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991.
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Long S Changmai P Tsaousis AD Skalický T Verner Z Wen YZ Roger AJ Lukeš J 《Molecular microbiology》2011,81(6):1403-1418
IscA/Isa proteins function as alternative scaffolds for the assembly of Fe-S clusters and/or provide iron for their assembly in prokaryotes and eukaryotes. Isa are usually non-essential and in most organisms are confined to the mitochondrion. We have studied the function of TbIsa1 and TbIsa2 in Trypanosoma brucei, where the requirement for both of them to sustain cell growth depends on the life cycle stage. The TbIsa proteins are abundant in the procyclic form, which contains an active organelle. Both proteins are indispensable for growth, as they are required for the assembly of Fe-S clusters in mitochondrial aconitase, fumarase and succinate dehydrogenase. Reactive oxygen species but not iron accumulate in the procyclic mitochondrion upon ablation of the TbIsa proteins, but their depletion does not influence the assembly of Fe-S clusters in cytosolic proteins. In the bloodstream form, which has a downregulated mitochondrion, the TbIsa proteins are non-essential. The Isa2 orthologue of the anaerobic protist Blastocystis partially rescued the growth and enzymatic activities of TbIsa1/2 knock-down. Rescues of single knock-downs as well as heterologous rescues with human Isa orthologues partially recovered the activities of aconitase and fumarase. These results show that the Isa1 and Isa2 proteins of diverse eukaryotes have overlapping functions. 相似文献
995.
Tert-butylhydroperoxide (tBHP) challenge caused an initial depletion of cellular reduced glutathione (GSH), which was followed by a gradual restoration of cellular GSH in AML12, H9c2, and differentiated PC12 cells. The time-dependent changes in cellular GSH induced by tBHP were monitored as a measure of GSH recovery capacity (GRC), of which glutathione reductase (GR)-mediated glutathione redox cycling and γ-glutamate cysteine ligase (GCL)-mediated GSH synthesis were found to play an essential role. While glutathione redox cycling sustained the GSH level during the initial tBHP-induced depletion, GSH synthesis restores the GSH level thereafter. The effects of (-)schisandrin B [(-)Sch B] and its analogs (Sch A and Sch C) on GRC were also examined in the cells. (-)Sch B and Sch C, but not Sch A, ameliorated the extent of tBHP-induced GSH depletion, indicative of enhanced glutathione redox cycling. However, the degree of restoration of GSH post-tBHP challenge was not affected or even decreased. Pretreatment with (-)Sch B and Sch C, but not Sch A, protected against oxidant injury in the cells. The (-)Sch B afforded cytoprotection was abolished by N,N'-bis(chloroethyl)-N-nitrosourea pretreatment suggesting the enhancement of glutathione redox cycling is crucially involved in the cytoprotection afforded by (-)Sch B against oxidative stress-induced cell injury. 相似文献
996.
Anna K. Kiss Agnieszka BazylkoAgnieszka Filipek Sebastian GranicaEdyta Jaszewska Urszula KiarszysAnita Ko?mider Jakub Piwowarski 《Phytomedicine》2011,18(7):557-560
Willow herb tea or preparation are available and relatively popular in the European market, and claimed to be effective inter alia because of their anti-inflammatory activity. The present study is therefore aimed at comparing the anti-inflammatory and antioxidant activity of extracts of the three most popular Epilobium species (E. angustifolium, E. hirsutum and E. parviflorum) and at juxtaposing this activity against the dominating compounds from the following extracts: oenothein B (OeB), quercetin-3-O-glucuronide and myricetin-3-O-rhamnoside. The phytochemical analysis of the extracts has shown that OeB quantities vary between 20% and 35%, while flavonoids content does not exceed 2%. All extracts have inhibited the activity of hyaluronidase and lipoxygenase with IC50 around 5 μg/ml and 25 μg/ml. The inhibition of hyaluronidase is related with the presence of OeB, a strong inhibitor of this enzyme (IC50 1.1 μM). Additionally, the extracts inhibited myeloperoxidase (MPO) release from stimulated neutrophils. OeB inhibited MPO release similarly to the anti-inflammatory drug indomethacin with IC50 7.7 μM and 15.4 μM, respectively. Tested extracts significantly reduced the production of reactive oxygen species (ROS) from f-MLP and PMA induced neutrophils with IC50 5 μg/ml and 25 μg/ml, respectively. The flavonoids content seems to exert little influence on extracts’ activity, contrary to OeB, whose high concentration explains the activity of extract obtained from Epilobium. Tested currently marketed Epilobium preparations are often wrongly assigned, but we should stress that the level of OeB in all tested herbs was high and always exceeded 2% in raw material. 相似文献
997.
