bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanism of amorphous state formation, crystalline structure, and hyperfine interactions in DyMn6−xGe6Fex (≤x≤6) alloys
Authors: Śniadecki Z. , Mielniczuk B. , Idzikowski B. , Greneche J.-M. , Rößler U. K.
Published: October 2010

Metallic glass formation is observed in rapidly quenched quaternary DyMn6−xGe6Fex (0≤x≤6) alloys. The easy formation of amorphous states competes with the nucleation of ternary 1:6:6 rare earth-transition metal-metal compounds DyMn6Ge6 and DyFe6Ge6. The ribbon shaped samples were quenched and investigated by x-ray diffraction, differential scanning calorimetry, and F57e Mössbauer spectrometry. Melt-spun alloys from the series of DyMn6−xGe6Fex with x=0, 2≤x≤3, and x=6 do not display an amorphous state but a crystalline chemically disordered structure similar to that of TbCu7- or TbFe6Sn6-type (space group P6/mmm). Amorphous samples exhibit two crystallization steps but there is no clear evidence for a glass transition effect in the calorimetric data. The Kissinger analysis was performed to calculate the effective activation energy Ea, which is equal to 345±20 kJ/mol for amorphous DyMn5.5Ge6Fe0.5 alloy. Mössbauer spectra at 77 and 300 K consist of either magnetic sextets or quadrupolar doublets for high and low Fe content, respectively. The features reflect the dilution of Fe on crystallographic sites and the subsequent increase in topological and chemical disorder when the Mn content increases. The Miedema's semiempirical model was used to calculate the formation enthalpies of amorphous alloys (ΔHform). The calculated values are consistent with experimental results. The present model allows thus to explain the better glass forming ability for the compositions with high Mn content, where ΔHform is the most negative.
Polarization relaxation mechanism of Ba0.6Sr0.4TiO3/Ni0.8Zn0.2Fe2O4 composite with giant dielectric constant and high permeability
Authors: Yang Haibo , Wang Hong , He Li , Shui Li , Yao Xi
Published: October 2010

Ba 0.6 Sr 0.4 TiO 3 / Ni 0.8 Zn 0.2 Fe 2 O 4 (BST/NZO) composites were synthesized via the conventional solid-state reaction method. The phase composition and surface morphology of the composites were investigated using x-ray diffractometry and scanning electron microscope, respectively. The dielectric and magnetic properties of the composites were studied. The results show that the BST/NZO composites have giant dielectric constants and very high permeabilities. For the 10%BST/90%NZO composite, the dielectric constant and permeability in low frequency range are about 150 000 and 29, respectively. The giant dielectric behavior of the BST/NZO composites is mainly attributed to the Maxwell–Wagner polarization.
Performance analysis of thermophotovoltaic system with an equivalent cut-off blackbody emitter
Authors: Zhai Xiaofeng , Lai Jianjun , Liang Huafeng , Chen Sihai
Published: October 2010

The general thermophotovoltaic (TPV) system can get high efficiency, by adding a spectral filter or using a selective thermal emitter, but the output power density is very low. However, the microgap TPV system can get high output power density, but the efficiency is relatively low, due to the difficulty of cropping the emissive spectrum of the thermal emitter in the near field. Thus, the ultimate goal of designing a TPV system is to get higher efficiency and higher output power density, simultaneously. Theoretically, the way used in this paper is to place a perfect edge reflector at the back of the PV diode to achieve an equivalent cut-off blackbody emitter. The performance of this ideal TPV system is calculated based on a fluctuational electrodynamics model. According to the simulation results, in the far field, the performance of this ideal TPV system is identical to the well known thermodynamic limit. In the near field, this ideal TPV system can simultaneously get higher efficiency and higher output power density. By assuming the emitter with a frequency-independent permittivity, a permittivity-match emitter is proposed to maximize the output power density, there is an optimal vacuum distance between 110 and 160 nm to maximize the efficiency, and near-field effect disappears for TPV system with a zero-refractivity emitter.
Influence of Ag thickness on structural, optical, and electrical properties of ZnS/Ag/ZnS multilayers prepared by ion beam assisted deposition
Authors: Leng Jian , Yu Zhinong , Xue Wei , Zhang Ting , Jiang Yurong , Zhang Jie , Zhang Dongpu
Published: October 2010

The structural, optical, and electrical characteristics of zinc sulfide (ZnS)/Ag/ZnS (ZAZ) multilayer films prepared by ion beam assisted deposition on k9 glass have been investigated as a function of Ag layer thickness. The characteristics of ZAZ multilayer are significantly improved up insertion of optimal Ag thickness between ZnS layers. The results show that due to bombardment of Ar ion beam, distinct Ag islands evolve into continuous Ag films at a thin Ag thickness of about 4 nm. The thinner Ag film as a thickness of 2 nm leads to high sheet resistance and low transmittance for the interface scattering induced by the Ag islands or noncontinuous films; and when the Ag thickness is over 4 nm, the ZAZ multilayer exhibits a remarkably reduced sheet resistance between 7–80 Ω/sq for the increase in carrier concentration and mobility of Ag layer, and a high transmittance over 90% for the interference phenomena of multilayers and low absorption and surface scattering of Ag layer. The ZAZ multilayer with 14 nm Ag film has a figure of merit up to 6.32×10−2 Ω−1, an average transmittance over 92% and a sheet resistance of 7.1 Ω/sq. The results suggest that ZAZ film has better optoelectrical properties than conditional indium tin oxide single layer.
Structural and ferroelectric properties of epitaxial Bi5Ti3FeO15 and natural-superlattice-structured Bi4Ti3O12–Bi5Ti3FeO15 thin films
Authors: Nakashima Seiji , Fujisawa Hironori , Ichikawa Satoshi , Park Jung Min , Kanashima Takeshi , Okuyama Masanori , Shimizu Masaru
Published: October 2010

