Glyceraldehyde-3-phosphate dehydrogenase is a mediator of hemocyte-spreading behavior and molecular target of immunosuppressive factor CrV1

Kumar, S.,Kim, Y. Pergamon Press ; Elsevier Science 2016 DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY Vol.54 No.1

<P>Cellular immunity is accompanied by hemocyte-spreading behavior, which undergoes cytoskeletal rearrangement. Polydnaviral factor CpBV-CrV1 can inhibit the hemocyte-spreading behavior and suppress host immune response of Plutella xylostella. However, host target molecule of CpBV-CrV1 that inhibits the hemocyte behavior has not been identified yet. This study used a pull-down approach to identify the target molecule of CpBV-CrV1. A protein bound to CpBV-CrV1 was co-precipitated and identified to be glyceraldehyde-3-phosphate dehydrogenase (GAPDH) by LC-MS/MS analysis. RNA interference (RNAi) specific to GAPDH of P. xylostella was found to be able to inhibit the hemocyte-spreading behavior, while RNAi treatments with other glycolytic genes had no effect on the spreading behavior. An addition of recombinant CpBV-CrV1 on hemocyte monolayer interrupted the association between GAPDH and a-tubulin in the cytoplasm. Overlay of mutant proteins (Y492A or Y501A with tyrosine to alanine at putative GAPDH-binding site) of CpBV-CrV1 on hemocyte monolayer revealed that they could enter hemocytes unlike a mutant in the N-terminal coiled-coil domain. However, they failed to inhibit the hemocyte-spreading behavior without any binding affinity to GAPDH. These results suggest that GAPDH plays a critical role in hemocyte-spreading behavior during immune challenge as a molecular target of viral factor CpBV-CrV1. (C) 2015 Elsevier Ltd. All rights reserved.</P>

Enhanced bolometric properties of nickel oxide thin films for infrared image sensor applications by substitutional incorporation of Li

Kang, In-Ku,Reddy, Y. Ashok Kumar,Shin, Young Bong,Kim, Woo Young,Lee, Hee Chul Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.7

<P><B>Abstract</B></P> <P>This study aims to investigate the influence of substitutionally incorporated Li on sensing performance of nickel oxide films for bolometer applications by comparing Ni<SUB>1-<I>x</I> </SUB>O and (Li<SUB> <I>y</I> </SUB>Ni<SUB>1-<I>y</I> </SUB>)<SUB>1-<I>x</I> </SUB>O films. From the results of structural analysis, it was confirmed that the film deposited from Li<SUB>0.2</SUB>Ni<SUB>0.8</SUB>O target contained Li which substitutionally occupies the Ni cation site while maintaining a cubic NiO structure. The substitutionally incorporated Li in nickel oxide can serve as an acceptor providing a hole carrier, like as a structural defect. However, in contrast to the structural defect, the substitutional incorporation of Li made it possible to increase the number of hole carriers in nickel oxide film while maintaining excellent film quality. In addition, the contact resistance with electrode was greatly reduced as a result of the substitutionally incorporated Li. These changes in structural and electrical properties lead to a significant reduction of 1/<I>f</I> noise arisen from the (Li<SUB> <I>y</I> </SUB>Ni<SUB>1-<I>y</I> </SUB>)<SUB>1-<I>x</I> </SUB>O film. As a result, the sensing performance of the (Li<SUB> <I>y</I> </SUB>Ni<SUB>1-<I>y</I> </SUB>)<SUB>1-<I>x</I> </SUB>O film as evaluated using the (<I>α</I> <SUB> <I>H</I> </SUB>/<I>n</I>)<SUP>1/2</SUP>/|<I>β</I>| value was nearly 10 times better than that of the Ni<SUB>1-<I>x</I> </SUB>O film. Consequently, it can be concluded that the substitutional incorporation of Li can significantly improve the sensing performance of nickel oxide films for bolometer applications.</P>

Novel dithiols as capping ligands for CdSe quantum dots: optical properties and solar cell applications

Kumar, A.,Huy, B.,Kumar, B.,Kim, J.,Dao, V. D.,Choi, H. S.,Lee, Y. I. Royal Society of Chemistry 2015 Journal of Materials Chemistry C Vol.3 No.9

Effect of Substrate Temperature on Structural, Optical and Electrical Properties of Sputtered NiO-Ag Nanocrystalline Thin Films

Y. Ashok Kumar Reddy,B. Ajitha,P. Sreedhara Reddy,프라탑 렙디,이정희 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.5

NiO-Ag thin films were deposited on Corning 7059 glass substrates by DC reactive magnetron sputtering technique and investigated the substrate temperature (Ts) dependent properties of NiO-Ag thin films. X-ray diffraction results showed that crystalline films can be obtained at high Ts and all films have a preferred crystal growth texture with face centered cubic (fcc) structure and was also confirmed by Raman studies. The grain size, transmittance, band gap, mobility and carrier concentrations were increased with Ts. Room temperature deposited films have an average roughness around 6.9 nm where as increment of Ts resulted in increased roughness up to 14 nm with nanocrystalline morphology. The optimum substrate temperature to obtain NiO-Ag films was found to be 200°C. It was found that with increasing the Ts, resistivity of the films was significantly decreased.

