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81.
82.
Jean-Thomas Vilquin Philippe Kennel Paul Fonteneau Jean-Marie Warter Philippe Poindron 《Biotechnology letters》1992,14(10):875-880
Summary When grown in DMEM supplemented with 10 % fetal calf serum and using Cytodex 3® as microcarriers, TE671 cells entering the stationary phase optimally expressed acetylcholine receptors. These, receptors could be conveniently extracted from cell-saturated, microbeads or monodispersed cells obtained by trypsinization of microbeads. Typically, a 500 ml-batch gave 6–7 pmol of receptors which could be used as antigen to assay anti-acetylcholine receptor antibodies in the sera of myasthenic patients. 相似文献
83.
Summary The influence of various storage solutions and temperature (4°C and 25°C) on viability ofStreptococcus salivarius subsp.thermophilus andLactobacillusdelbrueckii subsp.bulgaricus entrapped in κ-carrageenan-locust bean gum mixed gel beads was studied. The immobilized strains could be stored at 4°C in
all storage solutions studied for at least 14 and 11 days respectively before counts decreased to 105c.f.u./mL, which was considered to be the practical limit for their use as inoculum in a fermentation process. The most effective
storage solutions for preserving cell viability at 4°C were NaCl, glycerol and sorbitol solutions forS. thermophilus, and PO4 buffer and sorbitol solutions forL. bulgaricus. At 25°C,S. thermophilus could be stored for over 14 days in all solutions except glycerol, andL. bulgaricus for 4 days in 10% sorbitol. 相似文献
84.
Effects of Physicochemical Factors on the Adhesion to Cellulose Avicel of the Ruminal Bacteria Ruminococcus flavefaciens and Fibrobacter succinogenes subsp. succinogenes 下载免费PDF全文
Valrie Roger Grard Fonty Sylvie Komisarczuk-Bony Philippe Gouet 《Applied microbiology》1990,56(10):3081-3087
Ruminococcus flavefaciens adhered instantly to cellulose, while Fibrobacter succinogenes had the highest percentage of adherent cells after about 25 min of contact between bacteria and cellulose. Adhesion of R. flavefaciens was unaffected by high concentrations of sugars (5%), temperature, pH, oxygen, metabolic inhibitors, and lack of Na+. In contrast, the attachment was affected by the removal of divalent cations (Mg2+ and Ca2+), the presence of cellulose derivatives (methylcellulose and hydroxyethylcellulose), and cystine. Adhesion of F. succinogenes was sensitive to low and high temperatures, high concentrations of glucose and cellobiose (5%), hydroxyethylcellulose (0.1%), redox potential, pH, lack of monovalent cations, and the presence of an inhibitor of membrane ATPases or lasalocid and monensin. Cells of F. succinogenes heated at 100°C no longer were adherent. On the other hand, adhesion was insensitive to the lack of divalent cations (Mg2+ and Ca2+), the presence of 2,4-dinitrophenol, tetrachlorosalicylanilide, or inhibitors of the electron transfer chains. Adhesion of F. succinogenes seems to be related to the metabolic functions of the cell. External proteins and/or cellulases themselves might play a part in the attachment process. Several mechanisms are probably involved in the adhesion of R. flavefaciens, the main one being the interaction between the large glycocalyx and the divalent cations Ca2+ and Mg2+. Hydrophobic bonds and enzymes may also be involved. 相似文献
85.
Elvira Costantino-Ceccarini Thomas V. Waehneldt Helga Ginalski Philippe Burgisser Jacqueline Reigner Jean-Marie Matthieu 《Neurochemical research》1982,7(1):1-12
The distribution of UDP-galactose: ceramide galactosyltransferase (CGalT) was studied in subcellular fractions of rat forebrain during development using zonal centrifugation on linear gradients. Specialized subfractions: SN 1, a microsomal fraction, SN 4, a myelin-related fraction, and purified myelin were also used for this study. For comparison, two microsomal lipid synthesizing enzymes, a myelin-specific enzyme, 2,3-cyclic nucleotide 3-phosphodiesterase and myelin proteins were measured in the same subfractions. UDP-glucose: ceramide glucosyltransferase and cerebroside sulfotransferase were confined to microsomes. CGalT was ferase and cerebroside sulfotransferase were confined to microsomes. CGalT was localized in microsomes, but also in myelin and myelin-related fractions. The developmental change in distribution of CGalT in adult animals toward myelin containing fractions could indicate that the replacement of galactosylceramide in compact myelin could be carried out in close proximity to compact myelin (mesaxon, paranodal loops) rather than in the distant oligodendrocyte perikaryon. 相似文献
86.