Bismuth-layer-structured multiferroic Bi5Ti3FeO15 (BTFO15) (number of pseudoperovskite blocks, m=4) and natural-superlattice-structured Bi4Ti3O12–Bi5Ti3FeO15 (BIT-BTFO15) (m=3 or 4) thin films were prepared on (001)-oriented and (110)-oriented La-doped (3.73 wt %) SrTiO3 (La-STO) single-crystal substrates using pulsed laser deposition. X-ray diffraction patterns of these thin films on (001) La-STO single crystals indicated that the obtained thin films were single-phase (00l)-oriented layered perovskite, and that the BIT-BTFO15 (m=3 or 4) natural-superlattice structure was also obtained. On (110) La-STO single crystal, layered perovskite (11l)-oriented thin films were also obtained. Moreover, cross-sectional transmission electron microscope images of these thin films revealed four pseudoperovskite blocks (m=4) in the BTFO15 thin films, and an intergrowth structure of three and four pseudoperovskite blocks (m=3 or 4) in BIT-BTFO15 sandwiched by two (Bi2O2)2+ layers. In ferroelectric D-E hysteresis loop measurements, BTFO15 (m=4) and BIT-BTFO15 (m=3 or 4) thin films on (110) La-doped STO single crystals produced clear ferroelectric hysteresis loops with double remanent polarizations (2Pr) of 49 μC/cm2 and 44 μC/cm2, respectively. However, BTFO15 and BIT-BTFO15 thin films on (001) La-doped STO single crystals had paraelectric characteristics. These results demonstrate that the spontaneous polarization vectors of the BTFO15 and BIT-BTFO15 thin films were parallel to the a axis of their unit cells.
On Duffin–Kemmer–Petiau particles with a mixed minimal-nonminimal vector coupling and the nondegenerate bound-states for the one-dimensional inversely linear background
Authors: de Castro A. S.
Published: October 2010

The problem of spin-0 and spin-1 bosons in the background of a general mixing of minimal and nonminimal vector inversely linear potentials is explored in a unified way in the context of the Duffin–Kemmer–Petiau theory. It is shown that spin-0 and spin-1 bosons behave effectively in the same way. An orthogonality criterion is set up and it is used to determine uniquely the set of solutions as well as to show that even-parity solutions do not exist.
Topological insulator Bi2Se3 thin films grown on double-layer graphene by molecular beam epitaxy
Authors: Song Can-Li , Wang Yi-Lin , Jiang Ye-Ping , Zhang Yi , Chang Cui-Zu , Wang Lili , He Ke , Chen Xi , Jia Jin-Feng , Wang Yayu , Fang Zhong , Dai Xi , Xie Xin-Cheng , Qi Xiao-Liang , Zhang Shou-Cheng , Xue Qi-Kun , Ma Xucun
Published: October 2010

Atomically flat thin films of topological insulator Bi2Se3 have been grown on double-layer graphene formed on 6H–SiC(0001) substrate by molecular beam epitaxy. By a combined study of reflection high energy electron diffraction and scanning tunneling microscopy, we identified the Se-rich condition and temperature criterion for layer-by-layer growth of epitaxial Bi2Se3 films. The as-grown films without doping exhibit a low defect density of 1.0±0.2×1011/cm2, and become a bulk insulator at a thickness of ten quintuple layers, as revealed by in situ angle resolved photoemission spectroscopy measurement.
Orientation-dependent work function of graphene on Pd(111)
Authors: Murata Y. , Starodub E. , Kappes B. B. , Ciobanu C. V. , Bartelt N. C. , McCarty K. F. , Kodambaka S.
Published: October 2010

Selected-area diffraction establishes that at least six different in-plane orientations of monolayer graphene on Pd(111) can form during graphene growth. From the intensities of low-energy electron microscopy images as a function of incident electron energy, we find that the work functions of the different rotational domains vary by up to 0.15 eV. Density functional theory calculations show that these significant variations result from orientation-dependent charge transfer from Pd to graphene. These findings suggest that graphene electronics will require precise control over the relative orientation of the graphene and metal contacts.
Fracture toughness, hardness, and Young’s modulus of tantalum nanocrystalline films
Authors: Guisbiers G. , Herth E. , Buchaillot L. , Pardoen T.
Published: October 2010

The fracture toughness, hardness, and Young’s modulus of tantalum thin films are investigated based on nanoindentation measurements. A lower estimate of the fracture toughness of a 100 nm tantalum film is 0.28±0.07 MPa m1/2. The hardness increases when reducing the film thickness whereas Young’s modulus decreases slightly. More precisely, the hardness of the 100 nm thick film is four times higher than the bulk behavior. A simple theoretical model, based on the connection between Young’s modulus and melting temperature, predicts an inverse grain size variation in Young’s modulus confirmed by experiments.
Triggered single-photon emission from electrically excited quantum dots in the red spectral range
Authors: Reischle M. , Kessler C. , Schulz W.-M. , Eichfelder M. , Roßbach R. , Jetter M. , Michler P.
Published: October 2010

