• Korean Journal of Food Science and Technology
• /
• v.32 no.2
• /
• pp.439-443
• /
• 2000

In order to evaluate the safety of greenhouse horticulture products in Korea, we carried out this work by screening of Fusarium species, which produce deoxynivalenol (DON) from greenhouse horticulture in Western Gyeongnam and Northern Gyeongbuk, Korea. For this study, high sensitive enzyme-linked immunosorbent assay, ALP/NADP method, was applied to detection of DON by enzyme amplification system. From 192 samples of greenhouse horticulture soil and its products, 103 isolates of Fusarium species were obtained. The isolates were cultured at 28C for 15 days and the cultured mediums were extracted by ethyl acetate. The production of DON was verified by thin layer chromatography (TLC). As the results of TLC, 8 strains were identified as DON producing strain. We screened potential producers of DON by ALP/NADP. The levels of DON production were shown from 0.007 to 1.21 g/ml of YES medium. The maximum DON producing strain No. 32-D-3 was isolated from soil in Namhae, Korea. In conclusion, the above results indicate that DON producing fungi contaminated greenhouse horticulture products in Korea. Therefore, further studies are required to accumulate more detailed data about the contamination of DON in various cereals.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.22 no.6
• /
• pp.839-845
• /
• 1993

One of the major problems of cancer chemotheraphy is the development of drug resistance in tumors, resulting in reduced responsiveness to subsequent treatments. The folate antagonists are being used to treat such diverse illnesses as cancer, leukemia, psoriasis, rheumatoid arthritis, etc. Previous studies have established that resistance to antifolates may occur in mammalian tumor cells by one or more of five mechanisms ; (a) an increase in the levels of the target enzyme, generally as a consequence of gene amplification ; (b) an alteration in the target enzyme, leading to an enzyme with a decreased binding affinity for the drug ; (c) a decrease in the uptake of the drug into the cells ; (d) increased extrusion of drugs out of cells ; (e) impaired ability to polyglutamylate the parent drug which is capable of being intracellularly metabolized to longer chain length.

• Journal of the Korean Electrochemical Society
• /
• v.7 no.1
• /
• pp.44-48
• /
• 2004

The two-component type enzyme amplified amperometric DNA assay is described to use an ambient $O_2$ of the substrate of the DNA labeling enzyme. Although the assay detects DNA only at > 0.5M concentration, a concentration $\~10^6$ fold higher than the sandwich-type enzyme amplified amperometric DNA assay, it can be run with an always available substrate. The assay utilizes screen-printed carbon electrodes (SPEs) which were pre-coated by a co-electrodeposited film of an electron conducting redox hydrogel and a 37-base long single-stranded DNA sequence. The DNA in the electron conducting film hybridizes and captures, when present, the 37-base long detection-DNA, which is labeled with bilirubin oxidase (BOD), an enzyme catalyzing the four-electron reduction of $O_2$ to water. Because the redox hydrogel electrically connects the BOD reaction centers to the electrode, completion of the sandwich converts the film from non-electrocatalytic to electrocatalytic for the reduction of $O_2$ to water when the electrode is poised at 200 mV vs. Ag/hgCl. The advantage or the assay over the earlier reported sandwich type enzyme amplified amperometric DNA assay, in which the amplifying enzyme was horseradish peroxidase, is that it utilizes ambient $O_2$ instead of the less stable and naturally unavailable $H_2O_2$.

• The Plant Pathology Journal
• /
• v.17 no.4
• /
• pp.189-193
• /
• 2001

The relationships between the phytoplasmas infecting Zizyphus jujuba and Paulownia coreana were investigated by PCR-RELP. The 16S rRNA genes of the phytoplasmas were analyzed and compared with each other after PCR amplification. The amplified bands 1.4 kb in size were analyzed by both restriction digestion and sequencing after cloning into a plasmid vector. In some cases, two different kinds of inserts were observed in the isolates that originated from a single plant. However, many of them appeared to be the amplification products of chloroplastic 16S rRNA gene of host plants. The phytoplasma gene could be differentiated from the chloroplastic gene by restriction digestion of the plasmids carrying the amplification products. Only the recombinant plasmids carrying phytoplasma 16S rRNA gene produced a 1.4 kb band when digested with the enzyme BanII. Of the 52 recombinant plasmids analyzed, 42 appeared to contain inserts that originated from the chloroplastic 16S rRNA gene of the host plants. No variation was detected among 16S rRNA gene of nine phytoplasma isolates infecting Z. jujuba. However, the phytoplasmas infecting Z. jujuba were different from that infecting P. coreana.

• Korean Journal of Agricultural Science
• /
• v.47 no.1
• /
• pp.173-182
• /
• 2020

Human Astrovirus (HuAstV), known as a waterborne virus, is a group IV positive-sense single-stranded RNA that belongs to Astroviridae. The first outbreak of HuAstV was reported in England in 1975. HuAstV can exist not only among clinical patients but also in various water environments, such as water for agriculture and vegetables. For diagnosis of HuAstV from water samples, a polymerase chain reaction (PCR) system has been developed. However, the PCR-based diagnostic method has problems in field application, such as reaction time, sensitivity and specificity. For this reason, in this study we developed the loop-mediated isothermal amplification assay (LAMP) system, aimed specifically at HuAstV. Three prepared LAMP primer sets were tested by specificity, non-specificity and sensitivity; one LAMP primer set was selected with optimum reaction temperature. The developed LAMP primer set reaction conditions were confirmed at 62℃, and detection sensitivity was 1 fg/μL. In addition, restriction enzyme HaeIII (GG/CC) was introduced to confirm that the LAMP reaction was positive. As a result, selected LAMP primer set was 100 - 1000 times more specific, rapid, and sensitive than conventional-nested PCR methods. For verification of the developed LAMP assay, twenty samples of cDNA from groundwater samples were tested. We expect that the developed LAMP assay will be used to diagnose HuAstV from various samples.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.5
• /
• pp.607-613
• /
• 2012

