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11.
Inhibitors of eubacterial and eukaryotic DNA topoisomerases type II exhibited different effects on chloroplasts of the flagellateEuglena gracilis. Antibacterial agents (cinoxacin, nalidixic and oxolinic acids, ciprofloxacin, enoxacin, norfloxacin and ofloxacin) from the group of quinolones and coumarins (coumermycin A1, clorobiocin and novobiocin) — all inhibitors of prokaryotic DNA topoisomerase II — were very potent eliminators of chloroplasts fromE. gracilis. In contrast, antitumor drugs (adriamycin, etoposide, teniposide and mitoxantrone) — antagonists of the eukaryotic counterpart — did not affect these semiautonomous photosynthetic organelles. These findings point out again the close evolutionary relationships between eubacteria and chloroplasts and are in agreement with the hypothesis of an endosymbiotic origin of chloroplasts. 相似文献
12.
The mutagenic activity of 5 nitrofuran drugs (furadantin, furoxon, furacin, benzazon VII and lampit) was tested on strainsSalmonella typhimurium TA 100, TA 1535, TA 1538 andEscherichia coli WP2uvra
+ and WP2uvr A. All nitrofurans tested had a marked mutagenic effect on strain TA 100 and, partially, on strain TA 1535 except for furoxon
which was strongly toxic for this strain. No significant mutagenic effects of the drugs were observed with strain TA 1538.
With the exception of lympit, all drugs exerted a mutagenie action onE.coli WP2uvrA but no on WP2 uvrA+ which has an intact excision repair system. The only drug exerting a mutagenie effect on the latter strain was furoxon. All
five nitrofurans exhibited a positive repair rest. The results support the notion that the nitrofuran mutagens under study
induce single base substitutions. 相似文献
13.
Hydroxylamine, an inhibitor of deoxyribonucleic acids (DNA), ribonucleic acids (RNA) and proteosynthesis interferes with the
bleaching effect of streptomycin on growing cells ofEuglena gracilis. The addition of hydroxylamine to a green autotrophic culture ofEuglena gracilis inhibits, depigmentation of the culture by streptomycin. Otherwise, streptomycin alone, without, hydroxylamine, is a powerful
bleaching agent and when added to a growing culture ofEuglena gracilis, transforms the green, autotrophic cells to permanently colourless, heterotrophic cells. Phenethyl alcohol, an inhibitor
of RNA synthesis, and chloramphenicol, an inhibitor of proteosynthesis, do not block the bleaching effect of streptomycin.
It can be concluded from these results that the bleaching effect of streptomycin is related to its interference in the plastid
DNA. 相似文献
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The diethyl ether extracts isolated from unfermented milk and milk fermented byEnterococcus fœcium exhibited dose-dependent inhibition of mutagenesis induced by N-methyl-N′-nitro-N-nitrosoguanidine (MNNG), nitrovin (NIT),
5-nitro-2-furylacrylic acid (NFA) and UV-irradiation on the Ames bacterial test (Salmonella typhimurium strains TA97 and TA100) and the unicellular flagellateEuglena gracilis. Overall, the fermented milk extract was the most active against UV-irradiation, less active against NIT and MNNG, and the
least active against NFA on bacteria. The highest antibleaching effects were observed against MNNG. The differences between
antimutagenic effects from fermented and unfermented milk extracts were determined to be statistically significant at the
0.95 CI level. 相似文献
17.
Intramucosal bacteria in colon cancer and their elimination by probiotic strainEnterococcus faecium M-74 with organic selenium 总被引:1,自引:0,他引:1
Mego M Májek J Konceková R Ebringer L Cierniková S Rauko P Kovác M Trupl J Slezák P Zajac V 《Folia microbiologica》2005,50(5):443-447
Intraepithelial bacteria were isolated by the gentamicin protection assay (GPA) from biopsy samples obtained at colonoscopy (colon cancer, n = 10 patients; colonic adenoma, n = 20; control group, n = 20; cancer patients without gastrointestinal tract GIT malignancy, n = 10). After a three-month administration of E. faecium M-74 to patients with positive GPA biopsies, 172 biopsy specimens from 60 patients were examined with the GPA. The number of biopsies with intracellular bacteria was significantly higher in adenoma and carcinoma group than in control group (26 vs. 10%; p = 0.004); in cancer patients without GIT malignancy the difference was nonsignificant. E. faecium M-74 was also administered to 5 patients with colonic adenoma; according to a control colonoscopy the number of biopsies with intracellular bacteria was significantly lower after probiotic administration (48 vs. 16%; p = 0.03). A striking prevalence of intraepithelial bacteria was also showed in patients with large bowel adenoma and carcinoma. The administration of probiotic strain M-74 can thus be considered to be an effective and promising method for elimination of pathogenic bacteria in the case of inflammatory bowel disease and colon cancer. 相似文献
18.
Molecular mimicry between HLA-DR alleles associated with rheumatoid arthritis and Proteus mirabilis as the Aetiological basis for autoimmunity 总被引:2,自引:0,他引:2
Molecular mimicry is one of the pathological mechanisms proposed to explain the association between microorganisms and autoimmune diseases. This review deals with the association between bacteria and rheumatic diseases with a special emphasis on rheumatoid arthritis where upper urinary tract infection by Proteus mirabilis is the possible cause of this severe, arthritic condition. Prospective trials involving anti-Proteus therapy should be carried out. 相似文献
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Substitution with NO2, Cl, Br and I into position 6 of 2-benzthiazoIthiol derivatives increased their antimicrobial efficiency while the SH group
is preserved. This increase affected both G+ and G-bacteria, mycobacteria and some fungi The degree of efficiency of the benzthiazol
derivatives is also influenced by the substituent in position 2. 相似文献