• Korean Journal of Microbiology
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• v.27 no.1
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• pp.16-20
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• 1989

The effect of E. coli plasmid DNA sequences contained by chimeric vectors on plasmid replication was investigated. We constructed YRp7- or 2.$\mu$m circle-based plasmids containing E. coli plasmid DNA sequences and those not containing it. By examining their maintenance in yeast, we showed that plasmid without E. coli plasmid DNA sdquences was nore stable and presented higher copy number, and espressed higher level of hepatitis B viral surface antigen as a foreign gene. This result suggested that E. coli plasmid DNA sequences within chimeric plasmid somehow inhibited plasmid replication in yeast.

• KSBB Journal
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• v.15 no.1
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• pp.84-87
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• 2000

We studied the effect of ultrasoft X-ray obtained from the Pohang Light Source (PLS), on the mutation of E. coli and the damage of plasmid. After irradiation, the supercoiled plasmid DNA converted to the relaxed-form, and then to the linear-form. We transformed the irradiated plasmid DNA and isolated $\beta$-galactosidase mutants. We also isolated $\beta$-galactosidase mutants from the directly irradiated cells. There were preferred mutational sites on DNA induced by ultrasoft X-ray.

• Journal of Radiation Protection and Research
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• v.31 no.2
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• pp.65-68
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• 2006

In this study, the extent of plasmid DNA damage was observed according to concentration of BSH(Boron Sulfhydryl Hydride) and irradiation doses of neutron and ${\gamma}$-ray. The plasmid used was both pBR 322 (2870 bp) and ${\Phi}X174$ RF(5386 bp) DNA. Plasmid DNA damage by irradiation in the presence of BSH was analyzed by agarose gel electrophoresis. In the neutron experiment, DNA damage of both plasmid DNAs was increased according to increasing the concentration of BSH and neutron doses. But in the ${\gamma}$-ray experiment, there appeared no dose dependency as compared to the neutron experiment. The extent of the plasmid DNA damage in the presence of BSH was somewhat different according to irradiation by neutron or ${\gamma}$-ray.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.6
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• pp.1160-1165
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• 1998

When total cellular DNA was isolated from Porphyra tenera by ultracentrifugation on Hoechst dye/CsCl gradients method, plasmid like DNA's were concentrated at the upper band which were characterized with a A＋T rich organelle DNA's in the CsCl gradients. Based on their electrophoretic migration in different concentration of agarose gel, buffer system, and electric power etc. and the results of restriction digestion, the plasmid like DNA's were concluded to have circular conformation. This is the first report of putative circular plasmid DNA from the P. tenera, which is a autonomously replicating plasmid existing with a high copy number plasmid in the cell. The minimum size of this plasmid estimated by restriction endonuclease digestion was appeared to be 2.5kb in size.

• Archives of Pharmacal Research
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• v.27 no.12
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• pp.1263-1269
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• 2004

The objective of this study was to characterize immunoliposomes carrying plasmid DNA with optimal encapsulation efficiency and antibody density. Plasmid DNA was encapsulated by the freezing/thawing method into liposomes composed of POPC (1-palmitoyl-2-oleoyl-sn-glycerol- 3-phosphocholine), DDAB (didodecyl dimethyl ammonium bromide), DSPE-PEG 2000 (distearoyl phosphatidyl ethanolamine polyethylene glycol 2000) and DSPE-PEG 2000-maleimide. The liposomes carrying plasmid DNA were extruded through two stacked polycarbonate filters, of different pore size, to control the liposome size. Then, rat IgG molecules were conjugated to the liposomes. The immunoliposomes containing plasmid DNA were separated from the free plasmid DNA and unconjugated IgG by Sepharose CL-4B column chromatography. The DNA amount encapsulated was affected by DDAB (cationic lipid) concentration, the initial amount of plasmid DNA between 10 ${\mu}g$ and 200 ${\mu}g$, the total lipid amount and plasmid DNA size, but not significantly by liposome size. By varying the ratio of DSPE-PEG 2000-maleimide to IgG, the number of IgG molecules per liposome was changed significantly.