Improvement of endoglucanase activity was accomplished by utilizing error-prone rolling circle amplification, supplemented with 1.7 mM $MnCl_2$. This procedure generated random mutations in the Bacillus amyloliquefaciens endoglucanase gene with a frequency of 10 mutations per kilobase. Six mutated endoglucanase genes, recovered from six colonies, possessed endoglucanase activity between 2.50- and 3.12-folds higher than wild type. We sequenced these mutants, and the different mutated sites of nucleotides were identified. The mutated endoglucanase sequences had five mutated amino acids: A15T, P24A, P26Q, G27A, and E289V. Among these five substitutions, E289V was determined to be responsible for the improved enzyme activity. This observation was confirmed with site-directed mutagenesis; the introduction of only one mutation (E289V) in the wild-type endoglucanase gene resulted in a 7.93-fold (5.55 U/mg protein) increase in its enzymatic activity compared with that (0.7 U/mg protein) of wild type.

• Korean Journal of Microbiology
• /
• v.40 no.3
• /
• pp.254-256
• /
• 2004

Polymerase chain reaction (PCR) is a powerful tool for precisely amplifying selected DNA sequences that have had a broad impact on genomic studies. When examining human $\alpha$- and $\beta$- tryptase genes which have 95% DNA homology, inconsistent PCR amplification of genomic sequences hampered our progress. This study suggests that long PCR technique on the original DNA digested with restriction enzymes improves both efficiency and sensitivity of PCR. These improved results seem to derived from the effective denaturation of the original genomic DNA template or reduction of formation of secondary structures that block either primer annealing or extension in PCR. Elimination of homo- or hetero-duplex products derived from highly homologous genes provides an additional advantage in this study. This communication describes how the use of restriction enzymes improved these efficiencies, and also facilitated studies of highly homologous genes including tryptase genes.

• Microbiology and Biotechnology Letters
• /
• v.44 no.4
• /
• pp.493-496
• /
• 2016

Peach rosette mosaic virus (PRMV) is a plant virus that was first reported in 1933 by Peach. It can infect hosts including peach, grape, blueberry, dandelion, plum, cherry tree, and weeds. PRMV is non-reportable in Korea, but it is designated as a controlled virus requiring plant quarantine. In this study, for the rapid and specific detection of PRMV, we developed an assay using loop-mediated isothermal amplification (LAMP). Comparison between conventional polymerase chain reaction (PCR) methods (real time-PCR and nested PCR) and LAMP for the detection of PRMV revealed an equivalent level of sensitivity by all the tested methods. For the LAMP assay, outer primer sets were used to amplify a 264-bp PCR product, which was then digested using the restriction enzyme Pvu II (CAG/CTG), and the visualization of two digestion fragments (207 + 57 bp) indicated a positive reaction. The developed LAMP assay for PRMV is expected to enable the rapid monitoring of PRMV in plants.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.44 no.3
• /
• pp.253-255
• /
• 1999

Reverse transcription and polymerase chain reaction (RT-PCR) assay was used to detect SMV strains. A pair of oligonucleotide primers were designed to include the cylindrical inclusion (CI) coding region between 4,176 to 5,560 nt. Amplification from the total RNA extracted from infected plants with SMV yielded a 1,385 bp DNA fragment. RT-PCR was shown to be $10^3$ times more sensitive than the ELISA assay and it could detect a virus in $10^{-6}$ dilution. Restriction enzyme analysis of RT- PCR products using EcoR I showed that SMV isolates were classified into six groups according to the patterns of restriction fragments.

• Journal of Microbiology and Biotechnology
• /
• v.15 no.6
• /
• pp.1359-1367
• /
• 2005

The gene encoding Pyrobaculum arsenaticum DNA polymerase (Par DNA polymerase) was cloned and sequenced. The gene consists of 2,361 bp coding for a protein with 786 amino acid residues. The deduced amino acid sequence of Par DNA polymerase showed a high similarity to archaeal family B-type DNA polymerases (Group I), and contained all of the motifs conserved in the family B-type DNA polymerases for $3'{\rightarrow}5'$ exonuclease and polymerase activities. The Par DNA polymerase gene was expressed under the control of the T7lac promoter on the expression vector pET-22b(+) in Escherichia coli BL21-CodonPlus(DE3)-RP. The expressed enzyme was purified by heat treatment, and Cibacron blue 3GA and $Hirap^{TM}$ Heparin HP column chromatographies. The optimum pH of the purified enzyme was 7.5. The enzyme activity was activated by divalent cations, and was inhibited by EDTA and monovalent cations. The half-life of the enzyme at $95^{\circ}C$ was 6 h. Par DNA polymerase possessed associated $3'{\rightarrow}5'$ proofreading exonuclease activity, which is consistent with its deduced amino acid sequence. PCR experiment with Par DNA polymerase showed an amplified product, indicating that this enzyme might be useful in DNA amplification and PCR-based applications.