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181.
Summary Four strains of Fusarium oxysporum and a strain of Monilia brunnae were screened for their ability to convert cellulosic substrates into ethanol/acetic acid. These strains were found to utilize cellulose and produce extracellular cellulases. However, only F. oxysporum 841 was found to convert glucose, xylose, and cellulose into ethanol and acetic acid as major end-products under microaerobic conditions. Acetic acid at a level of 4.7 g/l resulted in a single-step process on potato pulp medium, indicating the potential of the strain for converting cellulosic substrates into acetic acid.
Offprint requests to: K. Schügerl 相似文献
182.
The N-terminal amino-acid sequence of the intrinsic membrane protein dipeptidyl peptidase IV (DP IV) was determined. The protein was isolated from pig kidney and solubilized by autolysis at pH 3.8. The first 34 amino acids were sequenced and indicated approximately 78% identity to the N-terminal sequence of rat liver DP IV. 相似文献
183.
For several weeks, boars were fed feedstuff containing mycotoxins (zearalenone, nivalenol, and deoxynivalenol). To determine a possible mutagenic effect of this feedstuff, the boars were examinated for structural chromosome aberrations in the lymphocytes. The investigations indicate a genotoxic effect on the boars’ lymphocytes. 相似文献
184.
Motility and orientation has been studied in the unicellular photosynthetic flagellate, Euglena gracilis, using real time image analysis capable of tracking up to 200 cells simultaneously in the slow rotating centrifuge microscope (NIZEMI) which allows one to observe the cells' swimming behavior during centrifugation accelerations between 1 g and 5 g. At 1 g the cells show a weak negative gravitaxis, which increases significantly at higher accelerations up to about 3 g. Though most cells were capable of swimming even against an acceleration of 4.5 g, the degree of gravitaxis decreased and some of the cells were passively moved downward by the acceleration force; this is true for most cells at 5 g. The velocity of cells swimming against 1 g is about 10% lower than that of cells swimming in other directions. The velocity decreases even more drastically in cells swimming against higher acceleration forces than those at 1 g. The degree of gravitactic orientation drastically decreases after short exposure to artificial UV radiation which indicates that gravitaxis may be due to an active physiological perception rather than a physical effect such as an asymmetry of the center of gravity within the cell.
Offprint requests to: D.-P. Häder 相似文献
185.
Günther Gätje Volker Müller Gerhard Gottschalk 《Applied microbiology and biotechnology》1991,34(6):778-782
Summary During growth on a complex medium containing 2% (w/v) lactose, Lactobacillus helveticus produced about 180 mm lactate. Due to the acidification, the external pH decreased to 3.7. The pH remained constant at a level of 0.5–0.7 units (40 mV), and µLac decreased gradually from –60 to 0 mV. The mechanism of lactate extrusion was studied with resting cells. Upon dilution of lactate-loaded cells in a buffer containing [14C]-lactate, a typical counterflow was observed, suggesting that a carrier system was employed in lactate excretion. Influx of lactate could not be driven by an artificial membrane potential, indicating that lactate was electroneutrally transported. By examining efflux under various lactate anion and lactic acid concentrations, the undissociated form of the acid was shown to influence the velocity of the transport process. A pH-dependent apparent K
m value of the carrier system was observed in efflux experiments with increasing internal lactate concentrations. It was concluded that the mode of end-product excretion can be defined as a carrier-mediated facilitated diffusion with the undissociated lactic acid or the lactate anion in symport with one proton, respectively, as the object of transport.Abbreviations
L
tota
total lactate
-
L
undissb
free lactic acid
-
L
dissc
lactate anion
- pHed
external pH
- pHie
internal pH
- pH
transmembrane H+ gradient
- µLacf
transmembrane gradient of total lactate
- µHLg
transmembrane gradient of the free lactic acid
- µLh
transmembrane gradient of the lactate anion
-
V
Effii
efflux velocity
Offprint requests to: G. Gottschalk 相似文献
186.
Ossi Renkonen Ritva Niemelä Anne Leppänen Hannu Maaheimo Antti Seppo Leena Penttilä Anja Vilkman 《Glycoconjugate journal》1991,8(4):368-375
Radiolabelled GlcNAc beta 1-3(GlcNAc beta 1-6)Gal (1), GlcNAc beta 1-3)GlcNAc beta 1-6)Gal beta 1-OCH3 (4), GlcNAc beta 1-3(GlcNAc beta 1-6)Gal beta 1-4Glc (7), and GlcNAc beta 1-3(GlcNAc beta 1-6)Gal beta 1-4GlcNAc (10) were cleaved partially with jack bean beta-N-acetylhexosaminidase (EC 3.2.1.30), and the digests were analysed chromatographically. All four oligosaccharides were hydrolysed faster at the (1-6) branch, than at the (1-3) branch, but a high branch specificity was observed only with the glycan 4. The saccharides 1 and 7 resembled each other in the kinetics of the enzyme-catalysed release of their two non-reducing N-acetylglucosamine units, but the glycan 10 was rather different. The partial digestions made it possible to obtain radiolabelled GlcNAc beta 1-6Gal, GlcNAc beta 1-6Gal beta 1-OCH3, GlcNAc beta 1-6Gal beta 1-4Glc, and, in particular, GlcNAc beta 1-6Gal beta 1-4GlcNAc. 相似文献
187.
