NK-lysin of channel catfish: Gene triplication, sequence variation, and expression analysis

Antimicrobial peptides (AMPs) are important components of the host innate immune response against microbial invasion. In addition to the previously known four classes of antimicrobial peptides, a fifth class of antimicrobial peptides has been recently identified to include NK-lysins that have a globular three-dimensional structure and are larger with 74-78 amino acid residues. NK-lysin has been shown to harbor antimicrobial activities against a wide spectrum of microorganisms including bacteria, fungi, protozoa, and parasites. To date, NK-lysin genes have been reported from only a limited number of organisms. We previously identified a NK-lysin cDNA in channel catfish. Here we report the identification of two noveltypes of NK-lysin transcripts in channel catfish. Altogether, three distinct NK-lysin transcripts exist in channel catfish. In this work, their encoding genes were identified, sequenced, and characterized. We provide strong evidence that the catfish NK-lysin gene is tripled in the same genomic neighborhood. All three catfish NK-lysin genes are present in the same genomic region and are tightly linked on the same chromosome, as the same BAC clones harbor all three copies of the NK-lysin genes. All three NK-lysin genes are expressed, but exhibit distinct expression profiles in various tissues. In spite of the existence of a single copy of NK-lysin gene in the human genome, and only a single hit from the pufferfish,genome, there are two tripled clusters of NK-lysin genes on chromosome 17 of zebrafish in addition to one more copy on its chromosome 5. The similarity in the genomic arrangement of the tripled NK-lysin genes in channel catfish and zebrafish suggest similar evolution of NK-lysin genes. (c) 2005 Elsevier Ltd. All rights reserved.

Inductive expression and characterization analysis of Paralichthys olivaceus pigment epithelium-derived factor in a virally infected cell line

Pigment epithelium-derived factor (PEDF) is acknowledged to be a non-inhibitory member of the serine protease inhibitor (serpin) superfamily, with antiangiogenesis, and neuroprotective and immumoregulatory function, mainly in the tissues of nervous system. Here, A PEDF gene homolog, Paralichthys olivaceus PEDF (PoPEDF), was isolated from flounder embryonic cells (FEC) treated with UV-inactivated Grass carp hemorrhage virus (GCHV) and subsequently identified as a differentially expressed gene. The full length of PoPEDF cDNA is 1803 bp with an open reading frame of 1212 bp encoding a 403-amino-acid protein. This deduced protein contains an N-terminal signal peptide, a glycosylation site, a consensus serpin motif, and a 34-mer and a 44-mer fragment, all of which are very conserved in the PEDF family. PoPEDF gene exhibits a conserved exon-intron arrangement with 8 exons and 7 introns. This conserved evolutionary relationship was further confirmed by a phylogenetic analysis, where fish PEDFs and mammalian members formed a well-supported clade. Constitutive expression of PoPEDF was widely detected in many tissues. In response to UV-inactivated GCHV or poly(I:C), PEDF mRNA was upregulated in FEC cells with time. This is the first report on the transcriptional induction of PEDF in virally infected cells. (C) 2005 Elsevier Inc. All rights reserved.

Characterization of transgene integration pattern in F4 hGH-transgenic common carp (Cyprinus carpio L.)

The integration pattern and adjacent host sequences of the inserted pMThGH-transgene in the F4 hGH-transgenic common carp were extensively studied. Here we show that each F4 transgenic fish contained about 200 copies of the pMThGH-transgene and the transgenes were integrated into the host genome generally with concatemers in a head-to-tail arrangement at 4-5 insertion sites. By using a method of plasmid rescue, four hundred copies of transgenes from two individuals of F4 transgenic fish, A and B, were recovered and clarified into 6 classes. All classes of recovered transgenes contained either complete or partial pMThGH sequences. The class I, which comprised 83% and 84.5% respectively of the recovered transgene copies from fish A and B, had maintained the original configuration, indicating that most transgenes were faithfully inherited during the four generations of reproduction. The other five classes were different from the original configuration in both molecular weight and restriction map, indicating that a few transgenes had undergone mutation, rearrangement or deletion during integration and germline transmission. In the five types of aberrant transgenes, three flanking sequences of the host genome were analyzed. These sequences were common carp beta-actin gene, common carp DNA sequences homologous to mouse phosphoglycerate kinase-1 and human epidermal keratin 14, respectively.

Redescription of Camallanus hypophthalmichthys Dogel and Akhmerov, 1959 (Nematoda : Camallanidae) and its first record from fishes in China

The nematode Camallanus hypophthalmichthys Dogel and Akhmerov, 1959 is redescribed from specimens collected from the intestine of the bighead carp Aristichthys nobilis, from Liangzihu Lake (Yangtze River basin), Hubei Province, central China. The light and scanning electron microscopical examination made it possible to study in detail the morphology of this so far little-known species and to confirm its validity. The main specific features of C. hypophthalmichthys distinguishing it from the most similar Camallanus spp. is the presence of 3 small caudal processes on the male tail tip, 13-16 longitudinal ridges on the inner surface of the valve of the buccal capsule, and the arrangement of preanal and postanal genital papillae in the male. This finding represents a new host record, the first record of this parasite in the Yangtze River basin, and the first documented record of C. hypophthalmichthys from China. Camallanus hypophthalmichthys is considered a specific intestinal parasite of fishes of the cyprinid Hypophthalmichthyinae.

