• Research in Plant Disease
• /
• v.21 no.1
• /
• pp.20-23
• /
• 2015

A sequential planting method was developed to screen rice plants with durable resistance against rice blast in a short time, and applied for several years in Korean rice breeding program. In this study, we showed the advantages of a sequential planting method compared to other pathogenicity tests. The correlation analysis among three pathogenicity tests and other factors demonstrated that durable resistance depended on the average of diseased leaf area and the number of compatible pathogens. Significant correlations were found in the nursery test but not in the field test result. In addition, we traced changes in the pathogen population during sequential planting stages through re-isolation of the pathogen. The portion of compatible pathogens was increased during sequential planting. Through this study, we provide an effective sequential planting method and direction of durable resistance in a breeding program.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.11
• /
• pp.1856-1861
• /
• 2007

Physiological cell conditions such as glucose deprivation and hypoxia play roles in the development of drug resistance in solid tumors. These tumor-specific conditions cause decreased expression of DNA topoisomerase $II{\alpha}$, rendering cells resistant to topo II target drugs such as etoposide. Thus, targeting tumor-specific conditions such as a low glucose environment may be a novel strategy in the development of anticancer drugs. On this basis, we established a novel screening program for anticancer agents with preferential cytotoxic activity in cancer cells under glucose-deprived conditions. We recently isolated an active compound, AA-98, from Streptomyces sp. AA030098 that can prevent stress-induced etoposide resistance in vitro. Furthermore, LC-MS and various NMR spectroscopic methods identified AA-98 as mithramycin, which belongs to the aureolic acid group of antitumor compounds. We found that mithramycin prevents the etoposide resistance that is induced by glucose deprivation. The etoposide-chemosensitive action of mithramycin was just dependent on strict low glucose conditions, and resulted in the selective cell death of etoposide-resistant HT-29 human colon cancer cells.

• Korean Journal of Pharmacognosy
• /
• v.26 no.4
• /
• pp.344-348
• /
• 1995

Preliminary screening test of modulators for multidrug resistance with 400 medicinal plants was carried out by using human multidrug resistance cell line, KB-V1. Among active medicinal plants, the unripe fruits of Evodia officinalis showed a potent modulating activity of MDR. From MeOH extract of this plant, we isolated two indole alkaloids, rutaecarpine (1) and evodiamine (2), by repeated silicagel column chromatography. Rutaecarpine increased the cytotoxicities of vinblastine and taxol against multidrug resistance cells, but evodiamine showed no modulating activity in spite of its potent cytotoxic activities.

• International Journal of Internet, Broadcasting and Communication
• /
• v.14 no.2
• /
• pp.129-135
• /
• 2022

Currently, the rapid growth of electric vehicles and the collection and disposal of waste batteries are becoming a social problem. The purpose of this paper is to propose a fast and efficient battery screening method through a safe inspection and storage method according to the collection and storage of waste batteries of electric vehicles. In addition, as the resistance inside the waste battery increases, an instantaneous voltage drop occurs, and there is a risk of overcharging and overdischarging compared to the initial state of the battery. Accordingly, there are great difficulties in operation, so the final goal of this study is to develop a device for diagnosing aging through real-time battery internal resistance measurement. Final result As a result of simulation of the internal resistance measurement test circuit through external impedance (AC), the actual simulation value was 0.05Ω, RS = Vrms / Irms => Vrms = 8.0036mV, Irms = 162.83Ma. Substitute the suggested method. The result was calculated as Rs = 0.0495Ω. It is possible to measure up to 64 impedances inside the aging diagnostic equipment that enables real-time monitoring of the developed battery cells, and the range can be changed according to the application method.

• The Plant Pathology Journal
• /
• v.39 no.2
• /
• pp.228-233
• /
• 2023

Two pear cultivars with different degrees of resistance to Venturia nashicola were evaluated on the basis of a disease severity rating for pear scab resistance under controlled environmental condition. Two inoculation techniques were tested: the procedure for inoculation by dropping conidia suspension of V. nashicola; the procedure by deposition of agar plug on the abaxial surface of pear leaves. All tested cultivars resulted in blight symptoms on the inoculated leaves and became spread to uninoculated region or other leaves. Although both methods provide satisfactory infection of V. nashicola on pear leaves, the mycelial plug method of inoculation was more reliable than the spray inoculation method for the evaluation of pear scab disease resistance. The incubation period of V. nashicola in the resistant pear cultivar, Greensis was longer than that in the susceptible cultivar, Hwasan.

• Horticultural Science & Technology
• /
• v.32 no.5
• /
• pp.673-683
• /
• 2014

This study was conducted to establish an efficient screening method to identify cucurbits resistant to powdery mildew. Powdery mildew fungus was obtained from a single lesion of infected cucumber leaf in 2010 at Daejeon. The fungus was identified as Podosphaera xanthii race 1 based on morphological characteristics and resistance responses of four melon differentials. Development of powdery mildew caused by the fungal isolate on 34 commercial cultivars of cucumber was investigated at three plant growth stages in a greenhouse. The degree of resistance of cotyledons of each cultivar to the fungus was not correlated with that of whole plant, but powdery mildew occurrence in the first true leaf was highly correlated with resistance at the level of the whole plant. Based on these results, the first true leaf of cucurbit cultivars can be used for screening of resistance to powdery mildew. In addition, variation of resistance of commercial 12 cucumber and 26 melon cultivars to the powdery mildew fungus due to different growing seasons was tested. In the case of cucumber, the resistance response in some cultivars was influenced by growing season. The resistant cultivars showed higher resistance in the warm season than in the cool season. By contrast, the resistant melon cultivars demonstrated strong resistance in all the tested growing seasons. Interestingly, the tested powdery mildew pathogen, a member of P. xanthii race 1, was not pathogenic on seven cultivars of watermelon (Citrullus lanatus). To follow up on this, diverse race 1 isolates of P. xanthii should be collected and tested.

