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21.
Geert Potters Nele Horemans Marcel A.K. Jansen 《Plant Physiology and Biochemistry》2010,48(5):292-300
Different redox-active compounds, such as ascorbate, glutathione, NAD(P)H and proteins from the thioredoxin superfamily, contribute to the general redox homeostasis in the plant cell. The myriad of interactions between redox-active compounds, and the effect of environmental parameters on them, has been encapsulated in the concept of a cellular redox state. This concept has facilitated progress in understanding stress signalling and defence in plants. However, despite the proven usefulness of the concept of a redox state, there is no single, operational definition that allows for quantitative analysis and hypothesis testing. 相似文献
22.
Dehydroascorbate uptake activity correlates with cell growth and cell division of tobacco bright yellow-2 cell cultures 总被引:1,自引:0,他引:1
Recently, ascorbate (ASC) concentration and the activity of a number of enzymes from the ASC metabolism have been proven to correlate with differences in growth or cell cycle progression. Here, a possible correlation between growth and the activity of a plasma membrane dehydroascorbate (DHA) transporter was investigated. Protoplasts were isolated from a tobacco (Nicotiana tabacum) Bright Yellow-2 cell culture at different intervals after inoculation and the activity of DHA transport was tested with (14)C-labeled ASC. Ferricyanide (1 mM) or dithiothreitol (1 mM) was included in the test to keep the external (14)C-ASC in its oxidized respectively reduced form. Differential uptake activity was observed, correlating with growth phases of the cell culture. Uptake of DHA in cells showed a peak in exponential growth phase, whereas uptake in the presence of dithiothreitol did not. The enhanced DHA uptake was not due to higher endogenous ASC levels that are normally present in exponential phase because preloading of protoplasts of different ages did not affect DHA uptake. Preloading was achieved by incubating cells before protoplastation for 4 h in a medium supplemented with 1 mM DHA. In addition to testing cells at different growth phases, uptake of DHA into the cells was also followed during the cell cycle. An increase in uptake activity was observed during M phase and the M/G1 transition. These experiments are the first to show that DHA transport activity into plant cells differs with cell growth. The relevance of the data to the action of DHA and ASC in cell growth will be discussed. 相似文献
23.
Transport and action of ascorbate at the plant plasma membrane 总被引:11,自引:0,他引:11
The plasmalemma is both a bridge and a barrier between the cytoplasm and the outside world. It is a dynamic interface that perceives and transmits information concerning changes in the environment to the nucleus to modify gene expression. In plants, ascorbate is an essential part of this dialogue. The concentration and ratio of reduced to oxidized ascorbate in the apoplast, for example, possibly modulates cell division and growth. The leaf apoplast contains millimolar amounts of ascorbate that protect the plasmalemma against oxidative damage. The apoplastic ascorbate-dehydroascorbate redox couple is linked to the cytoplasmic ascorbate-dehydroascorbate redox couple by specific transporters for either or both metabolites. Although evidence about the mechanisms driving ascorbate or dehydroascorbate transport remains inconclusive, these carrier proteins potentially regulate the level and redox status of ascorbate in the apoplast. The redox coupling between compartments facilitated by these transport systems allows coordinated control of key physiological responses to environmental cues. 相似文献
24.
