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排序方式: 共有294条查询结果,搜索用时 15 毫秒
61.
Klinger A Orzekowsky-Schroeder R von Smolinski D Blessenohl M Schueth A Koop N Huettmann G Gebert A 《Histochemistry and cell biology》2012,137(3):269-278
The mucosa of the gastrointestinal tract is a dynamic tissue composed of numerous cell types with complex cellular functions.
Study of the vital intestinal mucosa has been hampered by lack of suitable model systems. We here present a novel animal model
that enables highly resolved three-dimensional imaging of the vital murine intestine in anaesthetized mice. Using intravital
autofluorescence 2-photon (A2P) microscopy we studied the choreographed interactions of enterocytes, goblet cells, enteroendocrine
cells and brush cells with other cellular constituents of the small intestinal mucosa over several hours at a subcellular
resolution and in three dimensions. Vigorously moving lymphoid cells and their interaction with constituent parts of the lamina
propria were examined and quantitatively analyzed. Nuclear and lectin staining permitted simultaneous characterization of
autofluorescence and admitted dyes and yielded additional spectral information that is crucial to the interpretation of the
complex intestinal mucosa. This novel intravital approach provides detailed insights into the physiology of the small intestine
and especially opens a new window for investigating cellular dynamics under nearly physiological conditions. 相似文献
62.
63.
Davidson WS Koop BF Jones SJ Iturra P Vidal R Maass A Jonassen I Lien S Omholt SW 《Genome biology》2010,11(9):403
The International Collaboration to Sequence the Atlantic Salmon Genome (ICSASG) will produce a genome sequence that identifies
and physically maps all genes in the Atlantic salmon genome and acts as a reference sequence for other salmonids. 相似文献
64.
Sarah K. Huber Jeb P. Owen Jennifer A. H. Koop Marisa O. King Peter R. Grant B. Rosemary Grant Dale H. Clayton 《PloS one》2010,5(1)
Background
Invasive parasites are a major threat to island populations of animals. Darwin''s finches of the Galápagos Islands are under attack by introduced pox virus (Poxvirus avium) and nest flies (Philornis downsi). We developed assays for parasite-specific antibody responses in Darwin''s finches (Geospiza fortis), to test for relationships between adaptive immune responses to novel parasites and spatial-temporal variation in the occurrence of parasite pressure among G. fortis populations.Methodology/Principal Findings
We developed enzyme-linked immunosorbent assays (ELISAs) for the presence of antibodies in the serum of Darwin''s finches specific to pox virus or Philornis proteins. We compared antibody levels between bird populations with and without evidence of pox infection (visible lesions), and among birds sampled before nesting (prior to nest-fly exposure) versus during nesting (with fly exposure). Birds from the Pox-positive population had higher levels of pox-binding antibodies. Philornis-binding antibody levels were higher in birds sampled during nesting. Female birds, which occupy the nest, had higher Philornis-binding antibody levels than males. The study was limited by an inability to confirm pox exposure independent of obvious lesions. However, the lasting effects of pox infection (e.g., scarring and lost digits) were expected to be reliable indicators of prior pox infection.Conclusions/Significance
This is the first demonstration, to our knowledge, of parasite-specific antibody responses to multiple classes of parasites in a wild population of birds. Darwin''s finches initiated acquired immune responses to novel parasites. Our study has vital implications for invasion biology and ecological immunology. The adaptive immune response of Darwin''s finches may help combat the negative effects of parasitism. Alternatively, the physiological cost of mounting such a response could outweigh any benefits, accelerating population decline. Tests of the fitness implications of parasite-specific immune responses in Darwin''s finches are urgently needed. 相似文献65.
66.
A molecular phylogenetic investigation of the hypothesized antiquity of the hydrothermal vent endemic Neomphalina (Mollusca; Gastropoda) is reported. Sequences of two domains of the gene encoding for 28S ribosomal RNA were acquired for 3 outgroup and 32 gastropod genera. Use of the likelihood ratio test indicated complex substitution patterns for these domains and taxa, corresponding to a general time-reversible model with among-site rate variation. Phylogenetic analyses were performed using this model under maximum likelihood criteria. The data lacked resolution of gastropod radiations of the Paleozoic and all three of the outgroup sequences were randomized relative to the ingroup. Acceleration of evolutionary rates had additionally randomized the sequences of the Patellogastropoda relative to the other Gastropoda. The data resolved radiations of the Mesozoic and supported monophyly of the sampled Neritopsina, Vetigastropoda, Neomphalina, Caenogastropoda (including Campanile and the Architaenioglossa), and Heterobranchia (Valvata + Euthyneura), although several results were not significantly different from nonmonophyletic alternatives. Mesozoic origins of the hydrothermal vent endemic Neomphalina are preliminarily supported and implications for the hydrothermal vent refugia hypothesis discussed. Issues related to phylogenetic resolution of the Gastropoda are additionally discussed. 相似文献
67.
