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81.
Helena Kuerová Marie Strnadová Vladimír Vinter Peter Graba Jií Chaloupka 《FEMS microbiology letters》1986,34(1):21-26
Abstract Netropsin stimulated the rate of synthesis of an extracellular metalloproteinase in Bacillus megaterium incubated in a sporulation medium. The antibiotic delayed but did not suppress the decrease in the ability to synthesize the proteinase occurring at later sporulation stages. Netropsin also stimulated the synthesis of the proteinase when added to a growing culture; it inhibited the increase of protein turnover which was switched on between the 2nd and 3rd hour in the sporulating population. No refractile spores were developed during 6 h at 35°C in the antibiotic-treated culture. In the control 60% of sporulating cells were observed under similar conditions. 相似文献
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Molecular cloning of cDNA for rat L-type pyruvate kinase and aldolase B 总被引:13,自引:0,他引:13
M P Simon C Besmond D Cottreau A Weber P Chaumet-Riffaud J C Dreyfus J S Trépat J Marie A Kahn 《The Journal of biological chemistry》1983,258(23):14576-14584
Two double-stranded cDNA recombinant pBR322 plasmid libraries were constructed starting from high carbohydrate diet rat liver poly(A)+ mRNA, either fractionated by denaturing sucrose gradient centrifugation for the cloning of L-type pyruvate kinase cDNA, or nonfractionated for aldolase B. Both libraries were screened with single-stranded cDNA probes reverse transcribed from fasted or high carbohydrate diet rat liver mRNAs. mRNAs from fasted animals were also fractionated by sucrose gradient centrifugation and mRNAs from the fed animals were, in addition, further purified by high performance liquid gel filtration chromatography. Those clones hybridizing with the "positive" probe (from animals fed the high carbohydrate diet) and not with the "negative" one (from fasted animals) were preselected and their plasmid DNA was purified and analyzed by positive hybridization-selection. Thirty of 4500 bacteria colonies transformed by recombinant plasmids were preselected by differential screening for pyruvate kinase, and 8 of 864 colonies for aldolase B. Twenty-two recombinant plasmids for pyruvate kinase and two for aldolase B were shown to contain specific cDNA inserts by positive hybridization-selection. Plasmids DNAs of some pyruvate kinase and aldolase B clones (whose inserts ranged from 700 to 1050 bases in length) were labeled by nick translation and used as probes for Northern blot hybridization. The pyruvate kinase cDNA probes recognized mainly a 3400-base RNA species which was detected in high carbohydrate diet rat liver, but not in fasted rat liver and in tissues which do not synthesize L-type pyruvate kinase. In addition, some pyruvate kinase probes hybridized with minor RNA species of about 2000 bases in length, only observed after carbohydrate diet. For aldolase B, the recombinant plasmid DNA hybridized with a single RNA species of 1750 bases. This RNA, detected in kidney, small intestine and liver, was induced by a high carbohydrate diet and increased with liver development. The rat probe cross-hybridized with human aldolase B messenger RNA. 相似文献
85.
The budding capacity ofBegonia rex leaf fragments is well known; that of undetached leaves has been shown by us only recently after treating the leaves with 6γγ DMAAP. Benzyladenine is as effective as 6γγ DMAAP in stimulating budding. Lower temperatures (17°, 22–12°, 12°) are also capable of inducing bud formation but only after a small cut has been made in a main vein of the undetached leaf. Root formation can also be provoked on undetached leaves which have a cut in the main leaf vein by higher temperatures (24–22°) or by an IAA treatment. Differences in the first stages of bud formation on leaf fragments and on undetached leaves are observed using histochemical and histoautoradiographic techniques. 相似文献
86.
Polyamine Limitation of Growth Slows the Rate of Polypeptide Chain Elongation in Escherichia coli 总被引:8,自引:4,他引:4 下载免费PDF全文
The rate of polypeptide chain elongation during steady-state, polyamine-limited growth of a mutant of Escherichia coli was measured by two independent techniques. Analysis of polysome patterns gave values of 17.5 and 9.5 amino acids per s at 37 C in unstarved and polyamine-limited cells, respectively. From the kinetics of entry of labeled amino acids into polypeptides of defined molecular weights, values at 30 C of 10.1 and 5.8 amino acids per s were obtained for unstarved and polyamine-limited cultures, respectively. Correction of these values to 37 C resulted in rates of 15.0 and 8.7 amino acids per s. These results support the previous conclusion, based on the kinetics of beta-galactosidase induction, that polyamine starvation decreases the rate of protein synthesis by limiting the velocity of polypeptide chain elongation. 相似文献
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The virus origin of a Czechoslovak isolate of potato witches' broom disease is discounted: electron micrographs of ultrathin section of phloem tissues from plants infected with potato witches' broom disease demonstratedMycoplasma-like bodies, spherical or elongated showing binary fission and fragmentation. The minute corpuscles have a diameter of about 50–60 nm, the largest bodies of 1000 nm. The width of elongated filamentous structures is about 200 nm, most oval bodies have a diameter of 250 nm. A weak tetracycline treatment of diseased plants causes a delay of symptom development; a strong dose of tetracycline (applied by means of the wick method into the stem) inhibits symptom appearance completely. Tetracycline produces a phytotoxic effect inhibiting the growth of tomato plants and causing (at higher concentrations) necrosis and death of these plants. There is a note in the paper dealing with the term “mycoplasma”. The word mycoplasma in the sense ofEriksson (1897) or ofMereschkowsky (1910) does not correspond to the genus nameMycoplasma Nowak (1929). 相似文献
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