Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1432-2048
    Keywords: Key words: Chitinase ; Chitin elicitor ; Ectomycorrhiza ; Hebeloma ; Picea ; Plant defence (suppression)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Rapid reactions comprising efflux of K+ and Cl−, phosphorylation of a 63-kDa protein (pp63), extracellular alkalinization and synthesis of H2O2 are equally induced in cells of Picea abies (L.) Karst. by chitotetraose, colloidal chitin and cell wall elicitors from the ectomycorrhizal fungus Hebeloma crustuliniforme (Bull. ex Fries.) Quél. an ectomycorrhizal partner of spruce. Cleavage of fungal cell wall elicitors and of artificial chitin elicitors to monomeric and dimeric fragments by apoplasmic spruce chitinases (36-kDa class I chitinase, pI 8.0, and 28-kDa chitinase, pI 8.7; EC 3.2.1.14) equally prevented induction of these rapid reactions. Also, N-acetylglucosamine oligomers and elicitors from the fungal cell walls showed a similar dependence of their activity on the degree of polymerisation. From these results it is suggested that, during ectomycorrhiza formation, only some of the chitin-derived elicitors reach their receptors at the plant plasma membrane, initiating reactions of the hypersensitive response in the host cells. The remaining fungal elicitors will be degraded to varying extents by wall-localized chitinases of the host root, reducing the defence reactions of the plant and allowing symbiotic interactions of both organisms.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-2048
    Keywords: Key words: Cantharidin ; Ectomycorrhiza ; Elicitor-induced reactions ; Mastoparan ; Picea ; Protein Phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The first responses in spruce [Picea abies (L.) Karst.] cells induced by elicitors (N-acetylglucosamine oligomers) from ectomycorrhizal fungi have been described as follows: efflux of Cl− and K+, influx of Ca2+, extracellular alkalinization, phosphorylation of a 63-kDa protein (pp63), dephosphorylation of a 65-kDa protein (pp65) and synthesis of H2O2 (Salzer et al. 1996, Planta 198: 118–126). In order to obtain new insights into the triggering mechanism and the sequence of these rapid responses we used compounds which are known to activate or block specific steps within an elicitor-induced signal transduction cascade in plant cells. Comparable to elicitors the two protein phosphatase inhibitors, cantharidin and calyculin A, as well as mastoparan, an activator of trimeric G-proteins, were able to induce the release of Cl− and K+ from spruce cells and the alkalinization of the medium. Half-maximal activation of the alkalinization occurred at 133 nM calyculin A, 2.3 μM cantharidin and 1.6 μ mastoparan. The structural analogue of mastoparan, Mas 17, which has no G-protein-stimulating properties, was unable to trigger the above-mentioned reactions. In addition, cantharidin and calyculin A induced an increased synthesis of H2O2 in spruce cells which was prolonged in comparison to the elicitor-induced transient formation of H2O2. Also, the cantharidin-induced release of K+ was more pronounced and longer lasting than that caused by elicitors from the ectomycorrhizal fungus Hebeloma crustuliniforme (Bull. ex Fries.) and N-acetylglucosamine oligomers. Furthermore, cantharidin, calyculin A and mastoparan induced the phosphorylation of pp63. Remarkably, the protein kinase inhibitor, staurosporine, inhibited all the rapid responses described above, no matter whether they were triggered by fungal elicitors or by the protein phosphatase inhibitors. These results indicate that in the initial signalling events in spruce cells, essential protein phosphorylations occur either as an (auto) phosphorylation of a membrane-bound receptor kinase prior to the activation of a G-protein or (and) immediately downstream of the activated G-protein in a phosphorylation cascade and are the basic requirements for the ion fluxes following downstream.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2012-04-13
    Description: Understanding the molecular and cellular mechanisms that mediate magnetosensation in vertebrates is a formidable scientific problem. One hypothesis is that magnetic information is transduced into neuronal impulses by using a magnetite-based magnetoreceptor. Previous studies claim to have identified a magnetic sense system in the pigeon, common to avian species, which consists of magnetite-containing trigeminal afferents located at six specific loci in the rostral subepidermis of the beak. These studies have been widely accepted in the field and heavily relied upon by both behavioural biologists and physicists. Here we show that clusters of iron-rich cells in the rostro-medial upper beak of the pigeon Columbia livia are macrophages, not magnetosensitive neurons. Our systematic characterization of the pigeon upper beak identified iron-rich cells in the stratum laxum of the subepidermis, the basal region of the respiratory epithelium and the apex of feather follicles. Using a three-dimensional blueprint of the pigeon beak created by magnetic resonance imaging and computed tomography, we mapped the location of iron-rich cells, revealing unexpected variation in their distribution and number--an observation that is inconsistent with a role in magnetic sensation. Ultrastructure analysis of these cells, which are not unique to the beak, showed that their subcellular architecture includes ferritin-like granules, siderosomes, haemosiderin and filopodia, characteristics of iron-rich macrophages. Our conclusion that these cells are macrophages and not magnetosensitive neurons is supported by immunohistological studies showing co-localization with the antigen-presenting molecule major histocompatibility complex class II. Our work necessitates a renewed search for the true magnetite-dependent magnetoreceptor in birds.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Treiber, Christoph Daniel -- Salzer, Marion Claudia -- Riegler, Johannes -- Edelman, Nathaniel -- Sugar, Cristina -- Breuss, Martin -- Pichler, Paul -- Cadiou, Herve -- Saunders, Martin -- Lythgoe, Mark -- Shaw, Jeremy -- Keays, David Anthony -- England -- Nature. 2012 Apr 11;484(7394):367-70. doi: 10.1038/nature11046.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Molecular Pathology, Dr Bohr-Gasse, 1030 Vienna, Austria.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22495303" target="_blank"〉PubMed〈/a〉
    Keywords: Animal Migration ; Animals ; Beak/anatomy & histology/*cytology ; Columbidae/*anatomy & histology/physiology ; Feathers/cytology/ultrastructure ; Ferrocyanides/analysis ; Immunohistochemistry ; Iron/analysis/*metabolism ; Macrophages/*metabolism/ultrastructure ; *Magnetic Fields ; Magnetic Resonance Imaging ; Neurons/metabolism ; Orientation ; Respiratory Mucosa/cytology/ultrastructure ; *Sensation ; Tomography, Emission-Computed, Single-Photon
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...