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71.
Juan F Masello Petra Quillfeldt Gopi K Munimanda Nadine Klauke Gernot Segelbacher H Martin Schaefer Mauricio Failla Maritza Cortés Yoshan Moodley 《Frontiers in zoology》2011,8(1):1-17
Background
While the gene flow in some organisms is strongly affected by physical barriers and geographical distance, other highly mobile species are able to overcome such constraints. In southern South America, the Andes (here up to 6,900 m) may constitute a formidable barrier to dispersal. In addition, this region was affected by cycles of intercalating arid/moist periods during the Upper/Late Pleistocene and Holocene. These factors may have been crucial in driving the phylogeographic structure of the vertebrate fauna of the region. Here we test these hypotheses in the burrowing parrot Cyanoliseus patagonus (Aves, Psittaciformes) across its wide distributional range in Chile and Argentina.Results
Our data show a Chilean origin for this species, with a single migration event across the Andes during the Upper/Late Pleistocene, which gave rise to all extant Argentinean mitochondrial lineages. Analyses suggest a complex population structure for burrowing parrots in Argentina, which includes a hybrid zone that has remained stable for several thousand years. Within this zone, introgression by expanding haplotypes has resulted in the evolution of an intermediate phenotype. Multivariate regressions show that present day climatic variables have a strong influence on the distribution of genetic heterogeneity, accounting for almost half of the variation in the data.Conclusions
Here we show how huge barriers like the Andes and the regional environmental conditions imposed constraints on the ability of a parrot species to colonise new habitats, affecting the way in which populations diverged and thus, genetic structure. When contact between divergent populations was re-established, a stable hybrid zone was formed, functioning as a channel for genetic exchange between populations. 相似文献72.
Schoen C Kolb-Mäurer A Geginat G Löffler D Bergmann B Stritzker J Szalay AA Pilgrim S Goebel W 《Cellular microbiology》2005,7(5):709-724
The limited access to the nuclear compartment may constitute one of the major barriers after bacteria-mediated expression plasmid DNA delivery to eukaryotic cells. Alternatively, a self-destructing Listeria monocytogenes strain was used to release translation-competent mRNA directly into the cytosol of epithelial cells, macrophages and human dendritic cells. Enhanced green fluorescent protein (EGFP)-encoding mRNA, adapted for translation in mammalian cells by linking an IRES element to the 5'-end of the egfp coding sequence, was produced by T7 RNA polymerase in the carrier bacteria upon entry into the cytosol where the mRNA is efficiently released from the lysed bacteria and immediately translated in eukaryotic host cells. Besides the much earlier expression of EGFP being detectable already 4 h after infection, the number of EGFP expressing mammalian cells obtained with this novel RNA delivery technique is comparable to or - especially in phagocytic cells - even higher than that obtained with the expression plasmid DNA delivery strategy. Accordingly, bacteria-mediated delivery of ovalbumin-encoding mRNA to macrophages resulted in efficient antigen processing and presentation in vitro indicating that this approach may also be adapted for the in vivo delivery of antigen-encoding mRNA leading to a more efficient immune response when applied to vaccine development. 相似文献
73.
Dominik Hartl Matthias Griese Thomas Nicolai Gernot Zissel Christine Prell Dietrich Reinhardt Dolores J Schendel Susanne Krauss-Etschmann 《Respiratory research》2005,6(1):1-12
Background
Particulate matter (PM) can exacerbate allergic airway diseases. Although health effects of PM with a diameter of less than 100 nm have been focused, few studies have elucidated the correlation between the sizes of particles and aggravation of allergic diseases. We investigated the effects of nano particles with a diameter of 14 nm or 56 nm on antigen-related airway inflammation.Methods
ICR mice were divided into six experimental groups. Vehicle, two sizes of carbon nano particles, ovalbumin (OVA), and OVA + nano particles were administered intratracheally. Cellular profile of bronchoalveolar lavage (BAL) fluid, lung histology, expression of cytokines, chemokines, and 8-hydroxy-2'-deoxyguanosine (8-OHdG), and immunoglobulin production were studied.Results
Nano particles with a diameter of 14 nm or 56 nm aggravated antigen-related airway inflammation characterized by infiltration of eosinophils, neutrophils, and mononuclear cells, and by an increase in the number of goblet cells in the bronchial epithelium. Nano particles with antigen increased protein levels of interleukin (IL)-5, IL-6, and IL-13, eotaxin, macrophage chemoattractant protein (MCP)-1, and regulated on activation and normal T cells expressed and secreted (RANTES) in the lung as compared with antigen alone. The formation of 8-OHdG, a proper marker of oxidative stress, was moderately induced by nano particles or antigen alone, and was markedly enhanced by antigen plus nano particles as compared with nano particles or antigen alone. The aggravation was more prominent with 14 nm of nano particles than with 56 nm of particles in overall trend. Particles with a diameter of 14 nm exhibited adjuvant activity for total IgE and antigen-specific IgG1 and IgE.Conclusion
Nano particles can aggravate antigen-related airway inflammation and immunoglobulin production, which is more prominent with smaller particles. The enhancement may be mediated, at least partly, by the increased local expression of IL-5 and eotaxin, and also by the modulated expression of IL-13, RANTES, MCP-1, and IL-6. 相似文献74.