• Archives of Pharmacal Research
• /
• v.19 no.4
• /
• pp.286-291
• /
• 1996

Phenolic compounds are prevalent as toxins or environmental pollutants, but they are also widely used as drugs for various purpose including anticancer agent. A novel biphenolic compound, bis(2-hydroxy-3-tert-butyl-5-methylphenyl)methane (GERI-BPO02-A) was isolated from the fermentation broth of Aspergillus fumigatus F93 previously, and it has revealed cytotoxicity against human solid tumor cells. Its effective doses that cause 50% inhibition of cell growth in vitro against non-small cell lung cancer cell A549, ovarian cancer cell SK-OV-3, skin cancer cell SK-MEL-2 and central nerve system cancer cell XF498 were 8.24, 10.60, 8.83, $9.85\mug/ml$ respectively. GERI-BPO02-A has also revealed cytotoxicity against P-glycoproteinexpressed human colon cancer cell HCT15 and its multidrug-resistant subline HCT15/CL02, and its cytotoxicity was not affected by P-glycoprotein. We have also tested cytotoxicities of structurally related compounds of GERI-BPO02-A such as diphenylmethane, 1,1-bis(3,4dimethylphenyl)ethane, 2,2-diphenylpropane, 2-benzylpyridine, 3-benzylpyridine, $4,4^I-di-tert-butylphenyl$, bibenzyl, $2,2^I-dimethylbibenzyl$, cis-stilbene, trans-stilbene, 3-tert-butyl-4-hydroxy-5-methylphenyisulfide, sulfadiazine and sulfisomidine for studying of structure and activity relationship, and from these data we could suppose that hydroxyl group of GERI-BPO02A conducted important role in its cytotoxicity.

• Microbiology and Biotechnology Letters
• /
• v.32 no.1
• /
• pp.47-51
• /
• 2004

Drug resistance is one of the most significant impediments to successful chemotherapy of cancer. Multidrug-resistance Is characterized by decreased cellular sensitivity to anticancer agents due to the overexpression of P-glycoprotein. By using adriamycin-resistance CL02 cancer cells, we undertook the screening fur agents which were effective to multidrug-resistant cancer cells from strains of the species Sorangium cellulosum isolated in our laboratory. Sorangium cellulose, cellulose-degrading myxobacteria have recently proved to be a rich source of novel anticancer agents. One of the significant examples is the promising anticancer agent epothilone. JW 1006 is the first strain of Sorangium cellulosum which was selected by us for the isolation of a metabolite by a biological screening because of a high cytotoxic activity against the CL02 cancer cells. Cytotoxicity-guided chromatographic fractionation of the culture broth led to the Isolation of two active principles, disorazole $A_1$ and $A_2$. They showed potent cytotoxicity against CL02 cancer cells with $IC_{50}$ values in the picomolar range, and were as active against drug-resistant cancer cells CL02 and CP70 as against the corresponding sensitive cells.

• Korean journal of applied entomology
• /
• v.20 no.4 s.49
• /
• pp.207-211
• /
• 1981

It has been documented that the resistance to planthoppers is attributed to the feeding preference of the insects. This might be related to difference in the amount of feeding plant sap between resistant and susceptible hosts. In this aspect, this study was conducted to verify it and to develop an effective screening method for resistance to planthoppers by tracer technique. An effective P-32 labelling of rice seedlings at $2\~3$ leaf stage was dipping the roots in concentration of $0.1{\mu}Ci/ml$ solution for 48 hours. Radioactivity was significantly higher in planthopers fed on susceptible variety for 48 hours as compared to those fed on resistant variety. Radioactivity of adults was higher than that of nymphs and also higher in female than male. The results were highly correlated to that indicated by the feeding preference of the insects and therefore, considered to be valid for a screening technique.

• The Plant Pathology Journal
• /
• v.20 no.1
• /
• pp.67-74
• /
• 2004

A complete understanding of the epidemiological factors required for optimum for disease development facilitates the design of effective and reliable screening techniques and also disease prediction models. An attempt was made to study the effects of different temperatures ($15-35^{\circ}C$) and leaf wetness periods (4-24 h) on the development of late leaf spot (LLS) in three groundnut genotypes differing in their susceptibility to LLS infection. Irrespective of the genotype, the disease progress evaluated based on different components of resistance was maximum between $15-20^{\circ}C$ and minimum between $20-25^{\circ}C$. At temperatures $\geq$$30^{\circ}C$, LLS development was insignificant. The overall severity of LLS increased with an increase in the leaf wetness period from 4 h to 12 h a day. Further increase of wetness period to 16 h resulted in a rapid increase in the severity. Thereafter, the disease severity gradually decreased with an increase in the wetness period. The effect of temperature and wetness periods on the individual component of disease quantification was not uniform compared between genotypes with different levels of susceptibility/resistance to LLS infection. The results of this study indicate that temperature and leaf wetness period are critical in late leaf spot screening programs since the expression of disease symptoms measured from disease initiation till defoliation, varied differently in the test genotypes with respect to change in these two parameters.