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41.
J. Koníček M. Koníčková-Radochová G. Y. Daraselia M. Šlosárek 《Folia microbiologica》1988,33(1):71-79
It is generally assumed that genetic research of mycobacteria is delayed as compared with other, more commonly used, bacterial models, particularly in the field of genetic transfers. In the field of mutagenesis the problems have been studied to such an extent that replication maps of the chromosome of M. phlei and M. tuberculosis H37 Rv have already been constructed and a new model of the cell cycle of bacteria exhibiting a slow growth rate has been worked out. When the problems of mycobacterial genetics are looked upon in the light of gene manipulations it may be concluded that mycobacteria belong to a few models whose genes are used for cloning and that problems of practical significance will be studied by means of the most modern approaches. 相似文献
42.
The effect of twelve detergents on aspartate ammonia-lyase activity of Escherichia alcalescens used for the production of L-aspartic acid was tested. Best permeabilization was found with Triton X-100, Slovafol 910 and Corona, a mixed commercial preparation. In contrast to Triton X-100 and Slovafol 910, a much narrower range of suitable concentrations was observed with Corona. 相似文献
43.
Sterol composition of a δ5,7-sterol-rich strain ofSaccharomyces cerevisiae during batch growth 总被引:1,自引:0,他引:1
Sterol composition was examined during batch growth on complex media containing ethanol, molasses or glucose as the carbon source. The molasses-grown cells exhibited a balanced sterol composition throughout growth, maintaining the proportion of ergosterol to 24:28-dehydroergosterol equal to 1.4. The negative effect of glucose on sterol synthesis manifested itself by decreasing the accumulation of 24:28-dehydroergosterol and total sterols but not of ergosterol. Using ethanol as the sole carbon source, a large amount of 24:28-dehydroergosterol accumulated, partly at the expense of other sterols. The gradual addition of nitrogen source during growth significantly decreased the accumulation of ergosterol, 24:28-dehydroergosterol and of total sterols. A general scheme of regulation of sterol synthesis in baker's yeast is presented. 相似文献
44.
Single and repeated intravenous administration of cyclophosphamide significantly decreased the candidacidal activity of rabbit peritoneal macrophages. Using higher doses of the drug, a more pronounced decrease, persisting up to 10 d, was observed. The phagocytic index has not changed significantly 10 d after cyclophosphamide injection as compared with controls. No changes in the phagocytic activity were recorded. The decreased candidacidal activity may be one of the causes of serious microbial infections in cyclophosphamide-treated patients. 相似文献
45.
46.
Growth properties and morphological features of the saprophytic collection cultureClaviceps paspali strain FA were investigated. The strain was characterized by a range of utilization of 13 carbon sources in a basic synthetic and a peptone medium. A temperature of 23 °C was more favourable for growth than 28 °C. Stages of changes of the culture cultivated for a long time on Sabouraud’s medium were detected by electron microscopy. The white culture was characterized by true septated mycelium with different types of terminal parts of hyphae. Arthrospores occurred after a 14-d cultivation, small spherical conidia released individually from hyphae were quite rare. As compared with other strains of the same species, strain FA did not form spherical clusters of conidia. On the other hand, a spontaneous rupture of the surface cell wall in different parts of hyphae and release of the cytoplasm were observed. In corn-steep containing media the formation of individual, pair and chain-like forms of arthritic conidia was stimulated. Destructive autolytic changes of hyphae were detected in the medium with potato extract. 相似文献
47.
In submerged Claviceps cultures the activity of hydroxymethylglutaryl-CoA reductase preceded the increase of alkaloid production and of sterol content. During the first alkaloid phase, cell mevalonate was involved in the biosynthesis of both alkaloids and steroids. In the second production phase, it was predominantly used for alkaloid synthesis. Hydroxymethylglutaryl-CoA reductase appears to be a suitable target for physiological manipulation to increase clavine alkaloid yields. 相似文献
48.
49.
Curves relating net photosynthetic rate to irradiance [P(I) curve relation] were estimated and analysed inMercurialis perennis L. plants stemming from three forest (spruce, beech and ash) stands with different tree leaf canopy development and different
light regime.
The saturating irradiance (Is) reached the highest values in plants of all three stands in spring (spruce forest: 438 W m−2, beech forest: 440 W m−2 and ash forest: 367 W m−2), it declined sharply in the middle of the growing season (283, 285 and 297 W m-2, respectively) and this Is level persisted until autumn. A pronounced dynamics in plants from spruce and beech forests made itself manifest also in
the adaptation (Ia) and compensating (Ic) irradiances, respectively. After a sudden decline in summer, values in autumn were close to those of the vernal season.
The most pronounced parameter, which optimally expressed the adaptation ofMercurialis perennis to various light conditions, was the photosynthetic efficiency (α) calculated as the slope of the linear part of the curve
relating net photosynthetic rate to irradiance.
At the time of the highest PN sat. value in course of the growing season (August) (spruce forest: 100, beech forest: 98.7 and ash forest: 85.8 μg CO2 m−2 s−1), RD was in its minimum; in autumn PN sat. reached the lowest values which corresponded to the most intensive RD.
It was found thatMercurialis perennis plants stemming from forest stands with different light conditions did not make use equally of the altering light conditions
in the course of the growing season. By the underlying analysis of P(I) curves this rhizomatous perennial herb (geophyte)
may be characterized as a shade tolerant species. 相似文献
50.
The administration of diazepam 1.0 mg/kg decreased the level of plasma corticosterone in female but not in male Wistar rats. Picrotoxin, another drug affecting GABAergic transmission, also brought about an increase of plasma corticosterone in both sexes. However, in order to achieve a plasma corticosterone increase of similar magnitude (more than 500%) a threefold higher dose of picrotoxin had to be given to males. When the convulsive properties of picrotoxin were tested, it became evident that the dose of picrotoxin (2.5 mg/kg) which was subconvulsive in male was almost 100% convulsive in female rats. The existing sex differences in the response of rats to drugs affecting GABAergic transmission might have possible implications in the treatment of GABA system dysfunction. 相似文献