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Abundance and composition of the near-bottom zooplankton between 10 and 100 metres above the bottom (mab) were studied in the Levantine Basin, eastern Mediterranean, during four cruises of RV Meteor in June 1993, January 1998, April/May 1999 and October 2001. Copepoda made up 91% of all zooplankton caught. A strong dominance of one single species was observed on all cruises, with Lucicutia longiserrata reaching 50–90% of all Copepoda except in 1993, when Subeucalanus monachus was the most abundant species, with more than 90% of all Copepoda. The year 1993 was also exceptional in terms of total zooplankton abundance, being more than one order of magnitude higher than in the other years. Vertical differences in abundance and composition were small and did not indicate a near-bottom effect or a specialized benthopelagic zooplankton community in the layers sampled. 相似文献
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The cause of the pregnancy condition preeclampsia (PE) is thought to be endothelial dysfunction caused by oxidative stress. As abnormal glucose tolerance has also been associated with PE, we use a fluorinated-mimic of this metabolite to establish whether any oxidative damage to lipids and proteins in the erythrocyte membrane has increased cell membrane permeability. Data were acquired using 19F Dynamic-NMR (DNMR) to measure exchange of 3-fluoro-3-deoxyglucose (3-FDG) across the membrane of erythrocytes from 10 pregnant women (5 healthy control women, and 5 from women suffering from PE). Magnetisation transfer was measured using the 1D selective inversion and 2D EXSY pulse sequences, over a range of time delays. Integrated intensities from these experiments were used in matrix diagonalisation to estimate the values of the rate constants of exchange and membrane permeability. No significant differences were observed for the rate of exchange of 3-FDG and membrane permeability between healthy pregnant women and those suffering from PE, leading us to conclude that no oxidative damage had occurred at this carrier-protein site in the membrane. 相似文献
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Arnold N. Onyango 《Chemistry and physics of lipids》2012,165(7):777-786
Small reactive carbonyl compounds (RCCs) such as formaldehyde, acetaldehyde, acrolein, crotonaldehyde, glyoxal, methylglyoxal, glycolaldehyde, glycidaldehyde, and 2-butene-1,4-dial are involved in carbonyl and oxidative stress-related physiological disorders. While some evidence indicates that lipid oxidation could be an important source of these compounds in vivo, this has sometimes been doubted because the mechanisms of their formation thereby are poorly understood. Here, representative literature supporting the significant formation of these compounds during lipid oxidation under physiologically relevant conditions are highlighted, and the strengths and weaknesses of previously proposed mechanisms of their formation thereby are considered. In addition, based on the current understanding of lipid oxidation chemistry, some new pathways of their formation are suggested. The suggested pathways also generate 4-hydroxy-2-butenal, a precursor of the carcinogen furan, whose endogenous formation in tissues has hitherto not been seriously considered. 相似文献
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Bernd Stille 《Archives of microbiology》1956,24(1):31-40
Zusammenfassung In Anlehnung an frühere Untersuchungen von Wallhäusser u. Rippel-Baldes, in denen sich die Brauchbarkeit des Schnelltestes mit Triphenyltetrazoliumchlorid zur Wertbestimmung von Antibiotica und Desinfektionsmitteln ergab, wurde versucht, mit Hilfe dieses testes einen Einblick in das hemmstoffbedingte Abwehrvermögen höherer Pflanzen gegenüber Mikroorganismen zu gewinnen.
Bacterium coli und einige weitere vergleichsweise untersuchte Bakterienarten ließen nach Einwirkung frischer Preßsäfte aus den Blättern verschiedener Pflanzenarten stets eine deutliche — meistens sogar eine tatale — Hemmung ihres TTC-Reduktionsvermögens erkennen.Das Ausmaß der Hemmwirkung der einzelnen Preßsäfte wies erhebliche Unterschiede auf; eine totale Hemmung der mikrobiellen Formazanbildung bewirkten einige Preßsäfte noch in einer Verdünnung von 1/32, eine partielle Hemmung äußerstenfalls noch in einer Verdünnung von 1/128.Die besondere Eignung des Tetrazoltestes zur Untersuchung pflanzlicher Hemmstoffwirkungen auf Mikroorganismen ergibt sich einerseits aus seiner einfachen Handhabung, da er ein Arbeiten mit nichtsterilen Pflanzenpreßsäften gestattet, und andererseits aus der Tatsache, daß er bereits in kürzester Zeit zu Ergebnissen führt; infolgedessen lassen sich Wirksamkeitsveränderungen der Hemmstoffe, die bei anderen Testmethoden während der Bebrütung gegebenenfalls eintreten können, weitgehend vermeiden. 相似文献
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D. W. T. Crompton S. E. Arnold D. E. Walters A. E. Keymer R. W. Marrs 《Journal of Zoology》1988,214(2):313-324
Aspects of the reproductive performance of Moniliformis moniliformis were investigated in rats allowed to feed ad libitum on a purified diet containing 1% (w/w) fructose as an energy source for the worms. The rats were infected with either 10, 20, 40 or 80 cystacanths each with the intention of investigating density-dependent effects on worm fecundity. The establishment of the worms in the gut was independent of dose, but survival, growth and reproductive performance generally were shown to be related to the infective dose given to the rats. The effects could not be related to the absolute numbers of worms present in the small intestine at post-mortem examination. In general, some unidentified regulatory process appeared to operate to create severe density-dependence in survival so that surviving parasites were not present in numbers expected to generate competition. Attainment of sexual maturity, growth and the production of mature eggs by worms from rats given doses of 80 cystacanths each were delayed compared with worms from rats given the other doses, but eventually the performance of the high-dose worms caught up. Worms attached more anteriorly in the small intestine grew bigger and produced more mature eggs. Possible mechanisms responsible for the observed effects are discussed. 相似文献