Pulsed electrical excitation was used to excite single InP/Ga0.51In0.49P quantum dots and obtain triggered single-photon emission in the red spectral range at an excitation repetition rate of up to 200 MHz. Increased repetition rates are prevented by the finite decay-time, and autocorrelation measurements look similar to what is expected for dc injection above 1 GHz. Finally, it is shown that negative voltage pulses can increase the decay-rate considerably such that 1 GHz excitation rates should be possible.
Anomalous Raman features of silicon nanowires under high pressure
Authors: Bhattacharyya Somnath , Churochkin Dmitry , Erasmus Rudolph M.
Published: October 2010

The potential of silicon nanowires (SiNWs), (diameter <10 nm) to transform into rigid bundlelike structures with distinct phonon confinement under high pressure (≤15 GPa), instead of amorphizing as per previous reports, is demonstrated using in situ Raman spectroscopy. The observed splitting of the second order transverse optical (2TO) Raman mode into 2TO(L) and 2TO(W) phonon modes at ≥5 GPa establishes a highly anisotropic and mode-dependent pressure response of these SiNWs. Properties of these structures are superior compared to other nanostructured silicon and bulk-Si in terms of increased linear modulus, more localized phonon confinement, and less anharmonicity.
Disorder and electron interaction control in low-doped silicon metal-oxide-semiconductor field effect transistors
Authors: Ferrus T. , George R. , Barnes C. H. W. , Pepper M.
Published: October 2010

We fabricated silicon metal-oxide-semiconductor field effect transistors where an additional sodium-doped layer was incorporated into the oxide to create potential fluctuations at the Si–SiO2 interface. The amplitude of these fluctuations is controlled by both the density of ions in the oxide and their position relative to the Si–SiO2 interface. Owing to the high mobility of the ions at room temperature, it is possible to move them with the application of a suitable electric field. We show that, in this configuration, such a device can be used to control both the disorder and the electron-electron interaction strength at the Si–SiO2 interface.
CdTe surfaces: Characterizing dynamical processes with first-principles metadynamics
Authors: Pietrucci Fabio , Gerra Guido , Andreoni Wanda
Published: October 2010

We study dynamical processes at CdTe surfaces using ab initio metadynamics simulations. The c(2×2) to (2×1) transition of the Te-terminated (001) surface is found to involve a “c(2×2)+(2×1)” intermediate, consistent with experiment, and crossing of ∼0.5 eV free-energy barriers at 400 K. Higher free-energy barriers (1.6–2.5 eV) are estimated for desorption of a Cd ion from Cd-terminated (001) and a CdTe unit from either Te-terminated (001) or (110) surfaces. Cd and Te exhibit a very different behavior. Concomitant to desorption, Te surface diffusion is observed as well as Te dimerization and bulk-surface Cd exchange events.
Tip-enhanced Raman spectroscopic imaging of localized defects in carbon nanotubes
Authors: Georgi Carsten , Hartschuh Achim
Published: October 2010

We used tip-enhanced Raman spectroscopy to study defect induced D-band Raman scattering in metallic single-walled carbon nanotubes with a spatial resolution of 15 nm. The spatial extent of the D-band signal in the vicinity of localized defects is visualized and found to be about 2 nm only. Using the strong optical fields underneath the tip, we photogenerate localized defects and derive a relation between defect density and resulting D-band intensity.
p21-activated kinase 4 regulates ovarian cancer cell proliferation, migration, and invasion and contributes to poor prognosis in patients
Authors: Siu Michelle K. Y. , Chan Hoi Yan , Kong Daniel S. H. , Wong Esther S. Y. , Wong Oscar G. W. , Ngan Hextan Y. S. , Tam Kar Fai , Zhang Hongquan , Li Zhilun , Chan Queeny K. Y. , Tsao Sai Wah , Strömblad Staffan , Cheung Annie N. Y.
Published: October 2010

Ovarian cancer is a lethal gynecological malignancy, and to improve survival, it is important to identify novel prognostic and therapeutic targets. In this study, we present a role for p21-activated kinase 4 (Pak4) in ovarian cancer progression. We show a significant association between increased expression of Pak4 and its activated form, phosphorylated (p)-Pak4 Ser
474
, with metastasis of ovarian cancers, shorter overall and disease-free survival, advanced stage and high-grade cancers, serous/clear cell histological subtypes, and reduced chemosensitivity. Pak4 overexpression was also observed in ovarian cancer cell lines. Pak4 and p-Pak4 expression were detected both in the nucleus and cytoplasm of ovarian cancer cells, in vitro as well as in vivo. Stable knockdown of Pak4 in ovarian cancer cell lines led to reduced cell migration, invasion, and proliferation, along with reduced c-Src, ERK1/2, and epidermal growth factor receptor (EGFR) activation and decreased matrix metalloproteinase 2 (MMP2) expression. Conversely, Pak4 overexpression promoted ovarian cancer cell migration and invasion in a c-Src, MEK-1, MMP2, and kinase-dependent manner, and induced cell proliferation through the Pak4/c-Src/EGFR pathway that controls cyclin D1 and CDC25A expression. Stable knockdown of Pak4 also impeded tumor growth and dissemination in nude mice. This report reveals the association between Pak4 and important clinicopathologic parameters, suggesting Pak4 to be a significant prognostic marker and potential therapeutic molecular target in ovarian cancer. The implied possible cross-talk between Pak4 and EGFR suggests the potential of dual targeting of EGFR and Pak4 as a unique therapeutic approach for cancer therapy.
Amazons for Garibaldi: women warriors and the making of the hero of two worlds
Authors: Schwegman Marjan
Published: October 2010

