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Microbiological transformation of benzaldehyde accomplished by the fungus Rhodotorula mucilaginosa immobilized in the ultrafiltration cell was studied. A polysulfone membrane formed on a sintered PVC support was used for the separation of the transformation product from the cellular material. Kinetic investigations have led to results which are typical of continuously fed stirred tank reactors (CFSTR)-the value of the maximum reaction rate (V(max)) and apparent Michaelis constant (K'(m)) are practically independent of the substrate retention time (calculated in terms of the flow intensity value). A strong relationship was found to occur between V(max) and biomass concentration in the reactor. Study of the apparent enzyme stability shows that the decrease in the biocatalyst activity is chiefly caused by penetration of the cells through the membrane. The experimental results were approximated in terms of the adopted mathematical model. Based on this model, the half-lives (t(1/2)) of enzyme activities were determined. The t(1/2) value varies from 35 to 82 days and depends both on the permeate flux through the membrane and on the separation properties of the membrane. 相似文献
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Mikolaj B. Ogrodnik Tamar Pirtskhalava Nassir M. Thalji Michael Hagler Diana Jurk Leslie A. Smith Grace Casaclang‐Verzosa Yi Zhu Marissa J. Schafer Tamara Tchkonia James L. Kirkland Jordan D. Miller 《Aging cell》2016,15(5):973-977
While reports suggest a single dose of senolytics may improve vasomotor function, the structural and functional impact of long‐term senolytic treatment is unknown. To determine whether long‐term senolytic treatment improves vasomotor function, vascular stiffness, and intimal plaque size and composition in aged or hypercholesterolemic mice with established disease. Senolytic treatment (intermittent treatment with Dasatinib + Quercetin via oral gavage) resulted in significant reductions in senescent cell markers (TAF+ cells) in the medial layer of aorta from aged and hypercholesterolemic mice, but not in intimal atherosclerotic plaques. While senolytic treatment significantly improved vasomotor function (isolated organ chamber baths) in both groups of mice, this was due to increases in nitric oxide bioavailability in aged mice and increases in sensitivity to NO donors in hypercholesterolemic mice. Genetic clearance of senescent cells in aged normocholesterolemic INK‐ATTAC mice phenocopied changes elicited by D+Q. Senolytics tended to reduce aortic calcification (alizarin red) and osteogenic signaling (qRT–PCR, immunohistochemistry) in aged mice, but both were significantly reduced by senolytic treatment in hypercholesterolemic mice. Intimal plaque fibrosis (picrosirius red) was not changed appreciably by chronic senolytic treatment. This is the first study to demonstrate that chronic clearance of senescent cells improves established vascular phenotypes associated with aging and chronic hypercholesterolemia, and may be a viable therapeutic intervention to reduce morbidity and mortality from cardiovascular diseases. 相似文献
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Gralak MA Bertrandt J Klos A Stryczek AB Piastowska AW Morka A Debski B 《Biological trace element research》2004,98(1):85-93
The aim of the present study was to investigate the influence of nutritional deficiency and dietary addition of vitamins (B2, B6, and folate) on hepatic concentration of zinc and copper in rats. The experiment was performed on 260 growing male Wistar
rats divided into 13 groups. Animals of 11 groups were fed isocaloric diets (14.7 MJ/kg) in which the 20% of energy was derived
from protein. Another two groups of rats were offered diets with 9% or 4.5% of energy originating from protein. Animals of
both mentioned groups and of the control group (20% of energy from protein) were offered diets ad libitum. The other 10 groups were offered 50% and 30% of the amount consumed in the control group. Eight groups, from those 10 restricted
ones, were differentiated by dietary addition of vitamins B2 and B6 and folate (300% addition). Restricted feed intake did not affect the liver zinc concentration but significantly increased
the copper concentration. The addition of vitamin B6 decreased the liver Zn concentration. The highest liver Cu concentration was noted in rats offered restricted diets to only
