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排序方式: 共有1573条查询结果,搜索用时 15 毫秒
991.
Emma Strömberg Sigbritt Karlsson 《International biodeterioration & biodegradation》2009,63(8):1045-1053
Biocomposites were subject to exposure to a mixture of fungi and algae in a microenvironment chamber. Surface and bulk property changes of polypropylene/wood flour, recycled polypropylene/cellulose and polylactide/wood flour were monitored by tensile testing, Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA) and Field Emission Scanning Electron Microscope (FE-SEM).All the biocomposites showed a substantial decrease in toughness after 28 and 56 days of hydrolysis. The ductility increased after 28 and 56 days, but deteriorated after 84 days of hydrolysis. Biofilm formation occurred on all biocomposites even if the polymer itself was inert to biodegradation. The microbial colonization affected mainly the surface properties of polypropylene biocomposites while changes were monitored also in the bulk properties of polylactide biocomposites.The cellulose fibres in the composites gave a more easily colonized surface mainly attributed to water uptake. In the short term perspective, the water uptake offered better conditions for biofilm adhesion, and in the longer perspective the exposure to microorganisms also resulted in mechanical degradation, followed by biodegradation of cellulose. With time this will leave a porous matrix of polypropylene, while biodegradable polymers such as polylactide will degrade in parallel with the fibre part. 相似文献
992.
E. J. Eliason †‡ A. Kiessling § A. Karlsson § B. Djordjevic § A. P. Farrell † 《Journal of fish biology》2007,71(1):290-297
This study assessed the hepatic portal vein cannulation technique and surgical recovery in Atlantic salmon Salmo salar. Haematocrit levels were maintained and blood variables, including cortisol, returned to baseline levels within 1–3 days post-surgery, indicating that this technique is a viable, useful method to study the digestive physiology of fishes. 相似文献
993.
An intraocular injection of [3H]proline was used to label rabbit retinal ganglion cells including components subjected to axonal transport. Degradation of rapidly axonally transported labelled proteins was estimated in an in vitro system using homogenates of the nerve terminal regions. The energy requirements of this proteolytic process was characterized, as well as the type of enzymatic system. Evidence was obtained for a proteolytic system, active at a neutral pH, which was dependent upon calcium ions and intact sulfhydryl group. 相似文献
994.
Näsström T Fagerqvist T Barbu M Karlsson M Nikolajeff F Kasrayan A Ekberg M Lannfelt L Ingelsson M Bergström J 《Free radical biology & medicine》2011,50(3):428-437
Oxidative stress has been implicated in the etiology of neurodegenerative disorders with α-synuclein pathology. Lipid peroxidation products such as 4-oxo-2-nonenal (ONE) and 4-hydroxy-2-nonenal (HNE) can covalently modify and structurally alter proteins. Herein, we have characterized ONE- or HNE-induced α-synuclein oligomers. Our results demonstrate that both oligomers are rich in β-sheet structure and have a molecular weight of about 2000 kDa. Atomic force microscopy analysis revealed that ONE-induced α-synuclein oligomers were relatively amorphous, with a diameter of 40-80 nm and a height of 4-8 nm. In contrast, the HNE-induced α-synuclein oligomers had a protofibril-like morphology with a width of 100-200 nm and a height of 2-4 nm. Furthermore, neither oligomer type polymerized into amyloid-like fibrils despite prolonged incubation. Although more SDS and urea stable, because of a higher degree of cross-linking, ONE-induced α-synuclein oligomers were less compact and more sensitive to proteinase K treatment. Finally, both ONE- and HNE-induced α-synuclein oligomers were cytotoxic when added exogenously to a neuroblastoma cell line, but HNE-induced α-synuclein oligomers were taken up by the cells to a significantly higher degree. Despite nearly identical chemical structures, ONE and HNE induce the formation of off-pathway α-synuclein oligomers with distinct biochemical, morphological, and functional properties. 相似文献
995.