Witek-Krowiak A Witek J Gruszczyńska A Szafran RG Koźlecki T Modelski S 《World journal of microbiology & biotechnology》2011,27(8):1961-1964
Classic methods of biosurfactant separation are difficult and require large amounts of organic solvents, thus generate high
amounts of waste. This work presents and discusses in detail an original procedure to separate rhamnolipid from fermentation
broth using high performance membrane techniques. Due to the unique properties of surface active agents, such as capability
of forming aggregates above the critical micelle concentration, it is possible to easily purify the biosurfactant with high
efficacy using inexpensive and commonly used membranes. In this article, two-stage ultrafiltration is proposed as a method
for separating and purifying rhamnolipid from the culture medium. The obtained purified rhamnolipid solution was capable of
reducing surface tension of water down to 28.6 mN/m at critical micelle concentration of 40 mg/l. Separation of rhamnolipid
was confirmed by HPLC; three types of rhamnolipids were identified (RL1, RL2, RL4), with considerable predominance of RL2. 相似文献
998.
Ahn J Lee TH Li T Heo K Hong S Ko J Kim Y Shin YB Kim MG 《Biosensors & bioelectronics》2011,26(12):4690-4696
We demonstrated that the detection of human interleukin 5 (IL5) with a higher sensitivity than the enzyme-linked immunosorbent assay (ELISA) was possible using mass-producible submicron-gap interdigitated electrodes (IDEs) combined with signal amplification by a gold nanoparticle (AuNP) and gold enhancement. IDEs, facing comb-shape electrodes, can act as simple and miniaturized devices for immunoassay. An IDE with a gap size of 400nm was fabricated by a stepper photolithography process and was applied for the immunoassay of human IL5. A biotinylated anti-human IL5 was immobilized on the streptavidin-modified IDE, and biotin-bovine serum albumin (BSA) and BSA were added sequentially to reduce non-specific binding between the streptavidin-immobilized IDE surface and other proteins. The immunoassay procedure included three main steps: the reaction of human IL5 to form antigen-antibody complexes, the binding of AuNP conjugation with an antibody against human IL5 for the sandwich immunoassay, and gold enhancement for electrical signal amplification. The measurement of electrical current at each step showed that the gold enhancement step was very critical in detection of the concentration of human IL5. Analysis by scanning electron microscope (SEM) showed that close to 1μm particles were formed from 10nm AuNP by the gold enhancement reaction using gold ions and hydroxylamine. Under optimized conditions, human IL5 could be analyzed at 1pgmL(-1) with a wide dynamic range (from 10(-3) to 100ngmL(-1) concentrations). 相似文献
999.
1000.
Kateřina Bártová Klára Hilscherová Pavel Babica Blahoslav Maršálek 《Journal of applied phycology》2011,23(6):967-973
Cyanobacteria produce a wide spectrum of biologically active compounds such as microcystins, whose effects on photoautotrophic
organisms and role in the aquatic ecosystems have been most intensively discussed and studied. In our study, we examined effects
of semipurified Microcystis extract containing microcystins (0.2–20 nM corresponding to 0.2–20 μg L−1) on age-induced cell differentiation of filamentous cyanobacterium Trichormus variabilis. The heterocyst and akinete formation was significantly decreased after exposure to extract containing 2 or 20 nM of microcystins
within 10 days of exposure. To our knowledge, this is the first information about effects of metabolites produced by planktonic
cyanobacteria on cell differentiation in filamentous cyanobacteria. Since the effects were induced by environmentally relevant
concentrations of microcystins, our observations may indicate not only that microcystins or other bioactive peptides could
affect conservation, overwintering, and nitrogen-fixation in filamentous cyanobacteria under environmental conditions but
also contribute to the understanding of possible signaling function of cyanobacterial metabolites. 相似文献