The innate immune response to grass carp hemorrhagic virus (GCHV) in cultured Carassius auratus blastulae (CAB) cells

Virus infection of mammalian cells activates an innate antiviral immune response characterized by production of interferon (IFN) and the subsequent transcriptional upregulation of IFN-stimulated genes (ISGs) by the JAK-STAT signaling pathway. Here, we report that a fish cell line, crucian carp (Carassius auratus L.) blastulae embryonic (CAB) cells, can produce IFN activity and then form an antiviral state after infection with UV-inactivated grass carp hemorrhagic virus (GCHV), a double-stranded (ds) RNA virus. From UV-inactivated GCHV-infected CAB cells, 15 pivotal genes were cloned and sequenced, and all of them were shown to be involved in IFN antiviral innate immune response. These IFN system genes include the dsRNA signal sensing factor TLR3, IFN, IFN signal transduction factor STAT1, IFN regulatory factor IRF7, putative IFN antiviral effectors Mx1, Mx2, PKR-like, Viperin, IFI56, and other IFN stimulated genes (ISGs) IFI58, ISG15-1, ISG15-2, USP18, Gig1 and Gig2. The identified fish IFN system genes were highly induced by active GCHV, UV-inactivated GCHV, CAB IFN or poly(I).poly(C), and showed similar expression patterns to mammals. The data indicate that an IFN antiviral innate immune response similar to that in mammals exists in the UV-inactivated GCHV-infected CAB cells, and the IFN response contributes to the formation of an antiviral state probably through JAK-STAT signaling pathway. This study provides strong evidence for existence of IFN antiviral innate immune response in fish, and will assist in elucidating the origin and evolution of vertebrate IFN system. (c) 2006 Elsevier Ltd. All rights reserved.

Identification of two novel interferon-stimulated genes from cultured CAB cells induced by UV-inactivated grass carp hemorrhage virus

Interferon (IFN) exerts its antiviral effect by inducing the expression of a number of IFN-stimulated genes (ISGs) to establish a host antiviral state. Earlier studies identified some important fish IFN system genes from IFN-induced CAB cells (crucian carp Carassius auratus L. embryonic blastulae cells) after treatment with UV-inactivated GCHV (grass carp hemorrhage virus). Herein, the cloning of 2 novel IFN-stimulated genes, termed Gig1 and Gig2, is described for the same cell system. The complete cDNA sequences of Gig1 and Gig2 contain 1244 bp encoding for a 194-amino-acid protein and 693 bp for a 158-amino-acid protein, respectively. A search of public databases revealed that these are 2 novel IFN-stimulated genes, since neither significant homologous genes nor conserved motifs were identified. Active GCHV, UV-inactivated GCHV and CAB IFN-containing supernatant (ICS) induced transcription of these genes and distinct kinetics were observed. An analysis of differences in expression between the 2 genes and the IFN signal factors CaSTAT1 and CaIRF7 indicated that GCHV infection activated different signal pathways for their up-regulation. Upon virus infection, the transcription of Gig1 but not of Gig2 is strongly suppressed by cycloheximide (CHX). In contrast, following treatment with CAB IFN-containing supernatant, CHX does not inhibit either gene transcription. The results suggest that GCHV infection can induce expression of both Gig1 and Gig2 via newly synthesized CAB IFN, most probably through the JAK-STAT signal pathway, and can also directly activate Gig2 transcription without ongoing protein synthesis.

Molecular cloning and characterisation of a fish PKR-like gene from cultured CAB cells induced by UV-inactivated virus

The double-stranded-RNA-dependent protein kinase (PKR) is an important component in an antiviral defence pathway that is mediated by interferon (IFN) in vertebrates. Previously, some important IFN system genes had been identified from an IFN-producing CAB (crucian carp Carassius auratus blastulae embryonic) cells after treatment with UV-inactivated GCHV (grass carp haemorrhage virus). Here, a fish PKR-like gene, named CaPKR-like, is cloned and sequenced from the same virally infected CAB cells. It has 2192 base pairs in length with a largest open reading frame (ORF) encoding a protein of 513 amino acid residues. BLAST search reveals that the putative CaPKR-like protein is most homologous to human PKR and also has a high-level homology with all members of a family of eIF2alpha kinases. Structurally, CaPKR-like possesses a conserved C-terminal catalytic domain of eIF2alpha kinase family and the most similarity to mammalian PKRs. Within its N-terminus, there are no dsRNA-binding domains conserved in mammalian PKRs instead of two putative Z-DNA binding domains (Zalpha). Like mammalian PKRs, CaPKR-like had a very low level of constitutive expression in normal CAB cells but was up-regulated in response to active GCHV, UV-inactivated GCHV and CAB IFN, implying that the transcriptional activation of CaPKR-like by viral infection is mediated possibly by newly produced CAB IFN, which was further supported by using cycloheximide, a potent inhibitor of protein synthesis. The results together suggested that CaPKR-like was the first identified fish gene most similar to mammalian PKRs. (C) 2004 Elsevier Ltd. All rights reserved.

