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41.
Summary Ubiquinone-10 (Q10) production was measured in batch cultures of Paracoccus denitrificans grown for 8 h at increasing oxygen concentrations (0–21 % O2 in the sparging gas). Whereas the cellular level of Q10 decreased monotonically from 1.2 to 0.5 mol/g d.w., the total yield of Q10 was maximal at 2.5 % O2 and amounted to 350 nmol (0.3 mg) per L of culture. 相似文献
42.
Elena Driomina Igor Polnikov Victor Sharov Ofelia Azizova Yury Vladimirov 《Free radical research》1994,20(5):279-288
A chemiluminescence (CL) flash kinetics on the addition of Fe2+ ions into oxidized low density lipoprotein (LDL) suspension has been studied. LDL oxidation was carried out at 37°C without and in the presence of 5 or 50 μM of Cu.2+ It has been found that under certain experimental conditions (the addition of excess iron ions, more than 1 mM) the amplitude of CL flash depended almost linearly (1) on the concentration of oxidized LDL and (2) on the extent of LDL oxidation measured as diene conjugates (DC) and 2-thiobarbituric acid-reactive substance (TBARS) accumulation. The corresponding correlation coefficients were: for TBARS - 0.94 and for DC - 0.97, in the case of LDL autooxidation; 0.72 and 0.98, in the case of copper-induced LDL oxidation. A sensitivity of the CL method was shown to be significantly enhanced (by more than two orders) in the presence of CL sensitizer - 2, 3,5, 6-lH,4H-tetrahydro-9-(2' -benzoimidazolyl)-quinolizin-(9, 9a, 1 -gh)coumarin. 相似文献
43.
44.
The trophic role of rotifers in the zooplankton community of dimictic, oligotrophic lake Kozjak, the largest lake of the Plitvice
Lakes, NW Dinarid Mountains, is analyzed. Their spatial and temporal biomass distribution in relation to that of protozoans,
cladocerans and copepods shows that they form a significant part of the non-predatory zooplankton of this karstic standing
water. 相似文献
45.
Marco Patacca Marcus Lindner Manuel Esteban Lucas-Borja Thomas Cordonnier Gal Fidej Barry Gardiner Ylva Hauf Gediminas Jasinevičius Sophie Labonne Edgaras Linkevičius Mats Mahnken Slobodan Milanovic Gert-Jan Nabuurs Thomas A. Nagel Laura Nikinmaa Momchil Panyatov Roman Bercak Rupert Seidl Masa Zorana Ostrogović Sever Jaroslaw Socha Dominik Thom Dijana Vuletic Sergey Zudin Mart-Jan Schelhaas 《Global Change Biology》2023,29(5):1359-1376
Over the last decades, the natural disturbance is increasingly putting pressure on European forests. Shifts in disturbance regimes may compromise forest functioning and the continuous provisioning of ecosystem services to society, including their climate change mitigation potential. Although forests are central to many European policies, we lack the long-term empirical data needed for thoroughly understanding disturbance dynamics, modeling them, and developing adaptive management strategies. Here, we present a unique database of >170,000 records of ground-based natural disturbance observations in European forests from 1950 to 2019. Reported data confirm a significant increase in forest disturbance in 34 European countries, causing on an average of 43.8 million m3 of disturbed timber volume per year over the 70-year study period. This value is likely a conservative estimate due to under-reporting, especially of small-scale disturbances. We used machine learning techniques for assessing the magnitude of unreported disturbances, which are estimated to be between 8.6 and 18.3 million m3/year. In the last 20 years, disturbances on average accounted for 16% of the mean annual harvest in Europe. Wind was the most important disturbance agent over the study period (46% of total damage), followed by fire (24%) and bark beetles (17%). Bark beetle disturbance doubled its share of the total damage in the last 20 years. Forest disturbances can profoundly impact ecosystem services (e.g., climate change mitigation), affect regional forest resource provisioning and consequently disrupt long-term management planning objectives and timber markets. We conclude that adaptation to changing disturbance regimes must be placed at the core of the European forest management and policy debate. Furthermore, a coherent and homogeneous monitoring system of natural disturbances is urgently needed in Europe, to better observe and respond to the ongoing changes in forest disturbance regimes. 相似文献
46.
