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61.
An acyclic analogue of 9-deazainosine, 9-(2-hydroxyethoxymethyl)-9-deazahypoxanthine, and related compounds have been synthesized starting from 9-(hydroxyethyl)-9-deazahypoxanthine. The acyclo-9-deazainosine exhibited some cytotoxic activity.  相似文献   
62.
The strains isolated in natural foci of the Stavropol Territory and the Armenian SSR have been found to belong to the holarctic race of Francisella tularensis, biovar II. In natural foci of the Kalmyk ASSR the strains belonging to biovars I and II have been isolated. The study of the tularecinogenicity of the cultures has revealed the existence of strains which are not sensitive to their own tularecins. The phenomenon of tularecinogenicity in F. novocida has been established. Avirulent strain 319/38 belonging to the non-arctic race is recommended as an indicator strain for the determination of tularecinogenicity.  相似文献   
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There are two forms of motor activity of the skeletal muscles at the last stages of internatal ontogenesis, i. e. jerky (jMA) and prolonged (PMA). Vagal regulation of the cardiac activity of the fetus associated with development of temporary hypoxemia took place before and after the JMA and the PMA. JMA and PMA occurred during labour pains when the circulation in the uterus decreased and development of JMA and PMA resulted in the compensation of temporary fetal hypoxemia.  相似文献   
65.
A new glycolipid from Streptomyces   总被引:1,自引:0,他引:1  
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A set of Theiler's murine encephalomyelitis virus mutants with engineered alterations in the conserved oligopyrimidine/AUG tandem (E. V. Pilipenko, A. P. Gmyl, S. V. Maslova, G. A. Belov, A. N. Sinyakov, M. Huang, T. D. K. Brown, and V. I. Agol, J. Mol. Biol. 241:398-414, 1994) were assayed for their growth potential in BHK-21 cells (as reflected in plaque size) and for neurovirulence upon intracerebral inoculation of mice. Tandem-destroying mutations, which included substitutions in the oligopyrimidine moiety and extended insertions into the oligopyrimidine/AUG spacer, exerted relatively little effect on the plaque size but ensured a high level of attenuation. The attenuated mutants exhibited remarkable genetic stability upon growth in BHK-21 cells. However, the brains of rare animals that developed symptoms after the inoculation with high doses of these mutants invariably contained pseudorevertants with the oligopyrimidine/AUG tandem restored by diverse deletions or an AUG-generating point mutation. The AUG moiety of the tandem in the revertant genomes was represented by either a cryptic codon or initiator codon. The results demonstrate that the tandem, while dispensable for the Theiler's murine encephalomyelitis virus growth in BHK-21 cells, is essential for neurovirulence in mice. Thus, the oligopyrimidine/AUG tandem is a host-dependent cis-acting control element that may be essential for virus replication under certain conditions. The functional activity of the tandem was retained when its oligopyrimidine or AUG moieties were made double stranded. A possible role of the tandem in the cap-independent internal initiation of translation on the picornavirus RNA templates is discussed.  相似文献   
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