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61.
Joppe W. R. Hovius Maarten F. Bijlsma Gerritje J. W. van der Windt W. Joost Wiersinga Bastiaan J. D. Boukens Jeroen Coumou Anneke Oei Regina de Beer Alex F. de Vos Cornelis van 't Veer Alje P. van Dam Penghua Wang Erol Fikrig Marcel M. Levi Joris J. T. H. Roelofs Tom van der Poll 《PLoS pathogens》2009,5(5)
The causative agent of Lyme borreliosis, the spirochete Borrelia
burgdorferi, has been shown to induce expression of the urokinase
receptor (uPAR); however, the role of uPAR in the immune response against
Borrelia has never been investigated. uPAR not only acts as
a proteinase receptor, but can also, dependently or independently of ligation to
uPA, directly affect leukocyte function. We here demonstrate that uPAR is
upregulated on murine and human leukocytes upon exposure to B.
burgdorferi both in vitro as well as in vivo. Notably, B.
burgdorferi-inoculated C57BL/6 uPAR knock-out mice harbored
significantly higher Borrelia numbers compared to WT controls.
This was associated with impaired phagocytotic capacity of B.
burgdorferi by uPAR knock-out leukocytes in vitro. B.
burgdorferi numbers in vivo, and phagocytotic capacity in vitro,
were unaltered in uPA, tPA (low fibrinolytic activity) and PAI-1 (high
fibrinolytic activity) knock-out mice compared to WT controls. Strikingly, in
uPAR knock-out mice partially backcrossed to a B. burgdorferi
susceptible C3H/HeN background, higher B. burgdorferi numbers
were associated with more severe carditis and increased local TLR2 and
IL-1β mRNA expression. In conclusion, in B. burgdorferi
infection, uPAR is required for phagocytosis and adequate eradication of the
spirochete from the heart by a mechanism that is independent of binding of uPAR
to uPA or its role in the fibrinolytic system. 相似文献
62.
63.
The glycosylated pyrrolizidine alkaloid, thesinine-4'-O-beta-D-glucoside, has been isolated from the aqueous methanol extract of dried, defatted seeds of Borago officinalis (Boraginaceae). The structure was established by means of spectroscopic and chemical analysis. 相似文献
64.
65.
Heeney JL Koopman G Rosenwirth B Bogers W van Dijk J Nieuwenhuis I Niphuis H ten Haaft P Hanke T Rhodes G Berglund P Burny A Bex F Sutter G Liljeström P 《Journal of medical primatology》2000,29(3-4):268-273
A large number of recombinant of viral and bacterial systems have been engineered as vectors to express foreign genes for vaccination and/or gene therapy. A common problem is the immune response to the vector itself. The presence of anti-vector immune responses may preclude sufficient 'priming' or immunogenicity if pre-existing immune responses are present, or they may impair optimal 'boosting' upon repeated immunization or delivery with the same vector. To circumvent this problem we developed a strategy using different chimeric vectors which share only the expression of common specific antigens desired for immunization. This approach not only has the advantage of avoiding increased anti-vector responses, but allows the use of combinations of vectors which could subsequently present the same or related antigen differently to the immune system as well as at alternative sites to induce the optimal type of immunity against the pathogen of interest. 相似文献
66.
Reaction time (RT) is commonly observed to slow down after an error. This post-error slowing (PES) has been thought to arise from the strategic adoption of a more cautious response mode following deployment of cognitive control. Recently, an alternative account has suggested that PES results from interference due to an error-evoked orienting response. We investigated whether error-related orienting may in fact be a pre-cursor to adaptive post-error behavioral adjustment when the orienting response resolves before subsequent trial onset. We measured pupil dilation, a prototypical measure of autonomic orienting, during performance of a choice RT task with long inter-stimulus intervals, and found that the trial-by-trial magnitude of the error-evoked pupil response positively predicted both PES magnitude and the likelihood that the following response would be correct. These combined findings suggest that the magnitude of the error-related orienting response predicts an adaptive change of response strategy following errors, and thereby promote a reconciliation of the orienting and adaptive control accounts of PES. 相似文献
67.
