-complex protein 1 (CCT) was identified, and subsequent studies showed that CCT is required for efficient delivery of LF and related fusion proteins into the cytosol. We further show that knockdown of CCT inhibits the acid-induced delivery of LF and the fusion protein LFN-Bla (N terminal domain of LF fused to β-lactamase) across the plasma membrane of intact cells. Together, these results suggest that CCT is required for efficient delivery of enzymatically active toxin to the cytosol and are consistent with a direct role for CCT in translocation of LF through the protective antigen pore.
Ypt1 recruits the Atg1 kinase to the preautophagosomal structure
Authors: Wang Juan , Menon Shekar , Yamasaki Akinori , Chou Hui-Ting , Walz Thomas , Jiang Yu , Ferro-Novick Susan
Published: May 2013

When macroautophagy, a catabolic process that rids the cells of unwanted proteins, is initiated, 30–60 nm Atg9 vesicles move from the Golgi to the preautophagosomal structure (PAS) to initiate autophagosome formation. The Rab GTPase Ypt1 and its mammalian homolog Rab1 regulate macroautophagy and two other trafficking events: endoplasmic reticulum-Golgi and intra-Golgi traffic. How a Rab, which localizes to three distinct cellular locations, achieves specificity is unknown. Here we show that transport protein particle III (TRAPPIII), a conserved autophagy-specific guanine nucleotide exchange factor for Ypt1/Rab1, is recruited to the PAS by Atg17. We also show that activated Ypt1 recruits the putative membrane curvature sensor Atg1 to the PAS, bringing it into proximity to its binding partner Atg17. Since Atg17 resides at the PAS, these events ensure that Atg1 will specifically localize to the PAS and not to the other compartments where Ypt1 resides. We propose that Ypt1 regulates Atg9 vesicle tethering by modulating the delivery of Atg1 to the PAS. These events appear to be conserved in higher cells.
Giant surfactants provide a versatile platform for sub-10-nm nanostructure engineering
Authors: Yu Xinfei , Yue Kan , Hsieh I-Fan , Li Yiwen , Dong Xue-Hui , Liu Chang , Xin Yu , Wang Hsiao-Fang , Shi An-Chang , Newkome George R. , Ho Rong-Ming , Chen Er-Qiang , Zhang Wen-Bin , Cheng Stephen Z. D.
Published: May 2013

The engineering of structures across different length scales is central to the design of novel materials with controlled macroscopic properties. Herein, we introduce a unique class of self-assembling materials, which are built upon shape- and volume-persistent molecular nanoparticles and other structural motifs, such as polymers, and can be viewed as a size-amplified version of the corresponding small-molecule counterparts. Among them, “giant surfactants” with precise molecular structures have been synthesized by “clicking” compact and polar molecular nanoparticles to flexible polymer tails of various composition and architecture at specific sites. Capturing the structural features of small-molecule surfactants but possessing much larger sizes, giant surfactants bridge the gap between small-molecule surfactants and block copolymers and demonstrate a duality of both materials in terms of their self-assembly behaviors. The controlled structural variations of these giant surfactants through precision synthesis further reveal that their self-assemblies are remarkably sensitive to primary chemical structures, leading to highly diverse, thermodynamically stable nanostructures with feature sizes around 10 nm or smaller in the bulk, thin-film, and solution states, as dictated by the collective physical interactions and geometric constraints. The results suggest that this class of materials provides a versatile platform for engineering nanostructures with sub-10-nm feature sizes. These findings are not only scientifically intriguing in understanding the chemical and physical principles of the self-assembly, but also technologically relevant, such as in nanopatterning technology and microelectronics.
Pathogenic plasticity of Kv7.2/3 channel activity is essential for the induction of tinnitus
Authors: Li Shuang , Choi Veronica , Tzounopoulos Thanos
Published: May 2013

Tinnitus, the perception of phantom sound, is often a debilitating condition that affects many millions of people. Little is known, however, about the molecules that participate in the induction of tinnitus. In brain slices containing the dorsal cochlear nucleus, we reveal a tinnitus-specific increase in the spontaneous firing rate of principal neurons (hyperactivity). This hyperactivity is observed only in noise-exposed mice that develop tinnitus and only in the dorsal cochlear nucleus regions that are sensitive to high frequency sounds. We show that a reduction in Kv7.2/3 channel activity is essential for tinnitus induction and for the tinnitus-specific hyperactivity. This reduction is due to a shift in the voltage dependence of Kv7 channel activation to more positive voltages. Our in vivo studies demonstrate that a pharmacological manipulation that shifts the voltage dependence of Kv7 to more negative voltages prevents the development of tinnitus. Together, our studies provide an important link between the biophysical properties of the Kv7 channel and the generation of tinnitus. Moreover, our findings point to previously unknown biological targets for designing therapeutic drugs that may prevent the development of tinnitus in humans.
Glycolipozyme MPIase is essential for topology inversion of SecG during preprotein translocation
Authors: Moser Michael , Nagamori Shushi , Huber Maria , Tokuda Hajime , Nishiyama Ken-ichi
Published: May 2013

