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J H Richardson L L Steinmetz S B Deutscher W A Bookless W L Schmelzinger 《Analytical biochemistry》1979,97(1):17-23
A synchronously pumped krypton ion dye laser fluorescence system is shown to provide tunable, polarized, subnanosecond pulses at high repetition rates, modest peak powers, and low energy. Such a source is uniquely suited to fluorescence investigations of biochemical mechanisms. Applications of this fluorescence excitation source to analysis, life-time determination, and depolarization effects are discussed. 相似文献
3.
Sashko Spassov Dietmar Pfeifer Karl Strosing Stefan Ryter Matthias Hummel Simone Faller Alexander Hoetzel 《PloS one》2014,9(7)
Recently, we have shown that inhalation of hydrogen sulfide (H2S) protects against ventilator-induced lung injury (VILI). In the present study, we aimed to determine the underlying molecular mechanisms of H2S-dependent lung protection by analyzing gene expression profiles in mice. C57BL/6 mice were subjected to spontaneous breathing or mechanical ventilation in the absence or presence of H2S (80 parts per million). Gene expression profiles were determined by microarray, sqRT-PCR and Western Blot analyses. The association of Atf3 in protection against VILI was confirmed with a Vivo-Morpholino knockout model. Mechanical ventilation caused a significant lung inflammation and damage that was prevented in the presence of H2S. Mechanical ventilation favoured the expression of genes involved in inflammation, leukocyte activation and chemotaxis. In contrast, ventilation with H2S activated genes involved in extracellular matrix remodelling, angiogenesis, inhibition of apoptosis, and inflammation. Amongst others, H2S administration induced Atf3, an anti-inflammatory and anti-apoptotic regulator. Morpholino mediated reduction of Atf3 resulted in elevated lung injury despite the presence of H2S. In conclusion, lung protection by H2S during mechanical ventilation is associated with down-regulation of genes related to oxidative stress and inflammation and up-regulation of anti-apoptotic and anti-inflammatory genes. Here we show that Atf3 is clearly involved in H2S mediated protection. 相似文献
4.
Erin L. Hewett Ragheb Karl E. Miller Erin Hoerl Leone 《Journal of Field Ornithology》2019,90(4):309-324
Increasing nest survival by excluding predators is a goal of many bird conservation programs. However, new exclosure projects should be carefully evaluated to assess the potential risks of disturbance. We tested the effectiveness of predator exclosure fences (hereafter, fences) for nests of critically endangered Florida Grasshopper Sparrows (Ammodramus savannarum floridanus) at a dry prairie site (Three Lakes; 2015–2018) and a pasture site (the Ranch; 2015–2016) in Osceola County, Florida, USA. We installed fences at nests an average of 8 days after the start of incubation, and nest abandonment after fence installation was rare (2 of 149 installations). Predation was the leading cause of failure for unfenced nests at both sites (48–73%). At Three Lakes, nest cameras revealed that mammals and snakes were responsible for 61.5% and 38.5% of predation events, respectively, at unfenced nests. Fences reduced the daily probability of predation (0.016 for fenced nests vs. 0.074 for unfenced nests). The probability that a fenced nest would survive from discovery to fledging was more than double that of unfenced nests (60.4% vs. 27.7%). However, we found no difference in daily nest survival at the Ranch between the year before nests were fenced (2015; 0.874) and the year when all but one nest were fenced (2016; 0.867) because red imported fire ants (Solenopsis invicta) were responsible for 86% of predation events at fenced nests at the Ranch. The use of cameras at fenced nests revealed that site‐specific differences in nest predators explained variation in fence efficiency between sites. Our fence design may be useful for other species of grassland birds, but site‐specific predator communities and species‐specific response of target bird species to fences should be assessed before installing fences at other sites. 相似文献
5.