This article analyses the place and meaning of female heroism in the process of the making of modern Italy. Beginning with Garibaldi's first wife Anita in Brazil, a great number of women all over the world were attracted to Garibaldi and his movement. Theirs was a sentimental and political engagement, which in some cases turned them into real soldiers, like those who joined the ranks of Garibaldi's troops. Whereas until 1860 the Garibaldinian volunteer was not understood as an exclusively male category, this changed around that key year, both in reality and in the collective imagination of the Risorgimento. Women were denied the right to be soldiers in Garibaldi's legendary Thousand. Subsequently, stories of militant women like Anita Garibaldi were softened in the foundation fictions that narrate the birth of Italy, turning women into passive members of the Italian nation. This change is analysed in depth by focusing on the emblematic case of Esperance von Schwartz, one of Garibaldi's biographers, and for a time, one of his female companions in arms.
The Risorgimento and English literary history, 1867–1911: the liberal heroism of Trevelyan's Garibaldi
Authors: Voakes Lucy Turner
Published: October 2010

This article explores the relationship between Italian heroism and literary history in relation to G.M. Trevelyan's Garibaldi trilogy. It firstly summarises some important features of the Victorian culture of public moralism that shaped Trevelyan's early work. It then discusses the influence of the poet, novelist and man-of-letters, George Meredith, on Trevelyan's Garibaldi books and historical practice. The comparison of Meredith and Trevelyan suggests that Trevelyan's Garibaldi trilogy should be understood as part of a project self-consciously undertaken by Victorian literary and political elites to consolidate, celebrate and, less frequently, to critique British liberal culture and politics. The article concludes that while a Mazzinian notion ofdolcezzamay have influenced Trevelyan's notion of the hero, his interest in the Risorgimento was ultimately motivated by the usefulness of Italy and Garibaldi in promoting what he considered to be a distinctly ‘English’1form of ethical patriotism, whose intellectual antecedents – Whig gradualism, constitutional compromise in the form of parliamentary monarchy and a hierarchy-inflected anti-Republicanism – stood in ambivalent relation to the concept of democratic nationality.
Immunotherapies for Staphylococcus aureus: Current Challenges and Future Prospects
Authors: Deresinski Stan , Herrera Victor
Published: October 2010

Development of an effective vaccine against Staphylococcus aureus would provide great potential public health benefit. We present a brief overview of the current knowledge in this field, with emphasis on present challenges and lessons learned, together with a summary of vaccines and immunoglobulin preparations currently under investigation.
Pandemic Preparedness: Implementation of Infection Prevention Emergency Plans
Authors: Rebmann Terri
Published: October 2010

The H1N1 influenza pandemic provided a real-world test of hospital disaster plans. Challenges to hospitals included inconsistent use of isolation precautions; changing and conflicting guidelines; lack of available supplies, including N95 respirators and medications; and overwhelming amounts of information that required sifting. Further research is needed regarding pandemic planning.
Prevention of Methicillin-ResistantStaphylococcus aureusInfection: Is Europe Winning the Fight?
Authors: Struelens Marc J. , Monnet Dominique L.
Published: October 2010

Methicillin-resistantStaphylococcus aureus(MRSA) is a common cause of disease across Europe, except for Scandinavian countries and the Netherlands. Recently, MRSA incidence has decreased in many European countries following national interventions, including structural and regulatory changes in health care, promotion of hand hygiene, antibiotic stewardship, and targeted screening, isolation, and decolonization of hospitalized carriers of MRSA.
Maximizing Infection Prevention in the Next Decade: Defining the Unacceptable
Authors: Frieden Thomas R.
Published: October 2010

An important role of public health agencies is to define the unacceptable. This concept has particular relevance for healthcare-associated infections. Evidence indicates that, with focused efforts, these once-formidable infections can be greatly reduced in number, leading to a new normal for healthcare-associated infections as rare, unacceptable events.
RRP1B Targets PP1 to Mammalian Cell Nucleoli and Is Associated with Pre-60S Ribosomal Subunits
Authors: Chamousset Delphine , De Wever Veerle , Moorhead Greg B. , Chen Yan , Boisvert Francois-Michel , Lamond Angus I. , Trinkle-Mulcahy Laura
Published: October 2010

A pool of protein phosphatase 1 (PP1) accumulates within nucleoli and accounts for a large fraction of the serine/threonine protein phosphatase activity in this subnuclear structure. Using a combination of fluorescence imaging with quantitative proteomics, we mapped the subnuclear localization of the three mammalian PP1 isoforms stably expressed as GFP-fusions in live cells and identified RRP1B as a novel nucleolar targeting subunit that shows a specificity for PP1β and PP1γ. RRP1B, one of two mammalian orthologues of the yeast Rrp1p protein, shows an RNAse-dependent localization to the granular component of the nucleolus and distributes in a similar manner throughout the cell cycle to proteins involved in later steps of rRNA processing. Quantitative proteomic analysis of complexes containing both RRP1B and PP1γ revealed enrichment of an overlapping subset of large (60S) ribosomal subunit proteins and pre-60S nonribosomal proteins involved in mid-late processing. Targeting of PP1 to this complex by RRP1B in mammalian cells is likely to contribute to modulation of ribosome biogenesis by mechanisms involving reversible phosphorylation events, thus playing a role in the rapid transduction of cellular signals that call for regulation of ribosome production in response to cellular stress and/or changes in growth conditions.
Inner/Outer Nuclear Membrane Fusion in Nuclear Pore Assembly
Authors: Fichtman Boris , Ramos Corinne , Rasala Beth , Harel Amnon , Forbes Douglass J.
Published: October 2010

