• The Plant Pathology Journal
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• v.37 no.3
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• pp.291-298
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• 2021

False smut caused by Ustilaginoidea virens is an important rice fungal disease that significantly decreases its production. In the recent past, conventional methods have been developed for its detection that is time-consuming and need high-cost equipments. The research and development in nanotechnology have made it possible to assemble efficient recognition interfaces in biosensors. In this study, we present a simple, sensitive, and selective oxidized graphene-based geno-biosensor for the detection of rice false smut. The biosensor has been developed using a probe DNA as a biological recognition element on paper electrodes, and oxidized graphene to enhance the limit of detection and sensitivity of the sensor. Probe single-stranded DNA (ssDNA) and target ssDNA hybridization on the interface surface has been quantitatively measured with the electrochemical analysis tools namely, cyclic voltammetry, and linear sweep voltammetry. To confirm the selectivity of the device, probe hybridization with non-complementary ssDNA target has been studied. In our study, the developed sensor was able to detect up to 10 fM of target ssDNA. The paper electrodes were employed to produce an effective and cost-effective platform for the immobilization of the DNA and can be extended to design low-cost biosensors for the detection of the other plant pathogens.

• The Korean Journal of Mycology
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• v.25 no.4 s.83
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• pp.362-368
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• 1997

Five formae speciales of Fusarium oxysporum in Korea were examined using RFLP analysis to find the possibility for classification and analyze genetic variations. DNAs from F. oxysporum f. sp. lycopersici, cucumerinum, fragariae, garlic and sesami were used with three recombinant probes such as pFC46, pFC52 and pFC57. Distinct differences among five formae speciales of this fungus were detected in RFLP band patterns based on southern hybridization of genomic DNA using each recombinant clone, which was a repetitive copy probe. Strains belong to four formae speciales could be very stable in genetic variation except f. sp. sesami which has more variation than the others based on the RFLP analysis. They formed their own cluster which has high similarity within the same formae specialis resulted from the UPGMA analysis for genetic relationship analysis and each cluster represented its own formae specialis. The method using three recombinant DNA probes could be a good tool for classification of formae speciales in F. oxysporum.

• Korean Journal of Veterinary Research
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• v.33 no.3
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• pp.479-486
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• 1993

This study was attempted co develope a method for detection of Theileria sergenti infection on the basis of hybridization of parasite DNA with a probe. For construction of a T sergenti genomic library, T sergenti DNA was digested completely with Bam-HI and the fragments were ligated into the Bam-HI site of pUC-19 before transformation of Escherichia colistrain JM83. To detect clones containing the parasite's DNA sequences, a genomic DNA library of T sergenti constructed in pUC-19 was screened by cracking and Southern hybridization. Seven colonies were chosen from 29 colonies which were screened by transformation of Escherichia coli strain JM83. Seven transformants were comfirmed from seven colonies by cracking. The sizes of transformants were about 5Kb, 5.7Kb, 4.3Kb, 7.75Kb, 7.85Kb, 5.8Kb, 3.8Kb, respectively. DNA inserts, T sergenti DNA, and bovine DNA were hybridized with radio-labelled T sergenti DNA. Two($pT_1$, $pT_1$) of the seven inserts and T sergenti DNA reacted strongly but another 5 inserts and bovine DNA showed weak reation. All of the DNA inserts were not reaction, but T sergenti DNA were very weakly and bovine DNA were strongly reacted to hybridization with radio-labelled bovine DNA. Therefore, we obtained total 7 T sergenti DNA fragments in this study.

• Parasites, Hosts and Diseases
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• v.34 no.3
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• pp.177-184
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• 1996

In situ hybridization was performed to detect rat heumocwstis ca4nii in the lung sections. Rats were immunosuppressed by weekly subcutaneous injection of 10 mg/kg methylprednisolone. On the 6th, 8th and 9th week of immunosuppression, the lungs were removed and fled in 10% neutral formalin. A 22 base oligonucleotide probe complementary to p. carinii 5S ribosomal RMh was commercially synhesized and its 3' terminal was labeled wiH biotin. In situ hybridization was performed utilizing manual capillary action technolog)r on the Microprobe system. p. cnrinii were detected along the luminal surface of alveolar pneumocytes, in exudate of alveolar cavities, and also in secretory material of bronchioles. In the 6th week group, positive reaction was observed focally in the peripheral region of the lung sections, but the reaction was observed diffusely in the 8th or 9th week groups. In comparison with Grocott's methenamine silver stain, in situ hybridization technique can detect the organism rapidly, and can detect trophic forms very well. Furthermore, no nonspecific reaction with other pathogenic fungi and protozoa was recognized. Therefore, in situ hybridization can be a good technique to detect p. carinii in the lungs of infected rats.

