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91.
AVRAM HERSHKO PIERRE MAMONT ROBERT SHIELDS GORDON M. TOMKINS 《Nature: New biology》1971,232(33):206-211
A hypothesis has been developed to relate stringent control in bacteria to a set of interactions involved in the regulation of growth of transformed and untransformed mammalian cells. 相似文献
92.
Kimball and Wilson1 reported that the arabinose analogue of cytidine (ara-C) inhibited DNA polymerase in a crude extract prepared from Ehrlich ascites cells. Furth and Cohen2 observed cytosine arabinoside triphosphate (ara-CTP) inhibited DNA polymerase in extracts from either calf thymus or bovine lymphosarcoma tissue, although these investigators3 had already found no effect of ara-CTP on DNA polymerase from Escherichia coli. The inhibition in both of these cases could be substantially reversed by dCTP; but incorporation of the arabinose nucleotide (ara-CMP) into DNA could not be unequivocally demonstrated. Graham and Whitmore4 reported the incorporation of ara-C into DNA in vivo and the inhibition of a DNA polymerase from L cells by ara-CTP. They found that ara-CMP was initially incorporated into small DNA strands but subsequently appeared in long strands. Momparler5 has presented evidence that, in vitro, ara-C incorporation was limited to the 3′-hydroxyl end of DNA chains. Such incorporation might be expected to block further chain elongation but this expectation was not supported by the evidence presented by Graham and Whitmore. 相似文献
93.
ALINA TAYLOR 《Nature: New biology》1971,234(48):144-145
JACOB and Fuerst1,2 demonstrated the presence of a bacteriolytic enzyme (λ-endolysin) in the induced cultures of lysogenic Escherichia coli K12 (λ). The enzyme was later identified as the product of gene R; of phage λ3 which is involved in bacterial lysis at the end of a latent period. The enzyme is apt to form spheroplast-like structures in E. coli2 and one would therefore expect its substrate to be murein. 相似文献
94.
Differential Tolerance of Streptomycetes to Sodium Chloride as a Taxonomic Aid 总被引:2,自引:1,他引:1 下载免费PDF全文
A survey was made of the NaCl tolerance of approximately 1,300 Streptomyces strains belonging to 313 species. The growth medium of the organisms was supplemented with a graded series of NaCl concentrations (4, 7, 10, and 13%). Only 1.8% of the species could not tolerate 4% NaCl; 26.9% could grow at a maximum of 4%; 49.7% could tolerate a maximum of 7%; 18.8% could grow at a maximum of 10%; and only 2.8% could tolerate 13% NaCl. In evaluating the relationships of NaCl tolerance to various taxonomic features, higher tolerance was statistically associated with the "yellow" and possibly the "white"-spored streptomycetes, whereas the "red"-spored series tended to have lesser tolerance. Higher tolerance was also indicated for spiny-spored species, as a group, than for smooth-spored forms. Likewise, nonproducers of melanin, collectively, were more NaCl tolerant than melanin-producing species. Uniformity of test responses between strains of species studied suggested the usefulness of NaCl tolerance as a taxonomic criterion. 相似文献
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Coxsackie A9 virus was identified by the authors during the fall of 1965 in Montreal in six children with fever and exanthem. Three of the six children were siblings. The exanthem was centrally distributed as described by Lerner et al. and consisted of discrete maculopapules 3 to 4 mm. in diameter. The viral agent was recovered and identified in tissue culture in five cases, while in the sixth Coxsackie type-A lesions were produced in suckling mice. Serological confirmation was obtained in two patients from whom sera were available. In contrast, no exanthem was observed in three older patients with a diagnosis of aseptic meningitis associated with Coxsackie A9 virus. In only one of 16 patients with Coxsackie B virus infection was an exanthem observed during the same period.The true incidence of Coxsackie A9-associated exanthems is difficult to determine because of the benign nature of the disease. 相似文献
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Spores of Aspergillus niger obtained by solid state fermentation on buckwheat seeds produced gluconic acid from glucose with a high yield, near 1.06 g gluconic acid/g glucose, close to the stoichiometric value. The reaction itself could be carried out either with purified biocatalyst or with the whole buckwheat medium resulting from spore production process. 200 g gluconic acid/L were obtained in 200 h with sequential feedings of glucose up to 190 g/L. 相似文献