Plant defense signals: Players and pawns in plant-virus-vector interactions

Carr, John P.,Murphy, Alex M.,Tungadi, Trisna,Yoon, Ju-Yeon Elsevier 2019 Plant science Vol.279 No.-

<P><B>Abstract</B></P> <P>Plant viruses face an array of host defenses. Well-studied responses that protect against viruses include effector-triggered immunity, induced resistance (such as systemic acquired resistance mediated by salicylic acid), and RNA silencing. Recent work shows that viruses are also affected by non-host resistance mechanisms; previously thought to affect only bacteria, oomycetes and fungi. However, an enduring puzzle is how viruses are inhibited by several inducible host resistance mechanisms. Many viruses have been shown to encode factors that inhibit antiviral silencing. A number of these, including the cucumoviral 2b protein, the poytviral P1/HC-Pro and, respectively, geminivirus or satellite DNA-encoded proteins such as the C2 or βC1, also inhibit defensive signaling mediated by salicylic acid and jasmonic acid. This helps to explain how viruses can, in some cases, overcome host resistance. Additionally, interference with defensive signaling provides a means for viruses to manipulate plant-insect interactions. This is important because insects, particularly aphids and whiteflies, transmit many viruses. Indeed, there is now substantial evidence that viruses can enhance their own transmission through their effects on hosts. Even more surprisingly, it appears that viruses may be able to manipulate plant interactions with beneficial insects by, for example, ‘paying back’ their hosts by attracting pollinators.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Plants possess multiple antiviral defenses. </LI> <LI> Many of these depend on biosynthesis of signal chemicals. </LI> <LI> Plant viruses have evolved counter-defense factors. </LI> <LI> Viral proteins including counter-defense factors can affect host-insect interactions. </LI> <LI> Manipulation of host-insect interactions may facilitate virus transmission. </LI> </UL> </P>

Tissue Expanders in Staged Calvarial Reconstruction: A Systematic Review

Andrea Y. Lo,Roy P. Yu,Anjali C. Raghuram,Michael N. Cooper,Holly J. Thompson,Charles Y. Liu,Alex K. Wong 대한성형외과학회 2022 Archives of Plastic Surgery Vol.49 No.6

Cranioplasties are common procedures in plastic surgery. The use of tissue expansion (TE) in staged cranioplasties is less common. We present two cases of cranioplasties with TE and systematically review literature describing the use of TE in staged cranioplasties and postoperative outcomes. A systematic review was performed by querying multiple databases. Eligible articles include published case series, retrospective reviews, and systematic reviews that described use of TE for staged bony cranioplasty. Data regarding study size, patient demographics, preoperative characteristics, staged procedure characteristics, and postoperative outcomes were collected. Of 755 identified publications, 26 met inclusion criteria. 85 patients underwent a staged cranioplasty with TE. Average defect size was 122 cm2, and 30.9% of patients received a previous reconstruction. Average expansion period was 14.2 weeks. The most common soft tissue closures were performed with skin expansion only (75.3%), free/pedicled flap (20.1%), and skin graft (4.7%). The mean postoperative follow-up time was 23.9 months. Overall infection and local complication rates were 3.53 and 9.41%, respectively. The most common complications were cerebrospinal fluid leak (7.1%), hematoma (7.1%), implant exposure (3.5%), and infection (3.5%). Factors associated with higher complication rates include the following: use of alloplastic calvarial implants and defects of congenital etiology (p¼0.023 and 0.035, respectively). This is the first comprehensive review to describe current practices and outcomes in staged cranioplasty with TE. Adequate soft tissue coverage contributes to successful cranioplasties and TE can play a safe and effective role in selected cases.