30% of intake in the control group and high in vitamin B2 and in rats supplemented with all of studied vitamins together. It suggests that vitamin B2 had the strongest impact on liver Cu concentration in rats fed restricted diets. 相似文献
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Helmut Fuchs Valérie Gailus-Durner Thure Adler Juan Antonio Aguilar-Pimentel Lore Becker Julia Calzada-Wack Patricia Da Silva-Buttkus Frauke Neff Alexander Götz Wolfgang Hans Sabine M. Hölter Marion Horsch Gabi Kastenmüller Elisabeth Kemter Christoph Lengger Holger Maier Mikolaj Matloka Gabriele Möller Beatrix Naton Cornelia Prehn Martin Hrabě de Angelis 《Methods (San Diego, Calif.)》2011,53(2):120-135
Model organisms like the mouse are important tools to learn more about gene function in man. Within the last 20 years many mutant mouse lines have been generated by different methods such as ENU mutagenesis, constitutive and conditional knock-out approaches, knock-down, introduction of human genes, and knock-in techniques, thus creating models which mimic human conditions. Due to pleiotropic effects, one gene may have different functions in different organ systems or time points during development. Therefore mutant mouse lines have to be phenotyped comprehensively in a highly standardized manner to enable the detection of phenotypes which might otherwise remain hidden. The German Mouse Clinic (GMC) has been established at the Helmholtz Zentrum München as a phenotyping platform with open access to the scientific community (www.mousclinic.de; [1]). The GMC is a member of the EUMODIC consortium which created the European standard workflow EMPReSSslim for the systemic phenotyping of mouse models (http://www.eumodic.org/ [2]). 相似文献
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Krastev DB Slabicki M Paszkowski-Rogacz M Hubner NC Junqueira M Shevchenko A Mann M Neugebauer KM Buchholz F 《Nature cell biology》2011,13(7):809-818
TP53 (tumour protein 53) is one of the most frequently mutated genes in human cancer and its role during cellular transformation has been studied extensively. However, the homeostatic functions of p53 are less well understood. Here, we explore the molecular dependency network of TP53 through an RNAi-mediated synthetic interaction screen employing two HCT116 isogenic cell lines and a genome-scale endoribonuclease-prepared short interfering RNA library. We identify a variety of TP53 synthetic interactions unmasking the complex connections of p53 to cellular physiology and growth control. Molecular dissection of the TP53 synthetic interaction with UNRIP indicates an enhanced dependency of TP53-negative cells on small nucleolar ribonucleoprotein (snoRNP) assembly. This dependency is mediated by the snoRNP chaperone gene NOLC1 (also known as NOPP140), which we identify as a physiological p53 target gene. This unanticipated function of TP53 in snoRNP assembly highlights the potential of RNAi-mediated synthetic interaction screens to dissect molecular pathways of tumour suppressor genes. 相似文献
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Stochastic P systems and the simulation of biochemical processes with dynamic compartments 总被引:3,自引:0,他引:3
We introduce a sequential rewriting strategy for P systems based on Gillespie's stochastic simulation algorithm, and show that the resulting formalism of stochastic P systems makes it possible to simulate biochemical processes in dynamically changing, nested compartments. Stochastic P systems have been implemented using the spatially explicit programming language MGS. Implementation examples include models of the Lotka-Volterra auto-catalytic system, and the life cycle of the Semliki Forest virus. 相似文献
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K. Formicki M. Sadowski A. Taski A. Korzelecka-Orkisz A. Winnicki 《Zeitschrift fur angewandte Ichthyologie》2004,20(4):290-294
Effects of a constant magnetic field on the selection of swimming direction by trout (Salmo trutta L.) larvae and fry were investigated in an experimental facility consisting of chambers equipped with magnets as well as magnet‐free chambers placed at the entrance. The experiments showed a close relationship between the direction selected by the larvae and fry and the presence or absence of ferritic magnets generating a constant magnetic field. The results obtained indicate during early ontogenesis, when a newly hatched individual is no longer an embryo but also not a mature form, that the larva is sensitive to a magnetic field. This sensitivity seems to be related to an exteroreception system that develops at that time involving magnetoreceptors containing magnetite particles. 相似文献