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131.
Cleavage of vimentin by different retroviral proteases 总被引:7,自引:0,他引:7
Snásel J Shoeman R Horejsí M Hrusková-Heidingsfeldová O Sedlácek J Ruml T Pichová I 《Archives of biochemistry and biophysics》2000,377(2):241-245
Proteases (PRs) of retroviruses cleave viral polyproteins into their mature structural proteins and replication enzymes. Besides this essential role in the replication cycle of retroviruses, PRs also cleave a variety of host cell proteins. We have analyzed the in vitro cleavage of mouse vimentin by proteases of human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2), bovine leukemia virus (BLV), Mason-Pfizer monkey virus (M-PMV), myeloblastosis-associated virus (MAV), and two active-site mutants of MAV PR. Retroviral proteases display significant differences in specificity requirements. Here, we show a comparison of substrate specificities of several retroviral proteases on vimentin as a substrate. Vimentin was cleaved by all the proteases at different sites and with different rates. The results show that the physiologically important cellular protein vimentin can be degraded by different retroviral proteases. 相似文献
132.
Abstract
In acidic mining-impacted lake sediments, the microbial reduction of Fe(III) is the dominant electron-accepting process, whereas
the reduction of sulfate seems to be restricted to a narrow sediment zone of elevated pH and lower amounts of total and reactive
iron. To evaluate the microbial heterogeneity and the commensal interactions of the microbial community, the flow of supplemental
carbon and reductant was evaluated in four different zones of the sediment in anoxic microcosms at the in situ temperature of 12°C. Substrate consumption, product formation, and the potential to reduce Fe(III) and sulfate were similar
with both upper and lower sediment zones. In the upper acidic iron-rich sediment zone, the rate of Fe(II) formation 204 nmol
ml−1 d−1 was enhanced to 833 nmol ml−1 d−1 and 462 nmol ml−1 d−1 by supplemental glucose and H2, respectively. Supplemental lactate and acetate were not consumed under acidic conditions and decreased the rate of Fe(II)
formation to 130 nmol ml−1 d−1 and 52 nmol ml−1 d−1, respectively. When the pH of the upper sediment increased above pH 5, acetate-dependent reduction of sulfate was initiated
even though the pool of Fe(III) was not depleted. In deeper sediment zones with elevated pH, the rapid consumption of acetate
was always coincident to a decrease in the concentration of sulfate and soluble Fe(II), indicating the formation of Fe(II)
sulfides. Although the reduction of Fe(III) was still an ongoing process in deeper sediment zones, the formation of Fe(II)
was only slightly enhanced by the consumption of glucose or cellobiose, but not by H2 or acetate. H2-utilizing acetogens seemed to be involved in the consumption of H2. These collective results indicated (i) that the reduction of Fe(III) predominated over the reduction of sulfate as long
as the sediment remained acidic and carbon-limited, and (ii) that the sulfate-reducing microbiota in this heterogeneous sediment
were better adapted to the geochemical gradients present than were other neutrophilic dissimilatory Fe(III) reducers.
Received: 17 February 2000; Accepted: 22 June 2000; Online Publication: 28 August 2000 相似文献
133.
K Küsel H C Pinkart H L Drake R Devereux 《Applied and environmental microbiology》1999,65(11):5117-5123
Recent declines in sea grass distribution underscore the importance of understanding microbial community structure-function relationships in sea grass rhizospheres that might affect the viability of these plants. Phospholipid fatty acid analyses showed that sulfate-reducing bacteria and clostridia were enriched in sediments colonized by the sea grasses Halodule wrightii and Thalassia testudinum compared to an adjacent unvegetated sediment. Most-probable-number analyses found that in contrast to butyrate-producing clostridia, acetogens and acetate-utilizing sulfate reducers were enriched by an order of magnitude in rhizosphere sediments. Although sea grass roots are oxygenated in the daytime, colorimetric root incubation studies demonstrated that acetogenic O-demethylation and sulfidogenic iron precipitation activities were tightly associated with washed, sediment-free H. wrightii roots. This suggests that the associated anaerobes are able to tolerate exposure to oxygen. To localize and quantify the anaerobic microbial colonization, root thin sections were hybridized with newly developed (33)P-labeled probes that targeted (i) low-G+C-content gram-positive bacteria, (ii) cluster I species of clostridia, (iii) species of Acetobacterium, and (iv) species of Desulfovibrio. Microautoradiography revealed intercellular colonization of the roots by Acetobacterium and Desulfovibrio species. Acetogenic bacteria occurred mostly in the rhizoplane and outermost cortex cell layers, and high numbers of sulfate reducers were detected on all epidermal cells and inward, colonizing some 60% of the deepest cortex cells. Approximately 30% of epidermal cells were colonized by bacteria that hybridized with an archaeal probe, strongly suggesting the presence of methanogens. Obligate anaerobes within the roots might contribute to the vitality of sea grasses and other aquatic plants and to the biogeochemistry of the surrounding sediment. 相似文献
134.