The Wnt Receptor Ryk Reduces Neuronal and Cell Survival Capacity by Repressing FOXO Activity During the Early Phases of Mutant Huntingtin Pathogenicity

Tourette, Cendrine,Farina, Francesca,Vazquez-Manrique, Rafael P.,Orfila, Anne-Marie,Voisin, Jessica,Hernandez, Sonia,Offner, Nicolas,Parker, J. Alex,Menet, Sophie,Kim, Jinho,Lyu, Jungmok,Choi, Si Ho,C Public Library of Science 2014 PLoS biology Vol.12 No.6

<▼1><P>A study of Huntington's disease reveals that neurons might fail to cope with maintaining their function during the pre-symptomatic, pathogenic phases of HD, possibly due to the early repression of key longevity-promoting transcription factors by abnormal developmental signaling.</P></▼1><▼2><P>The Wnt receptor Ryk is an evolutionary-conserved protein important during neuronal differentiation through several mechanisms, including γ-secretase cleavage and nuclear translocation of its intracellular domain (Ryk-ICD). Although the Wnt pathway may be neuroprotective, the role of Ryk in neurodegenerative disease remains unknown. We found that Ryk is up-regulated in neurons expressing mutant huntingtin (HTT) in several models of Huntington's disease (HD). Further investigation in <I>Caenorhabditis elegans</I> and mouse striatal cell models of HD provided a model in which the early-stage increase of Ryk promotes neuronal dysfunction by repressing the neuroprotective activity of the longevity-promoting factor FOXO through a noncanonical mechanism that implicates the Ryk-ICD fragment and its binding to the FOXO co-factor β-catenin. The Ryk-ICD fragment suppressed neuroprotection by <I>lin-18</I>/Ryk loss-of-function in expanded-polyQ nematodes, repressed FOXO transcriptional activity, and abolished β-catenin protection of mutant htt striatal cells against cell death vulnerability. Additionally, Ryk-ICD was increased in the nucleus of mutant htt cells, and reducing γ-secretase PS1 levels compensated for the cytotoxicity of full-length Ryk in these cells. These findings reveal that the Ryk-ICD pathway may impair FOXO protective activity in mutant polyglutamine neurons, suggesting that neurons are unable to efficiently maintain function and resist disease from the earliest phases of the pathogenic process in HD.</P></▼2><▼3><P><B>Author Summary</B></P><P>Neuronal cell decline in neurodegenerative disease can be caused by inherited mutations and involves neuronal dysfunction followed by neuronal death. The ability of neurons to cope with the chronic stress induced by mutant protein expression may determine the course of their decline and eventual demise. Although the pathophysiological importance of these stress responses has been previously shown, very little is known about the signaling networks that regulate neuronal homeostasis during the early presymptomatic—but pathogenic—phases of a neurodegenerative disorder such as Huntington's disease (HD). In particular, it remains unclear whether neuronal differentiation factors regulate stress response pathways during neurodegenerative disease and how this might impact the overall capacity of neurons to cope with stress and maintain their function. Here, we show that the Wnt receptor Ryk, a protein known to be important for neurogenesis, is increased in different animal models of HD, before or during the early phases of the disease process. Interestingly, increased levels of Ryk repress activity of the FOXO proteins—a family of transcription factors that play a role in cell survival/longevity and in neuronal homeostasis and protection. Ryk represses FOXO protective activity, possibly directly, through its intracellular domain, a product of γ-secretase–mediated cleavage previously implicated in the birth of new cortical neurons. This highlights the regulation of HD neuron survival by a Ryk-dependent pathway that is distinct from canonical Wnt/Ryk signaling. From our findings, we postulate that neurons are unable to develop an efficient FOXO-mediated survival response during the very early, pathogenic phases of HD.</P></▼3>

Charge Transfer Dynamics of Phase-Segregated Halide Perovskites: CH₃NH₃PbCl₃ and CH₃NH₃PbI₃ or (C₄H₉NH₃)₂(CH₃NH₃)<sub><i>n

Cao, Duyen H.,Guo, Peijun,Mannodi-Kanakkithodi, Arun,Wiederrecht, Gary P.,Gosztola, David J.,Jeon, Nari,Schaller, Richard D.,Chan, Maria K. Y.,Martinson, Alex B. F. American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.9