Horvath G Wessjohann L Bigirimana J Jansen M Guisez Y Caubergs R Horemans N 《Phytochemistry》2006,67(12):1185-1195
Tocopherols and tocotrienols are vitamin E compounds, differing only in the saturation state of the isoprenoid side chain. Tocopherol biosynthesis, physiology and distribution have been studied in detail. Tocopherols have been found in many different plant species, and plant tissues. In contrast, comparatively little is known about the physiology and distribution of tocotrienols. These compounds appear to be considerably less widespread in the plant kingdom. In this study 80 different plant species were analysed for the presence of tocotrienols. Twenty-four species were found to contain significant amounts of tocotrienols. No taxonomic relation was apparent among the 16 dicotyledonous species that were found to contain tocotrienol. Monocotyledonous species (eight species) belonged either to the Poaceae (six species) or the Aracaceae (two species). A more detailed analysis of tocotrienol accumulation revealed the presence of tocotrienols in several non-photosynthetic tissues and organs, i.e. seeds, fruits and in latex, in concentrations up to 2000 ppm. No tocotrienols could be detected in mature photosynthetic tissues. However, we found the transient accumulation of low levels of tocotrienols in the young coleoptiles of plant species whose seeds contained tocotrienols. No measurable tocotrienol biosynthesis was apparent in coleoptiles, or in chloroplasts isolated from such coleoptiles. In line with these results, we found that tocotrienol accumulation in coleoptiles was not associated with chloroplasts. Based on our data, we conclude that tocotrienols may be transiently present in photosynthetically active tissues, however, it remains to be proven whether the tocotrienols are biosynthesised in such tissues, or imported from elsewhere in the plant. 相似文献
25.
26.
Kristof Theys Koen Deforche Jurgen Vercauteren Pieter Libin David AMC van de Vijver Jan Albert Birgitta ?sj? Claudia Balotta Marie Bruckova Ricardo J Camacho Bonaventura Clotet Suzie Coughlan Zehava Grossman Osamah Hamouda Andrzei Horban Klaus Korn Leondios G Kostrikis Claudia Kücherer Claus Nielsen Dimitrios Paraskevis Mario Poljak Elisabeth Puchhammer-Stockl Chiara Riva Lidia Ruiz Kirsi Liitsola Jean-Claude Schmit Rob Schuurman Anders S?nnerborg Danica Stanekova Maja Stanojevic Daniel Struck Kristel Van Laethem Annemarie MJ Wensing Charles AB Boucher Anne-Mieke Vandamme 《Retrovirology》2012,9(1):1-13
Background
Bone marrow stromal cell antigen 2 (BST-2) is a cellular factor that restricts the egress of viruses such as human immunodeficiency virus (HIV-1) from the surface of infected cells, preventing infection of new cells. BST-2 is variably expressed in most cell types, and its expression is enhanced by cytokines such as type I interferon alpha (IFN-??). In this present study, we used the beta-retrovirus, mouse mammary tumor virus (MMTV) as a model to examine the role of mouse BST-2 in host infection in vivo.Results
By using RNA interference, we show that loss of BST-2 enhances MMTV replication in cultured mammary tumor cells and in vivo. In cultured cells, BST-2 inhibits virus accumulation in the culture medium, and co-localizes at the cell surface with virus structural proteins. Furthermore, both scanning electron micrograph (SEM) and transmission electron micrograph (TEM) show that MMTV accumulates on the surface of IFN??-stimulated cells.Conclusions
Our data provide evidence that BST-2 restricts MMTV release from naturally infected cells and that BST-2 is an antiviral factor in vivo. 相似文献27.
Jasper Bloemen Régis Fichot Joanna A. Horemans Laura S. Broeckx Melanie S. Verlinden Terenzio Zenone Reinhart Ceulemans 《Global Change Biology Bioenergy》2017,9(2):370-384
Short‐rotation coppice (SRC) has great potential for supplying biomass‐based heat and energy, but little is known about SRC's ecological footprint, particularly its impact on the water cycle. To this end, we quantified the water use of a commercial scale poplar (Populus) SRC plantation in East Flanders (Belgium) at tree and stand level, focusing primarily on the transpiration component. First, we used the AquaCrop model and eddy covariance flux data to analyse the different components of the stand‐level water balance for one entire growing season. Transpiration represented 59% of evapotranspiration (ET) at stand scale over the whole year. Measured ET and modelled ET were lower as compared to the ET of reference grassland, suggesting that the SRC only used a limited amount of water. Secondly, we compared leaf area scaled and sapwood area scaled sap flow (Fs) measurements on individual plants vs. stand scale eddy covariance flux data during a 39‐day intensive field campaign in late summer 2011. Daily stem diameter variation (?D) was monitored simultaneously with Fs to understand water use strategies for three poplar genotypes. Canopy transpiration based on sapwood area or leaf area scaling was 43.5 and 50.3 mm, respectively, and accounted for 74%, respectively, 86%, of total ecosystem ET measured during the intensive field campaign. Besides differences in growth, the significant intergenotypic differences in daily ?D (due to stem shrinkage and swelling) suggested different water use strategies among the three genotypes which were confirmed by the sap flow measurements. Future studies on the prediction of SRC water use, or efforts to enhance the biomass yield of SRC genotypes, should consider intergenotypic differences in transpiration water losses at tree level as well as the SRC water balance at stand level. 相似文献
28.
