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81.
Selective Utilization of Pyrimidine Deoxyribonucleosides for Deoxyribonucleic Acid Synthesis in Pneumococcus 总被引:1,自引:1,他引:0 下载免费PDF全文
When pyrimidine deoxyribonucleosides are supplied to growing cultures of Diplococcus pneumoniae, they are selectively used for incorporation into deoxyribonucleic acid (DNA). Differently labeled molecules of deoxyuridine, thymidine, and deoxycytidine were used to study the precursor pathways of this organism. Each of these preformed pyrimidine deoxynucleosides is incorporated intact (i.e., without cleavage of the glycosidic bond) and is predominantly recoverable as DNA thymidine. During the utilization of deoxycytidine and deoxyuridine by pneumococci, large proportions of the available precursor are converted to free thymidine, which is secreted back into the growth medium. The biochemical pathways for selective incorporation into DNA and the regulation of concentrations of intracellular thymidine compounds by excretion of free thymidine are discussed. 相似文献
82.
Metabolism of Glutamic Acid and N-Acetylglutamic Acid in Leaf Discs and Cell-free Extracts of Higher Plants 总被引:9,自引:9,他引:0 下载免费PDF全文
Radioactive glutamic acid and N-acetylglutamic acid have been incubated with normal and wilted leaf discs and radioactivity recovered in uncombined proline. The discs which had been placed under moisture stress incorporated considerably more label in uncombined proline than did normal discs. 相似文献
83.
Incomplete bacteriophage-like particles in ultraviolet-irradiated haemophilus 总被引:14,自引:10,他引:4 下载免费PDF全文
Incomplete phagelike particles were found in competent and incompetent cells of Haemophilus influenzae Rd (transformable) lysed after exposure to ultraviolet radiation. 相似文献
84.
1. The relative concentrations of the inactive ribosomal components were compared in normal and regenerating rat liver and in two transplantable rat hepatomas (hepatomas 7800 and 5123D). 2. The size of the ribosomal-subunit pools in normal liver was not significantly affected by partial hepatectomy or neoplasia although, as shown previously, significant changes do occur in the monomer pool. 3. Further, the subunit pools in both liver and hepatoma were not significantly influenced by several treatments that caused dramatic changes in the size of the ribosomal monomer (and dimer) pools. 4. The high concentration of inactive monomers and dimers in the hepatomas appears to arise from limitations at the translational level, since they can be incorporated into pre-existing polyribosomes under the influence of cycloheximide. 相似文献
85.
D. G. McLarty W. D. Alexander R. McG. Harden D. H. Clark 《BMJ (Clinical research ed.)》1969,3(5664):200-203
Ninety patients who had a recurrence of thyrotoxicosis after thyroidectomy have been reviewed. All 10 patients who had a second operation and 18 out of 20 patients treated with a full course of antithyroid drugs relapsed. These results differ greatly from the results of treatment of the first episode of thyrotoxicosis, whether by thyroidectomy or antithyroid drugs. Radioiodine is the treatment of choice in this group of patients, despite the high incidence of hypothyroidism. 相似文献
86.
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88.
SOME CLINICAL LABORATORY BRIEFS ON STAPHYLOCOCCI 总被引:5,自引:0,他引:5
Alexander Kimler 《Journal of bacteriology》1962,83(1):207-208
89.
The nodulation of adventitious roots growing from segments of bean hypocotyl tissue was used as a bioassay for the material present in coconut water which stimulated nodulation. The active material in coconut water is acidic, but it was not possible to extract it from an acid solution with organic solvents. A purification of approximately 70-fold (on a dry wt basis) was obtained using activated charcoal, but at least 10 different compounds were present in the active fractions. A purified fraction of coconut water, which is stimulatory to the growth of carrot root explants, was active in the nodulation assay at a concentration of 2 μg/ml. This represents a 4000-fold purification of the diffusible fraction of coconut water. The charcoal fractionation procedure can be applied to the active material present in extracts of bean leaves. 相似文献
90.
David Morris 《BMJ (Clinical research ed.)》1960,1(5174):727-728