• The Korean Journal of Physiology and Pharmacology
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• v.1 no.6
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• pp.699-705
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• 1997

Although it is known that neuronal cell death during development occurs by apoptosis, the mechanisms underlying excitatory amino acid-induced neuronal cell death remain poorly understood. In this study we have examined the mechanism by which L-glutamate, an excitatory amino acid neurotransmitter, induces cell death in PC12 cell lines. To characterize cell death, we employed sandwich enzyme-linked immunosorbent assay(ELISA) method for cellular DNA fragmentation, DNA agarose gel electrophoresis and chromatin staining by acridine orange and ethidium bromide after treating the PC12 cells with L-glutamate. L-Glutamate caused dose-dependent cell death with a maximum at 24 hrs after the treatment. These cellular fragmentation was blocked by pretreatment of MK-801, a noncompetitive N-methyl-D-aspartic acid(NMDA) receptor antagonist, and nerve growth factor(NGF). Analysis of DNA integrity from L-glutamate-treated cells revealed cleavage of DNA into regular sized fragments, a biochemical hallmark of apoptosis. The PC12 cells that were induced to die by L-glutamate treatment exhibited classical chromatin condensation under the light microscopy after acridine orange and ethidium bromide staining. These results suggest that apoptosis is one of the key features that are involved in L-glutamate-induced excitotoxic cell death in PC12 cells, and these cell death are mediated by NMDA receptor and depend on NGF.

• Korean Journal of Microbiology
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• v.20 no.1
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• pp.11-20
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• 1982

A study was undertaken to examine the effect of curing agents on the stability, curing and segregation of R plasmid pSL100. And also the stability, transfer frequency, and recombination of its segregants obtained from curing agent treatment were studied. Ethidium bromide, acridine orange, and mitomycin-C were used as curing agent. The results obtained were as follows ; 1. The curing agent ethidium bromide, acridine orange, and mitomycin-C were not effective for curing the multiple antibiotic resistant determinant of pSL100 in Salmonella typhimurium and Escherichia coli. However, they induced plasmid segregation with high frequency in S.typhimuruim LT-2strains. TcApSmCm, TcSmCmKm, TcApCm, TcAp, TcKm, Tc segregants were obtained. 2. The resistant markers of the segregents were transferred to S.typhimurium LT-2 strains with high frequencies whereas they were transferred to E.coli K-12 only with low frequencies. 3. The transconjugants obtained from conjugation between two different S.typhimurium segregants were similar to the phenotype of the original R factor pSL100 and the resistant markers were transferred to the S.typhimurium LT-2 or E.coli strain with equal frequencies, indicating that they are recombinants. 4. The transconjugants obtained from conjugation between pSL100 segrgants and pKM101, or pBR322 possessed the resistant markers of the two parental plasmids and they were transferred to both S.typhimurium and E.coli K-12 strains with the same frequencies and maintained stably, suggesting that they are also recombinants. 5. The recombinant pSL100 could be also obtained in rec A-strains of E.coli, suggesting that the gene function of rec A is required for the recombination of pSL100 segregants in E.coli.

• The Korean Journal of Mycology
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• v.24 no.2 s.77
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• pp.135-141
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• 1996

Auxotrophs and drug resistant mutants from the mycelia of Lentinus edodes were obtained by UV irradiation at survival rates of $0.024{\sim}2.45%$ and ethidium bromide (EtBr) enrichment after UV irradiation. The mutation rate was 0.40%, and back mutation rate was $4.81{\times}10^{-4}{\sim}8.46{\times}10^{-4}$. Various amino acid-, nucleic acid-, and vitamin-requiring auxotrophs were isolated. The concentrations of several fungicides, antibiotics and amino acid analogues inhibiting the growth of L. edodes were determined. The MIC values for cycloheximide, benomyl, and p-fluorophenylalanine were 2, 2000, and 1000 ug/ml respectively. Five p-fluorophenylalanine-resistant mutants and eight benomyl-resistant mutants were selected by UV irradiation.

• Journal of Photoscience
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• v.11 no.3
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• pp.133-139
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• 2004

The metal-ligand complex, $[Ru(phen)_2(dppz)]^{2+}$ (phen=1,10-phenanthroline, dppz=dipyrido[3,2-a:2',3'-c]phenazine) (RuPD), was used as a spectroscopic probe for studying nucleic acid dynamics. The RuPD complex displays a long lifetime and a molecular light switch property upon DNA binding due to shielding of its dppz ligand from water. To show the usefulness of this luminophore (RuPD) for probing nucleic acid dynamics, we compared its intensity and anisotropy decays when intercalated into the $tRNA^{val}$ and pBluescript (pBS) II SK(+) phagemid through a comparison with ethidium bromide (EB), a conventional nucleic acid probe. We used frequency-domain fluorometry with a blue light-emitting diode (LED) as the modulated light source. The mean lifetime for the $tRNA^{val}$ (<${\tau}$> = 166.5 ns) was much shorter than that for the pBS II SK(+) phagemid (<${\tau}$> = 481.3 ns), suggesting a much more efficient shielding from water by the phagemid. Because of their size difference, the anisotropy decay data showed a much shorter rotational correlation times for the $tRNA^{val}$ (99.9 and 23.6 ns) than for the pBS II SK(+) phagemid (968.7 and 39.5 ns). These results indicate that RuPD can be useful for studying nucleic acid dynamics.

