IL-8-induced L-selectin shedding regulates its binding kinetics to PSGL-1

L-selectin plays a crucial role in inflammation cascade by initiating the tethering and rolling of leukocytes on endothelium wall. While many L-selectin molecules are rapidly shed from the cell surface upon activation, the remaining membrane-anchored L-selectin may still play an important role in regulating leukocyte rolling and adhesion with different binding kinetics. Here we developed an in vitro model to activate Jurkat cells via interlukin-8 (IL-8) and quantified the two-dimensional (2D) binding kinetics, using a micropipette aspiration assay, of membrane-anchored L-selectin to P-selectin glycoprotein ligand 1 (PSGL-1) ligand coupled onto human red blood cells (RBCs). The data indicated that L-selectin shedding reduced the amount of membrane-anchored L-selectin and lowered both its reverse and forward rates. These results suggested that the rolling dynamics of activated leukocytes was determined by two opposite impacts: reducing the surface presentation would enhance the rolling but lowering the kinetic rates would decrease the rolling. This finding provides a new insight into understanding how L-selectin shedding regulates leukocyte rolling and adhesion.

Phenotype and Function of Monocyte-Derived Dendritic Cells from Chinese Rhesus Macaques

Dendritic cells (DCs) play a pivotal role in linking the innate immunity and acquired immunity in responses to pathogen. Non-human primates such as Chinese Rhesus Macaque (CRM) are the favorable models for preclinical study of potential therapeutic drugs,

The search for the IFN-gamma receptor in fish: Functional and expression analysis of putative binding and signalling chains in rainbow trout Oncorhynchus mykiss

Interferons (IFNs), consisting of three major subfamilies, type I, type II (gamma) and type III (lambda) IFN, activate vertebrate antiviral defences once bound to their receptors. The three IFN subfamilies bind to different receptors, IFNAR1 and IFNAR2 for type I IFNs, IFN gamma R1 and IFN gamma R2 for type II IFN, and IL-28R1 and IL-10R2 for type III IFNs. In fish, although many types I and II IFN genes have been cloned, little is known about their receptors. In this report, two putative IFN-gamma receptor chains were identified and sequenced in rainbow trout (Oncorhynchus mykiss), and found to have many common characteristics with mammalian type II IFN receptor family members. The presented gene synteny analysis, phylogenetic tree analysis and ligand binding analysis all suggest that these molecules are the authentic IFN gamma Rs in fish. They are widely expressed in tissues, with IFN gamma R1 typically more highly expressed than IFN gamma R2. Using the trout RTG-2 cell line it was possible to show that the individual chains could be differentially modulated, with rIFN-gamma and rIL-1 beta down regulating IFN gamma R1 expression but up regulating IFN gamma R2 expression. Overexpression of the two receptor chains in RTG-2 cells revealed that the level of IFN gamma R2 transcript was crucial for responsiveness to rIFN-gamma, in terms of inducing gamma IP expression. Transfection experiments showed that the two putative receptors specifically bound to rIFN-gamma. These findings are discussed in the context of how the IFN gamma R may bind IFN-gamma in fish and the importance of the individual receptor chains to signal transduction. (c) 2009 Elsevier Ltd. All rights reserved.

Molecular characterization and expression profiles in response to bacterial infection of Chinese soft-shelled turtle interleukin-8 (IL-8), the first reptilian chemokine gene

In this study, an IL-8 homologue has been cloned and identified from a reptile, Chinese soft-shelled turtle for the first time. The full-length cDNA of turtle IL-8 was 1188 bp and contained a 312 bp open reading frame (ORF) coding for a protein of 104 amino acids. The chemokine CXC domain, which contained Glu-Leu-Arg (ELR) motif and four cysteine residues, was well conserved in turtle IL-8. The 4924 bp genomic DNA of turtle IL-8 contained four exons and three introns. Phylogenetic analysis showed that the amino acid sequence of turtle IL-8 clustered together with birds. RT-PCR analysis showed that turtle IL-8 mRNA was constitutively expressed liver, spleen, kidney, heart, blood and intestine tissues of control turtles. Real-time quantitative PCR analysis further indicated that the turtle IL-8 mRNA expression was apparent in various tissues at 8 h and up-regulated significantly during 8 h-7 d after Aeromonas hydrophila infection. The present studies will help us to understand the evolution of IL-8 molecule and the inflammatory response mechanism in reptiles. (C) 2009 Elsevier Ltd. All rights reserved.