• Korean Journal of Veterinary Research
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• v.35 no.3
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• pp.515-530
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• 1995

Coronaviridae에 속하는 transmissible gastroenteritis virus(TGEV)와 porcine epidemic diarrhea virus(PEDV)를 specific하게 detection할 수 있는 방법을 개발하고자 본 연구를 수행하였다. 두 바이러스 모두 RNA 바이러스이기 때문에 reverse transcription-polymerase chain reaction(RT-PCR)으로 nucleocapsid(N) protein gene의 cDNA를 증폭시켰다. SmaI으로 처리한 pTZ19R에 ligation시킨 후 염기서열을 밝히고자 sequencing하였다. 각각의 prototype virus와 비교하여 상동성을 밝혔다. 두 바이러스에 대한 cDNA probe를 제작하여 Southern blot hybridization을 실시하였다. TGEV의 경우 백신주인 P45와 병독주인 Miller strain을 사용하였다. cDNA를 증폭시키기 위해 N1/N1R과 N2/N2R 두 가지 primer를 이용한 결과, N1/N1R primer의 경우 586bp 크기의 PCR product를 얻을 수 있었고, N2/N2R primers로 582bp의 cDNA를 증폭시킬 수 있었다. PEDV 실험을 위하여 PED 임상 증상을 나타내는 분변을 이용하여 RT-PCR을 실시하였다. P2/P2R primer로 753bp의 PCR product를 얻을 수 있었다. TGEV의 두 가지 strain의 N protein gene을 sequencing하여 prototype인 Purdue strain과 염기서열 상동성을 조사한 결과, 97%이상의 높은 homology를 나타내었다. PED-V 역시 N protein gene을 sequencing하여 CV777과 염기서열 상동성을 조사한 결과 97%이상의 homology로 PEDV임을 알 수 있었다. TGEV와 PEDV의 염기서열을 비교한 결과 29%의 낮은 homology를 관찰할 수 있었다. 두 가지 바이러스의 N protein gene에 대한 cDNA probe를 제작하여 Southern blot hybridization을 한 결과, 각 바이러스에 매우 특이적 반응을 나타내었다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.05a
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• pp.183-187
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• 2002

DNA microarray는 분자생물학 및 DNA 컴퓨팅 분야에 널리 사용되고 있는 실험 도구이다. DNA microarray를 이용하는 한 예는 알려진 유전자 집합을 바탕으로 하여 hybridization을 통해 새로운 DNA 서열을 분석하는 것이다. 이를 위한 가장 간단한 방법은 알려진 유전자의 모든 서열을 DNA microarray 상에 올려놓는 것이지만 이는 결과의 정확도 및 칩 제작비용 면에서 비효율적이다. 따라서 일반적으로는 유전자 서열 정보를 파악한 후 일련의 DNA 서열을 선택하는 probe 디자인 과정을 거친다. 그러나 현재 유전자 서열을 바탕으로 최적의 probe 집합을 찾는 결정적인 방법이 존재하고 있지 않다. 이에 본 논문은 oligo DNA microarray을 이용한 DNA 서열 분석 문제에 있어서 가능한 많은 유전자를 인식하면서 최소의 probe 개수를 갖는 집합을 찾는 방법을 제안한다. 제시된 방법은 가능한 probe 집합들로 해집합을 구성한 후, 유전알고리즘을 이용한 진화 과정을 통해 목적하는 probe 집합을 찾는다. 본 논문에서는 GenBank로부터 얻은 일련의 유전자 집합을 대상으로 실험하였으며 그 결과를 분석하였다.

• The Journal of the Acoustical Society of Korea
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• v.24 no.3
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• pp.160-165
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• 2005

We have developed SH (shear horizontal) surface acoustic wave (SAW) sensors for detection of the immobilization and hybridization of DNA (deoxyribonucleic acid) on the gold coated delay line of transverse SAW devices. The experiments of DNA immobilization and hybridization were performed with 15-mer oligonucleotides (probe and complementary target DNA). The sensor consists of twin SAW delay line oscillators operating at 100 MHz fabricated on $36^{\circ}$ rotated Y-cut $LiTaO_3$ piezoelectric single crystals. The relative change in the frequency of the two oscillators was monitored to detect the hybridization between target DNA and immobilized probe DNA in pH 7.4 PBS (phosphate buffered saline) solution. The measurement results showed a good response of the sensor to the mass loading effects of the DNA immobilization and hybridization with the sensitivity up to $1.55{\cal}ng/{\cal}ml/Hz$.

