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151.
152.
Boon Chin Tan Chiew Foan Chin Peter Alderson 《Plant Cell, Tissue and Organ Culture》2011,105(3):457-463
An indirect in vitro plant regeneration protocol for Vanilla planifolia has been established. Juvenile leaf and nodal segments from V. planifolia were used as explants to initiate callus. Nodal explants showed better callus initiation than juvenile leaf explants, with
35.0% of explants forming callus when cultured on Murashige and Skoog (MS) basal medium supplemented with 2.0 mg/l 1-naphthylacetic
acid (NAA) and 1.0 mg/l 6-benzyladenine (BA). Almost 10.0% of juvenile leaf explants were induced to form callus on the MS
basal medium containing 2.0 mg/l NAA and 2.0 mg/l BA, whereas no callus formed in the presence of any concentrations of 2,4-dichlorophenoxyacetic
acid (2,4-D) and BA. After 8 weeks, callus generated was transferred to MS basal medium containing 1.0 mg/l BA and 0.5 mg/l
NAA. A mean number of 4.2 shoots per callus was produced on this medium, with a mean length of 3.8 cm after 8 weeks of culture.
Roots formed on 88.3% of plantlets when they were cultured on MS medium supplemented with 1.0 mg/l NAA, with a mean length
of 4.4 cm after 4 weeks of culture. Of the rooted plantlets, 90.0% survived acclimatisation and were making new growth after
4 weeks. 相似文献
153.
Long-chain acylhomoserine lactones increase the anoxic ammonium oxidation rate in an OLAND biofilm 总被引:2,自引:0,他引:2
De Clippeleir H Defoirdt T Vanhaecke L Vlaeminck SE Carballa M Verstraete W Boon N 《Applied microbiology and biotechnology》2011,90(4):1511-1519
The oxygen-limited autotrophic nitrification/denitrification (OLAND) process comprises one-stage partial nitritation and anammox,
catalyzed by aerobic and anoxic ammonium-oxidizing bacteria (AerAOB and AnAOB), respectively. The goal of this study was to
investigate whether quorum sensing influences anoxic ammonium oxidation in an OLAND biofilm, with AnAOB colonizing 13% of
the biofilm, as determined with fluorescent in situ hybridization (FISH). At high biomass concentrations, the specific anoxic ammonium oxidation rate of the OLAND biofilm significantly
increased with a factor of 1.5 ± 0.2 compared to low biomass concentrations. Supernatant obtained from the biofilm showed
no ammonium-oxidizing activity on itself, but its addition to low OLAND biomass concentrations resulted in a significant activity
increase of the biomass. In the biofilm supernatant, the presence of long-chain acylhomoserine lactones (AHLs) was shown using
the reporter strain Chromobacterium violaceum CV026, and one specific AHL, N-dodecanoyl homoserine lactone (C12-HSL), was identified via LC-MS/MS. Furthermore, C12-HSL was detected in an AnAOB-enriched community, but not in an AerAOB-enriched community. Addition of C12-HSL to low OLAND biomass concentrations resulted in a significantly higher ammonium oxidation rate (p < 0.05). To our knowledge, this is the first report demonstrating that AHLs enhance the anoxic ammonium oxidation process.
Future work should confirm which species are responsible for the in situ production of C12-HSL in AnAOB-based applications. 相似文献
154.
Correlations between molecular and operational parameters in continuous lab-scale anaerobic reactors
Carballa M Smits M Etchebehere C Boon N Verstraete W 《Applied microbiology and biotechnology》2011,89(2):303-314
In this study, the microbial community characteristics in continuous lab-scale anaerobic reactors were correlated to reactor
functionality using the microbial resource management (MRM) approach. Two molecular techniques, denaturing gradient gel electrophoresis
(DGGE) and terminal-restriction fragment length polymorphism (T-RFLP), were applied to analyze the bacterial and archaeal
communities, and the results obtained have been compared. Clustering analyses showed a similar discrimination of samples with
DGGE and T-RFLP data, with a clear separation between the meso- and thermophilic communities. Both techniques indicate that
bacterial and mesophilic communities were richer and more even than archaeal and thermophilic communities, respectively. Remarkably,
the community composition was highly dynamic for both Bacteria and Archaea, with a rate of change between 30% and 75% per 18 days, also in stable performing periods. A hypothesis to explain the latter
in the context of the converging metabolism in anaerobic processes is proposed. Finally, a more even and diverse bacterial
community was found to be statistically representative for a well-functioning reactor as evidenced by a low Ripley index and
high biogas production. 相似文献
155.
