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521.
C-Banded Chromosomes Stained with Methyl Green-Pyronin 总被引:1,自引:0,他引:1
522.
Enrique Merino Paulina Balbás Francisco Bolivar 《Origins of life and evolution of the biosphere》1992,21(4):251-254
The comma-less hypothesis represents a theoretical effort to describe one of the steps in the early evolution of the translation apparatus. This hypothesis emphasizes the advantages that a RNY coding pattern would have provided in a primitive RNA adaptor-catalyst system. This theory has been debated for years, both in conceptual and statistical terms, and no consensus about its validity has been ascertained. In this work, a statistical model refuting this theory was reconsidered. This new approach eliminates the bias due to the absence of stop codons in the open reading frame, and to the amino acid composition of bacterial genes. The results obtained support the biological significance of the RNY coding pattern. 相似文献
523.
524.
Felipe San-Blas Gioconda San-Blas Joseph Hallak Enrique Merino 《Current microbiology》1983,8(2):85-88
Results of chemical analysis and ultrastructural study of the cell wall of a thermosensitive dimorphic mutant ofParacoccidioides brasiliensis support the involvement of α-1,3-glucan in the process of dimorphism, but do not support a possible role of this glucan as being responsible for the yeast-like morphology of this pathogenic fungus. 相似文献
525.
526.
R Zemelman C Gonzalez C Merino H Bello M A Mondaca 《The Journal of applied bacteriology》1983,55(2):371-372
A method is described for testing antibiotic susceptibility of invasive and noninvasive micro-organisms in which strains are grown on small agar discs. 相似文献
527.
Role of tumor necrosis factor in oxygen toxicity. 总被引:4,自引:0,他引:4
J C Jensen H W Pogrebniak H I Pass C Buresh M J Merino D Kauffman D Venzon H N Langstein J A Norton 《Journal of applied physiology》1992,72(5):1902-1907
mRNA from lungs of mice exposed to high-dose oxygen (greater than 95%) for 3 days demonstrated increased expression of the genes for tumor necrosis factor (TNF), interleukin-1, and interleukin-6 compared with mRNA from lungs of mice exposed to room air. Daily treatment of mice exposed to high-dose oxygen with an antibody to TNF improved survival compared with mice receiving a similar dose of control immunoglobulin G. Pretreatment of mice with repetitive sublethal intraperitoneal doses of recombinant human TNF for 3 days or a single intravenous dose followed by exposure to high-dose oxygen afforded a significant survival advantage compared with high-dose oxygen-exposed mice pretreated with vehicle or interleukin-1. The repetitive intraperitoneal TNF pretreatment reduced the development of interstitial pneumonitis, pulmonary edema, and lung weight gain associated with oxygen toxicity and enhanced expression of the gene for the free radical protective enzyme manganous superoxide dismutase in lung tissue, a gene that is augmented as mice are exposed to high-dose oxygen. Furthermore a single intravenous dose of TNF 24 h after oxygen exposure was still protective. The results suggest that the toxicity of oxygen therapy can be partially ameliorated by either treatment with anti-TNF antibody or pretreatment and early treatment with TNF. These findings are consistent with the hypothesis that oxygen exposure induces TNF, which causes part of the toxicity of high-dose oxygen, and that pretreatment or early treatment with TNF induces the gene for an enzyme that recently has been shown to be very effective in protecting mice from the toxicity of oxygen. 相似文献