<P>Lead halide perovskites present a versatile class of solution-processable semiconductors with highly tunable bandgaps that span ultraviolet, visible, and near-infrared portions of the spectrum. We explore phase-separated chloride and iodide lead perovskite mixtures as candidate materials for intermediate band applications in future photovoltaics. X-ray diffraction and scanning electron microscopy reveal that deposition of precursor solutions across the MAPbCl<SUB>3</SUB>/MAPbI<SUB>3</SUB> composition space affords quasi-epitaxial cocrystallized films, in which the two perovskites do not alloy but instead remain phase-segregated. First-principle calculations further support the formation of an epitaxial interface and predict energy offsets in the valence band and conduction band edges that could result in intermediate energy absorption. The charge dynamics of variable mixtures of the relatively narrow bandgap (1.57 eV) MAPbI<SUB>3</SUB> perovskite and wide bandgap (3.02 eV) MAPbCl<SUB>3</SUB> are probed to map charge and energy flow direction and kinetics. Time-resolved photoluminescence and transient absorption measurements reveal charge transfer of photoexcited carriers in MAPbCl<SUB>3</SUB> to MAPbI<SUB>3</SUB> in tens of picoseconds. The rate of quenching can be further tuned by replacing MAPbI<SUB>3</SUB> with two-dimensional Ruddlesden-Popper (BA)<SUB>2</SUB>(MA)<SUB><I>n</I>−1</SUB>Pb<I><SUB>n</SUB></I>I<SUB>3<I>n</I>+1</SUB> (<I>n</I> = 3, 2, and 1) perovskites, which also remain phase-separated.</P> [FIG OMISSION]</BR>

Layer-by-Layer Assembled Films of Perylene Diimide- and Squaraine-Containing Metal–Organic Framework-like Materials: Solar Energy Capture and Directional Energy Transfer

Park, Hea Jung,So, Monica C.,Gosztola, David,Wiederrecht, Gary P.,Emery, Jonathan D.,Martinson, Alex B. F.,Er, Sü,leyman,Wilmer, Christopher E.,Vermeulen, Nicolaas A.,Aspuru-Guzik, Alá,n,S American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.38

<P>We demonstrate that thin films of metal organic framework (MOF)-like materials, containing two perylenedlimides (PDICl4, PDIOPh2) and a squaraine dye (S1); can be fabricated by, layer-by-layer assembly (LbL). Interestingly, these LbL films absorb across the visible light region (400-750 nm) and facilitate directional energy transfer. Due to the high spectral overlap and oriented transition dipole moments of the donor (PDICl4 and PDIOPh2) and acceptor (S1) components, directional long-range energy transfer from the bluest to reddest absorber was successfully demonstrated in the multicomponent MOF-like films. These findings have significant implications for the development of solar energy conversion devices based on MOFs.</P>

SINGULAR THIRD-ORDER 3-POINT BOUNDARY VALUE PROBLEMS

ALEX P. PALAMIDES,ANASTASIA N. VELONI,STAMATIS ALATSATHIANOS 한국전산응용수학회 2010 Journal of applied mathematics & informatics Vol.28 No.3

In this paper, we prove existence of infinitely many positive and concave solutions , by means of a simple approach, to 3th order three-point singular boundary value problem [수식]Moreover with respect to multiplicity of solutions, we don’t assume any monotonicity on the nonlinearity. We rely on a combination of the analysis of the corresponding vector field on the phase-space along with Knesser’s type properties of the solu-tions funnel and the well-known Krasnosel’ski˘ı’s fixed point theorem. The later is applied on a new very simple cone K, just on the plane R². These extensions justify the efficiency of our new approach compared to the com-monly used one, where the cone K ⊂ C ([0, 1] ,R) and the existence of a positive Green’s function is a necessity.

Graphene Nanopore with a Self-Integrated Optical Antenna

Nam, SungWoo,Choi, Inhee,Fu, Chi-cheng,Kim, Kwanpyo,Hong, SoonGweon,Choi, Yeonho,Zettl, Alex,Lee, Luke P. American Chemical Society 2014 NANO LETTERS Vol.14 No.10

<P>We report graphene nanopores with integrated optical antennae. We demonstrate that a nanometer-sized heated spot created by photon-to-heat conversion of a gold nanorod resting on a graphene membrane forms a nanoscale pore with a self-integrated optical antenna in a single step. The distinct plasmonic traits of metal nanoparticles, which have a unique capability to concentrate light into nanoscale regions, yield the significant advantage of parallel nanopore fabrication compared to the conventional sequential process using an electron beam. Tunability of both the nanopore dimensions and the optical characteristics of plasmonic nanoantennae are further achieved. Finally, the key optical function of our self-integrated optical antenna on the vicinity of graphene nanopore is manifested by multifold fluorescent signal enhancement during DNA translocation.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2014/nalefd.2014.14.issue-10/nl503159d/production/images/medium/nl-2014-03159d_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl503159d'>ACS Electronic Supporting Info</A></P>