Denitrifying organisms are essential in removing fixed nitrogen pollutants from ecosystems (e.g. sewage sludge). They can be detrimental (e.g. for agricultural soil) and can also produce the greenhouse gas N2O (nitrous oxide). Therefore a more comprehensive understanding of this process has become increasingly important regarding its global environmental impact. Even though bacterial genome sequencing projects may reveal new data, to date the denitrification abilities and features in Gram-positive bacteria are still poorly studied and understood. The present review evaluates current knowledge on the denitrification trait in Gram-positive bacteria and addresses the likely existence of unknown denitrification genes. In addition, current molecular tools to study denitrification gene diversity in pure cultures and environmental samples seem to be highly biased, and additional novel approaches for the detection of denitrifying (Gram-positive) bacteria appear to be crucial in re-assessing the real diversity of denitrifiers. 相似文献
156.
Marcelin G Aldridge JR Duan S Ghoneim HE Rehg J Marjuki H Boon AC McCullers JA Webby RJ 《Journal of virology》2011,85(21):11208-11219
Pandemic A (H1N1) 2009 influenza virus (pH1N1) infection in pregnant women can be severe. The mechanisms that affect infection outcome in this population are not well understood. To address this, pregnant and nonpregnant BALB/c mice were inoculated with the wild-type pH1N1 strain A/California/04/09. To determine whether innate immune responses are associated with severe infection, we measured the innate cells trafficking into the lungs of pregnant versus nonpregnant animals. Increased infiltration of pulmonary neutrophils and macrophages strongly correlated with an elevated mortality in pregnant mice. In agreement with this, the product of nitric oxide (nitrite) and several cytokines associated with recruitment and/or function of these cells were increased in the lungs of pregnant animals. Surprisingly, increased mortality in pregnant mice was not associated with higher virus load because equivalent virus titers and immunohistochemical staining were observed in the nasal cavities or lungs of all mice. To determine whether exacerbated inflammatory responses and elevated cellularity resulted in lung injury, epithelial regeneration was measured. The lungs of pregnant mice exhibited reduced epithelial regeneration, suggesting impaired lung repair. Despite these immunologic alterations, pregnant animals demonstrated equivalent percentages of pulmonary influenza virus-specific CD8(+) T lymphocytes, although they displayed elevated levels of T-regulator lymphocytes (Tregs) in the lung. Also, pregnant mice mounted equal antibody titers in response to virus or immunization with a monovalent inactivated pH1N1 A/California/07/09 vaccine. Therefore, immunopathology likely caused by elevated cellular recruitment is an implicated mechanism of severe pH1N1 infection in pregnant mice. 相似文献
157.
Although several Gram-positive denitrifiers have been characterized in the past, there is still uncertainty about the occurrence of the denitrification trait among these bacteria. In an isolation campaign on luvisol soil, Bacillus spp. were among the most abundant retrieved cultured denitrifiers next to members of Rhizobiaceae family and genus Cupriavidus. Subsequent screening of 180 representatives of the genus Bacillus (encompassing more than half of the current validly described species diversity in Bacillus) was performed and demonstrated the potential for dissimilatory reduction of nitrogen compounds in 45 of the 87 investigated species, with 19 species containing denitrifying members. The influence of several electron donors and acceptors was tested. The use of more than one electron acceptor, e.g. both nitrate and nitrite, was crucial to detect the denitrification potential of reference strains. Complex electron donors, most suitable for aerobic growth, were ideal for denitrification testing, while retrieval of denitrifiers from the environment was facilitated by the use of defined electron donors, due to less interference of other anaerobic growers. The outcome of the isolation campaign and screening of reference strain set suggest that bacilli may be potential contributors to denitrification in terrestrial and possibly other ecosystems. 相似文献
158.