Self-organization of spinal reflexes involving homonymous, antagonist and synergistic interactions

Recent results in spinal research are challenging the historical view that the spinal reflexes are mostly hardwired and fixed behaviours. In previous work we have shown that three of the simplest spinal reflexes could be self-organised in an agonist-antagonist pair of muscles. The simplicity of these reflexes is given from the fact that they entail at most one interneuron mediating the connectivity between afferent inputs and efferent outputs. These reflexes are: the Myotatic, the Reciprocal Inibition and the Reverse Myotatic reflexes. In this paper we apply our framework to a simulated 2D leg model actuated by six muscles (mono- and bi-articular). Our results show that the framework is successful in learning most of the spinal reflex circuitry as well as the corresponding behaviour in the more complicated muscle arrangement. © 2012 Springer-Verlag.

Distinct two dimensional lateral ordering of self-assembled quantum dots

We report a quantum dot (QD) ensemble structure in which the in-plane arrangements of the dots are in a hexagonal way while the dots are also vertically aligned. Such a distinct lateral ordering of QDs is achieved on a planar GaAs(l 0 0) rather than on a prepatterned substrate by strain-mediated multilayer vertical stacking of the QDs. The analysis indicates that the strain energy of the lateral island-island interaction is minimum for arrangement of the hexagonal ordering. The ordered dots demonstrate strong photoluminescence (PL) emission at room temperature (RT) and the full width at half maximum of PL peak at RT is only 50 meV. (C) 2007 Elsevier B.V. All rights reserved.

Self-organized hexagonal ordering of quantum dot arrays

We report a structure of (In, Ga)As/GaAs quantum dots which are vertically correlated and laterally aligned in a hexagonal way thus forming three-dimensionally ordered arrays. The growth pathway is based on a mechanism of self-assembly by strain-mediated multilayer vertical stacking on a planar GaAs(100) substrate, rather than molecular-beam epitaxy on a prepatterned substrate. The strain energy of lateral island-island interaction is minimum for the arrangement of hexagonal ordering. However, realization of hexagonal ordering not only depends on a complicated trade-off between lateral and vertical island-island interaction but is also related to a delicate and narrow growth kinetics window.

Molecular beam epitaxy InAs dot arrays on InGaAs/GaAs

Periodical alignment of the InAs dots along the < 100 > and < 110 > directions was observed on an elastically relaxed InGaAs buffer layer grown at 500 and 450 degrees C, respectively, on the vicinal GaAs(001) substrate. Due to alignment along these directions, the InAs dots were arranged into a quasi-two-dimensional hexagonal lattice. Such a periodical arrangement of InAs dots may be explained in terms of modulation in strain as well as composition along [110] as observed by using cross-sectional transmission electron microscopy.

Efficiently producing single-walled carbon nanotube rings and investigation of their field emission properties

Single-walled carbon nanotube (SWNT) rings with a diameter of about 100 nm have been prepared by thermally decomposing hydrocarbon in a floating catalyst system. These rings appeared to consist mostly of SWNT toroids. High resolution transmission electron microscopy showed that these rings were composed of tens of SWNTs with a tightly packed arrangement. The production of SWNT rings was improved through optimizing various growth parameters, such as growth temperature, sublimation temperature of the catalyst, different gas flows and different catalyst components. The growth mechanism of the SWNT rings is discussed. In the field emission measurements we found that field emission from a halved ring is better than that from a whole SWNT ring, which contributed to the better emission from two opened ends of the nanotubes of the halved SWNT ring.

Two-dimensional ordering of self-assembled InxGal-xAs quantum dots grown on GaAs(311)B surfaces

Two-dimensional (2D) ordering of self-assembled InxGa1-xAs quantum dots (QDs) fabricated on GaAs(311)B surface by molecular beam epitaxy (MBE) are reported. The QDs are aligned into rows deferring from the direction of the misorientation of the substrate, and strongly dependent on the mole In content x of InxGa1-xAs solid solution. The ordering alignment deteriorates significantly as the In content is increased to above 0.5. The 2D ordering can be described as a centered rectangular unit mesh with the two sides parallel to [01 (1) over bar] and [(2) over bar 33], respectively. Their relative arrangement seems to be determined by a combination of the strongly repulsive elastic interaction between neighbouring islands and the minimization of the strain energy of the whole system. The ordering also helps to improve the size homogeneity of the InGaAs islands. Photoluminescence (PL) result demonstrates that QDs grown on (311)B have the narrowest linewidth and the strongest integrated intensity, compared to those grown on (100) and other high-index planes under the same condition. (C) 1999 Elsevier Science B.V. All rights reserved.

