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Fenge Christel Klein Cornelia Heuer Carsten Siegel Ursula Fraune Elisabeth 《Cytotechnology》1993,11(3):233-244
For an optimized bioreactor design which is adapted to the cultivation of sensitive animal cells different modular bioreactor components for gentle agitation, sufficient aeration and long-term perfusion were developed and investigated with respect to their suitability from laboratory to production scale. Aeration systems have been designed for both shear sensitive cells and cells which tolerate bubbles. The systems are based on either membranes for bubble-free aeration or stainless steel sparger systems. They were characterized by determination of their oxygen transfer capacity and optimized in cultivation processes of different cell lines under process conditions such as batch and perfusion mode.Different impellers for suspension cells and cells grown on carriers were investigated for their suitability to ensure homogeneous gentle mixing. A large pitch blade impeller as well as a novel 3-blade segment impeller are appropriate for homogeneous mixing at low shear rates. Especially with the 3-blade segment impeller fluid mechanical stress can be reduced at a given stirrer speed which is advantageous for the cultivation of cells attached to microcarriers or extremely shear sensitive suspension cells. However, our results indicate that shear sensitivity of animal cells has been generally overestimated.Continuous perfusion of both suspension cell cultures and cells cultivated on microcarriers could be successfully performed over extended periods of time using stainless steel spinfilters with appropriate pore sizes and systems based on microporous hydrophilic membranes. Spinfilters are suitable cell retention systems for technical scale bioreactors allowing continuous perfusion cultures of suspension cells (pore size 10 to 20 m) as well as anchorage dependent cells grown on microcarriers (pore size 75 m) over six weeks to 3 months.Applying the developed modules for agitation, aeration and perfusion process adapted bioreactor set-ups can be realized which ensure optimum growth and product formation conditions in order to maximize cell and product yields. 相似文献
15.
Carsten Bresch und Thomas Trautner 《Molecular & general genetics : MGG》1956,87(4):590-594
Summary Three different groups of mutations in bacteriophage are discussed with special reference to the coliphage T 1. One of these groups can be detected only by application of the Zweifarb-Nährboden. This technique, its advantages, and difficulties are described. Coloured photographs are shown of the most important genetic types of T 1 and of some heterozygotes which appear in genetic crosses.
Mit 6 Textabbildungen, davon 5 farbigen Teilfiguren 相似文献
Mit 6 Textabbildungen, davon 5 farbigen Teilfiguren 相似文献
16.
Carsten Mei?ner Reinhold Deppisch Friederike Hug Matthias Schulze Eberhard Ritz Horst Ludwig Gertrud M. H?nsch 《Glycoconjugate journal》1995,12(5):632-638
Contact of mononuclear human leukocytes with cellulose dialysis membranes may result in complement-independent cell activation, i.e. enhanced synthesis of cytokines, prostaglandins and an increase in 2-microglobulin synthesis. Cellular contact activation is specifically inhibited by the monosaccharidel-fucose suggesting that dialysis membrane associatedl-fucose residues are involved in leukocyte activation. In this study we have detected and quantitatedl-fucose on commercially-available cellulose dialysis membranes using two approaches. A sensitive enzymatic fluorescence assay detectedl-fucose after acid hydrolysis of flat sheet membranes. Values ranged from 79.3±3.6 to 90.2±5.0 pmol cm–2 for Hemophan® or Cuprophan® respectively. Enzymatic cleavage of terminal -l-fucopyranoses with -l-fucosidase yielded 7.7±3.3 pmoll-fucose per cm2 for Cuprophan. Enzymatic hydrolysis of the synthetic polymer membranes AN-69 and PC-PE did not yield detectable amounts ofl-fucose. In a second approach, binding of the fucose specific lectins ofLotus tetragonolobus andUlex europaeus (UEAI) demonstrated the presence of biologically accessiblel-fucose on the surface of cellulose membranes. Specific binding was observed with Cuprophan®, and up to 2.6±0.3 pmoll-fucose per cm2 was calculated to be present from Langmuir-type adsorption isotherms. The data presented are in line with the hypothesis that surface-associatedl-fucose residues on cellulose dialysis membranes participate in leukocyte contact activation. 相似文献
17.
Expression of TRPC3 in Chinese Hamster Ovary Cells Results in Calcium-activated Cation Currents Not Related to Store Depletion 总被引:16,自引:0,他引:16 下载免费PDF全文
Christof Zitt Alexander G. Obukhov Carsten Strübing Andrea Zobel Frank Kalkbrenner Andreas Lückhoff Günter Schultz 《The Journal of cell biology》1997,138(6):1333-1341
TRPC3 (or Htrp3) is a human member of the trp family of Ca2+-permeable cation channels. Since expression of TRPC3 cDNA results in markedly enhanced Ca2+ influx in response to stimulation of membrane receptors linked to phospholipase C (Zhu, X., J. Meisheng, M. Peyton, G. Bouley, R. Hurst, E. Stefani, and L. Birnbaumer. 1996. Cell. 85:661–671), we tested whether TRPC3 might represent a Ca2+ entry pathway activated as a consequence of depletion of intracellular calcium stores. CHO cells expressing TRPC3 after intranuclear injection of cDNA coding for TRPC3 were identified by fluorescence from green fluorescent protein. Expression of TRPC3 produced cation currents with little selectivity for Ca2+ over Na+. These currents were constitutively active, not enhanced by depletion of calcium stores with inositol-1,4,5-trisphosphate or thapsigargin, and attenuated by strong intracellular Ca2+ buffering. Ionomycin led to profound increases of currents, but this effect was strictly dependent on the presence of extracellular Ca2+. Likewise, infusion of Ca2+ into cell through the patch pipette increased TRPC3 currents. Therefore, TRPC3 is stimulated by a Ca2+-dependent mechanism. Studies on TRPC3 in inside-out patches showed cation-selective channels with 60-pS conductance and short (<2 ms) mean open times. Application of ionomycin to cells increased channel activity in cell-attached patches. Increasing the Ca2+ concentration on the cytosolic side of inside-out patches (from 0 to 1 and 30 μM), however, failed to stimulate channel activity, even in the presence of calmodulin (0.2 μM). We conclude that TRPC3 codes for a Ca2+-permeable channel that supports Ca2+-induced Ca2+-entry but should not be considered store operated. 相似文献
18.