Laboratory and field experiments towards the development of an attract and kill strategy for the control of the codling moth, Cydia pomonella 总被引:1,自引:0,他引:1
Peter M. Lösel Gunter Penners Roel P.J. Potting Dirk Ebbinghaus Alfred Elbert Jürgen Scherkenbeck 《Entomologia Experimentalis et Applicata》2000,95(1):39-46
A viscous formulation based on castor oil containing the pyrethroid insecticide cyfluthrin and E8, E10-dodecadienol, the main component of the codling moth sex pheromone, (Cydia pomonellaL.: Tortricidae, Olethreutinae) was developed. The insecticidal performance of the formulation was evaluated in the laboratory using a tarsal-contact bioassay. The pheromone dosage required to attract male moths to the formulation was determined in behavioural tests performed in a wind tunnel. The efficacy of formulations applied to seedlings of the host plant was further investigated in glasshouse experiments conducted with male moths in small wire-gauze cages. The laboratory tests resulted in a formulation for preliminary field trials containing 4% cyfluthrin and 0.1% pheromone. During the 1995 growing season, experiments were conducted in apple orchards at three locations in Germany. The formulation was first applied to the bark of apple trees (Malus domestica) in mid May and then again in late July. A good level of control, comparable with a spray treatment using the insect growth regulator Alsystin was achieved. The potential of the attract and kill strategy, combining selective attraction of a pest species with the efficacy associated with a pyrethroid insecticide treatment, as a means of controlling the codling moth in commercial apple growing, is discussed. 相似文献
135.
In cells of the green alga Chlorella fusca, which contain active hydrogenase(s), the concentration of ATP, NADH and NADPH were measured during a 5 h period of anaerobiosis in the dark and upon subsequent illumination with high light intensities (770 W/m2), conditions which favour optimal hydrogen photoproduction.ATP concentrations were also determined in cells of Chlorella fusca, whose hydrogenase was inactivated prior to illumination, and in cells of Chlorella vulgaris which do not contain hydrogenase. In the dark, the ATP concentration increased slightly during anaerobiosis in cells with active hydrogenase. This increase in ATP concentration was accompanied by an increase of NADH and a decrease of NADPH content.Upon illumination, the ATP content increased in cells with an active hydrogenase, whereas the NADH content decreased. The rate of phosphorylation was twice that observed in cells without active hydrogenase.This ATP synthesis in the light was not inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) (10 mol/l) nor by carbonylcyanide-3-chlorophenyl-hydrazone (CCCP) (1 mol/l) but was diminished by 500 mol/l dibromothymoquinone (DBMIB) and 6 mol/l carbonylcyanide-3-chlorophenyl-hydrazone (CCCP).It was concluded that an active hydrogenase can support ATP production under anaerobic conditions in the dark as well as in the light. NADH might serve in vivo as electron donor for a fermentative production of hydrogen in the light.Possible mechanisms underlying ATP production under anaerobiosis and hydrogen productive conditions are discussed.Abbreviations CCCP
Carbonylcyanide-3-chlorophenyl-hydrazone
- DBMIB
dibromothymoquinone
- DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- FCCP
carbonylcyanide-p-trifluormethoxyphenyl-hydrazone
- HEPES
N-2-hydroxyethylpiperazin-N-2-ethan-sulfonic acid
- PSI
II, photosystem I, II respectively
- PQ
plastoquinone 相似文献
136.
137.
Markus Hösel Roar R. Søndergaard Mikkel Jørgensen Frederik C. Krebs 《Liver Transplantation》2014,4(7)
Steadily increasing efficiencies of organic solar cells are frequently published but the practical demonstration of actual large‐scale installations with high power output has been very limited. Here, the real‐world challenges and opportunities of organic solar cells fabricated on thin plastic foil and mounted in solar cell arrays of more than 1 kW are shown. In this configuration defects in form of burns that have never been reported before are observed. The reason can be seen in the combination of high power production, water ingress, and the use of thin plastic foil as the substrate. Environmental impact such as lightning was also observed to cause randomly distributed burn holes that initiate self‐sustained damaging under illumination. The large solar cell modules each with more than 220 Wpeak are based only on serially connected cells and need no time‐consuming manual wiring of single cells. Although burns that locally destroy the modules are observed the efficiency is not much affected. Simple repair procedures developed throughout the lifetime study enable the cut and replace of small pieces of the module. A complete replacement as it is carried out for malfunctioning conventional Si‐based PV modules is not necessary. This enables cost‐effective maintenance over the lifetime of the organic solar cells. 相似文献
138.
Kirsten Küsel Tanja Trinkwalter Richard Devereux 《Journal of experimental marine biology and ecology》2006,337(1):49-58
Sediment microbial communities are important for seagrass growth and carbon cycling, however relatively few studies have addressed the composition of prokaryotic communities in seagrass bed sediments. Selective media were used enumerate culturable anaerobic bacteria associated with the roots of the seagrass, Halodule wrightii, the fresh to brackish water plant, Vallisneria americana, and the respective vegetated and unvegetated sediments. H. wrightii roots and sediments had high numbers of sulfate-reducing bacteria whereas iron-reducing bacteria appeared to have a more significant role in V. americana roots and sediments. Numbers of glucose-utilizing but not acetate-utilizing iron reducers were higher on the roots of both plants relative to the vegetated sediments indicating a difference within the iron reducing bacterial community. H. wrightii roots had lower glucose-utilizing iron reducers, and higher acetogenic bacteria than did V. americana roots suggesting different aquatic plants support different anaerobic microbial communities. Sulfur-disproportionating and sulfide-oxidizing bacteria were also cultured from the roots and sediments. These results provide evidence of the potential importance of sulfur cycle bacteria, in addition to sulfate-reducing bacteria, in seagrass bed sediments. 相似文献
139.
140.