Two-dimensional ordering of self-assembled InxGa1-xAs quantum dots grown on GaAs(311)B surfaces

The two-dimensional (2D) ordering of self-assembled InxGa1-xAs quantum dots (QDs) fabricated on GaAs(3 1 1)B surface by molecular beam epitaxy (MBE) are reported. The QDs are aligned into rows differing from the direction of the misorientation of the substrate, and strongly dependent on the mole In content x of InxGa1-As-x solid solution. The ordering alignment deteriorates significantly as the In content is increased to above 0.5. The 2D ordering can be described as a centered rectangular unit mesh with the two sides parallel to [0 1 (1) over bar] and [(2) over bar 3 3], respectively. Their relative arrangement seems to be determined by a combination of the strongly repulsive elastic interaction between the neighboring islands and the minimization of the strain energy of the whole system. The ordering also helps to improve the size homogeneity of the InGaAs islands. The photoluminescence (PL) result demonstrates that QDs grown on (3 1 1)B have the narrowest linewidth and the strongest integrated intensity, compared to those on (1 0 0) and other high-index planes under the same condition. (C) 1999 Elsevier Science B.V. All rights reserved.

Ordered InAs quantum dots in InAlAs matrix on (001) InP substrates grown by molecular beam epitaxy

InAs self-organized quantum dots in InAlAs matrix lattice-matched to exactly oriented (001) InP substrates were grown by solid source molecular beam epitaxy (MBE) using the Stranski-Krastanow mode. Preliminary characterizations have been performed using photoluminescence and transmission electron microscopy. The geometrical arrangement of the quantum dots is found to be strongly dependent on the amount of coverage. At low deposition thickness. InAs QDs are arranged in chains along [1(1) over bar0$] directions. Luminescence from the quantum dots and the wetting layer consisting of quantum wells with well widths of 1, 2, and 3 monolayers is observed. (C) 1998 American Institute of Physics.

Influence of interdot electronic coupling on photoluminescence spectra of self-assembled InAs/GaAs quantum dots

The influence of interdot electronic coupling on photoluminescence (PL) spectra of self-assembled InAs/GaAs quantum dots (QDs) has been systematically investigated combining with the measurement of transmission electron microscopy. The experimentally observed fast red-shift of PL energy and an anomalous reduction of the linewidth with increasing temperature indicate that the QD ensemble can be regarded as a coupled system. The study of multilayer vertically coupled QD structures shows that a red-shift of PL peak energy and a reduction of PL linewidth are expected as the number of QD layers is increased. On the other hand, two layer QDs with different sizes have been grown according to the mechanism of a vertically correlated arrangement. However, only one PL peak related to the large QD ensemble has been observed due to the strong coupling in InAs pairs. A new possible mechanism to reduce the PL linewidth of QD ensemble is also discussed.

The influence of substrate nucleation on HVPE-grown GaN thick films - art. no. 684105

Thick GaN films were grown on sapphire in a home-made vertical HVPE reactor. Effect of nucleation treatments on the properties of GaN films was investigated, including the nitridation of sapphire, low temperature GaN buffer and MOCVD-template. Various material characterization techniques, including AFM, SEM, XRD, CL and PL have been used to assess these GaN epitaxial films. It was found that the surface of sapphire after high temperature nitridation was flat and showed high density nucleation centers. In addition, smooth Ga-polarity surface of epitaxial layer can be obtained on the nitridation sapphire placed in air for several days due to polarity inversion. This may be caused by the atoms re-arrangement because of oxidation. The roughness of N-polarity film was caused by the huge inverted taper domains, which can penetrate up to the surface. The low temperature GaN buffer gown at 650 degrees C is favorable for subsequent epitaxial film, which had narrow FWHM of 307 arcsec. The epitaxial growth on MOCVD-template directly came into quasi-2D growth mode due to enough nucleation centers, and high quality GaN films were acquired with the values of the FWHM of 141 arcsec for (002) reflections. After etching in boiled KOH, that the total etch-pit density was only 5 x 106 cm(-2) illustrated high quality of the thick film on template. The photoluminescence spectrum of GaN film on the MOCVD-template showed the narrowest line-width of the band edge emission in comparison with other two growth modes.

大型制冷机组的冲洗与调试

大型制冷机组部件众多，管路比较复杂，又是必须承受高压的容器，安装、调试都有严格的要求。以30HXC165A制冷机组的现场冲洗、调试为例，详细介绍了大型制冷机组在试运行之前标准的准备工作。这些工作包括吹扫、试压、排污、充注制冷剂和冲洗调试等全部过程及注意事项。本文为大型螺杆式制冷机组这种压力容器设备的运行和维护管理提供了工程实践经验。结果表明：在施工调试过程中，只有各方互相协调，并且严格按照相关文件和规范要求才能顺利完成制冷机组的安装调试，为以后的正常运行打下基础。