Nuclear pore complexes (NPCs) are large proteinaceous channels embedded in double nuclear membranes, which carry out nucleocytoplasmic exchange. The mechanism of nuclear pore assembly involves a unique challenge, as it requires creation of a long-lived membrane-lined channel connecting the inner and outer nuclear membranes. This stabilized membrane channel has little evolutionary precedent. Here we mapped inner/outer nuclear membrane fusion in NPC assembly biochemically by using novel assembly intermediates and membrane fusion inhibitors. Incubation of a Xenopus in vitro nuclear assembly system at 14°C revealed an early pore intermediate where nucleoporin subunits POM121 and the Nup107-160 complex were organized in a punctate pattern on the inner nuclear membrane. With time, this intermediate progressed to diffusion channel formation and finally to complete nuclear pore assembly. Correct channel formation was blocked by the hemifusion inhibitor lysophosphatidylcholine (LPC), but not if a complementary-shaped lipid, oleic acid (OA), was simultaneously added, as determined with a novel fluorescent dextran-quenching assay. Importantly, recruitment of the bulk of FG nucleoporins, characteristic of mature nuclear pores, was not observed before diffusion channel formation and was prevented by LPC or OA, but not by LPC+OA. These results map the crucial inner/outer nuclear membrane fusion event of NPC assembly downstream of POM121/Nup107-160 complex interaction and upstream or at the time of FG nucleoporin recruitment.
The Roles of Two Distinct Regions of PINCH-1 in the Regulation of Cell Attachment and Spreading
Authors: Ito Satoko , Takahara Yuko , Hyodo Toshinori , Hasegawa Hitoki , Asano Eri , Hamaguchi Michinari , Senga Takeshi
Published: October 2010

Cells attach to the extracellular matrix (ECM) through integrins to form focal adhesion complexes, and this process is followed by the extension of lamellipodia to enable cell spreading. PINCH-1, an adaptor protein essential for the regulation of cell–ECM adhesion, consists of five tandem LIM domains and a small C-terminal region. PINCH-1 is known to interact with integrin-linked kinase (ILK) and Ras suppressor protein 1 (Rsu-1); however, the precise mechanism by which this complex regulates cell–ECM adhesion is not fully understood. We report here that the LIM1 domain of PINCH-1, which associates with ILK to stabilize the expression of this protein, is sufficient for cell attachment but not for cell spreading. In contrast, the C-terminal region of PINCH-1, which binds to Rsu-1, plays a pivotal role in cell spreading but not in cell attachment. We also show that PINCH-1 associates with Rsu-1 to activate Rac1 and that Rac1 activation is necessary for cell spreading. Thus, these data reveal how specific domains of PINCH-1 direct two independent pathways: one utilizing ILK to allow cell attachment, and the other recruiting Rsu-1 to activate Rac1 in order to promote cell spreading.
C-junInhibits Mammary Apoptosis In Vivo
Authors: Katiyar Sanjay , Casimiro Mathew C. , Dettin Luis , Ju Xiaoming , Wagner Erwin F. , Tanaka Hirokazu , Pestell Richard G.
Published: October 2010

c-jun, which is overexpressed in a number of human cancers encodes a critical component of the AP-1 complex. c-jun has been shown to either induce or inhibit cellular apoptosis. Germ line deletion of both c-jun alleles is embryonically lethal. To determine the role of the endogenous c-jun gene in apoptosis, we performed mammary epithelial cell–targeted somatic deletion using floxed c-jun (c-junf/f) conditional knockout mice. Laser capture microdissection demonstrated endogenous c-jun inhibits expression of apoptosis inducing genes and reactive oxygen species (ROS)-reducing genes (MnSOD, catalase). ROS have been implicated in apoptosis and undergo enzymatic elimination via MnSOD and CuZnSOD with further detoxification via catalase. c-jun–mediated survival was in part dependent on ROS production. c-jun–mediated repression of MnSOD and catalase occurred via mitochondrial complex I and NOX I. Collectively, these studies define a pivotal role of endogenous c-jun in promoting cell survival via maintaining mitochondrial integrity and expression of the key regulators of ROS production.
Dysfunction of Heterotrimeric Kinesin-2 in Rod Photoreceptor Cells and the Role of Opsin Mislocalization in Rapid Cell Death
Authors: Lopes Vanda S. , Jimeno David , Khanobdee Kornnika , Song Xiaodan , Chen Bryan , Nusinowitz Steven , Williams David S.
Published: October 2010

