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61.
Heribert Keweloh Hermann-Josef Heipieper Hans-Jürgen Rehm 《Applied microbiology and biotechnology》1989,31(4):383-389
Summary The antibacterial activity of phenol was determined by measuring inhibition of exponentially growing free and immobilized cells of Escherichia coli, Pseudomonas putida and Staphylococcus aureus. Immobilization of microorganisms in calcium alginate beads reduced the growth inhibition caused by bacteriostatic concentrations of phenol. The increase in phenol tolerance occurred at different culture conditions and growth rates of the cells. The strength of the effect, however, was found to correlate with the formation of colonies in the gel matrix. Dissolution of gel beads led to a substantial loss of the protection against phenol of immobilized-grown cells. 相似文献
62.
The effects of iontophoretically ejected angiotensin II (Ang II) on the firing rate of neurons in the basolateral complex and the central and cortical amygdala were investigated in two strains of urethane anesthetized rats. In normotensive Sprague-Dawley rats, Ang II induced a significant increase in the discharge rate of responsive amygdaloid neurons. In contrast, in the hypertensive transgenic [TGR(mREN-2)27] rats with higher brain Ang II level, Ang II more often caused inhibitory effects on the amygdaloid firing rate in comparison with controls. The distribution of nonresponsive, excited, and inhibited neurons differed significantly in the two rat strains. Moreover, the responsiveness of amygdaloid neurons was significantly higher in transgenic rats in comparison with controls. Both the increase and the decrease in the firing rate caused by Ang II could be blocked either by angiotensin AT(1) or by AT(2) receptor-specific antagonists. In many cases, the Ang II-induced decrease in the firing rate was antagonized by bicuculline, a gamma-aminobutyric acid (GABA(A)) antagonist. The higher responsiveness of amygdaloid neurons in transgenic rats as well as the predominance of inhibitory effects, presumedly mediated by GABAergic interneurons, could change the output of the amygdala and its influence on thirst, kidney, and cardiovascular function or on processes of learning and anxiety. 相似文献
63.
Andreas Wagner Mirko Platzgummer Günther Kreismayr Heribert Quendler Gabriela Stiegler Boris Ferko 《Journal of liposome research》2013,23(3):311-319
A new scalable liposome production system is presented, which is based on the ethanol injection technique. The system permits liposome manufacture regardless of production scale, as scale is determined only by free disposable vessel volumes. Once the parameters are defined, an easy scale up can be performed by just changing the process vessels. These vessels are fully sterilizeable and all raw materials are transferred into the sanitized and sterilized system via 0.2 μm filters to guarantee an aseptic production.Liposome size can be controlled by the local lipid concentration at the injection point depending on process parameters like injection pressure, lipid concentration and injection rate. These defined process parameters are furthermore responsible for highly reproducible results with respect to vesicle diameters and encapsulation rates Compared to other technologies like the film method which is normally followed by size reduction through high pressure homogenization, ultrasonication or extrusion, no mechanical forces are needed to generate homogeneous and narrow distributed liposomes.Another important advantage of this method is the suitability for the entrapment of many different drug substances such as large hydrophilic proteins by passive encapsulation, small amphiphilic drugs by a one step remote loading technique or membrane association of antigens for vaccination approaches 相似文献
64.
Competition and habitat filtering jointly explain phylogenetic structure of soil bacterial communities across elevational gradients 下载免费PDF全文
Qian Zhang Marta Goberna Yuguo Liu Ming Cui Haishui Yang Qixiang Sun Heribert Insam Jinxing Zhou 《Environmental microbiology》2018,20(7):2386-2396
The importance of assembly processes in shaping biological communities is poorly understood, especially for microbes. Here, we report on the forces that structure soil bacterial communities along a 2000 m elevational gradient. We characterized the relative importance of habitat filtering and competition on phylogenetic structure and turnover in bacterial communities. Bacterial communities exhibited a phylogenetically clustered pattern and were more clustered with increasing elevation. Biotic factors (i.e., relative abundance of dominant bacterial lineages) appeared to be most important to the degree of clustering, evidencing the role of the competitive ability of entire clades in shaping the communities. Phylogenetic turnover showed the greatest correlation to elevation. After controlling the elevation, biotic factors showed greater correlation to phylogenetic turnover than all the habitat variables (i.e., climate, soil and vegetation). Structural equation modelling also identified that elevation and soil organic matter exerted indirect effects on phylogenetic diversity and turnover by determining the dominance of microbial competitors. Our results suggest that competition among bacterial taxa induced by soil carbon contributes to the phylogenetic pattern across elevational gradient in the Tibetan Plateau. This highlights the importance of considering not only abiotic filtering but also biotic interactions in soil bacterial communities across stressful elevational gradients. 相似文献
65.
66.