Production of volatile fatty acids by fermentation of waste activated sludge pre-treated in full-scale thermal hydrolysis plants 总被引:2,自引:0,他引:2
Morgan-Sagastume F Pratt S Karlsson A Cirne D Lant P Werker A 《Bioresource technology》2011,102(3):3089-3097
This work focuses on fermentation of pre-treated waste activated sludge (WAS) to generate volatile fatty acids (VFAs). Pre-treatment by high-pressure thermal hydrolysis (HPTH) was shown to aid WAS fermentation. Compared to fermentation of raw WAS, pre-treatment enabled a 2-5x increase in VFA yield (gVFA(COD)gTCOD(-1)) and 4-6x increase in VFA production rate (gVFA(COD) L(-1) d(-1)). Three sludges, pre-treated in full-scale HPTH plants, were fermented. One was from a plant processing a mix of primary sludge and WAS and the other two from plants processing solely WAS. The HPTH plants solubilised suspended matter, evidenced by a 20-30% decrease in suspended solids and an increase of soluble COD : total COD from 0.04 to 0.4. Fermentation of the three sludges yielded similar VFA concentrations (15-20gVFA(COD) L(-1)). The yields were largely independent of retention time (1 d-6 d) and temperature (42°C, 55°C). Also, the product spectrum depended mostly on the composition of the sludge rather than on operating conditions. 相似文献
996.
Gupta S Fallarero A Järvinen P Karlsson D Johnson MS Vuorela PM Mohan CG 《Bioorganic & medicinal chemistry letters》2011,21(4):1105-1112
Dual binding site acetylcholinesterase (AChE) inhibitors are promising for the treatment of Alzheimer’s disease (AD). They alleviate the cognitive deficits and AD-modifying agents, by inhibiting the β-amyloid (Aβ) peptide aggregation, through binding to both the catalytic and peripheral anionic sites, the so called dual binding site of the AChE enzyme. In this Letter, chemical features based 3D-pharmacophore models were developed based on the eight potent and structurally diverse AChE inhibitors (I-VIII) obtained from high-throughput in vitro screening technique. The best 3D-pharmacophore model, Hypo1, consists of two hydrogen-bond acceptor lipid, one hydrophobe, and two hydrophobic aliphatic features obtained by Catalyst/HIPHOP algorithm adopted in Discovery studio program. Hypo1 was used as a 3D query in sequential virtual screening study to filter three small compound databases. Further, a total of nine compounds were selected and followed on in vitro analysis. Finally, we identified two leads—Specs1 (IC50 = 3.279 μM) and Spec2 (IC50 = 5.986 μM) dual binding site compounds from Specs database, having good AChE enzyme inhibitory activity. 相似文献
997.
The anti-apoptotic B cell CLL/lymphoma-2 (Bcl-2) protein is a key player in the regulation of programmed cell death and is linked to various types of cancer and their resistance to drug treatment. Biophysical and structural studies of the full-length intact Bcl-2 have been hampered due to difficulties in expression and severe solubility problems, precluding isolation of this hydrophobic membrane protein. Therefore, previous work has so far mainly been carried out using structurally modified Bcl-2 variants, lacking the transmembrane region. Thus, biophysical information regarding the full-length protein is still missing. Here, a protocol is presented for expression and purification of preparative amounts of the full-length human isoform 2 of Bcl-2 (Bcl-2(2)). A batch-based cell-free expression system, using extract isolated from Escherichia coli (E. coli) was employed to produce recombinant protein encoded by an optimized gene sequence. Presence of polyoxyethylene-(20)-cetyl-ether (Brij-58) in the reaction mixture and subsequently in the immobilized metal-affinity purification steps was crucial to keep Bcl-2(2) soluble. The obtained yield was 0.25-0.3mg per ml of cell-free reaction. Far-UV circular dichroism (CD) spectroscopy confirmed the α-helical structure of the purified protein, characteristic for members of the Bcl-2 protein family. 相似文献
998.