Torbjörn Holmberg Anna Breitholtz-Emanuelsson Per Häggblom Olof Schwan Karl Hult 《Mycopathologia》1991,116(3):169-176
Ochratoxin A contamination of cereal feed grain was monitored during October 1989–September 1990 by analysis of blood samples from slaughter swine in Sweden. The detection of ochratoxin A in swine blood was used as a method to identify swine herds fed ochratoxin A contaminated feed. The contamination level of ochratoxin A in the blood of the positive herds was in the range 2–45 ng/ml with the mean concentration 5.2 ng/ml. Feed samples for mycological analysis were collected from both ochratoxin A positive herds (2 ng/ml blood) and ochratoxin A negative herds (<2 ng/ml blood). From the ochratoxin A positive herds and the ochratoxin A negative herds 22 and 21 feed samples were collected, respectively. No quantitative differences in mould content, as determined by colony forming units, were observed between the two groups. However, there were differences in the mycoflora. The incidence of storage fungi (Penicillium and Aspergillus spp.) was significantly higher (p < 0.05) in feed from ochratoxin A positive herds. Particularly, Penicillium verrucosum was found to be significantly more common (p < 0.001). Altogether 274 isolates were screened for their ability to produce ochratoxin A. Ochratoxin A producers were found only within P. verrucosum; 38% of the 63 isolates produced detectable amounts of ochratoxin A. Ochratoxin A producing isolates of P. verrucosum were found in 60% of the feed samples collected from ochratoxin A positive swine herds and in one sample (5% ) of the feed samples collected from the ochratoxin A negative herds. 相似文献
188.
The effects of solar and artifical ultraviolet radiation on the marine cryptoflagellate, Cryptomonas maculata, were studied. Even after short exposure to UV the accessory photosynthetic pigment phycoerythrin is bleached; likewise the fluorescence undergoes significant changes both in amplitude and in the maximal peak wavelength. In parallel, the photosynthetic oxygen production decreases rapidly during exposure. Gel electrophoresis and FPLC of membrane proteins show a significant decrease in chromoproteins after 2 h UV, which is confirmed by fluorescence excitation and emission spectra of the FPLC fractions.Abbreviations APS
ammonium persulfate
- DCMU
3-(3,4dichlorophenyl)1,1-dimethylurea; Emulphogen, polyoxyethylene 10 tridecyl ether
- FPLC
fast protein liquid chromatography
- PMSF
phenylmethylsulfonyl fluoride
- SDS
sodium dodecylsulfate
- SDS PAGE
sodium dodecylsulfate polyacrylamide gel electrophoresis
- TEMED
NN NNtetramethylethylene diamine
- UV-A
wavelength range between 320 nm and 400 nm
- UV-B
wavelength range between 280 nm and 320 nm
Dedicated to the 60th birthday of Professor Dr. W. Wehrmeyer 相似文献
189.
Summary We have studied the effect of uridine on the expression of fragile X (fra[X]) in lymphocyte cultures established in the folate and thymidine deficient medium TC199. The results indicate that uridine enhances the expression of fra(X) and gives a higher mitotic rate. The excess of uridine during DNA synthesis might further promote the previously suggested cycle of misincorporation and removal of deoxyuridine monophosphate when the pool of deoxythymidine triphosphate is continuously depleted. 相似文献
190.
Volker Schirrmacher Sabine Leidig Andreas Griesbach 《Cancer immunology, immunotherapy : CII》1991,33(5):299-306
Summary Tumour-specific cytotoxic T lymphocytes (CTL) are usually obtained after immunization in vivo and restimulation of immune cells in vitro. We here describe the generation of syngeneic tumour-specific CTL within no more than 9 days by priming and restimulation in vivo. This is achieved only if the correct sites are used both for primary immunization (ear pinna) and for restimulation (peritoneal cavity). The kinetics of immune T cell induction and of the secondary response in vivo will be reported. While a secondary CTL response could be generated in the peritoneal cavity, this was not possible in the spleen, no matter which routes of antigen restimulation were used. Upon transfer of immune spleen cells into the peritoneal cavity but not into the spleen, a secondary response could be generated upon in situ restimulation, indicating the importance of the correct microenvironment for this type of response. The peritoneal effector cells were true T cells and recognized a tumour-associated antigen in association with the Kd major histocompatibility (MHC class I) antigen. Finally the activated tumour-specific peritoneal exudate cells were able to transfer protective immunity without exogenous interleukin-2 into normal syngeneic mice. 相似文献