Presecretory proteins are translocated across biological membranes through protein-conducting channels such as Sec61 (eukaryotes) and SecYEG (bacteria). SecA, a translocation ATPase, pushes preproteins out with dynamic structural changes through SecYEG. SecG, a subunit of the SecYEG channel possessing two transmembrane stretches (TMs), undergoes topology inversion coupled with SecA-dependent translocation. Recently, we characterized membrane protein integrase (MPIase), a glycolipozyme involved in not only protein integration into membranes but also preprotein translocation. We report here that SecG inversion occurs only when MPIase associates with SecYEG. We also found that MPIase modulates the dimer orientation of SecYEG. Cysteine-scanning mutagenesis mapped SecG TM 2 to a relatively hydrophilic environment. The dimer formation of SecG, crosslinked at TM 2, was not observed on SecG inversion, indicating that SecYEG undergoes a dynamic structural change during preprotein translocation.
Hybrid DNA virus in Chinese patients with seronegative hepatitis discovered by deep sequencing
Authors: Xu Baoyan , Zhi Ning , Hu Gangqing , Wan Zhihong , Zheng Xiaobin , Liu Xiaohong , Wong Susan , Kajigaya Sachiko , Zhao Keji , Mao Qing , Young Neal S.
Published: May 2013

Seronegative hepatitis—non-A, non-B, non-C, non-D, non-E hepatitis—is poorly characterized but strongly associated with serious complications. We collected 92 sera specimens from patients with non-A–E hepatitis in Chongqing, China between 1999 and 2007. Ten sera pools were screened by Solexa deep sequencing. We discovered a 3,780-bp contig present in all 10 pools that yielded BLASTx E scores of 7e-05–0.008 against parvoviruses. The complete sequence of the
in silico
-assembled 3,780-bp contig was confirmed by gene amplification of overlapping regions over almost the entire genome, and the virus was provisionally designated NIH-CQV. Further analysis revealed that the contig was composed of two major ORFs. By protein BLAST, ORF1 and ORF2 were most homologous to the replication-associated protein of bat circovirus and the capsid protein of porcine parvovirus, respectively. Phylogenetic analysis indicated that NIH-CQV is located at the interface of
Parvoviridae
and
Circoviridae
. Prevalence of NIH-CQV in patients was determined by quantitative PCR. Sixty-three of 90 patient samples (70%) were positive, but all those from 45 healthy controls were negative. Average virus titer in the patient specimens was 1.05 e4 copies/µL. Specific antibodies against NIH-CQV were sought by immunoblotting. Eighty-four percent of patients were positive for IgG, and 31% were positive for IgM; in contrast, 78% of healthy controls were positive for IgG, but all were negative for IgM. Although more work is needed to determine the etiologic role of NIH-CQV in human disease, our data indicate that a parvovirus-like virus is highly prevalent in a cohort of patients with non-A–E hepatitis.
HMGA2/TET1/HOXA9 signaling pathway regulates breast cancer growth and metastasis
Authors: Sun Miao , Song Chun-Xiao , Huang Hao , Frankenberger Casey A. , Sankarasharma Devipriya , Gomes Suzana , Chen Ping , Chen Jianjun , Chada Kiran K. , He Chuan , Rosner Marsha R.
Published: May 2013

The ten–eleven translocation (TET) family of methylcytosine dioxygenases initiates demethylation of DNA and is associated with tumorigenesis in many cancers; however, the mechanism is mostly unknown. Here we identify upstream activators and downstream effectors of
TET1
in breast cancer using human breast cancer cells and a genetically engineered mouse model. We show that depleting the architectural transcription factor high mobility group AT-hook 2 (
HMGA2
) induces
TET1
. TET1 binds and demethylates its own promoter and the promoter of homeobox A (
HOXA
) genes, enhancing its own expression and stimulating expression of
HOXA
genes including
HOXA7
and
HOXA9
. Both TET1 and HOXA9 suppress breast tumor growth and metastasis in mouse xenografts. The genes comprising the HMGA2–TET1–HOXA9 pathway are coordinately regulated in breast cancer and together encompass a prognostic signature for patient survival. These results implicate the HMGA2–TET1–HOX signaling pathway in the epigenetic regulation of human breast cancer and highlight the importance of targeting methylation in specific subpopulations as a potential therapeutic strategy.
Proteasome overload is a common stress factor in multiple forms of inherited retinal degeneration
Authors: Lobanova Ekaterina S. , Finkelstein Stella , Skiba Nikolai P. , Arshavsky Vadim Y.
Published: May 2013

Inherited retinal degenerations, caused by mutations in over 100 individual genes, affect approximately 2 million people worldwide. Many of the underlying mutations cause protein misfolding or mistargeting in affected photoreceptors. This places an increased burden on the protein folding and degradation machinery, which may trigger cell death. We analyzed how these cellular functions are affected in degenerating rods of the transducin γ-subunit (Gγ
1
) knockout mouse. These rods produce large amounts of transducin β-subunit (Gβ
1
), which cannot fold without Gγ
1
and undergoes intracellular proteolysis instead of forming a transducin βγ-subunit complex. Our data revealed that the most critical pathobiological factor leading to photoreceptor cell death in these animals is insufficient capacity of proteasomes to process abnormally large amounts of misfolded protein. A decrease in the Gβ
1
production in Gγ
1
knockout rods resulted in a significant reduction in proteasomal overload and caused a striking reversal of photoreceptor degeneration. We further demonstrated that a similar proteasomal overload takes place in photoreceptors of other mutant mice where retinal degeneration has been ascribed to protein mistargeting or misfolding, but not in mice whose photoreceptor degenerate as a result of abnormal phototransduction. These results establish the prominence of proteasomal insufficiency across multiple degenerative diseases of the retina, thereby positioning proteasomes as a promising therapeutic target for treating these debilitating conditions.