Phosphate limited grown Anabaena variabilis has the capability of processing information about external phosphate fluctuations by means of interconnected adaptive events. Adaptive events are physiological processes that are characterized by two opposite manifestations, namely adapted states and adaptive operation modes. In adapted states the energy-converting constituents of the uptake system operate under the prevailing external conditions in a coherent manner with least energy dissipation. Adaptive operation modes take place when adapted states are disturbed by persistent changes in phosphate supply. In this mode the outcome of former adaptations to elevated phosphate levels guides the emergence of a new adapted state. The influence of antecedent adapted states on subsequent adaptations was studied experimentally and characteristic examples for such information processing are given. The theory of self-referential systems allowed analyzing these examples. For this purpose adaptive events had to be considered as elements of a communicating network, in which, along a historic succession of alternating adapted states and adaptive operation modes, information pertaining to the self-preservation of the organism is transferred from one adaptive event to the next: the latter “interprets” environmental changes by means of distinct adaptive operation modes, aimed at preservation of the organism. The result of this interpretation is again leading to a coherent state that is passed on to subsequent adaptive events. A generalization of this idea to the adaptive interplay of other energy converting subsystems of the cell leads to the dynamic view of cellular information processing in which the organism recreates itself in every new experience.Key Words: adaptation, cyanobacteria, information processing, phosphate uptake, self-referential systems 相似文献
75.
76.
Oskolkova OV Afonyushkin T Preinerstorfer B Bicker W von Schlieffen E Hainzl E Demyanets S Schabbauer G Lindner W Tselepis AD Wojta J Binder BR Bochkov VN 《Journal of immunology (Baltimore, Md. : 1950)》2010,185(12):7706-7712
Polyunsaturated fatty acids are precursors of multiple pro- and anti-inflammatory molecules generated by enzymatic stereospecific and positionally specific insertion of oxygen, which is a prerequisite for recognition of these mediators by cellular receptors. However, nonenzymatically oxidized free and esterified polyunsaturated fatty acids also demonstrate activities relevant to inflammation. In particular, phospholipids containing oxidized fatty acid residues (oxidized phospholipids; OxPLs) were shown to induce proinflammatory changes in endothelial cells but paradoxically also to inhibit inflammation induced via TLR4. In this study, we show that half-maximal inhibition of LPS-induced elevation of E-selectin mRNA in endothelial cells developed at concentrations of oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (OxPAPC) 10-fold lower than those required to induce proinflammatory response. Similar concentration difference was observed for other classes and molecular species of OxPLs. Upon injection into mice, OxPAPC did not elevate plasma levels of IL-6 and keratinocyte chemoattractant but strongly inhibited LPS-induced upregulation of these inflammatory cytokines. Thus, both in vitro and in vivo, anti-LPS effects of OxPLs are observed at lower concentrations than those required for their proinflammatory action. Quantification of the most abundant oxidized phosphatidylcholines by HPLC/tandem mass spectrometry showed that circulating concentrations of total oxidized phosphatidylcholine species are close to the range where they demonstrate anti-LPS activity but significantly lower than that required for induction of inflammation. We hypothesize that low levels of OxPLs in circulation serve mostly anti-LPS function and protect from excessive systemic response to TLR4 ligands, whereas proinflammatory effects of OxPLs are more likely to develop locally at sites of tissue deposition of OxPLs (e.g., in atherosclerotic vessels). 相似文献
77.
