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51.
52.
Mouse hybridoma cells cultured on the verge of starvation-induced apoptosis, i.e. in a medium diluted with saline, proved to serve as a sensitive screening system for apoptosis-suppressing activity of nutrient medium components. Conventional amino acid mixtures were found to suppress the starvation-induced apoptosis, whereas a vitamin mixture was ineffective. (Frank F (1995) Biotechnol. Bioeng. 45: 86–90). Recent experiments showed that suppression of apoptosis, and concurrent resumption of growth, could be achieved by addition of single substances at millimolar concentrations. The set of active substances included certain coded L-amino acids (glycine, alanine, serine, threonine, proline, asparagine, glutamine, histidine), non-coded amino acids (-alanine, taurine, 4-aminobutyric acid), and a non-metabolizable analogue (2-aminoisobutyric acid). This finding shows that some amino acids do not act solely as nutrients, but also as specific signal molecules. The specificity of the effect points to the involvement of adaptively regulated amino acid transport systems A and N in maintaining the balance between triggering and suppression of starvation-induced apoptosis. 相似文献
53.
54.
55.
The effect of ten derivatives of carbonylcyanide phenylhydrazone on growth of bacteria, yeast and different species of filamentous
fungi was investigated. In yeast and mitochondria isolated from rat liver the effect of these derivatives on the respiratory
activity was also followed. The relative efficiency of the individual derivatives of earbonylcyanide phenylhydrazone was determined
on the basis of the results obtained. It was shown that derivatives, in which the substituent on the benzene ring causes simultaneously
an increase of acidity and lipophilicity of the derivative as compared with the non-substituted carbonylcyanide phenylhydrazone
(4-trifluoromethoxy-, 3-chloro-, 4-chloro and 3,4-dichloroderivatives) were most effective. 相似文献
56.
M. Šlosárek 《Folia microbiologica》1977,22(4):262-268
It was the aim of the present communication to find a simple test for a reliable discrimination ofMycobacterium bovis BCG fromMycobacterium tuberculosis. A total of 26 BCG strains, out of them 10 Czechoslovak strains (2 lyophilized cultures of BCG of different batch, 6 strains
isolated from abscesses of children after BCG-vaccination and 2 strains from fatal cases after BCG-vaccination) and 16 strains
obtained from foreign laboratories, were used. Of the tested characteristics a combination of 3 tests, sensitivity to 1 μg
of 2-thiophene carbonylhydrazide (TCH), activity of 3 acylamidases (urease, nicotinamidase and pyrazinamidase) and a quantitative
nitrate test, was found to be most advantageous. The Czechoslovak strains ofMycobacterium bovis BCG were fully sensitive to TCH, of the 3 acylamidases mentioned above only urease was positive and nitrate was reduced only
little or not at all. On the other hand, strains ofMycobacterium tuberculosis were always resistant to TCH, had positive urease, nicotinamidase and pyrazinamidase and reduced nitrate very intensively. 相似文献
57.
An auxotrophic strain ofEscherichia coli with therecB recC sbcB genotype was transformed by chromosomal DNA of the prototrophic strain and by plasmid DNA carrying genes for antibiotic resistance
(R1drd 19). The donor plasmid DNA obtained by cell lysis in the presence of Triton X-100 and subsequent centrifugation in a caesium
chloride-ethidium bromide gradient was shown to have a circulaf molecule and to retain its completeness after penetration
into the recipient. Experiments with mixtures or plasmid and chromosomal DNA indicate a competition between these two DNA
types during the transformation reaction in the given system. 相似文献
58.
When flax seedlings are decapitated above cotyledons and three days later one of the two cotyledons is removed then the remaining
cotyledon stimulates in four to five days growth of its axillary bud. It has been found that content of endogenous cytokinins
was higher in the stimulated bud as compared with the other one already 12 h after the cotyledon removal.
Flax seedlings decapitated under cotyledons regenerate adventitious buds on thy hypocotyl stump during 5–6 days. The endogenous
fytohormonal preparation of this regeneration was investigated in the 20 mm apical part of the hypocotyl stump. Decrease in
auxin and increase in gibberellins was already found during the first day after decapitation while the level of cytokinins
increased as late as three days after the apex removal. 相似文献
59.
60.
On integrating experimental data published previously, the following picture of the mitochondrial adenine nucleotide (AdN) translocation system is being presented: 1. The AdN translocation system serves not only to transport ATP synthesized within mitochondria into the cytosol but also to transport cytosolic ATP into the mitochondria when oxidative phosphorylation is not functioning. 2. The AdN translocator is coded for by nuclear genes and the mitochondrial protein synthesis is not involved in its formation. 3. The AdN translocation system must be preserved and functioning even in cells which could dispense with oxidative phosphorylation. It assures appropriate concentrations of intramitochondrial ATP. 4. The intramitochondrial ATP is required for normal replication of mitochondrial DNA. Tis supports the view that the mitochondrion is a self-replicating semi-autonomous organelle. 5. The appropriate concentration of ATP must be present in mitochondria to make possible cell growth or multiplication. This points to a direct or indirect role of mitochondria in the control of cell proliferation. 相似文献