Due to extensive elaboration of the photoreceptor cilium to form the outer segment, axonemal transport (IFT) in photoreceptors is extraordinarily busy, and retinal degeneration is a component of many ciliopathies. Functional loss of heterotrimeric kinesin-2, a major anterograde IFT motor, causes mislocalized opsin, followed by rapid cell death. Here, we have analyzed the nature of protein mislocalization and the requirements for the death of kinesin-2-mutant rod photoreceptors. Quantitative immuno EM showed that opsin accumulates initially within the inner segment, and then in the plasma membrane. The light-activated movement of arrestin to the outer segment is also impaired, but this defect likely results secondarily from binding to mislocalized opsin. Unlike some other retinal degenerations, neither opsin–arrestin complexes nor photoactivation were necessary for cell loss. In contrast, reduced rod opsin expression provided enhanced rod and cone photoreceptor survival and function, as measured by photoreceptor cell counts, apoptosis assays, and ERG analysis. The cell death incurred by loss of kinesin-2 function was almost completely negated by Rho−/−. Our results indicate that mislocalization of opsin is a major cause of photoreceptor cell death from kinesin-2 dysfunction and demonstrate the importance of accumulating mislocalized protein per se, rather than specific signaling properties of opsin, stemming from photoactivation or arrestin binding.
Intrathecal Injection of Hepatocyte Growth Factor Gene-modified Marrow Stromal Cells Attenuates Neurologic Injury Induced by Transient Spinal Cord Ischemia in Rabbits
Authors: Shi Enyi , Jiang Xiaojing , Wang Lingling , Akuzawa Satoshi , Nakajima Yoshiki , Kazui Teruhisa
Published: October 2010

Background

Our previous studies showed that transfer of hepatocyte growth factor (HGF) gene or transplantation of marrow stromal cells (MSCs) remarkably attenuated neurologic injuries after spinal cord ischemia. We sought to investigate a novel neuroprotective strategy of transplantation of human HGF gene-modified MSCs on ischemic spinal cords.

Methods

Human HGF gene was transferred into MSCs in vitro. The HGF gene-modified MSCs were transplanted by means of intrathecal injection. Two days later, spinal cord ischemia was induced by occlusion of the infrarenal aorta with a balloon catheter for 40 or 50 min. Hind-limb motor function was assessed during a 14-day recovery period with Tarlov criteria, and then histologic examination was performed.

Results

Human HGF was detected in the cerebrospinal fluid from 2 to 16 days after transplantation of HGF gene-modified MSCs. Compared with the controls, transplantation of HGF gene-modified MSCs or MSCs alone significantly improved the Tarlov scores 1, 2, 7, and 14 days after spinal cord ischemia of 40 or 50 min (P < 0.01, respectively) and increased the number of intact motor neurons in the lumbar spinal cord (P < 0.01, respectively). When the ischemic period was extended to 50 min, the Tarlov scores and the number of intact motor neurons of rabbits transplanted with HGF gene-modified MSCs were markedly higher than those of the rabbits transplanted with MSCs only (P < 0.05, respectively).

Conclusions

Transplantation of HGF gene-modified MSCs induces powerful neuroprotection on spinal cords against ischemia-reperfusion injury and is more therapeutically efficient than transplantation of MSCs only.
Alignment hierarchies: engineering architecture from the nanometre to the micrometre scale
Authors: Kureshi Alvena , Cheema Umber , Alekseeva Tijna , Cambrey Alison , Brown Robert
Published: October 2010

Natural tissues are built of metabolites, soluble proteins and solid extracellular matrix components (largely fibrils) together with cells. These are configured in highly organized hierarchies of structure across length scales from nanometre to millimetre, with alignments that are dominated by anisotropies in their fibrillar matrix. If we are to successfully engineer tissues, these hierarchies need to be mimicked with an understanding of the interaction between them. In particular, the movement of different elements of the tissue (e.g. molecules, cells and bulk fluids) is controlled by matrix structures at distinct scales. We present three novel systems to introduce alignment of collagen fibrils, cells and growth factor gradients within a three-dimensional collagen scaffold using fluid flow, embossing and layering of construct. Importantly, these can be seen as different parts of the same hierarchy of three-dimensional structure, as they are all formed into dense collagen gels. Fluid flow aligns collagen fibrils at the nanoscale, embossed topographical features provide alignment cues at the microscale and introducing layered configuration to three-dimensional collagen scaffolds provides microscale- and mesoscale-aligned pathways for protein factor delivery as well as barriers to confine protein diffusion to specific spatial directions. These seemingly separate methods can be employed to increase complexity of simple extracellular matrix scaffolds, providing insight into new approaches to directly fabricate complex physical and chemical cues at different hierarchical scales, similar to those in natural tissues.
Caste-specific visual adaptations to distinct daily activity schedules in AustralianMyrmeciaants
Authors: Narendra Ajay , Reid Samuel F. , Greiner Birgit , Peters Richard A. , Hemmi Jan M. , Ribi Willi A. , Zeil Jochen
Published: October 2010

Animals are active at different times of the day and their activity schedules are shaped by competition, time-limited food resources and predators. Different temporal niches provide different light conditions, which affect the quality of visual information available to animals, in particular for navigation. We analysed caste-specific differences in compound eyes and ocelli in four congeneric sympatric species ofMyrmeciaants, with emphasis on within-species adaptive flexibility and daily activity rhythms. Each caste has its own lifestyle: workers are exclusively pedestrian; alate females lead a brief life on the wing before becoming pedestrian; alate males lead a life exclusively on the wing. While workers of the four species range from diurnal, diurnal-crepuscular, crepuscular-nocturnal to nocturnal, the activity times of conspecific alates do not match in all cases. Even within a single species, we found eye area, facet numbers, facet sizes, rhabdom diameters and ocelli size to be tuned to the distinct temporal niche each caste occupies. We discuss these visual adaptations in relation to ambient light levels, visual tasks and mode of locomotion.
Genetic diversity, parasite prevalence and immunity in wild bumblebees
Authors: Whitehorn Penelope R. , Tinsley Matthew C. , Brown Mark J. F. , Darvill Ben , Goulson Dave
Published: October 2010