• The Korean Journal of Mycology
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• v.26 no.2 s.85
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• pp.135-143
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• 1998

Contour-clamped homogeneous electric field gel electrophoresis was used to establish electrophoretic karyotype for 10 species of Fusarium sections Sporotrichiella, Liseola, Gibbosum, Discolor and Martiella. Intact chromosomal DNA was isolated from fungal protoplast and separated under various conditions according to their size in order to improve DNA separation. The numbers of chromosome-sized DNA molecules for individual species ranged from 5-13, with individual chromosomes ranging from 0.78 Mb to 7.20 Mb in size. The total genome DNA size of each species was estimated at about 18.32 Mb to 48.20 Mb. Comparison of karyotype profiles following Southern hybridization analysis with a randomly selected genomic probe of F. oxysporum formae speciales litii was carried out.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04c
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• pp.455-457
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• 2003

DNA microarray는 분자생물학에서 널리 사용되고 있는 실험 도구로써 크게 cDNA와 oligonucleotide microarray로 나뉘어진다. DNA microarray는 일련의 DNA 서열로 이루어진 probe들의 집합으로 구성되며 알려지지 않은 서열과의 hybridization 과정을 통해 특정 서열을 인식할 수 있게 된다. O1igonucieotide microarray는 cDNA 방법과는 다르게 probe를 구성하는 서열을 제작자가 임의로 구성할 수 있기 때문에 목표 서열이 가지는 고유한 부분만을 probe 서열로 사용함으로써 비용절감과 실험의 정확도를 높일 수 있다는 장점이 있다. 그러나 현재 목표 유전자 서열에 대해 probe 집합을 생성하는 결정적인 방법은 존재하지 않으며, 따라서 넓은 해 공간에서 효과적으로 최적 해를 찾아 주는 진화 연산이 probe 선택을 위한 좋은 대안으로 사용될 수 있다［1.2］. 그러나 진화연산을 이용한 probe 선택방법에 있어서 인식하고자 하는 목표 서열의 개수가 많아질 경우, 해 공간의 크기가 커짐으로 인해 문제점이 발생할 수 있다. 따라서 본 논문에서는 다수의 목표 유전자 서열을 대상으로 한 probe 선택 방법에 일어서 보다 효율적인 진화연산 접근 방법을 소개한다. 제시된 방법은 인식하고자 하는 목표 서얼의 일부를 선택해 이를 probe 집합의 후보로 사용하며. 유전 연산자를 이용한 진화과정을 통해 최적에 가까운 probe 집합을 찾는다. 본 논문은 GenBank로부터 유전자 서열을 대상으로 제안된 방법을 실험하였으며, 축소된 목표 서열만을 이용해 probe 집합을 선택하더라도 적합한 probe 집합을 찾을 수 있었다.

• Applied Biological Chemistry
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• v.39 no.5
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• pp.403-408
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• 1996

Total bacterial community DNA, which was extracted from microcosm soil and field soil after 2,4-D amendments, was analyzed on Southern blots, using the tfdA gene probe derived from plasmid pJP4 and the Spa probe from Sphingomonas paucimobilis. Southern blot analyses with total bacterial DNA extracted from soils Inoculated with Pseudomonas cepacia/pJP4 revealed that DNA probe method could detect the 2,4-D degrading bacteria down to $10^5\;cells/g$ dry soil. In the microcosm experiment, there was a good correlation between 2,4-D degradation and banding patterns in hybridization analyses performed after each 2,4-D treatment using the two probes. When bacterial DNA extracted from microcosm soil was hybridized with the Spa probe, a change in the position of hybrid bands was observed over time in a Southern blot, suggesting that population change or possibly genetic rearrangement in 2,4-D degrading microbial populations occurred in this soil. With the Spa probe, one hybrid DNA band was persistently observed throughout the five 2,4-D additions. When bacterial DNA isolated from the field soil was probed with the tfdA and Spa, strong hybridization signal was observed in the 100 ppm-treated subplot, weak signal In the 10 ppm-treated subplot, and no significant signal in the 1 ppm-treated and control subplots. The data show that DNA probe analyses were capable of detecting and discriminating the indigenous 2,4-D degrading microbial populations in soil amended with 2,4-D under laboratory and field conditions.