Gut contents of bighead carp (Aristichthys nobilis) and the processing and digestion of algal cells in the alimentary canal

Bighead carp is one of the most important freshwater filter-feeding fish of Chinese aquaculture. In recent decades, there have been a number of contradictory conclusions on the digestibility of algae by bighead carp based on the results from gut contents and digestive enzyme analysis or radiolabelled isotope techniques. Phytoplankton in the gut contents of bighead carp (cultured in a large net cage in Lake Donghu) were studied during March-May. In biomass, the dominant phytoplankters in the fore-gut contents were the centric diatom Cyclotella (average 54.5%, range 33.8-74.3%) and the dinoflagellate Cryptomonas (average 22.8%, range 6.8-55.8%). Phytoplankton in water samples were generally present in proportionate amounts in samples from the fore-guts of bighead carp. The size of most phytoplankton present in the intestine of bighead carp was between 8 and 20 mum in length. Bighead carp was also able to collect particles (as small as 5-6 mum) much smaller than their filtering net meshes, suggesting the importance of mucus in collecting small particles, Examination of the change in the integrity of Cyclotella on passage through the esophagus of bighead carp indicated that disruption of the algal cell walls is principally by the pharyngeal teeth, explaining the previous contradictory conclusions. (C) 2001 Elsevier Science B.V. All rights reserved.

A new technique for boosting efficiency of silicon solar cells

A new type of photovoltaic system with higher generation power density has been studied in detail. The feature of the system is a V-shaped module (VSM) with two tilted monocrystalline solar cells. Compared to solar cells in a flat orientation, the VSM enhances external quantum efficiency and leads to an increase of 31% in power conversion efficiency. Due to the VSM technique, short-circuit current density was raised from 24.94 to 33.7mA/cm(2), but both fill factor and open-circuit voltage were approximately unchanged. For the VSM similar results (about 30% increase) were obtained for solar cells fabricated by using mono-crystal line silicon wafers with only conventional background impurities. (c) 2004 Elsevier B.V. All rights reserved.

High efficiency AlxGa1-xAs/GaAs solar cells: Fabrication, irradiation and annealing effect

High efficiency AlxGa1-xAs/GaAs heteroface solar cells have been fabricated by an improved multi-wafer squeezing graphite boat liquid phase epitaxy (LPE) technique, which enables simultaneous growth of twenty 2.3 X 2.3cm(2) epilayers in one run. A total area conversion efficiency of 17.33% is exhibited (1sun, AM0, 2.0 x 2.0cm(2)). The shallow junction cell shows more resistance to 1 MeV electron radiation than the deep one. After isochronal or isothermal annealing the density and the number of deep level traps induced by irradiation are reduced effectively for the solar cells with deep junction and bombardment under high electron fluences.

IL-2基因的突变及其与肠毒素融合基因的克隆和表达

由金黄色葡萄球菌分泌到胞外的单亚基蛋白中有肠毒素A和B。近年来两种毒素在肿瘤治疗研究方面取得了很大进展。白介素-2作为靶向分子，在抗肿瘤的药物中很有应用前景。本文分别对肠毒素A、肠毒素B和白介素-2进行了克隆和表达，并将白介素-2（125Ala）分别与肠毒素A227AI。肠毒素B进行了融合表达。从筛选到的天然金黄色葡萄球菌STSw的基因组中，通过PCR方法扩增出seb基因，同时突变了该基因两端几个稀有密码子。并将其克隆到7ZTS载体上进行表达，表达量占细胞总蛋白的33.5％。以seam基因为模板，通过重叠PCR将其227位天冬氨酸突变为丙氨酸，以降低其毒性。该突变基因重组到7ZTS载体中，并在JM109（DE3）中表达，表达量占细胞总蛋白的51.5％。通过重叠PCR法，对人的IL-2基因进行定点突变。共突变60个碱基，涉及51个氨基酸，其中第125位的半肤氨酸被突变为丙氨酸。该基因在大肠杆菌中表达量占总蛋白的30％。分别对上述三个工程菌的表达条件进行了探索。先制备出融合基因，再对融合基因进行表达，得到两种融合蛋白。它们是以6个甘氨酸和1个苏氨酸为链，将IL一2（125Ala）与肠毒素A227（Ala）、B分别连接起来，即IL-2（125Ala）-SEA227（Ala）和IL-2（125Ala）-SEB二者在大肠杆菌中表达量分别占总蛋白的10％和12％。以上实验结果为将几种蛋白开发成抗肿瘤靶向药物奠定了坚实基础。

Low temperature preparation of ceria solid solutions doubly doped with rare-earth and alkali-earth and their properties as solid oxide fuel cells

A series of solid electrolytes, (Ce(0.8)Ln(0.2))(1 - x)MxO2 - delta(Ln = La, Nd, Sm, Gd, M:Alkali-earth), were prepared by amorphous citrate gel method. XRD patterns indicate that a pure fluorite phase is formed at 800 degreesC. The electrical conductivity and the AC impedance spectra were measured. XPS spectra show that the oxygen vacancies increase owing to the MO doping, which results in the increase of the oxygen ionic transport number and conductivity. The performance of ceria-based solid electrolyte is improved. The effects of rare-earth and alkali-earth ions on the electricity were discussed. The open-circuit voltages and maximum power density of planar solid oxide fuel cell using (Ce0.8Sm0.2)(1 - 0.05)Ca0.05O2 - delta as electrolyte are 0.86 V and 33 mW . cm(-2), respectively.