Inbreeding and a consequent loss of genetic diversity threaten small, isolated populations. One mechanism by which genetically impoverished populations may become extinct is through decreased immunocompetence and higher susceptibility to parasites. Here, we investigate the relationship between immunity and inbreeding in bumblebees, using Hebridean island populations of
Bombus muscorum
. We sampled nine populations and recorded parasite prevalence and measured two aspects of immunity: the encapsulation response and levels of phenoloxidase (PO). We found that prevalence of the gut parasite
Crithidia bombi
was higher in populations with lower genetic diversity. Neither measure of immune activity was correlated with genetic diversity. However, levels of PO declined with age and were also negatively correlated with parasite abundance. Our results suggest that as insect populations lose heterozygosity, the impact of parasitism will increase, pushing threatened populations closer to extinction.
Dispersal and diversity in the earliest North American sauropodomorph dinosaurs, with a description of a new taxon
Authors: Rowe Timothy B. , Sues Hans-Dieter , Reisz Robert R.
Published: October 2010

Sauropodomorph dinosaurs originated in the Southern Hemisphere in the Middle or Late Triassic and are commonly portrayed as spreading rapidly to all corners of Pangaea as part of a uniform Late Triassic to Early Jurassic cosmopolitan dinosaur fauna. Under this model, dispersal allegedly inhibited dinosaurian diversification, while vicariance and local extinction enhanced it. However, apomorphy-based analyses of the known fossil record indicate that sauropodomorphs were absent in North America until the Early Jurassic, reframing the temporal context of their arrival. We describe a new taxon from the Kayenta Formation of Arizona that comprises the third diagnosable sauropodomorph from the Early Jurassic of North America. We analysed its relationships to test whether sauropodomorphs reached North America in a single sweepstakes event or in separate dispersals. Our finding of separate arrivals by all three taxa suggests dispersal as a chief factor in dinosaurian diversification during at least the early Mesozoic. It questions whether a ‘cosmopolitan’ dinosaur fauna ever existed, and corroborates that vicariance, extinction and dispersal did not operate uniformly in time or under uniform conditions during the Mesozoic. Their relative importance is best measured in narrow time slices and circumscribed geographical regions.
Dominant expression of survival signals of endoplasmic reticulum stress response in Hodgkin lymphoma
Authors: Chang Kung‐Chao , Chen Paul C.‐H. , Chen Ya‐Ping , Chang Yao , Su Ih‐Jen
Published: October 2010

The accumulation of viral proteins in endoplasmic reticulum (ER) may cause ER stress responses and lead to either apoptosis or survival depending on the driving signals. The strong expression of latent membrane protein‐1 (LMP1) in Epstein–Barr virus (EBV)‐positive Hodgkin lymphoma (HL) cells raises the question whether LMP1‐induced ER stress response is associated with the characteristic tumor biology in HL. In this study, we investigated the expression of ER stress signals (glucose‐regulated protein 78 [GRP78], X‐box binding protein 1 [XBP1], activating transcription factor 6 [ATF6], CCAAT enhance‐binding protein homologous protein [CHOP] and phospho‐apoptosis signal‐regulating kinase 1 [pASK1]) on 156 cases of HL. Furthermore, LMP1 transfection on EBV‐negative HL cell lines was used to explore the regulation of ER stress signals by EBV‐LMP1. Interestingly, we demonstrated that the survival signals of ER stress response (GRP78, 62%; XBP1u [unspliced], 55%; XBP1s [spliced], 38%; ATF6, 91%) were dominantly expressed over the ER death signals (CHOP, 10%; pASK1, 7%) in all histological subtypes of HL with a similar level in both EBV‐positive and EBV‐negative cases. However, expression of ER signals did not bear prognostic significance.In vitro,LMP1 transfection increased the expression of GRP78 and XBP1, but attenuated the expression of death signals, CHOP and pASK1. These data indicate that EBV‐LMP1 may play a role in shifting EBV‐infected cells towards the survival pathway in the presence of ER stress in EBV‐positive HL cases. (Cancer Sci2011; 102: 275–281)
The direct and indirect effects of guppies: implications for life‐history evolution in Rivulus hartii
Authors: Walsh Matthew R. , Fraser Douglas F. , Bassar Ronald D. , Reznick David N.
Published: October 2010

1. Ecological factors that alter mortality rates, such as predation, can cause evolutionary change. However, in addition to killing prey, predators can reduce prey abundance and increase food to survivors. Such indirect effects may also cause evolution. Predictions from theory that models how life histories evolve in response to increased mortality rates often change when they include indirect effects. Thus, indirect effects need to be evaluated to couple theory with natural systems.

2. Trinidadian killifish, Rivulus hartii, are found in communities with and without guppies Poecilia reticulata. Rivulus densities decline when guppies are present, which may be due to competitive or predatory interactions with guppies that increase Rivulus mortality rates. We previously showed that Rivulus from sites with guppies begin reproduction earlier and have increased reproductive allotment compared to Rivulus from sites with just Rivulus. Such divergence is inconsistent with theory that considers changes in juvenile mortality alone, but is consistent with theory that incorporates indirect effects. Here, we explored the mechanism of divergence with mark–recapture studies that compared the population biology of Rivulus between communities that are and are not sympatric with guppies.