From the Namurian B of the Bergisches Land the oldest known remain of the Dictyoneuridae is described, namedSchmidtopteron adictyon n. g., n. sp. Present is a wing with the following characteristics: 1. shape long and slender; 2. subcosta relativly short; 3. radius nearly as long as the wing; 4. radius-sector branched off from the radius at 1/5 of the length of the wing (prox.), subdivided into 4 branches; 5. medialis subdivided also at 1/5 of the length of the wing; MEp with 2 branches; 6. cubitus subdivided at 1/10 of the length of the wing, CUp undivided; 7. anal veins 4 in number, separated each from the others in full length; at least A1 und A2 bifurcated; 8. A1 and CUp joined by a short connecting vein; 9. archaeodictyon not present. Schmidtopteron adictyon is the most primitive Namurian wing known. Its systematic position results from the structure of the only little branched veins. The absence of the archaeodictyon may be attributed to preservation: only the external mould of the upper surface of the wing is preserved. From all other genera of the Dictyoneuridae,Schmidtopteron is separated by the connection between A1 and CUp. This feature, and the relative large anal area, show thatSchmidtopteron is not the ancestor of younger Dictyoneuridae, but an early side branch of the evolution of this family. 相似文献
19.
Mineralization of 2,4-dichlorophenoxyacetic acid (2,4-D) by two Alcaligenes eutrophus strains and one Pseudomonas cepacia strain containing the 2,4-D degrading plasmids pJP4 or pRO101 (=pJP4::Tn1721) was tested in 50 g (wet wt) samples of non-sterile soil. Mineralization was measured as 14C-CO2evolved during degradation of uniformly-ring-labelled 14C-2,4-D. When the strains were inoculated to a level of approximately 108 CFU/g soil, between 20 and 45% of the added 2,4-D (0.05 ppm, 10 ppm or 500 ppm) was mineralized within 72 h. Mineralization of 0.05 ppm and 10 ppm, 2,4-D by the two A. eutrophus strains was identical and rapid whereas mineralization by P. cepacia DBO1(pRO101) occurred more slowly. In contrast, mineralization of 500 ppm 2,4-D by the two A. eutrophus strains was very slow whereas mineralization by P. cepacia DBO1 was more rapid. Comparison of 2,4-D mineralization at different levels of inoculation with P. cepacia DBO1(pRO101) (6×104, 6×106 and 1×108 CFU/g soil) revealed that the maximum mineralization rate was reached earlier with the high inoculation levels than with the low level. The kinetics of mineralization were evaluated by nonlinear regression analysis using five different models. The linear or the logarithmic form of a three-half-order model were found to be the most appropriate models for describing 2,4-D mineralization in soil. In the cases in which the logarithmic form of the three-half-order model was the most appropriate model we found, in accordance with the assumptions of the model, a significant growth of the inoculated strains.Abbreviations 2,4-D
2,4-dichlorophenoxyacetic acid
- CFU
colony forming units
- PTYG
peptone, tryptone, yeast & glucose
- DPM
disintegrations per minute 相似文献
20.
James M. Bullock Stephen J. Galsworthy Pablo Manzano Peter Poschlod Carsten Eichberg Katherine Walker Matthias C. Wichmann 《Oikos》2011,120(8):1201-1208
Studies of external seed transport on animals usually assume that the probability of detachment is constant, so that seed retention should show a simple exponential relationship with time. This assumption has not been tested explicitly, and may lead to inaccurate representation of long distance seed dispersal by animals. We test the assumption by comparing the fit to empirical data of simple, two‐parameter functions. Fifty‐two data sets were obtained from five published studies, describing seed retention of 32 plant species on sheep, cattle, deer, goats and mice. Model selection suggested a simple exponential function was adequate for data sets in which seed retention was followed for short periods ( <48 h). The data gathered over longer periods (49–219 days) were best described by the power exponential function, a form of the stretched exponential which allows a changing dropping rate. In these cases the power exponential showed that seed dropping rate decreased with time, suggesting that seeds vary in attachment, with some seeds becoming deeply buried or wound up in the animal's coat. Comparison of fitted parameters across all the data sets also confirmed that seeds with adhesive structures have lower dropping rates than those without. We conclude that the seed dropping rate often changes with time during external transport on animals and that the power exponential is an effective function to describe this change. We advise that, to analyse seed dropping rates adequately, retention should be measured over reasonable time periods – until most seeds are dropped – and both the simple and power exponential functions should be fitted to the resulting data. To increase its utility, we provide functions describing the seed dropping rate and the dispersal kernel resulting from the power exponential relationship. 相似文献