Bruce M. Taylor Ronald W. Sarver Gregory Fici Roger A. Poorman Barry S. Lutzke Antonio Molinari Thomas Kawabe Karl Kappenman Allen E. Buhl Dennis E. Epps 《The protein journal》2003,22(1):31-40
The time dependency of the spontaneous aggregation of the fibrillogenic β-Amyloid peptide, Aβ1–40, was measured by turbidity, circular dichroism, HPLC, and fluorescence polarization. The results by all methods were comparable and they were most consistent with a kinetic model where the peptide first slowly forms an activated monomeric derivative (AM), which is the only species able to initiate, by tetramerization, the formation of linear aggregates. The anti-Aβ antibody 6E10, raised against residues 1–17, at concentrations of 200–300 nM delayed significantly the aggregation of 50 μM amyloid peptide. The anti–Aβ antibody 4G8, raised against residues 17–24, was much less active in that respect, while the antibody A162, raised against the C-terminal residues 39–43 of the full-length Aβ was totally inactive at those concentrations. Concomitant with the aggregation experiments, we also measured the time dependency of the Aβ1–40–induced toxicity toward SH-EP1 cells and hippocampal neurons, evaluated by SYTOX Green fluorescence, lactate dehydrogenase release, and activation of caspases. The extent of cell damage measured by all methods reached a maximum at the same time and this maximum coincided with that of the concentration of AM. According to the kinetic scheme, the latter is the only transient peptide species whose concentration passes through a maximum. Thus, it appears that the toxic species of Aβ1–40 is most likely the same transient activated monomer that is responsible for the nucleation of fibril formation. These conclusions should provide a structural basis for understanding the toxicity of Aβ1–40 in vitro and possibly in vivo. 相似文献
6.
Catherine E. Rogers Karl R. Mattox Kenneth D. Stewart 《American journal of botany》1980,67(5):774-783
Chlorokybus atmophyticus has a sarcinoid growth habit and produces scale-covered zoospores. Flagella are laterally inserted and attached internally to a multilayered structure characteristic of the Charophyceae. There are two kinds of pyrenoid in each cell, a feature previously observed in only one scaly green flagellate. C. atmophyticus demonstrates that the sarcinoid growth habit arose independently at least twice in the green algae and cannot be used to define taxonomic groups unless combined with other criteria. It is further concluded that C. atmophyticus should be classified in a separate family Chlorokybaceae and a separate order Chloroky bales. 相似文献
7.
Georg Steinhauser Johannes H. Sterba Karin Poljanc Max Bichler Karl Buchtela 《Journal of trace elements in medicine and biology》2006,20(3):119-153
In this study, 18 partly commercially available samples of rock salt from Austria, Germany, Pakistan, Poland, Switzerland, and Ukraine were investigated with respect to their content of trace elements using instrumental neutron activation analysis. Elements detected were Al, Ba, Br, Ca, Ce, Cl, Co, Cr, Cs, Eu, Fe, Hf, La, Mn, Na, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Th, and Zn, some of them only in individual cases. An estimation of the bioavailability of these trace elements was performed by dissolving an equivalent of the sodium chloride samples in diluted hydrochloric acid (simulating stomach acid), filtering off the insoluble components, and analyzing the evaporated filtrate. It could be shown that in most cases bioactive trace elements like Fe can be found in rock salt in the form of almost insoluble compounds and are therefore not significantly bioavailable, whereas thorium, for example, was partly bioavailable in two cases. A significant contribution to the recommended daily intake of metal trace elements by using rock salt for nutrition can be excluded. 相似文献
8.
J T Streelman S A Karl 《Proceedings. Biological sciences / The Royal Society》1997,264(1384):1011-1020
Fifteen per cent of all living fishes are united in a single suborder (Labroidei) and display a dazzling array of behavioural and ecological traits. The labroids are considered monophyletic and members share a pharyngeal jaw apparatus (PJA) modified for crushing and processing prey. Outside of the explicitly functional PJA, there is no corroborative evidence for a monophyletic Labroidei. Here, we report the first molecular phylogenetic analysis of the suborder. Contrary to morphology-based phylogenies, our single-copy nuclear DNA data do not support labroid families as a natural group. Our data indicate that pharyngognathy has evolved independently among labroid families and that characters of the PJA are not reliable markers of perciform evolution. This work ''crushes'' conventional views of fish phylogeny and should engender novel concepts of piscine life history evolution. 相似文献
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10.
Escherichia coli strain CAN is unable to support the growth of bacteriophage T4 strains requiring the suppressor function of T4 tRNASer. Biochemical analysis of the mutant strain revealed that it is deficient in a RNase which acts on the artificial tRNA precursor tRNA-C-U. 相似文献