Differential expression of two Carassius auratus Mx genes in cultured CAB cells induced by grass carp hemorrhage virus and interferon

UV-inactivated GCHV (grass carp hemorrhage virus) is able to induce an antiviral state in cultured CAB cells (crucian carp Carassius auratus blastulae embryonic cells) via the production of interferon (IFN). In the current work, the full-length cDNAs of two Mx genes, termed CaMx1 and CaMx2, have been cloned and sequenced from UV-inactivated GCHV-infected and still IFN-producing CAB cells by suppression subtractive hybridization. Their putative proteins show the characteristically structural features of mammalian IFN-induced Mx proteins, including GTP-binding motif, dynamin family signature and leucine zipper motif. CaMx1 exhibits 85% sequence identity to zebrafish MxA and 72-74% to three Atlantic salmon Mx proteins. CaMx2 is most similar to zebrafish MxE, with 80% identity, and then rainbow trout Mx3, with 52%. Constitutive expression was detected by RT-PCR for CaMx1, but not for CaMx2, in normal CAB cells, but their up-regulations could be induced after treatment with active GCHV, UV-inactivated GCHV and CAB IFN. Distinct kinetics of expression was observed for either CaMx1 or CaMx2 corresponding to the three stimuli, and even between CaMx1 and CaMx2, corresponding to the same stimulus. Upon virus infection, the transcriptional induction was strongly blocked for CaMx2 by cycloheximide (CHX), whereas almost nothing was observed for CaMx1. By contrast, following treatment with CAB IFN, CHX did not inhibit either gene transcription. Collectively, these results suggest that there are very distinct mechanisms for modulating the expression of both CaMx1 and CaMx2 in normal and GCHV-infected CAB cells.

Role of Bi3+ ions for Er3+ ions efficient 1.54 mu m light emission in Er/Bi codoped SiO2 thin film prepared by sol-gel method

Er/Bi codoped SiO2 thin films were prepared by sol-gel method and spin-on technology with subsequent annealing process. The bismuth silicate crystal phase appeared at low annealing temperature while vanished as annealing temperature exceeded 1000 degrees C, characterized by X-ray diffraction, and Rutherford backscattering measurements well explained the structure change of the films, which was due to the decrease of bismuth concentration. Fine structures of the Er3+-related 1.54 mu m light emission (line width less than 7 nm) at room temperature was observed by photoluminescence (PL) measurement. The PL intensity at 1.54 gm reached maximum at 800 degrees C and decreased dramatically at 1000 degrees C. The PL dependent annealing temperature was studied and suggested a clear link with bismuth silicate phase. Excitation spectrum measurements further reveal the role of Bi3+ ions for Er3+ ions near infrared light emission. Through sol-gel method and thermal treatment, Bi3+ ions can provide a perfect environment for Er3+ ion light emission by forming Er-Bi-Si-O complex. Furthermore, energy transfer from Bi3+ ions to Er3+ ions is evidenced and found to be a more efficient way for Er3+ ions near infrared emission. This makes the Bi3+ ions doped material a promising application for future erbium-doped waveguide amplifier and infrared LED

Enhancement of field emission properties in La-doped ZnO films prepared by magnetron sputtering

Field emissions (FE) from La-doped zinc oxide (ZnO) films are both experimentally and theoretically investigated. Owing to the La-doped effect, the FE characteristic of ZnO films is remarkably enhanced compared with an undoped sample, and a startling low turn-on electric field of about 0.4 V/mu m (about 2.5 V/mu m for the undoped ZnO films) is obtained at an emission current density of 1 mu A/cm(2) and the stable current density reaches 1 mA/cm(2) at an applied field of about 2.1 V/mu m. A self-consistent theoretical analysis shows that the novel FE enhancement of the La-doped sample may be originated from its smaller work function. Due to the effect of doping with La, the Fermi energy level lifts, electrons which tunnelling from surface barrier are consumedly enhancing, and then leads to a huge change of field emission current. Interestingly, it suggests a new effective method to improve the FE properties of film materials.