Van Tyne D Park DJ Schaffner SF Neafsey DE Angelino E Cortese JF Barnes KG Rosen DM Lukens AK Daniels RF Milner DA Johnson CA Shlyakhter I Grossman SR Becker JS Yamins D Karlsson EK Ndiaye D Sarr O Mboup S Happi C Furlotte NA Eskin E Kang HM Hartl DL Birren BW Wiegand RC Lander ES Wirth DF Volkman SK Sabeti PC 《PLoS genetics》2011,7(4):e1001383
The Plasmodium falciparum parasite's ability to adapt to environmental pressures, such as the human immune system and antimalarial drugs, makes malaria an enduring burden to public health. Understanding the genetic basis of these adaptations is critical to intervening successfully against malaria. To that end, we created a high-density genotyping array that assays over 17,000 single nucleotide polymorphisms (~ 1 SNP/kb), and applied it to 57 culture-adapted parasites from three continents. We characterized genome-wide genetic diversity within and between populations and identified numerous loci with signals of natural selection, suggesting their role in recent adaptation. In addition, we performed a genome-wide association study (GWAS), searching for loci correlated with resistance to thirteen antimalarials; we detected both known and novel resistance loci, including a new halofantrine resistance locus, PF10_0355. Through functional testing we demonstrated that PF10_0355 overexpression decreases sensitivity to halofantrine, mefloquine, and lumefantrine, but not to structurally unrelated antimalarials, and that increased gene copy number mediates resistance. Our GWAS and follow-on functional validation demonstrate the potential of genome-wide studies to elucidate functionally important loci in the malaria parasite genome. 相似文献
999.
Ayako Shimono Xiao-Ru Wang Takeshi Torimaru Dag Lindgren Bo Karlsson 《Tree Genetics & Genomes》2011,7(3):499-509
Currently, Norway spruce (Picea abies) breeding in Sweden is based on crosses between the best clones followed by clonal testing of the progenies to select for
the long-term breeding population. An alternative breeding strategy called “Breeding without Breeding” (BwB) is proposed,
which, in principle, relies on the DNA marker-based pedigree reconstruction from wind-pollinated progenies instead of controlled
crosses. To test whether the pedigree structure could be established from progenies of clonal trials, we investigated the
spatial pattern of local pollen flow and paternity assignment in a clone archive of Norway spruce. The results showed that
42% of the progeny can be assigned to fathers within 30-m distance with high confidence. Effective pollen dispersal decreased
rapidly with distance and followed exponential distribution on local scale. The extent of close-neighbor (within 6 m) mating
ranged from 0% to 48% among grafts with an average of 13%. Distance explained 25% deviance in mating success, and other factors
such as phenology and spatial configuration of the clones should have contributed the rest. The success of parentage assignment
in clone archive opens up the possibility to apply BwB in clonal trials of species that are easy to propagate vegetatively.
This procedure could substantially shorten the breeding cycle and still give similar gain per year as the conventional breeding. 相似文献
1000.
Campbell MP Hayes CA Struwe WB Wilkins MR Aoki-Kinoshita KF Harvey DJ Rudd PM Kolarich D Lisacek F Karlsson NG Packer NH 《Proteomics》2011,11(21):4117-4121
Despite the success of several international initiatives the glycosciences still lack a managed infrastructure that contributes to the advancement of research through the provision of comprehensive structural and experimental glycan data collections. UniCarbKB is an initiative that aims to promote the creation of an online information storage and search platform for glycomics and glycobiology research. The knowledgebase will offer a freely accessible and information-rich resource supported by querying interfaces, annotation technologies and the adoption of common standards to integrate structural, experimental and functional data. The UniCarbKB framework endeavors to support the growth of glycobioinformatics and the dissemination of knowledge through the provision of an open and unified portal to encourage the sharing of data. In order to achieve this, the framework is committed to the development of tools and procedures that support data annotation, and expanding interoperability through cross-referencing of existing databases. Database URL: http://www.unicarbkb.org. 相似文献