Groundwater contamination with 2,6-dichlorobenzamide (BAM) and perspectives for its microbial removal 总被引:1,自引:0,他引:1
Ellegaard-Jensen Lea Horemans Benjamin Raes Bart Aamand Jens Hansen Lars Hestbjerg 《Applied microbiology and biotechnology》2017,101(13):5235-5245
Applied Microbiology and Biotechnology - The pesticide metabolite 2,6-dichlorobenzamide (BAM) is very persistent in both soil and groundwater and has become one of the most frequently detected... 相似文献
29.
MG Mullender NA Blom M De Kleuver JM Fock WMGC Hitters AMC Horemans CJ Kalkman JEH Pruijs RR Timmer PJ Titarsolej NC Van Haasteren Tol-de MJ Van Jager AJ Van Vught BJ Van Royen 《Scoliosis》2008,3(1):1-14
Background
Children with neuromuscular disorders with a progressive muscle weakness such as Duchenne Muscular Dystrophy and Spinal Muscular Atrophy frequently develop a progressive scoliosis. A severe scoliosis compromises respiratory function and makes sitting more difficult. Spinal surgery is considered the primary treatment option for correcting severe scoliosis in neuromuscular disorders. Surgery in this population requires a multidisciplinary approach, careful planning, dedicated surgical procedures, and specialized after care.Methods
The guideline is based on scientific evidence and expert opinions. A multidisciplinary working group representing experts from all relevant specialties performed the research. A literature search was conducted to collect scientific evidence in answer to specific questions posed by the working group. Literature was classified according to the level of evidence.Results
For most aspects of the treatment scientific evidence is scarce and only low level cohort studies were found. Nevertheless, a high degree of consensus was reached about the management of patients with scoliosis in neuromuscular disorders. This was translated into a set of recommendations, which are now officially accepted as a general guideline in the Netherlands.Conclusion
In order to optimize the treatment for scoliosis in neuromuscular disorders a Dutch guideline has been composed. This evidence-based, multidisciplinary guideline addresses conservative treatment, the preoperative, perioperative, and postoperative care of scoliosis in neuromuscular disorders. 相似文献30.
Genetic evidences indicate that alkaline/neutral invertases are present in plant cell organelles, and they might have a novel physiological function in mitochondria. The present study demonstrates an invertase activity in the mitochondrial matrix of Helianthus tuberosus tubers. The pH optimum, the kinetic parameters and the inhibitor profile of the invertase activity indicated that it belongs to the neutral invertases. In accordance with this topology, transport activities responsible for the mediation of influx/efflux of substrate/products were studied in the inner mitochondrial membrane. The transport of sucrose, glucose and fructose was shown to be bidirectional, saturable and independent of the mitochondrial respiration and membrane potential. Sucrose transport was insensitive to the inhibitors of the proton-sucrose symporters. The different kinetic parameters and inhibitors as well as the absence of cross-inhibition suggest that sucrose, glucose and fructose transport are mediated by separate transporters in the inner mitochondrial membrane. The mitochondrial invertase system composed by an enzyme activity in the matrix and the corresponding sugar transporters might have a role in both osmoregulation and intermediary metabolism. 相似文献