78.
Understanding the neural mechanisms underlying object recognition is one of the fundamental challenges of visual neuroscience. While neurophysiology experiments have provided evidence for a "simple-to-complex" processing model based on a hierarchy of increasingly complex image features, behavioral and fMRI studies of face processing have been interpreted as incompatible with this account. We present a neurophysiologically plausible, feature-based model that quantitatively accounts for face discrimination characteristics, including face inversion and "configural" effects. The model predicts that face discrimination is based on a sparse representation of units selective for face shapes, without the need to postulate additional, "face-specific" mechanisms. We derive and test predictions that quantitatively link model FFA face neuron tuning, neural adaptation measured in an fMRI rapid adaptation paradigm, and face discrimination performance. The experimental data are in excellent agreement with the model prediction that discrimination performance should asymptote as faces become dissimilar enough to activate different neuronal populations. 相似文献
79.
Marschall HU Wagner M Bodin K Zollner G Fickert P Gumhold J Silbert D Fuchsbichler A Sjövall J Trauner M 《Journal of lipid research》2006,47(3):582-592
Farnesoid X receptor knockout (Fxr(-/-)) mice cannot upregulate the bile salt export pump in bile acid loading or cholestatic conditions. To investigate whether Fxr(-/-) mice differ in bile acid detoxification compared with wild-type mice, we performed a comprehensive analysis of bile acids extracted from liver, bile, serum, and urine of naive and common bile duct-ligated wild-type and Fxr(-/-) mice using electrospray and gas chromatography mass spectrometry. In addition, hepatic and renal gene expression levels of Cyp2b10 and Cyp3a11, and protein expression levels of putative renal bile acid-transporting proteins, were investigated. We found significantly enhanced hepatic bile acid hydroxylation in Fxr(-/-) mice, in particular hydroxylations of cholic acid in the 1beta, 2beta, 4beta, 6alpha, 6beta, 22, or 23 position and a significantly enhanced excretion of these metabolites in urine. The gene expression level of Cyp3a11 was increased in the liver of Fxr(-/-) mice, whereas the protein expression levels of multidrug resistance-related protein 4 (Mrp4) were increased in kidneys of both genotypes during common bile duct ligation. In conclusion, Fxr(-/-) mice detoxify accumulating bile acids in the liver by enhanced hydroxylation reactions probably catalyzed by Cyp3a11. The metabolites formed were excreted into urine, most likely with the participation of Mrp4. 相似文献
80.
Paschen A Song M Schenk S Janda J Nguyen XD Osen W Schadendorf D Geginat G 《Microbes and infection / Institut Pasteur》2006,8(8):2034-2043
Cholesterol-binding cytolysins constitute an evolutionarily conserved family of pore-forming proteins expressed by different gram-positive pathogens. Listeriolysin O, one well-characterized member of the cytolysin family, is also known to induce specific CD4 and CD8 T cell responses upon infection of mice with Listeria monocytogenes. Here we describe an HLA-DRB1*0301-restricted listeriolysin O-derived T cell epitope that is conserved among several members of the cytolysin family. An HLA-DRB1*0301-restricted CD4+ T cell line, established from spleen lymphocytes of L. monocytogenes-infected HLA-DRB1*0301-transgenic mice, cross-reacted with a homologous peptide from perfringolysin O, a cytolysin expressed by Clostridium perfringens. Ex vivo analysis of infected mice revealed an even broader cross-reaction of T cells with homologous peptides derived from perfringolysin O, streptolysin O, and cereolysin O. Interestingly, a cross-reactive memory CD4+ T cell response against the homologous peptides derived from listeriolysin O and perfringolysin O could also be detected in the blood from healthy HLA-DRB1*0301+ human donors. Remarkably, this response was even present in donors who did not exhibit a memory T cell reactivity against a second, non-conserved HLA-DRB1*0301-restricted LLO-derived CD4 T cell epitope, suggesting that cytolysin-producing bacteria other than L. monocytogenes can stimulate a cross-reactive cytolysin-specific immunity. 相似文献