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101.
Studies on the Linkage of Energy Metabolism and Neuronal Activity in the Isolated Perfused Rat Brain 总被引:3,自引:2,他引:1
An isolated rat brain preparation was perfused using glucose-free (=aglycemic) media. The high-energy phosphates, substrates of the glycolytic pathway, free atnino acids, acetylcholine as well as the intracellular distribution of hexokinase activity were determined in brain tissues. The EEG was evaluated visually. The levels of glycolytic substrates, glutamate, and glutamine in cortical tissue decreased after aglycemic perfusion, whereas the aspartate level increased and the GABA level remained unchanged. The high-energy phosphate content seemed to be unaffected for about 15 min of aglycemic perfusion and fell significantly after 20 min. The EEG of the isolated brain changed rapidly after starting aglycemic perfusion and became isoelectric after 12–15 min. Hyperglycemic perfusion (35 mmol glucose per liter perfusion medium) did not alter the energy metabolism of the isolated brain. The breakdown of cerebral energy metabolism and of EEG activity was postponed when thiopental was added to the perfusion medium. The soluble hexokinase activity measured in cortical tissue was reduced after aglycemic perfusion and was enhanced after thiopental. Hyperglycemic perfusion did not influence the intracellular hexokinase distribution. The acetylcholine level in the striatum of the isolated rat brain was significantly decreased by aglycemia and was increased in hypothalamus by thiopental. It was suggested that hexokinase bound to the mitochondrial membrane may play an important role in the relationship of energy metabolism and neuronal activity. 相似文献
102.
Becca Asquith Angelina J Mosley Adrian Heaps Yuetsu Tanaka Graham P Taylor Angela R McLean Charles RM Bangham 《Retrovirology》2005,2(1):1-9
Background
Cellular infection with human immunodeficiency virus (HIV) both in vitro and in vivo requires a member of the chemokine receptor family to act as a co-receptor for viral entry. However, it is presently unclear to what extent the interaction of HIV proteins with chemokine receptors generates intracellular signals that are important for productive infection.Results
In this study we have used a recently described family of chemokine inhibitors, termed BSCIs, which specifically block chemokine-induced chemotaxis without affecting chemokine ligands binding to their receptors. The BSCI termed Peptide 3 strongly inhibited CCR5 mediated HIV infection of THP-1 cells (83 ± 7% inhibition assayed by immunofluoresence staining), but had no effect on gp120 binding to CCR5. Peptide 3 did not affect CXCR4-dependent infection of Jurkat T cells.Conclusion
These observations suggest that, in some cases, intracellular signals generated by the chemokine coreceptor may be required for a productive HIV infection. 相似文献103.
RNA molecules lighting up under the microscope 总被引:4,自引:0,他引:4
R. W. Dirks 《Histochemistry and cell biology》1996,106(2):151-166
104.
K. van der Meijden N. Bravenboer N.F. Dirks A.C. Heijboer M. den Heijer G.M.J. de Wit C. Offringa P. Lips R.T. Jaspers 《Journal of cellular physiology》2016,231(11):2517-2528
An adequate vitamin D status is essential to optimize muscle strength. However, whether vitamin D directly reduces muscle fiber atrophy or stimulates muscle fiber hypertrophy remains subject of debate. A mechanism that may affect the role of vitamin D in the regulation of muscle fiber size is the local conversion of 25(OH)D to 1,25(OH)2D by 1α‐hydroxylase. Therefore, we investigated in a murine C2C12 myoblast culture whether both 1,25(OH)2D3 and 25(OH)D3 affect myoblast proliferation, differentiation, and myotube size and whether these cells are able to metabolize 25(OH)D3 and 1,25(OH)2D3. We show that myoblasts not only responded to 1,25(OH)2D3, but also to the precursor 25(OH)D3 by increasing their VDR mRNA expression and reducing their proliferation. In differentiating myoblasts and myotubes 1,25(OH)2D3 as well as 25(OH)D3 stimulated VDR mRNA expression and in myotubes 1,25(OH)2D3 also stimulated MHC mRNA expression. However, this occurred without notable effects on myotube size. Moreover, no effects on the Akt/mTOR signaling pathway as well as MyoD and myogenin mRNA levels were observed. Interestingly, both myoblasts and myotubes expressed CYP27B1 and CYP24 mRNA which are required for vitamin D3 metabolism. Although 1α‐hydroxylase activity could not be shown in myotubes, after treatment with 1,25(OH)2D3 or 25(OH)D3 myotubes showed strongly elevated CYP24 mRNA levels compared to untreated cells. Moreover, myotubes were able to convert 25(OH)D3 to 24R,25(OH)2D3 which may play a role in myoblast proliferation and differentiation. These data suggest that skeletal muscle is not only a direct target for vitamin D3 metabolites, but is also able to metabolize 25(OH)D3 and 1,25(OH)2D3. J. Cell. Physiol. 231: 2517–2528, 2016. © 2016 The Authors. Journal of Cellular Physiology Published by Wiley Periodicals, Inc. 相似文献
105.