3. Rivulus were 50% less abundant when guppies were present but guppies were not associated with increased adult mortality rates. Related experiments show that the declines in density are likely due to guppy predation on young Rivulus. Guppies do not appear to negatively impact Rivulus growth via competition. Rivulus with guppies grow >3× faster than Rivulus from sites upstream, above waterfalls that exclude guppies. If guppies competed with Rivulus for resources, then we would instead expect to see their presence be associated with a decline in Rivulus growth rates. When Rivulus were transplanted from above to below this barrier, their growth accelerated to match the residents. This response instead argues that the differences in growth are mediated by an environmental factor, likely lower population densities, which allow Rivulus from sites with guppies to grow faster.

4. These results imply that an indirect effect of guppy predation on young Rivulus, which is the presumed agent of selection, improves the fit of empirical findings with theoretical predictions.
The ecology and evolution of induced resistance against herbivores
Authors: Karban Richard
Published: October 2010

1. Induced resistance is now widely accepted as a potent and widespread ecological force although several pieces of the story remain very poorly known. Theory predicts that induced defences should be favoured in variable environments especially when plants can use cues to reliably predict future conditions; however, this idea has not been seriously evaluated for plants.

2. Theory also predicts that plastic, induced defences should be favoured over permanent, constitutive defences if defences are costly and not always needed. This hypothesis has received considerable attention and limited support; resource allocation costs have been difficult to detect although ecological costs of defence may be more common. Recently, priming has emerged as a mechanism that may further reduce costs. Primed plants do not immediately produce the gene products associated with induced resistance but later respond more rapidly and strongly to severe or repeated attacks. It remains to be determined how common priming is.

3. Much of what we know about induced resistance is from the herbivore’s point of view. Induced resistance will be beneficial from the plant’s point of view if herbivores avoid induced plants, but the behavioural responses of herbivores to induced plant variation are still poorly studied.

4. Recent progress in understanding the detailed spatial and temporal extent of induced resistance has improved our appreciation of the phenomenon. Although some induced responses are systemic throughout entire plant individuals, many others have been found to be localized to damaged tissues. Plant vascular architecture and transpiration rates greatly constrain the distribution of vascular cues. Some plants rely on volatile cues that are active over relatively short distances and may be subject to eavesdropping by other plants, herbivores, and carnivores. Similarly, the temporal duration of induced responses may have important consequences on effectiveness although limited information is available concerning lag times before induction and relaxation times following induction.

5. Limited spatial and temporal scales of induced responses make plants more variable from the herbivore’s point of view. Recent work suggests that plant heterogeneity may be difficult for herbivores to cope with although this hypothesis awaits further empirical testing.
Egg size and food abundance interactively affect juvenile growth and behaviour
Authors: Segers Francisca H.I.D. , Taborsky Barbara
Published: October 2010

1. Comparative evidence from several animal taxa suggests that juveniles hatching from larger eggs have fitness benefits when growing up in a harsh environment, whereas under benign conditions egg size should be of less importance. However, the physiological and behavioural mechanisms responsible for these context‐dependent fitness differences are as yet poorly understood.

2. We studied the interactions between the phenotype of developing offspring and their environment in the mouthbrooding cichlidSimochromis pleurospilus.We hand‐raised young from large and small eggs, and measured their initial body size and burst swimming speed. Thereafter we raised half of each egg‐size class on high and half on low food ration and followed their growth trajectories and behavioural development until the age of 12 weeks.

3. We found that larger eggs gave rise to larger young that had a higher burst swimming speed. Food ration greatly influenced long‐term growth, while egg size predominantly affected fish size during the first 2 weeks of life. However, large egg size caused a size advantage of juveniles persisting throughout the experimental period.

4. Egg size and food ration interactively affected the hiding and foraging behaviour of young. In the low‐food treatment, individuals from small eggs spent less time in shelter and showed a higher commitment to foraging than individuals from large eggs. In a natural setting, this should markedly increase predation risk of young originating from small eggs, particularly in poor environments. In contrast, when food was plentiful juveniles behaved similarly, irrespective of egg size.

5. Our results show that egg size affects juvenile growth trajectories and behaviour differently in different environments. While it is well‐established that a large egg size raises offspring fitness particularly in harsh environments, our study suggests that this advantage arises through risk‐averse behaviour being tightly linked to offspring size.
Gicerin/Cd146 is involved in zebrafish cardiovascular development and tumor angiogenesis
Authors: So Ju‐Hoon , Hong Sung‐Kook , Kim Hyun‐Taek , Jung Seung‐Hyun , Lee Mi‐Sun , Choi Jung‐Hwa , Bae Young‐Ki , Kudoh Tetsuhiro , Kim Ji‐Hun , Kim Cheol‐Hee
Published: October 2010

Angiogenesis plays an important role in vertebrate development and tumor growth. In this process, gicerin, which is known as a kind of cell adhesion molecule, has recently been reported to play an important role but its in vivo function is still unclear in developing vasculature. To address this issue, we used gain‐of‐function and loss‐of‐function analyses of gicerin in zebrafish. In the gain of function experiments using enforced expression of various domains of gicerin constructs, extracellular domain induced angiogenic sprouting defects, most notably in the intersegmental vessels, whereas the cytoplasmic domain of gicerin did not affect angiogenic sprouting. Moreover, morpholino‐mediated knockdown of gicerin in embryos resulted in angiogenic sprouting defects in intersegmental vessels. Mechanistically, the angiogenic function of gicerin was found to be genetically linked to VEGF signaling in the knock‐down experiments using vegf‐a mRNA, VEGFR inhibitor and gicerin morpholino. In addition to the physiological angiogenesis during development, gicerin morphants efficiently blocked the tumor angiogenesis in zebrafish. Thus, knock‐down of gicerin might have an important implication in controlling tumor angiogenesis.