The effects of substrate temperature on the structure and properties of ZnO films prepared by pulsed laser deposition

ZnO thin films were prepared by pulsed laser deposition (PLD) on glass substrates with growth temperature from room temperature (RT) to 500 degrees C. The effects of substrate temperature on the structural and optical properties of ZnO films have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission spectra, and RT photoluminescence (PL) measurements. The results showed that crystalline and (0 0 2)-oriented ZnO films were obtained at all substrate temperatures. As the substrate temperature increased from RT to 500 degrees C, the ratio of grain size in height direction to that in the lateral direction gradually decreased. The same grain size in two directions was obtained at 200 degrees C, and the size was smallest in all samples, which may result in maximum E, and E-0 of the films. UV emission was observed only in the films grown at 200 degrees C, which is probably because the stoichiometry of ZnO films was improved at a suitable substrate temperature. It was suggested that the UV emission might be related to the stoichiometry in the ZnO film rather than the grain size of the thin film. (c) 2007 Elsevier Ltd. All rights reserved.

Quasi-hexagonal ordered arrays of FePt nanoparticles prepared by a micellar method

Hexagonally ordered arrays of magnetic FePt nanoparticles on Si substrates are prepared by a self assembly of diblock copolymer PS-b-P2VP in toluene, a dip coating process and finally plasma treatment. The as-treated FePt nanoparticles are covered by an oxide layer that can be removed by a 40 s Ar+ sputtering. The effects of the sequence of adding salts on the composition distribution are revealed by x-ray photoelectron spectroscopy measurements. No particle agglomeration is observed after 600 degrees C annealing for the present ordered array of FePt nanoparticles, which exhibits advantages in patterning FePt nanoparticles by a micellar method. Moreover, magnetic properties of the annealed FePt nanoparticles at room temperature are investigated by a vibrating sample magnetometer.

Photoluminescence from heterogeneous SiGe/Si nanostructures prepared via a two-step approach strategy

A two-step approach of preparation for SiGe/Si heterogeneous nanostructures, which combined with ultra-high vacuum chemical deposition and electrochemical anodization techniques, is demonstrated. Uniformly distributed nanostructures with a quite uniform distribution of size and morphology are obtained. A strong room-temperature photoluminescence from the nanostructures was observed with a narrow full-width at half-maximum of around 110 meV. The possible origins of the two main peaks at around 1.6 and 1.8 eV have been discussed in detail. The two-step approach is proved to be a promising method to fabricate new Si-based optoelectronic materials. (C) 2009 Elsevier B.V. All rights reserved.

Raman scattering study on Ga1-xMnxAs prepared by Mn ions implantation, deposition and post-annealing

Raman scattering measurements have been performed in Ga1-xMnxAs crystals prepared by Mn ions implantation, deposition, and post-annealing. The Raman spectrum measured from the implanted surface of the sample shows some weak phonon modes in addition to GaAs-like phonon modes, where the GaAs-like LO and TO phonons are found to be shifted by approximately 4 and 2 cm(-1), respectively, in the lower frequency direction compared to those observed from the unimplanted surface of the sample. The weak vibrational modes observed are assigned to hausmannite Mn3O4 like. The coupled LO-phonon plasmon mode (CLOPM), and defects and As related vibrational modes caused by Mn ions implantation, deposition, and post-annealing are also observed. The compositional dependence of GaAs-like LO phonon frequency is developed for strained and unstrained conditions and then using the observed LOGaAs peak, the Mn composition is evaluated to be 0.034. Furthermore, by analyzing the intensity of CLOPM and unscreened LOGaAs phonon mode, the hole density is evaluated to be 1.84 x 10(18) cm(-3). (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Amorphous silicon carbide films prepared by H-2 diluted silane-methane plasma

This paper reports on the preparation and characterization of hydrogenated amorphous silicon carbide films prepared by H-2 diluted silane-methane plasma. Carbon-rich a-SiC:H film with band gap of up to 3.3 eV has been achieved. IR and UV Vis spectra were employed to characterize the chemical bonding and optical properties of as-prepared films. It is shown that hydrogen dilution is crucial in obtaining these wide band gap carbon-rich films. Raman and PL measurements were performed to probe the microstructure and photoelectronic properties of these films before and after annealing. Films with intermediate carbon concentration seem more defective and exhibit stronger photoluminescence and subband absorption than others. Films with different compositions exhibit different annealing behaviours. For silicon rich and carbon rich films, high temperature annealing results in the formation of silicon crystallites and graphite clusters, respectively. (C) 2003 Elsevier B.V. All rights reserved.