Effect of a through-building gap on wind-induced loading and dynamic responses of a tall building

Alex P. To,K.M. Lam,S.Y. Wong,Z.N. Xie 한국풍공학회 2012 Wind and Structures, An International Journal (WAS Vol.15 No.6

Many tall buildings possess through-building gaps at middle levels of the building elevation. Some of these floors are used as sky gardens, or refuge floors, through which wind can flow with limited blockage. It has been reported in the literature that through-building gaps can be effective in reducing across-wind excitation of tall buildings. This paper systematically examines the effectiveness of two configurations of a through-building gap, at the mid-height of a tall building, in reducing the windinduced dynamic responses of the building. The two configurations differ in the pattern of throughbuilding opening on the gap floor, one with opening through the central portion of the floor and the other with opening on the perimeter of the floor around a central core. Wind forces and moments on the building models were measured with a high-frequency force balance from which dynamic building responses were computed. The results show that both configurations of a through-building gap are effective in reducing the across-wind excitation with the one with opening around the perimeter of the floor being significantly more effective. Wind pressures were measured on the building faces with electronic pressure scanners to help understand the generation of wind excitation loading. The data suggest that the through-building gap reduces the fluctuating across-wind forces through a disturbance of the coherence and phase-alignment of vortex excitation.

Dlg5 Regulates Dendritic Spine Formation and Synaptogenesis by Controlling Subcellular <i>N</i>-Cadherin Localization

Wang, Shih-Hsiu J.,Celic, Ivana,Choi, Se-Young,Riccomagno, Martin,Wang, Qiang,Sun, Lu O.,Mitchell, Sarah P.,Vasioukhin, Valera,Huganir, Richard L.,Kolodkin, Alex L. Society for Neuroscience 2014 The Journal of neuroscience Vol.34 No.38

<P>Most excitatory synapses in the mammalian brain are formed on dendritic spines, and spine density has a profound impact on synaptic transmission, integration, and plasticity. Membrane-associated guanylate kinase (MAGUK) proteins are intracellular scaffolding proteins with well established roles in synapse function. However, whether MAGUK proteins are required for the formation of dendritic spines <I>in vivo</I> is unclear. We isolated a novel <I>disc large-5</I> (<I>Dlg5</I>) allele in mice, <I>Dlg5</I><SUP>LP</SUP>, which harbors a missense mutation in the DLG5 SH3 domain, greatly attenuating its ability to interact with the DLG5 GUK domain. We show here that DLG5 is a MAGUK protein that regulates spine formation, synaptogenesis, and synaptic transmission in cortical neurons. DLG5 regulates synaptogenesis by enhancing the cell surface localization of <I>N</I>-cadherin, revealing a key molecular mechanism for regulating the subcellular localization of this cell adhesion molecule during synaptogenesis.</P>

Effect of a through-building gap on wind-induced loading and dynamic responses of a tall building

To, Alex P.,Lam, K.M.,Wong, S.Y.,Xie, Z.N. Techno-Press 2012 Wind and Structures, An International Journal (WAS Vol.15 No.6

Many tall buildings possess through-building gaps at middle levels of the building elevation. Some of these floors are used as sky gardens, or refuge floors, through which wind can flow with limited blockage. It has been reported in the literature that through-building gaps can be effective in reducing across-wind excitation of tall buildings. This paper systematically examines the effectiveness of two configurations of a through-building gap, at the mid-height of a tall building, in reducing the wind-induced dynamic responses of the building. The two configurations differ in the pattern of through-building opening on the gap floor, one with opening through the central portion of the floor and the other with opening on the perimeter of the floor around a central core. Wind forces and moments on the building models were measured with a high-frequency force balance from which dynamic building responses were computed. The results show that both configurations of a through-building gap are effective in reducing the across-wind excitation with the one with opening around the perimeter of the floor being significantly more effective. Wind pressures were measured on the building faces with electronic pressure scanners to help understand the generation of wind excitation loading. The data suggest that the through-building gap reduces the fluctuating across-wind forces through a disturbance of the coherence and phase-alignment of vortex excitation.