47.
Takafumi Tadano Hiroki Otani Masanori Taira Igor B. Dawid 《Genesis (New York, N.Y. : 2000)》1993,14(3):204-211
Mesoderm development in Xenopus laevis depends on inductive cell interactions mediated by diffusible molecules. The mesoderm inducer activin is capable of redirecting the development of animal explants both morphologically and biochemically. We have studied the induction of four regulatory genes, Mix. 1, goosecoid (gsc), Xlim-1 and Xbra in such explants by activin, and the influence of other factors on this induction. Activin induction of gsc is strongly enhanced by dorsalization of the embryo by LiCl, while expression of the other genes is only slightly enhanced. The protein synthesis inhibitor cycloheximide (CHX) inhibits the activin-dependent induction of Xbra partially, while induction of Mix. 1 and Xlim- 1 is essentially unaffected. In contrast, gsc shows strong superinduction in the presence of activin and CHX, and can be induced in animal explants by CHX alone. Induction and superinduction by CHX have previously been observed for immediate early genes in a variety of systems, notably for the activation of c-fos expression by serum stimulation, but have not been reported in early amphibian embryos. © 1993Wiley-Liss, Inc. 相似文献
48.
Darja Fer
ej-Temeljotov Matev Kmet Darko Kocjan Sonja Kotnik Aleksander Resman Uro Urleb Katarina Verhnjak Igor Zver Janko
mitek 《Chirality》1993,5(4):288-292
Structure–interaction relationships, stereoselectivity, and solubility enhancement in inclusion compexation of β-cyclodextrins (CDs) with some racemic and enantiomerically pure 1,4-dihydropyridine derivatives (DHPs) were investigated. 1:1 and 1:2 (mole ratio) complexes were prepared and characterized by X-ray powder diffraction, differential scanning calorimetry (DSC), MS-FAB spectrometry, 1H-NMR spectroscopy, water and phase solubility. The solubility studies have revealed different complexation equilibria for optically pure DHP enantiomers, and corresponding racemic mixtures in water solutions. By means of 1H-NMR chemical shift measurements, the inclusion of aromatic fragments of racemic and enantiomerically pure DHP molecules within the cavities of different CDs was elucidated. Considerable stereoselectivity in complexation interactions was observed. The results indicate the potential use of cyclodextrins as chiral selectors for enantiomeric resolution of 1,4-DHP calcium antagonists. © 1993 Wiley-Liss, Inc. 相似文献
49.
Mirjana D. Mosić Jelena Đ. Trifković Petar M. Ristivojević Dušanka M. Milojković-Opsenica 《化学与生物多样性》2023,20(3):e202201141
The aim of this study is to develop a rapid, effect-directed screening method for quality assessment of bee pollen-honey mixtures. The comparative antioxidant potential and phenolic content of honey, bee pollen, and the bee pollen-honey mixtures, was performed using spectrophotometry. The total phenolic content and antioxidative activity of bee pollen-honey mixtures with 20 % bee pollen share were in the range 3.03–3.11 mg GAE/g, and 6.02–6.96 mmol TE/kg, respectively, while mixtures with 30 % bee pollen share contained 3.92–4.18 mg GAE/g, and 9.69–10.11 mmol TE/kg. Chromatographic fingerprint of bee pollen-honey mixtures was performed by high-performance thin-layer chromatography with conditions developed by authors and reported for the first time. Fingerprint analysis hyphenated with chemometrics enabled authenticity assessments of honey in mixtures. Results indicate that bee pollen-honey mixtures represent a food with highly, both, nutritious characteristics and health-promoting effect. 相似文献
50.