Parameters determining crystallinity in beta-SiC thin films prepared by catalytic chemical vapor deposition

The effects of deposition gas pressure and H-2 dilution ratio (H-2/SiH4+CH4+H-2), generally considered two of dominant parameters determining crystallinity in beta-SiC thin films prepared by catalytic chemical vapor deposition (Cat-CVD), often called hot-wire CVD method, on the films properties have been systematically studied. As deposition gas pressure increase from 40 to 1000 Pa, the crystallinity of the films is improved. From the study of H-2 dilution ratio, it is considered that H-2 plays a role as etching gas and modulating the phases in beta-SiC thin films. On the basis of the study on the parameters, nanocrystalline beta-SiC films were successfully synthesized on Si substrate at a low temperature of 300degreesC. The Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) spectra show formation of beta-SiC. Moreover, according to Sherrer equation, the average grain size of the films estimated is in nanometer-size. (C) 2003 Elsevier B.V. All rights reserved.

Formation of self-assembly and the mechanism of Si nanoquantum dots prepared by low pressure chemical vapor deposition

Si nanoquantum dots have been formed by self-assembled growth on the both Si-O-Si and Si-OH bonds terminated SiO2 surfaces using the low-pressure chemical vapor deposition (LPCVD) and surface thermal decomposition of pure SiH4 gas. We have experimentally studied the variation of Si. dot density with Si-OH bonds density, deposition temperature and SiH4 pressure, and analyzed qualitatively the formation mechanism of the Si nanoquantum dots based on LPCVD surface thermal dynamics principle. The results are very. important for the control of the density and size of Si nanoquantum dots, and have potential applications in the new quantum devices.

Study on growth mechanism of low-temperature prepared microcrystalline Si thin films

Microcrystalline silicon thin films at different growth stages were prepared by hot wire chemical vapor deposition. Atomic force microscopy has been applied to investigate the evolution of surface topography of these films. According to the fractal analysis I it was found that, the growth of Si film deposited on glass substrate is the zero-diffused stochastic deposition; while for the film on Si substrate, it is the finite diffused deposition on the initial growth stage, and transforms to the zero-diffused stochastic deposition when the film thickness reaches a certain value. The film thickness dependence of island density shows that a maximum of island density appears at the critical film thickness for both substrates. The data of Raman spectra approve that, on the glass substrate, the a-Si: H/mu c-Si:H transition is related to the critical film thickness. Different substrate materials directly affect the surface diffusion ability of radicals, resulting in the difference of growth modes on the earlier growth stage.

Effect of the variation of temperature on the structural and optical properties of ZnO thin films prepared on Si (111) substrates using PLD

ZnO thin films were prepared on Si (1 11) substrates at various temperatures from 250 to 700 degrees C using pulsed laser deposition (PLD) technique in order to investigate the structural and optical properties of the films. The structural and morphological properties of the films were investigated by XRD and SEM measurements, respectively. The quality of the films was improved with the increase of the temperature. By XRD patterns the FWHMs of the (0 0 2) peaks of the ZnO films became narrower when the temperatures were above 500 degrees C. The FWHMs of the peaks of (0 0 2) of the films were as narrow as about 0. 19 degrees when films were grown at 650 and 700 degrees C. This indicates the superior crystallinity of the films. The optical properties of the films were studied by photoluminescence spectra using a 325 nm He-Cd laser. The two strongest UV peaks were found at 377.9 nm from ZnO films grown at 650 and 700 degrees C. This result is consistent with that of the XRD investigation. Broad bands in visible region from 450 to 550 nm were also observed. Our works suggest that UV emissions have close relations with not only the crystallinity but also the stoichiometry of the ZnO films. (c) 2005 Elsevier Ltd. All rights reserved.