Material of the hypsilophodontid dinosaur Valdosauruscanaliculatus (Ornithischia: Ornithopoda) is described from the Lower Cretaceous (Barremian) of southern England and a new species is recognized from the Lower Cretaceous (Aptian) of Niger, West Africa. This occurrence of Valdosaurus in Europe and Africa provides evidence of a land connection between these continents across Tethys sometime in the early Cretaceous. 相似文献
87.
Philippe Janvier 《Geobios》1982,15(3):431-432
88.
Part of a large capitosaurid skull, similar to that of Cyclotosaurus posthumus from the Upper Triassic of Germany, has been discovered in the upper part of the Huai Hin Lat Formation near Chulabhorn (Nam Phrom) Dam. This discovery is consistent with the presumed Norian age of this formation. Although the phylogeny of the Capitosauridae is still unclear, the group of Upper Triassic Cyclotosaurus species to which C. posthumus belongs is monophyletic and seems to be known only from Laurasia or Northwestern Gondwana (Morocco). The occurrence of C. cf. posthumus in Thailand is consistent with the hypothesis previously put forward, that this part of Southeast Asia was bound to Laurasia in Mesozoic times. 相似文献
89.
A method is described for purification of MSV-MuLV from culture supernatant of chronically infected 78A1 rat embryo cell line. This method involves direct polyethylene glycol-NaCl precipitation of the low speed supernatant of culture fluid followed by digestion of the pellet with trypsin. This procedure efficiently disrupts large aggregates which normally entrap most of the virus. Highly purified virus can be obtained in very good yield by a combination of sedimentation velocity and isopycnic centrifugation : yields up to 100 A280 units (17 mg of protein) of purified virus per liter of culture fluid can be observed. This procedure appears well suited for large scale isolation of virion associated enzymatic activities. 相似文献
90.
The presence of a nuclear DNA polymerase in mouse sperm from adult testes has been confirmed and the properties of this enzyme further investigated. This activity was shown to be greatly enhanced by treating the spermatozoa with methanol or ethanol before incubation in the reaction medium or by their addition in small amounts to this medium. It was protected against degradation by nuclear proteases by adding soybean trypsin inhibitor and was stimulated by ATP. It was found to be Mg2+ dependent (optimum concentration: 7.5 mM), DNA dependent, and all four deoxynucleoside triphosphates were needed for optimal reaction. The radioactive acid-precipitable product of polymerization was not eliminated by organic solvents, nor by pronase, ribonuclease or by nuclease S1; however, it was converted to a large extent to acid-soluble products by pancreatic deoxyribonuclease. Since it was only partially solubilized by Triton X-100, it therefore did not appear to be preferentially associated with the nuclear membranes. The activity recovered after incubation depended also on the pH (optimum at pH 8.3) and did not work well in a medium for DNA polymerase alpha. The temperature for maximum incorporation of nucleotides was found to be 32 degrees C and, under our conditions, the reaction was linear for 30 min. The DNA polymerase activity was inhibited by low and high concentrations of KCl. It was not lowered by N-ethylmaleimide or p-hydroxymercuribenzoate; urea slightly stimulated the reaction and this stimulation was reversed by subsequent treatment with N-ethylmaleimide. Actinomycin D (40 mug/ml), ethidium bromide (25--50 muM), netropsin (5--50 mug/ml), and spermidine (0.5--2.5 mM) lowered the polymerization of DNA precursors. The nuclear enzyme could shift from the endogenous template to activated exogenous calf thymus DNA, the resulting nuclear radioactivity being reduced. The endogenous DNP template ability was not increased by deoxyribonuclease activation according to the method of Aposhian and Kornberg (J. Biol. Chem. (1962) 237, 519--525) suggesting that the amount of DNA polymerase associated with chromatin was probably limiting the reaction. The DNA polymerase activity detected in mouse sperm nuclei has numerous properties of low molecular weight DNA polymerases (DNA polymerase beta) reported in several eukaryotic organisms. 相似文献