Bai J Lai L Yeo HC Goh BC Tan TM 《The international journal of biochemistry & cell biology》2004,36(2):247-257
Multidrug resistance proteins (MRPs) are ATP-dependent export pumps that mediate the export of organic anions. ABCC1 (MRP1), ABCC2 (MRP2) and ABCC3 (MRP3) are all able to facilitate the efflux of anionic conjugates including glutathione (GSH), glucuronide and sulfate conjugates of xenobiotics and endogenous molecules. Earlier studies showed that ABCC4 functions as an ATP-driven export pump for cyclic AMP and cyclic GMP, as well as estradiol-17-beta-D-glucuronide. However, it was unclear if other conjugated metabolites can be transported by ABCC4. Hence in this study, a fluorescent substrate, bimane-glutathione (bimane-GS) was used to further examine the transport activity of ABCC4. Using cells stably overexpressing ABCC4, this study shows that ABCC4 can facilitate the efflux of the glutathione conjugate, bimane-glutathione. Bimane-glutathione efflux increased with time and >85% of the conjugate was exported after 15min. This transport was abolished in the presence of 2.5microM carbonylcyanide m-chlorophenylhydrasone (CCCP), an uncoupler of oxidative phosphorylation. Inhibition was also observed with known inhibitors of MRP transporters including benzbromarone, verapamil and indomethacin. In addition, 100microM methotrexate, an ABCC4 substrate or 100microM 6-thioguanine (6-TG), a compound whose monophosphate metabolite is an ABCC4 substrate, reduced efflux by >40%. A concentration-dependent inhibition of bimane-glutathione efflux was observed with 1-chloro-2,4-dinitrobenzene (CDNB) which is metabolized intracellularly to the glutathione conjugate, 2,4-dinitrophenyl-glutathione (DNP-GS). The determination that ABCC4 can mediate the transport of glucuronide and glutathione conjugates indicates that ABCC4 may play a role in the cellular extrusion of Phase II detoxification metabolites. 相似文献
159.
Angela Logan Helena M. Cochemé Pamela Boon Li Pun Nadezda Apostolova Robin A.J. Smith Lesley Larsen David S. Larsen Andrew M. James Ian M. Fearnley Sebastian Rogatti Tracy A. Prime Peter G. Finichiu Anna Dare Edward T. Chouchani Victoria R. Pell Carmen Methner Caroline Quin Stephen J. McQuaker Thomas Krieg Richard C. Hartley Michael P. Murphy 《Biochimica et Biophysica Acta (BBA)/General Subjects》2014
Background
The ability to measure the concentrations of small damaging and signalling molecules such as reactive oxygen species (ROS) in vivo is essential to understanding their biological roles. While a range of methods can be applied to in vitro systems, measuring the levels and relative changes in reactive species in vivo is challenging.Scope of review
One approach towards achieving this goal is the use of exomarkers. In this, exogenous probe compounds are administered to the intact organism and are then transformed by the reactive molecules in vivo to produce a diagnostic exomarker. The exomarker and the precursor probe can be analysed ex vivo to infer the identity and amounts of the reactive species present in vivo. This is akin to the measurement of biomarkers produced by the interaction of reactive species with endogenous biomolecules.Major conclusions and general significance
Our laboratories have developed mitochondria-targeted probes that generate exomarkers that can be analysed ex vivo by mass spectrometry to assess levels of reactive species within mitochondria in vivo. We have used one of these compounds, MitoB, to infer the levels of mitochondrial hydrogen peroxide within flies and mice. Here we describe the development of MitoB and expand on this example to discuss how better probes and exomarkers can be developed. This article is part of a Special Issue entitled Current methods to study reactive oxygen species - pros and cons and biophysics of membrane proteins. Guest Editor: Christine Winterbourn. 相似文献160.
Nanthawan Mekha Masako Takashima Jotika Boon‐long Otomi Cho Takashi Sugita 《Microbiology and immunology》2014,58(1):9-14