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101.
Use of whey for production of exocellular polysaccharide by a mutant strain ofXanthomonas campestris
Growth and kinetics of the production of exocellular polysaccharide was studied in a mutant strain ofXanthomonas campestris lac
+ during cultivation in a submerged culture in a medium containing whey. The maximum production of the polymer was observed
at the initial stage of the stationary growth phase of the culture. The mean production yield was about 1.4%. The results
were comparable with those obtained during cultivation on a lactose medium.
Translated by Č. Novotny 相似文献
102.
Summary During subculturing of recombinant Escherichia coli under conditions blocking cloned gene expression the plasmid was structurally stable for 200 generations. However, under conditions permitting foreign gene expression only 10% of plasmid containing cells had this gene functional after 100 generations. 相似文献
103.
Darja Barlič Maganja Borut Štrukelj Jože Pungerčar Franc Gubenšek Vito Turk Igor Kregar 《Plant molecular biology》1992,20(2):311-313
A genomic DNA clone encoding an aspartic proteinase inhibitor of potato was isolated from a lambda EMBL3 phage library using the aspartic proteinase inhibitor cDNA as a hybridization probe. The gene has all characteristic sequences normally found in eucaryotic genes. Typical CAAT and TATA box sequences were found in the 5-upstream region. In this part are also two putative regulatory AGGA box sequences located. In the genomic sequence there are no intron sequences interrupting the coding region. An open reading frame of the gene encodes a precursor protein of 217 amino acids which shows high percent identity with the aspartic proteinase inhibitor cDNA. 相似文献
104.
Naturally occurring benzodiazepines in human milk 总被引:1,自引:0,他引:1
C Pe?a J H Medina M Piva L E Diaz C Danilowicz A C Paladini 《Biochemical and biophysical research communications》1991,175(3):1042-1050
The presence of benzodiazepine-like molecules was detected radioimmunologically in the plasma and milk of 12 women and in the plasma of 9 men. All subjects were non-users of benzodiazepines. The concentration of these biological materials expressed as diazepam equivalents per mL amounted to 2.54 +/- 0.74 ng in male plasma; to 2.20 +/- 0.35 ng in female plasma and to 1.91 +/- 0.54 ng in milk. Further investigation of the active compounds in milk permitted the unequivocal identification of diazepam, both free and bound to a presumably protein carrier and, at least, three more benzodiazepine-like molecules. Their origin either from dietary sources or as a result of endogenous biosynthesis is still unclear. 相似文献
105.
An energy-dependent efflux system for potassium ions in yeast 总被引:3,自引:0,他引:3
An efflux of potassium ions was demonstrated in mutants of yeast cells lacking a functional high affinity carrier system for monovalent cations. This efflux showed the following characteristics: (a) It was stimulated by the presence of a substrate, either glucose or ethanol. (b) It was stimulated by several cationic organic molecules, such as ethidium bromide, dihydrostreptomycin, diethylaminoethyldextran, and also by trivalent cations, such as Al3+ and lanthanides; this stimulation also depended on the presence of a substrate. (c) K+ efflux was decreased in yeast mutants with decreased ATPase activity, which generated a lower membrane potential. (d) Although the efflux appeared to be of an electrogenic nature, producing hyperpolarization of cells, it was accompanied by the efflux of phosphate, probably as an anion partially compensating for the large amount of cations leaving the cell. (e) K+ efflux was also accompanied by an uptake of protons. (f) The efflux appeared more clearly in cells grown in YPD medium, and not in more complex media nor in the same YPD medium if supplemented with Ca2+ or Mg2+. Efflux of monovalent cations produced by Tb3+ and organic cationic agents was also demonstrated in wild type strains. This efflux system appears to be, at least partially, electrogenic, but seems to be also an exchange system for protons and to function as a symport with phosphate; it may be involved in the regulation of the internal pH of the cell, and appears to be regulated by its link to the energetic status of the cell, probably through the membrane potential. 相似文献
106.
107.
21-day old plants ofChenopodium rubrum L. ecotype 374 were used. Organ relationships in the shoots were investigated by32P distribution, which indicated different organ correlations in plants grown in continuous light and in plants treated with
flower-inducing and non-inducing dark periods. Dark periods were associated with a low32P distribution in young leaves and a high one in axillary buds. In the following light period the high32P distribution in axillary buds continued whereas the32P distribution in the leaves on the main axis increased and was similar to that in plants grown in continuous light. The high32P distribution in axillary buds was brought about by both, flower-inducing and non-inducing dark treatments. Decapitation
resulted in a high32P distribution in buds, in continuous light an increased32P distribution was also found in leaves. These effects were not fully cancelled by IAA application.
The results are discussed with respect to an assumption that decrease of apical dominance represents a step in a sequence
of events leading to flowering. 相似文献
108.
Ivana Macháková Jan Krekule Dagmar Souková Zdenk Pikryl Jaroslav Ullmann 《Journal of Plant Growth Regulation》1991,10(1):203-209
Aminoethoxyvinylglycine (AVG) applied as a droplet (3 l, 0.1 mM) to the plumule of seedlings of both the short-day plantChenopodium rubrum and the long-day plantChenopodium murale counteracted to a great extent or even canceled the inhibition of flowering due to exogenous indole-3-acetic acid (IAA). This effect was more pronounced with the two substances administered simultaneously than with later application of AVG alone. AVG by itself in some cases promoted the percentage of flowering in bothChenopodium species. Application of IAA to the shoot apex was shown to elevate ethylene production in both species, whereas application of AVG alone was shown to suppress it. Thus, ethylene may be considered an active agent of flowering inhibition brought about by IAA application. 相似文献
109.
110.
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