• Korean Journal of Microbiology
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• v.24 no.2
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• pp.106-112
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• 1986

The large plasmid (about 180 megadaltons) was isolated from the aquatic strain of Pseudomonas which was found to degrade salicylate. It was found that the plasmid could be isolated under gentle conditions in comparison with other methods. The yield of covalently closed circular DNA was enganced by heat treatment at $55^{\circ}C$ after denaturing the chromosomal DNA with alkaline sodium dodecyl sulfate (pH 12.45), and the plasmid DNA was selectively concentrated by utilizing 10% polyethylene glycol as final concentration. It was also found that the cured strains with mitomycin C did not show any growth on the medium containing salicylat6e, therefore, it was concluded that the plasmid might play and important role on the salicylate degradation.

• Microbiology and Biotechnology Letters
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• v.11 no.3
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• pp.163-168
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• 1983

The penicillin resistant plasmid DNA was prepared from Streptomyces bobili YS-40, producing penicillinase, by the phenol extraction method and introduced into Bocillus subtilis IAM 12118 by the transformation procedure of Mahler method. The optimal pH and temperature on the transformation was 7.0, 3$0^{\circ}C$ respectively. Above 20 minutes contact of plasmid DNA and recipient cell was shown the high transformation frequency. The transformant of penicillin resistance was proportionally increased as increase of the DNA concentration. The addition of lysine in transformation system increased the transformation frequency about 6-fold and the addition of the chloramphenicol did not affect the transformation frequency.

• Korean Journal of Agricultural Science
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• v.41 no.4
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• pp.351-359
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• 2014

For identifying the plasmid DNA coding cry gene of Bacillus thuringiensis subsp. aizawai KB098 with high insecticidal activity against Spodoptera exigua, mutant isolates with no crystal protein were produced by $42^{\circ}C$ incubation condition and then mutant plasmid DNA band patterns were compared with those of KB098. KB098 isolates had 4 cry genes, cry1Aa, cry1Ab, cry1C, cry1D, and also had been found seven plasmid DNA. Though the SDS-PAGE experiment, it was confirmed that mutant didn't produce 130~145kDa protein band involved in bipyramidal shape crystal. Also, five mutant isolates had no cry genes coding plasmid DNA in PCR. In result of comparison the plasmid DNA of KB098 and 5 mutant isolates, only 1 plasmid DNA band was left out in mutant plasmid DNA pattern, so that the missing band was extracted from the gel. The missing(disappeared) plasmid DNA was the largest molecular size among the 7 plasmid DNA of KB098 and it was also confirmed this plasmid DNA had all 4 cry genes through PCR.

• Korean Journal of Microbiology
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• v.37 no.2
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• pp.120-123
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• 2001

Sphingomonas chungbukensis DJ77 is able to use phenanthrene and biphenyl as the sole carbon and energy source. Mitomycin C curing experiment suggested that polyaromatic hydrocarbon (PAH) utilization in strain DJ77 was plasmid-encoded. The plasmid cured strains were failed to grow on the minimal medium sprayed with biphenyl or phenanthrene. This was evident from southern hybridizations using a previously cloned DNA segment as a probe. There were positive signals in the palsmid DNA of the wild-type strain DJ77 and the absence of hybridizations with chromosomal DNA from the plasmid DNA of the wild-type strain DJ77 and the absence of hybridizations with chromosomal DNA from the palsmid-cured mutant strains.

• Journal of Pharmaceutical Investigation
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• v.26 no.4
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• pp.291-297
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• 1996

Liposomes of $pSV-{\beta}-Galactosidase$ vector plasmid DNA with various lipid composition were prepared by the thin-film method. Size distribution, shape and the efficiency of plasmid DNA encapsulation were investigated. Effect of sonication time on the plasmid DNA entrapment in liposomes and stability at $4^{\circ}C$ were also examined. Sizes of neutral liposomes were about 100-200 nm and above $1\;{mu}m$, and those of cationic liposomes were about 400-600 nm and above $1\;{mu}m$. Shapes of liposomes entrapped plasmid DNA were spherical. Proper sonication time for better entrapment was below 15 minutes and stability at $4^{\circ}C$ was decreased rapidly after 1 day. Plasmid DNA entrapments of complex liposomes of various lipids were higher than those of liposomes made from one sort of lipid. Plasmid DNA entrapments of cationic liposomes were higher than those of neutral liposomes.