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1.
Twenty-eight strains of pectolytic clostridia were isolated from sugar beet pulp silages. Seventeen non-pigmented strains were presumed to be Clostridium acetobutylicum ; the remaining 11 pigmented strains were similar to Cl. felsineum. The addition of molasses to sugar beet pulps favoured the growth of other bacteria, particularly lactic acid organisms, whereas pectolytic clostridia were only occasionally found. The pectolytic clostridia promoted the structure loss of simulated silages. The use of molasses in sugar beet pulp ensiling was suggested to prevent texture loss of the ensiled mass. 相似文献
2.
Abstract Pseudomonas fluorescens EB carries genes for the catabolism of ethylbenzene and 1-phenylethanol on a plasmid. The size of the plasmid as measured by analysis of agarose electrophoresis gels after restriction endonuclease hydrolysis, was 253–267 kb. By treatment with Mitomycin C, mutants of EB strain were obtained bearing a plasmid which had undergone an extensive deletion of about 80 kb. These mutants have lost the ability to grow on ethylbenzene and 1-phenylethanol as well as to synthesize meta-cleavage enzymes. 相似文献
3.
Ethanol Administration in the Rat Decreases Prostacyclin Production by Isolated Brain Microvessels 总被引:1,自引:0,他引:1
The effects of short- and long-term ethanol administration to rats on basal levels and formation of prostacyclin (PGI2) measured as 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), and on lipid class content and fatty acid composition of isolated brain microvessels (BMV) were studied. After acute treatment (2 h, at the peak of plasma ethanol concentration) basal 6-keto-PGF1 alpha levels in BMV and release on incubation were reduced to 50% of control values. After chronic administration (15 days), PGI2 release was reduced to about 40% of control values, without changes in basal levels. Total lipid, phospholipid, and cholesterol levels in BMV, measured after prolonged administration of alcohol, were not modified. Also, only minor changes in the fatty acid composition of individual phospholipid classes were detected. The observed reduction of PGI2 synthesis in BMV thus could not be related to changes of the fatty acid precursor pool in the preparation. Precursor release and/or the biosynthetic pathways may be affected by ethanol administration. 相似文献
4.
At high survival levels (85%), point mutation and gene conversion frequencies were determined in strain D7 of Saccharomyces cerevisiae after treatment with methyl methanesulfonate (MMS) either after cells were incubated in complete medium before plating or following a split-dose protocol. It is shown that induction of gene conversion by MMS post-incubation leads to an additional enhancement in frequency. This increase is not observed for point mutation. By fractionation of the MMS dose (1 mM + 1 mM) with incubation in complete medium between the 2 doses the frequency of gene conversion is twice as high as with a single equal total dose (2 mM). This treatment does not modify the frequencies of point mutation. These data support the notion that an inducible recombinogenic function exists in wild-type yeast. 相似文献
5.
—The lipid composition of the central nervous system of some marine vertebrates and two mammalian species (rat and man) was analysed by one- and two-dimensional quantitative thin-layer chromatography, and the cerebroside fatty acids were analysed by gas chromatography. The concentrations of sphingomyelin and cerebrosides are higher in mammals than in fishes, while no significant differences are observed for other lipid classes. Furthermore, in mammals the ratio between hydroxy and normal fatty acids in the cerebrosides is much higher than in fishes. The cerebrosides of mammals contain more very long chain fatty acids than those of marine vertebrates. 相似文献
6.
Maura Turriani Rossana Pesi Antonella Nardone Gino Turchi Francesco Sgarrella Pier Luigi Ipata Maria Grazia Tozzi 《Journal of biochemical and molecular toxicology》1994,9(1):51-57
Nucleoside phosphotransferase acting on inosine and deoxyinosine has been partially purified from cultured Chinese hamster lung fibroblasts (V79). The activity is associated with a cytosolic 5′-nucleotidase acting on IMP and deoxyIMP. The transfer of the phosphate group from IMP to inosine catalyzed by this enzyme was activated by ATP and 2,3-bisphosphoglycerate. Inosine, deoxyinosine, guanosine, deoxyguanosine, and the nucleoside analogs 2′,3′-dideoxyinosine and 8-azaguanosine are substrates, while adenosine and deoxyadenosine are not. IMP, deoxyIMP, GMP, and deoxyGMP are the best phosphate donors. The cytosolic 5′-nucleotidase/phosphotransferase substrate, 8-azaguanosine, was found to be very toxic for cultured fibroblasts (LD50 = 0.32 μM). Mutants resistant to either 8-azaguanosine and the correspondent base 8-azaguanine were isolated and characterized. Our results indicated that the 8-azaguanosine-resistant cells were lacking both cytosolic 5′-nucleotidase and hypoxanthine-guanine phosphoribosyltransferase, while 8-azaguanine resistant cells were lacking only the latter enzyme. Despite this observation, both mutants displayed 8-azaguanosine resistance, thus indicating that cytosolic 5′-nucleotidase is not essential for the activation of this nucleoside analog. 相似文献
7.
Ilan Hammel Joseph Alroy Vibha Goyal Stephen J. Galli 《Virchows Archiv. B, Cell pathology including molecular pathology》1993,64(1):83-89
The effect of lysosomal storage diseases on the ultrastructure of human mast cells has not previously been reported. Indeed,
there has been little published evidence indicating that mast cells contain typical lysosomes. However, mast cell cytoplasmic
granules contain hydrolases similar to those found in lysosomes, but which differ from lysosomal hydrolases in exhibiting
optimal activity at higher pH. We therefore examined by transmission electron microscopy the dermal mast cells in 58 biopsies
of patients exhibiting 1 of 29 different lysosomal storage diseases. We found mast cells containing abnormal lysosomes in
16 of these disorders. In 6 of these 16 diseases, the mast cells' cytoplasmic granules appeared normal. These observations
indicate that human mast cells can contain lysosomes, and provide evidence that the enzymes affected by lysosomal storage
diseases are active in mast cells. 相似文献
8.
A new method for the evaluation of 3-hydroxy-3-methylglutaryl-CoA reductase activity is described, based on the multiple-selected ion monitoring of the amount of mevalonate formed in incubations of 3-hydroxy-3-methylglutaryl-CoA with microsomal proteins. Analysis is carried out on crude extracts using deuterated mevalonic acid lactone as internal standard. The sensitivity of the technique allows the quantitative evaluation of mevalonate in microassays (100 μg microsomal protein) of the enzyme activity at the minimum value of the diurnal rhythm. 相似文献
9.
C Spagnuolo L Sautebin G Galli G Racagni C Galli S Mazzari M Finesso 《Prostaglandins》1979,18(1):53-61
The effects of ligation of both common carotid arteries in the gerbil on the levels of PGF2 alpha, TXB2, HETE and of energy metabolites in brain cortex, have been investigated. Also, in the same experimental conditions the changes of cyclic AMP in brain cortex, cerebellum, striatum and hippocampus have been monitored. ATP, glycogen, glucose and phosphocreatine decrease whereas, lactate and cyclic AMP are enhanced in the ischemic brain, as previously reported. In contrast, levels of arachidonic acid metabolites are not modified. During ischemia following decapitation, instead, PGF2 alpha, and TXB2, show considerable increase. 相似文献
10.
Substrate and steric specificity of hydropyrimidine hydrase. 总被引:7,自引:0,他引:7