106.
Silvia Bulgheresi Harald R Gruber-Vodicka Niels R Heindl Ulrich Dirks Maria Kostadinova Heimo Breiteneder Joerg A Ott 《The ISME journal》2011,5(6):986-998
Selection of a specific microbial partner by the host is an all-important process. It guarantees the persistence of highly specific symbioses throughout host generations. The cuticle of the marine nematode Laxus oneistus is covered by a single phylotype of sulfur-oxidizing bacteria. They are embedded in a layer of host-secreted mucus containing the mannose-binding protein Mermaid. This Ca2+-dependent lectin mediates symbiont aggregation and attachment to the nematode. Here, we show that Stilbonema majum—a symbiotic nematode co-occurring with L. oneistus in shallow water sediment—is covered by bacteria phylogenetically distinct to those covering L. oneistus. Mermaid cDNA analysis revealed extensive protein sequence variability in both the nematode species. We expressed three recombinant Mermaid isoforms, which based on the structural predictions display the most different carbohydrate recognition domains (CRDs). We show that the three CRDs (DNT, DDA and GDA types) possess different affinities for L. oneistus and S. majum symbionts. In particular, the GDA type, exclusively expressed by S. majum, displays highest agglutination activity towards its symbionts and lowest towards its L. oneistus symbionts. Moreover, incubation of L. oneistus in the GDA type does not result in complete symbiont detachment, whereas incubation in the other types does. This indicates that the presence of particular Mermaid isoforms on the nematode surface has a role in the attachment of specific symbionts. This is the first report of the functional role of sequence variability in a microbe-associated molecular patterns receptor in a beneficial association. 相似文献
107.
Disentangling the mechanisms that maintain the stability of communities and ecosystem properties has become a major research focus in ecology in the face of anthropogenic environmental change. Dispersal plays a pivotal role in maintaining diversity in spatially subdivided communities, but only a few experiments have simultaneously investigated how dispersal and environmental fluctuation affect community dynamics and ecosystem stability. We performed an experimental study using marine phytoplankton species as model organisms to test these mechanisms in a metacommunity context. We established three levels of dispersal and exposed the phytoplankton to fluctuating light levels, where fluctuations were either spatially asynchronous or synchronous across patches of the metacommunity. Dispersal had no effect on diversity and ecosystem function (biomass), while light fluctuations affected both evenness and community biomass. The temporal variability of community biomass was reduced by fluctuating light and temporal beta diversity was influenced interactively by dispersal and fluctuation, whereas spatial variability in community biomass and beta diversity were barely affected by treatments. Along the establishing gradient of species richness and dominance, community biomass increased but temporal variability of biomass decreased, thus highest stability was associated with species-rich but highly uneven communities and less influenced by compensatory dynamics. In conclusion, both specific traits (dominance) and diversity (richness) affected the stability of metacommunities under fluctuating conditions. 相似文献
108.
R Quintero‐Torres HA Castillo‐Matadamas Jeff F Young RM Bermúdez Cruz 《Luminescence》2014,29(5):440-444
Relaxation dynamics is universal in science and engineering; its study serves to parameterize a system's response and to help identify a microscopic model of the processes involved. When measured data for a phenomenon cannot be fitted using one exponential, the choice of an alternative function to describe the decay becomes nontrivial. Here, we contrast two different, but fundamentally related approaches to fitting nontrivial decay curves; exponential decomposition and the gamma probability density function. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
109.
Rob Dirks Kees van Dun C. Bastiaan de Snoo Mark van den Berg Cilia L. C. Lelivelt William Voermans Leo Woudenberg Jack P. C. de Wit Kees Reinink Johan W. Schut Eveline van der Zeeuw Aat Vogelaar Gerald Freymark Evert W. Gutteling Marina N. Keppel Paul van Drongelen Matthieu Kieny Philippe Ellul Alisher Touraev Hong Ma Hans de Jong Erik Wijnker 《Plant biotechnology journal》2009,7(9):837-845
Reverse breeding (RB) is a novel plant breeding technique designed to directly produce parental lines for any heterozygous plant, one of the most sought after goals in plant breeding. RB generates perfectly complementing homozygous parental lines through engineered meiosis. The method is based on reducing genetic recombination in the selected heterozygote by eliminating meiotic crossing over. Male or female spores obtained from such plants contain combinations of non-recombinant parental chromosomes which can be cultured in vitro to generate homozygous doubled haploid plants (DHs). From these DHs, complementary parents can be selected and used to reconstitute the heterozygote in perpetuity . Since the fixation of unknown heterozygous genotypes is impossible in traditional plant breeding, RB could fundamentally change future plant breeding. In this review, we discuss various other applications of RB, including breeding per chromosome. 相似文献
110.
Narayan P Subramaniyam Outi RM Väisänen Katrina E Wendel Jaakko AV Malmivuo 《Nonlinear biomedical physics》2010,4(Z1):S4