• Journal of Microbiology and Biotechnology
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• v.6 no.2
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• pp.145-146
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• 1996

The 2.4-kb cryptic plasmid (pKH8) of multidrug-resistant Staphylococcus aureus SA2 was characterized by complete nucleotide sequencing and homology comparison. pKH8 was found to contain three open reading frames. Protein analysis of pKH8 showed that pKH8 was a multidrug resistance plasmid and mediated resistance to ethidium bromide and quaternary ammonium compounds.

• Archives of Pharmacal Research
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• v.11 no.3
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• pp.218-224
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• 1988

The preparation of Clostridium butyricum is used as a normalizing agent for human intestinal flora. When the microbe is simultaneously used with rifampicin, it is inactivated by the antibiotic. To develop rifampicin-resistant mutants, rifampicin-sensitive strain Miyairi II 588 of C. butyricum was treated with nitrosoguanidine (NTG). To ensure stable resistance to rifampicin, we examined whether the resistance was plasmid-mediated or chromosome-mediated. It was found that the resistance of four mutant strains was not mediated by its inherent plasmid, but by the chromosomal mutation. These strains were examined for the susceptibility and resistance to other antituberculosis agents and antibiotics. The results showed that these mutants were resistant to the high concentration of the antituberculosis agents.

• Korean Journal of Microbiology
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• v.23 no.3
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• pp.184-189
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• 1985

The cured mutant strains (CW, CSM, CEM, CAM) we obtained from Lactobacillus casei YIT 9018 spontaneously and by ethidium bromide treatments. The lactose fermenting ability of those mutants was tested and plasmid was found to have some functions in lactose metabolism. Plasmid (PLC) has been detected in Lactobacillus casei YIT 9018, but has not been detected in mutants CSM, CEM, CAM. These plasmid curred mutants showed a decrease in the ability to produce lactic acid from lactose.

• Korean Journal of Microbiology
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• v.18 no.3
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• pp.115-122
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• 1980

We have demonstrated that both L-histidine as an amino acid factor and dextrin as a carbon source were required for the glucose repression. 1% glucose was sufficient to the glucose repression of aerial mycelium formation in Streptomyces lavendulae and Streptomyces aureofacience. the synthesized medium, KK, which is lack of all orgnic nutrients except dextrin was able to induce glucose repression, but the addition of 0.003% or more L-histidiner recovers the capacity of glucose repression. 0.02% or more histidine was reuqired for glucose repression of aerial mycelium formation in the absence of dextrin. Treatments of $5{\mu}M$ ormore ethidium bromide (EtBr0 gave rise to bald mutants at high frequency in Streptomyces aureofaciens, and it is probable that the gene(s) for the function of aerial mycelium formation is linked to plasmed DNA in this species.

• Journal of Microbiology and Biotechnology
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• v.19 no.8
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• pp.787-791
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• 2009

In the course of screening for substances that inhibit etoposide (10 ${\mu}g$/ml)-induced apoptosis in human leukemia U937 cells, fungal strain F000120, which exhibits potent inhibitory activity, was selected. The active compound was purified from an ethyl acetate extract of the microorganism by Sep-pak $C_{18}$ column chromatography and HPLC, and was identified as heptelidic acid (koningic acid) by spectroscopic methods. This compound inhibited caspase-3 induction in U937 cells with an $IC_{50}$ value of 40 ${\mu}M$ after 8 h of etoposide treatment. Fluorescent dye staining with acridine orange and ethidium bromide showed that heptelidic acid inhibited apoptosis. Furthermore, it was found that DNA fragmentation and caspase-3 activation, the biological hallmarks of apoptosis, were inhibited by the compound in a dose-dependent manner, suggesting that heptelidic acid inhibits etoposide-induced apoptosis via downregulation of caspases.

• The Journal of the Korean Society for Microbiology
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• v.22 no.1
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• pp.95-99
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• 1987

When tetracycline resistancy were cured by ethidium bromide treatment, some of the cured strains lost the tetracycline resistance plasmid while other strains kept the plasmids. Both strains of lost and remained plasmids were digested with restriction endonuclease Hind III and these cleaved plasmids were compared with that of parent strains, two plasmid remained strains showed same cleavage patterns between parent and cured strains, however, one plasmid lost strain showed dissimilarity with parent strain, but in the other one strain, among 4 plasmid lost colonies, 2 showed same but other 2 showed different patterns compared to parent strain. Tetracycline was transfered by conjugation in on set(Staphylococcus aureus donor versus Staphylococcus epidermidis, recipient) with relative high frequency but the other 2 sets showed a low degree of frequency and the other 2 sets exhibited no transfer.