Arabidopsis thaliana RECEPTOR DEAD KINASE1 Functions as a Positive Regulator in Plant Responses to ABA

Kumar, D.,Kumar, R.,Baek, D.,Hyun, T.K.,Chung, W.S.,Yun, D.J.,Kim, J.Y. Oxford University Press 2017 Molecular plant Vol.10 No.2

Abscisic acid (ABA) is a major phytohormone involved in important stress-related and developmental plant processes. Membrane-delimited ABA signal transduction plays an important role in early ABA signaling, but the molecular mechanisms connecting core signaling components to the plasma membrane remain unclear. Plants have evolved a large number of receptor-like kinases (RLKs) to modulate diverse biological processes by perceiving extracellular stimuli and activating downstream signaling responses. In this study, a putative leucine-rich repeat-RLK gene named RECEPTOR DEAD KINASE1 (AtRDK1) was identified and characterized in Arabidopsis thaliana. RDK1 promoter-GUS analysis revealed that RDK1 is expressed ubiquitously in the various tissues in Arabidopsis, and its expression is mainly induced by ABA. In the presence of ABA, RDK1-deficient rdk1-1 and rdk1-2 lines showed significant resistance in cotyledon greening and root growth, whereas RDK1-overexpressing lines showed enhanced sensitivity. Consistently, the expression of ABA-responsive genes was significantly downregulated in rdk1 mutant seedlings, which were also hypersensitive to drought stress with increased water loss. Interestingly, RDK1 was found to be an atypical kinase localized to the plasma membrane and did not require its kinase activity during ABA-mediated inhibition of seedling development. Accordingly, RDK1 interacted in the plasma membrane with type 2C protein phosphatase ABSCISIC ACID INSENSITIVE1 (ABI1); this interaction was further enhanced by exogenous application of ABA, suggesting that RDK1-mediated recruitment of ABI1 onto the plasma membrane is important for ABA signaling. Taken together, these results reveal an important role for RDK1 in plant responses to abiotic stress conditions in an ABA-dependent manner.

Structural and magnetic properties of chemically synthesized Fe doped ZnO

Kumar, Shalendra,Kim, Y. J.,Koo, B. H.,Sharma, S. K.,Vargas, J. M.,Knobel, M.,Gautam, S.,Chae, K. H.,Kim, D. K.,Kim, Y. K.,Lee, C. G. American Institute of Physics 2009 JOURNAL OF APPLIED PHYSICS - Vol.105 No.7

<P>We report on the synthesis of Fe-doped ZnO with nominal composition of Zn0.99Fe0.01O by using a coprecipitation method. X-ray diffraction and selective area electron diffraction studies reveal a single phase wurtzite crystal structure without any secondary phase. Field emission transmission electron microscopy measurements infer that Zn0.99Fe0.01O have nanorod-type microstructures. Magnetic hysteresis measurement performed at different temperatures show that Zn0.99Fe0.01O exhibits a weak ferromagnetic behavior at room temperature. A detailed investigation of the electronic and local structure using O K-, Fe L-3,L-2 near edge x-ray absorption fine structure suggests that Fe is substituting Zn in ZnO matrix and is in Fe3+ state. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3073933]</P>

Spatially-resolved spectroscopic investigations on the formation of PtSi by annealing on a silicon surface

Kumar, Y.,Yang, M.,Ihm, K.,Lee, K.J.,Hwang, C.C. North Holland 2014 Chemical physics letters Vol.608 No.-

We report spatially-resolved spectroscopic investigations on the effect of annealing a Pt (100A)/Si interface in the presence of a native silicon oxide layer. Scanning photoelectron microscopy showed a spatially non-uniform growth pattern of PtSi depending on the annealing temperature and annealing time. Pt 4f and Si 2p core-level spectra measured using different photon energies and at different points suggest both in-plane and out-of-plane inhomogeneous growth of PtSi at 773K.