Cloning and functional expression of a human heparanase gene. 总被引:32,自引:0,他引:32
P H Kussie J D Hulmes D L Ludwig S Patel E C Navarro A P Seddon N A Giorgio P Bohlen 《Biochemical and biophysical research communications》1999,261(1):183-187
We have cloned a gene (HSE1) from a human placental cDNA library that encodes a novel protein exhibiting heparanase activity. The cDNA was identified through peptide sequences derived from purified heparanase isolated from human SK-HEP-1 hepatoma cells. HSE1 contains an open reading frame encoding a predicted polypeptide of 543 amino acids and possesses a putative signal sequence at its amino terminus. Northern blot analysis suggested strong expression of HSE1 in placenta and spleen. Transient transfection of HSE1 in COS7 cells resulted in the expression of a protein with an apparent molecular mass of 67-72 kDa. HSE1 protein was detectable in conditioned media but was also associated with the membrane fraction following cell lysis. The HSE1 gene product was shown to exhibit heparanase activity by specifically cleaving a labeled heparan sulfate substrate in a similar manner as purified native protein. 相似文献
67.
Phosphorylation of Ribosomal Protein S6 (RPS6) was the first post-translational modification of the ribosome to be identified and is a commonly-used readout for mTORC1 activity. Although the cellular and organismal functions of RPS6 phosphorylation are known, the molecular consequences of RPS6 phosphorylation on translation are less well understood. Here we use selective ribosome footprinting to analyze the location of ribosomes containing phosphorylated RPS6 on endogenous mRNAs in cells. We find that RPS6 becomes progressively dephosphorylated on ribosomes as they translate an mRNA. As a consequence, average RPS6 phosphorylation is higher on mRNAs with short coding sequences (CDSs) compared to mRNAs with long CDSs. We test whether RPS6 phosphorylation differentially affects mRNA translation based on CDS length by genetic removal of RPS6 phosphorylation. We find that RPS6 phosphorylation promotes translation of mRNAs with short CDSs more strongly than mRNAs with long CDSs. Interestingly, RPS6 phosphorylation does not promote translation of mRNAs with 5′ TOP motifs despite their short CDS lengths, suggesting they are translated via a different mode. In sum this provides a dynamic view of RPS6 phosphorylation on ribosomes as they translate mRNAs and the functional consequence on translation. 相似文献
68.
Marlies Knipper Lika Gestwa Wouter‐Jan Ten Cate Jürgen Lautermann Heribert Brugger Hannes Maier Ulrike Zimmermann Karin Rohbock Iris Kpschall Barbara Wiechers Hans‐Peter Zenner 《Developmental neurobiology》1999,38(3):338-356
Analyzing the thyroid hromone (TH)‐dependent period of the inner ear, we observed that the presence of triiodothyronine (T3) between postnatal day 3 (P3) and P12 is sufficient for functional maturation of the auditory system. Within this short time period, an unusual transient TH‐dependent expression of nonneuronal neurotrophin receptors (NT‐R) trkB and p75NGFR was observed in correlation with neuronal and morphogenetic processes. The availability of thyroid hormone was revealed to be invariably correlated with (a) a transient expression of full‐length trkB in TRα1‐, TRα2‐ and TRβ1‐expressing hair cells concomitant to the segregation of afferent fibers and the synaptogenesis of efferent fibers; and (b) a transient expression of p75NGFR in TRα1‐ and TRβ1‐expressing great epithelia ridge cells in direct spatiotemporal correlation with the appearance of apoptotic cells and morphogenetic maturation of the organ. For the first time, these data suggest a TH dependency of the expression of neurotrophin receptors in nonneuronal cells. A potential role of these peculiar neurotrophin receptor expression for the conversion of the biological function of TH on innervation patterning and morphogenesis during the critical TH‐dependent period of the inner ear may be considered. © 1999 John Wiley & Sons, Inc. J Neurobiol 38: 338–356, 1999 相似文献
69.
70.
Influence of Surfactants on Lipase Fat Digestion in a Model Gastro-intestinal System 总被引:1,自引:0,他引:1
Pedro M. Reis Thomas W. Raab Jean Y. Chuat Martin E. Leser Reinhard Miller Heribert J. Watzke Krister Holmberg 《Food biophysics》2008,3(4):370-381
In the present study, we use a model gastro-intestinal system to study the influence of different food-grade surface-active
molecules (Sn-2 monopalmitin, β-lactoglobulin, or lysophosphatodylcholine) on lipase activity. The interfacial activity of
lipase and surfactants are assessed with the pendant drop technique, a commonly used tensiometry instrument. A mathematical
model is adopted which enables quantitative determination of the composition of the water–oil interface as a function of bulk
surfactant concentration in the water–oil mixtures. Our results show a decrease in gastric lipolysis when interfacially active
molecules are incorporated into a food matrix. However, only the Sn-2 monopalmitin caused a systematic decrease in triglyceride
hydrolysis throughout the gastro-intestinal tract. This effect is most likely due to exclusion of both lipase and triglyceride
from the water–oil interface together with a probable saturation of the solubilization capacity of bile with monoglycerides.
Addition of β-lactoglobulin or lysophopholipids increased the hydrolysis of fat after the gastric phase. These results can
be attributed to an increasing interfacial area with lipase and substrate present at the interface. Otherwise, β-lactoglobulin,
or lysophopholipids reduced fat hydrolysis in the stomach. From the mathematical modeling of the interface composition, we
can conclude that Sn-2 monopalmitin can desorb lipase from the interface, which, together with exclusion of substrate from
the interface, explains the gradually decreased triglyceride hydrolysis that occurs during the digestion. Our results provide
a biophysics approach on lipolysis that can bring new insights into the problem of fat uptake. 相似文献