The CYP inhibitor 1-aminobenzotriazole does not prevent oxidative stress associated with alcohol-induced liver injury in rats and mice 总被引:6,自引:0,他引:6
Isayama F Froh M Bradford BU McKim SE Kadiiska MB Connor HD Mason RP Koop DR Wheeler MD Arteel GE 《Free radical biology & medicine》2003,35(12):1568-1581
Cytochrome P450 (CYP) 2E1 is induced by ethanol and is postulated to be a source of reactive oxygen species during alcoholic liver disease. However, there was no difference in liver pathology and radical formation between wild-type and CYP2E1 knockout mice fed ethanol. Other CYP isoforms may contribute these effects if CYP2E1 is inhibited or absent. The purpose of this study was, therefore, to determine if blocking most of the P450 isoforms with 1-aminobenzotriazole (ABT; 100 mg/kg i.g.), has any effect on liver damage and oxidative stress due to alcohol in rats and mice. Male C57BL/6 mice and Wistar rats were fed either high-fat control or ethanol-containing enteral diet for 4 weeks. ABT had a significant inhibitory effect on many P450 isoforms independent of concomitant alcohol administration. However, ABT did not protect against liver damage due to alcohol in either species. Indices of oxidative stress and inflammation were also similar in livers from vehicle-treated and ABT-treated animals fed ethanol. In summary, suppression of P450 activity with ABT had no apparent effect on oxidative stress caused by alcohol in both rats and mice. These data support the hypothesis that oxidative stress and liver damage can occur independently of CYP activities in both rats and mice during early alcohol-induced liver injury. 相似文献
68.
Protoplasts, because they lack the wall of a typical higher plant cell, offer unique opportunities for experimental manipulation of their organellar constituents. Here, we report on modification of the organellar content of Nicotiana tabacum protoplasts by microfusion-induced transfer of defined numbers of chloroplasts into albino recipient cells. A single chloroplast is found to be sufficient for establishing a new plastid population in the progeny of the recipient cell. The frequency of green or variegated regenerants is shown to be genotype dependent. It can be drastically increased by using selection pressure for the transferred organelle. We also report on transient expression of plastid specific reporter gene constructs in plastids after PEG-mediated direct gene transfer into Nicotiana plumbaginifolia protoplasts. The expression is shown to be localized in the plastids by determining gene expression in isolated chloroplasts under conditins which completely remove cytoplasmic enzyme activity derived from a nuclear reporter gene construct. These data demonstrate for the first time that functional DNA, introduced into the cytoplasm by direct gene transfer, enters the organellar compartment and is expressed. 相似文献
69.
Mutations of the forkhead/winged-helix gene, FKHL7, in patients with Axenfeld-Rieger anomaly. 总被引:4,自引:0,他引:4
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70.
A. Mehra-Palta H.-U. Koop S. Goes E.-M. Troidl G. Nagy S. Tyagi W. Kofer R. G. Herrmann 《Plant cell reports》1998,17(8):605-611
A favourable combination of genetic features in the genus Oenothera offers access to fundamental biological aspects that are not readily approached with other materials. We have developed protocols
for cell and tissue culture as well as for transformation, in order to establish the basis for a comprehensive cell and molecular
biology of Euoenothera species, their genome/plastome hybrids and plastome mutants. Regeneration of plants from excised seedling parts (roots, hypocotyl,
cotyledons, shoot tips) and leaf explants was optimal on NT medium containing 1 mg ⋅ l–1 6-benzylaminopurine and 3 mg ⋅ l–1
α-naphtalene acetic acid. This medium also proved to be efficient in the propagation of various wild-type genotypes, interspecific
hybrids and plastome mutants. Using Ti-based approaches we also succeeded in generating transgenic Oenothera plants with relatively high efficiency.
Received: 17 February 1997 / Revision received: 16 April 1997 / Accepted: 20 April 1997 相似文献