Identification and evaluation of potent Middle East respiratory syndrome coronavirus (MERS-CoV) 3CL^Pro inhibitors

Kumar, V.,Shin, J.S.,Shie, J.J.,Ku, K.B.,Kim, C.,Go, Y.Y.,Huang, K.F.,Kim, M.,Liang, P.H. Elsevier/North-Holland 2017 ANTIVIRAL RESEARCH Vol.141 No.-

<P>Middle East respiratory syndrome coronavirus (MERS-CoV) causes severe acute respiratory illness with fever, cough and shortness of breath. Up to date, it has resulted in 1826 human infections, including 649 deaths. Analogous to picornavirus 3C protease (3C(PrO)), 3C-like protease (3CL(PrO)) is critical for initiation of the MERS-CoV replication cycle and is thus regarded as a validated drug target. As presented here, our peptidomimetic inhibitors of enterovirus 3C(PrO) (6b. 6c and 6d) inhibited 3CLPr0 of MERS-CoV and severe acute respiratory syndrome coronavirus (SARS-CoV) with IC50 values ranging from 1.7 to 4.7 M and from 0.2 to 0.7 M, respectively. In MERS-CoV-infected cells, the inhibitors showed antiviral activity with EC50 values ranging from 0.6 to 1.4 1.1M, by downregulating the viral protein production in cells as well as reducing secretion of infectious viral particles into culture supernatants. They also suppressed other cc and 8-CoVs from human and feline origin. These compounds exhibited good selectivity index (over 70 against MERS-CoV) and could lead to the development of broad-spectrum antiviral drugs against emerging CoVs and picornaviruses. (C) 2017 Elsevier B.V. All rights reserved.</P>

The Role of External Defects in Chemical Sensing of Graphene Field-Effect Transistors

Kumar, B.,Min, K.,Bashirzadeh, M.,Farimani, A. Barati,Bae, M.-H.,Estrada, D.,Kim, Y. D.,Yasaei, P.,Park, Y. D.,Pop, E.,Aluru, N. R.,Salehi-Khojin, A. American Chemical Society 2013 Nano letters Vol.13 No.5

<P>A fundamental understanding of chemical sensing mechanisms in graphene-based chemical field-effect transistors (chemFETs) is essential for the development of next generation chemical sensors. Here we explore the hidden sensing modalities responsible for tailoring the gas detection ability of pristine graphene sensors by exposing graphene chemFETs to electron donor and acceptor trace gas vapors. We uncover that the sensitivity (in terms of modulation in electrical conductivity) of pristine graphene chemFETs is not necessarily intrinsic to graphene, but rather it is facilitated by external defects in the insulating substrate, which can modulate the electronic properties of graphene. We disclose a mixing effect caused by partial overlap of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of adsorbed gas molecules to explain graphene’s ability to detect adsorbed molecules. Our results open a new design space, suggesting that control of external defects in supporting substrates can lead to tunable graphene chemical sensors, which could be developed without compromising the intrinsic electrical and structural properties of graphene.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2013/nalefd.2013.13.issue-5/nl304734g/production/images/medium/nl-2012-04734g_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl304734g'>ACS Electronic Supporting Info</A></P>

Oxidative stress induced by chlorine dioxide as an insecticidal factor to the Indian meal moth, Plodia interpunctella

Kumar, S.,Park, J.,Kim, E.,Na, J.,Chun, Y.S.,Kwon, H.,Kim, W.,Kim, Y. Academic Press 2015 Pesticide biochemistry and physiology Vol.124 No.-

A novel fumigant, chlorine dioxide (ClO<SUB>2</SUB>) is a commercial bleaching and disinfection agent. Recent study indicates its insecticidal activity. However, its mode of action to kill insects is yet to be understood. This study set up a hypothesis that an oxidative stress induced by ClO<SUB>2</SUB> is a main factor to kill insects. The Indian meal moth, Plodia interpunctella, is a lepidopteran insect pest infesting various stored grains. Larvae of P. interpunctella were highly susceptible to ClO<SUB>2</SUB> gas, which exhibited an acute toxicity. Physiological damages by ClO<SUB>2</SUB> were observed in hemocytes. At high doses, the larvae of P. interpunctella suffered significant reduction of total hemocytes. At low doses, ClO<SUB>2</SUB> impaired hemocyte behaviors. The cytotoxicity of ClO<SUB>2</SUB> was further analyzed using two insect cell lines, where Sf9 cells were more susceptible to ClO<SUB>2</SUB> than High Five cells. The cells treated with ClO<SUB>2</SUB> produced reactive oxygen species (ROS). The produced ROS amounts increased with an increase of the treated ClO<SUB>2</SUB> amount. However, the addition of an antioxidant, vitamin E, significantly attenuated the cytotoxicity of ClO<SUB>2</SUB> in a dose-dependent manner. To support the oxidative stress induced by ClO<SUB>2</SUB>, two antioxidant genes (superoxide dismutase (SOD) and thioredoxin-peroxidase (Tpx)) were identified from P. interpunctella EST library using ortholog sequences of Bombyx mori. Both SOD and Tpx were expressed in larvae of P. interpunctella especially under oxidative stress induced by bacterial challenge. Exposure to ClO<SUB>2</SUB> gas significantly induced the gene expression of both SOD and Tpx. RNA interference of SOD or Tpx using specific double stranded RNAs significantly enhanced the lethality of P. interpunctella to ClO<SUB>2</SUB> gas treatment as well as to the bacterial challenge. These results suggest that ClO<SUB>2</SUB> induces the production of insecticidal ROS, which results in a fatal oxidative stress in P. interpunctella.