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31.
Stabursvik (1959) described the saponin fraction of Narthecium ossifragum as a sarsasapogenin glycoside with the structure arabinosegalactose-xylose-glucose-sarsasapogenin. In a renewed study of the phototoxic lamb disease alveld, in which this saponin has been implicated (Ender 1955), we have looked more closely at the saponin fraction. We find that there are two saponins, one major and one minor. Both have a branched trisaccharide on C-3 of the sapogenin. Galactose is directly attached to C-3 in both saponins. The major saponin has glucose and arabinose attached to galactose, the minor saponin has glucose and xylose. We suggest the names narthecin and xylosin for the spirostanol form of these two saponins. In fresh juice from leaves we find little narthecin, however. Most of the saponin is present in the furostanol form, with glucose on C-26. Enzymatic hydrolysis showed this glucose to be bound as a β-glucoside. From specific rotations in partial hydrolysates we conclude that the saccharide on C-3 is a β-D-glucoside, α-L-araboside, β-D-galactoside. 相似文献
32.
A new type of flow bioreactor designed to remove nitrate from water was developed. Denitrification activity of native Paracoccus denitrificans cells was used, the cells being separated from the refined medium by a semipermeable membrane. Relationships between the degree of nitrate conversion and the denitrification rate, on the one hand, and the volume flow rate and the amount of biomass, on the other, together with the results concerning denitrification during closed-circuit recirculation of the medium are discussed. 相似文献
33.
Callus was induced from mature leaf lamina, petiole, stem, and main and branch root of Panax ginseng and maintained under different nutrient and light conditions. Heterogenous callus cultures differentiated organoids and/or embryoids. Embryoids that arose from callus cultures of leaf origin germinated into shoots. The occurrence of the early stages of different regenerated structures was proved on histological level. 相似文献
34.
Spring barley seedling were grown in the dark for 21 d and respiration rates of the whole plant (including the seed), of the
shoots, and of the roots were determined. A function describing the growth and maintenance components of respiration was interpolated
through the experimental points and its parameters in plants under different mineral nutrition were compared. The plants grown
in a complete nutrient solution showed the highest growth rate in the initial phase of development and thus reached the maximum
respiration rate earlier than plants in the other variants. The highest proportion of substrate was respired in the shoot.
Plants grown under deficiency of phosphorus and magnesium had a slower respiration rate than plants grown in the complete
nutrient solution (NP), whereas the amount of respired substrate in plant parts was similar to that recorded in the NP plants.
Plants grown in distilled water showed the lowest growth efficiency and respirated the highest proportion of substrate in
the root. 相似文献
35.
The effect of soluble glucan derivates on spleen colony-forming units in sublethally irradiated mice
A. Líšková J. Wagnerová L. Červeňáková A. Krištofová M. Ferenčík 《Folia microbiologica》1990,35(4):353-362
We examined the effects of 5 soluble derivatives of yeast glucan on the formation of exogenous (CFU-S) and endogenous (E-CFU)
colony-forming units in the spleens of sublethally irradiated (60Co, 6.5–7.0 Gy) mice of two inbred strains. For the estimation of CFU-S, glucans were administered intravenously either to
donors or recipients of spleen cells 24 h prior to irradiation or removal of the spleen. The number of CFU-S was increased
when both the donors and recipients were treated with glucan; the highest increase was obtained with glucans S, P and K. All
glucan preparations increased significantly also the number of E-CFU even when administered 90 min after irradiation. There
exist differences in the response to the stimulatory effect of glucans among individual mouse strains. Thus, for example,
the stimulatory effect of glucan KM on the E-CFU number was significantly more pronounced in strain A/Ph than in strain C57B1/6. 相似文献
36.
Apyrase (ATP-diphosphohydrolase, EC 3.6.1.5) and inorganic pyrophosphatase (EC 3.6.1.1) were partially purified fromS. aureofaciens RIA 57 and characterized. Apyrase degrades, in addition to ATP, other nucleoside triphosphates and nucleoside diphosphates,
diphosphate, thiamine diphosphate, phosphoenolpyruvate and oligophosphates of chain lengthn ≦ 90. The apyrase activity was detected in the membrane and supernatant fractions. Its properties (substrate specificity, effect
of inhibitors, pH optimum and effect of Mg2+ ions) were similar in both fractions except for the effect of oligomycin that inhibited only the membrane fraction. Pyrophosphatase
exhibited a strict substrate specificity, substrates other than diphosphate being degraded relatively slowly. Of other enzymes
exhibiting the phosphatase activity acid phosphatase (EC 3.1.3.2) and alkaline phosphatase (EC 3.1.3.1), trimetaphosphatase
(EC 3.6.1.2) and exopolyphosphatase (EC 3.6.1.11) degrading oligophosphates of chain lengthn = 15, 40 and 60, were detected. 相似文献
37.
The effect of 1-dodecylpiperidine 1-oxide and N,N’-bis(dodecyldimethyl)-1,2-ethane diammonium dibromide on the spores ofBacillus cereus. particularly their binding to intact spores and spores with reduced cystine bonds, was investigated. The Langmuir type of binding is involved in both cases. Both compounds decreased the thermoresistance of spores. DPNO decreased the fraction of non-germinating spores, the effect of the drug increasing with increasing concentration. This phenomenon was associated with a faster release of dipicolinic acid to the medium. Only microgermination proceeded in the presence of BDED and dipicolinic acid was released only in substantially lower amounts. Both compounds also influenced respiration. 相似文献
38.
Tomáš Trnka Miloslav Černý Anna Ya. Shmyrina Alexander S. Shashkov Alexander F. Sviridov Oleg S. Chizhov 《Carbohydrate research》1979,76(1):39-44
13C-N.m.r. spectra of all possible 1,6:2,3- and 1,6:3,4-dianhydro-β-D-hexo-pyranoses and their O-acetyl and deoxy derivatives are presented. Relations between chemical shifts of certain carbon atoms and the structure of the dianhydrides are outlined, and their application in structural analysis is discussed. Inversion of configuration of the oxirane ring from the endo to the exo position is associated with typical upfield-shifts for oxirane-ring carbon atoms C-2 or C-4, respectively. Possible inter-relationships between 13C-chemical shifts and steric and polar interactions in the dianhydro derivatives are discussed. 相似文献
39.
M. Proštenik I. Burcar A. Častek Č. Ćosović J. Golem Z. Jandrić K. Kljaić V. Ondrušek 《Chemistry and physics of lipids》1978,22(2):97-103
Total fatty acids derived from 12 species of mushrooms were separated into fatty acid and 2-hydroxy fatty acid fractions (FA and HFA), and analyzed quantitatively. The HFA content varied from 0 to 22% of total fatty acids. The major fatty acids were 16:0, 18:0, 18:1, 18:2, and the major 2-hydroxy fatty acids were h16:0, h18:0, h22:0, h24:0. The predominant HFA in the mushrooms investigated had chain-lengths greater than 20 C-atoms, and were derived from sphingolipids — ceramides and cerebrosides. 相似文献
40.