68.
Bart P. S. Nieuwenhuis Alfons J. M. Debets Duur K. Aanen 《Proceedings. Biological sciences / The Royal Society》2011,278(1702):152-157
We expect that sexual selection may play an important role in the evolution of mushroom-forming basidiomycete fungi. Although these fungi do not have separate sexes, they do play female and male roles: the acceptance and the donation of a nucleus, respectively. The primary mycelium (monokaryon) of basidiomycete fungi, growing from a germinating sexual spore, is hermaphroditic, but it loses female function upon the acceptance of a second nucleus. The resulting dikaryon with two different nuclei in each cell retains a male potential as both nuclei can fertilize receptive mycelia. We tested the occurrence of sexual selection in the model species of mushroom-forming basidiomycetes, Schizophyllum commune, by pairing monokaryons with fully compatible dikaryons. In most pairings, we found a strong bias for one of the two nuclei although both were compatible with the monokaryon when paired alone. This shows that sexual selection can occur in mushroom-forming basidiomycetes. Since the winning nucleus of a dikaryon occasionally varied depending on the receiving monokaryon, we infer that sexual selection can operate through choosiness of the receiving individual (analogous to female choice). However, in other cases the same nucleus won, irrespective of the receiving monokaryon, suggesting that competition between the two nuclei of the donating mycelium (analogous to male–male competition) might also play a role. 相似文献
69.
T. A. Egorova-Zachernyuk V. I. Shvets K. Versluis W. Heerma A. F. L. Creemers S. A. M. Nieuwenhuis J. Lugtenburg J. Raap 《Journal of peptide science》1996,2(6):341-350
A simple procedure for the preparation of the specifically labelled peptide antibiotic zervamicins IC, IIA and IIB has been developed. The zervamicin molecules are labelled with stable isotopes by culturing the Emericellopsis salmosynnemata on a well-defined synthetic medium containing the highly isotopically enriched amino acid. To obtain the peptide with the specifically and highly enriched amino acid residue, precautions have been taken to prevent any de novo biosynthesis of the particular amino acid from unlabelled precursors. The enrichment of the labelled peptide is determined by mass spectrometric analysis. Following this method we have incorporated [2′,4′, 5′,6′,7′-2H5]-L -Trp-1, [1′-15N]-L -Trp-1 and [2′, 3′,4′,5′,6′-2H5]-L - Phl-16 into zervamicins IC, IIA and IIB on the preparative scale and without scrambling of the label. Thus, using the procedures described, isotopically labelled zervamicins can be prepared, allowing them to be studied by solid- state NMR. 相似文献
70.
The significance of sexual selection, the component of natural selection associated with variation in mating success, is well established for the evolution of animals and plants, but not for the evolution of fungi. Even though fungi do not have separate sexes, most filamentous fungi mate in a hermaphroditic fashion, with distinct sex roles, that is, investment in large gametes (female role) and fertilization by other small gametes (male role). Fungi compete to fertilize, analogous to ‘male‐male’ competition, whereas they can be selective when being fertilized, analogous to female choice. Mating types, which determine genetic compatibility among fungal gametes, are important for sexual selection in two respects. First, genes at the mating‐type loci regulate different aspects of mating and thus can be subject to sexual selection. Second, for sexual selection, not only the two sexes (or sex roles) but also the mating types can form the classes, the members of which compete for access to members of the other class. This is significant if mating‐type gene products are costly, thus signalling genetic quality according to Zahavi's handicap principle. We propose that sexual selection explains various fungal characteristics such as the observed high redundancy of pheromones at the B mating‐type locus of Agaricomycotina, the occurrence of multiple types of spores in Ascomycotina or the strong pheromone signalling in yeasts. Furthermore, we argue that fungi are good model systems to experimentally study fundamental aspects of sexual selection, due to their fast generation times and high diversity of life cycles and mating systems. 相似文献