• Korean journal of applied entomology
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• v.12 no.4 s.17
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• pp.139-142
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• 1973

Experiment was conducted to study resistance of rice varieties and lines originated from Korea and IRRI-sources to the white-backed planthopper, Sogatella furcifera Horvath. The nature of varietal resistance to the insects was evaluated from the viewpoints of nymphal period and adult emergence. The varieties Colombia, Muthumanikam and Pankhari-203 were resistant, the varieties CO-22, Mudgo and Vellailangalayan moderately susceptible, the other varieties all susceptible. Nymphal period and rate of adult emergence were significantly different according to the degree of resistance of the rice varieties. Nymphal period was short (about 10 days) in the susceptible varieties and long (about 14-16 days) in the resistant varieties. The .ate of adult emergence was significantly lower in the resistant varieties than in the susceptible varieties. The lower rate of adult emergence in the resistant varieties may be due to the fact that the insects were suffered higher nymphal mortality in the resistant than in the susceptible varieties.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.6
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• pp.839-845
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• 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 Life Science
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• v.22 no.8
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• pp.1018-1023
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• 2012

Snail is a zinc finger transcription factor that induces epithelial-to-mesenchymal transition (EMT), which promotes tumor invasion and metastasis by repressing E-cadherin expression. In addition, Snail restricts the cellular apoptotic response to apoptotic stimuli or survival factor withdrawal; however, its molecular mechanism remains largely unknown. In this study, we have investigated the mechanism underlying Snail-mediated chemoresistance to 5-fluorouracil (5-FU), one of the most widely used anti-cancer drugs. When Snail was overexpressed by doxycycline (DOX) in MCF-7 #5 cells, it inhibited 5-FU-induced apoptotic cell death and switched the cell death mode to necrosis. Snail expression, either by DOX treatment in MCF-7 #5 cells or by the transfection of Snail expression vectors pCR3.1-Snail-Flg, phosphorylation-resistant pCR3.1-S104, and 107A Snail-Flg in MCF-7 cells specifically induced PTEN down-regulation/inactivation and Akt/PKB activation, without affecting ERK1/2 activity. In addition, Snail prominently suppressed 5-FU-induced increases in p53 levels. These findings demonstrate that Snail switches 5-FU-induced apoptosis to necrosis through the activation of Akt/PKB and the down-regulation of p53 levels.

• Korean journal of applied entomology
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• v.15 no.3 s.28
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• pp.147-151
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• 1976

Laboratory experiments were conducted to evaluate the resistance of the new rice varieties Milyang $\#$21 and $\#$23 at the seedling stage to the brown planthopper(Nilaparvata lugens), small brown planthopper(Laodelphax striatellus), white-back planthopper(Sogatella furcifera), green rorice leafhopper(Nephotettix cincticeps) and zigzag-striped leafhopper (Recilia dorsalis) The varieties Yushin and T(N)-1 were used as susceptible check and the resistant check varieties were Mudgo to brown planthopper, ASD-7 :o small brown planthopper, Colombo to white-back planthopper, IR2061 (46763) to green rice leafhopper and Vellailanalgayan to zigzag-striped leafhopper. The varieties Milyang $\#$21 and $\#$23 were moderate in plant reaction only to the green rice leafhopper and $\#$23 was moderately resistant in plant rection only to the small brown planthopper. The nymphs of plant-and leaf-hoppers were more prefered Milyang $\#$21 and $\#$23 and susceptible check-varieties were more preferred for feeding than the resistant check-varieties. The green rice leafhopper and aigzag·striped leafhopper much more prefered Milyang $\#$21 and $\#$23 for oviposition, while brown planthopper and small brown planthopper more prefered the resistant cheeks than test varieties and susceptible checks. However, there was no any steady relationship in ovipositional preference between resistant and susceptible to the hoppers. Shorter nymphal-periods and higher rate of adult emergence were observed in the test varieties and the susceptible checks compared with the resistant checks. In conclusion, the varieties Milyang $\#$21 and $\#$23 seemed to be lack of true resistance to the plant-and leaf-hoppers from the viewpoints of antibiosis and feeding preference.

• Korean journal of applied entomology
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• v.59 no.4
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• pp.341-348
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• 2020

The ATP-binding cassette (ABC) transporter superfamily represents the largest transmembrane protein that transports a variety of substrates across extra- and intra-cellular membranes. In insects, the ABC transporter proteins play crucial roles in insecticide resistance. To date, no studies have investigated the involvement of ABC transporter gene for cross-resistance to insecticide chemistries. Here, we studied such possible mechanisms against six conventional insecticides using transgenic Drosophila melanogaster strains carrying Mdr49 transcript variant A. For the 91-R and 91-C strains of Drosophila melanogaster, although they have a common origin, 91-R has been intensely selected with DDT for over 60 years, while 91-C has received no insecticide selection. Our transgenic analyses showed that overexpression of 91-R-MDR49 transcript variant A along with three amino acid variations can yield a relatively low degree of cross-resistance to carbofuran (2.0~6.7-fold) and permethrin (2.5~10.5-fold) but did not show cross-resistance to abamectin, imidacloprid, methoxychlor, and prothiofos as compared to the Gal4-driver control strain without transgene expression. These results indicate that the overexpression of Mdr49A in itself leads to a cross-resistance and three amino acid changes have additional effects on positive cross-resistance to carbofuran and permethrin.

• Korean journal of applied entomology
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• v.25 no.1 s.66
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• pp.27-32
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• 1986

To establish a method for measuring varietal resistance against rice stem maggot in field and pot, 20 varieties were used in $1981{\sim}1983$. The degree of injured stems by the 1st generation larvae was significantly correlated with that of injured panicles by the 2nd ($r=0.864^{**}$). There was no ovipositional preference in rice stem maggot. The larval mortality after artificial infestation varied widly from 5.6 to 100% in varieties and that of the resistant varieties was high after boring. There was a negative correlation between number of injured leaves and larval mortality after artificial infestation ($'81:r=-0.833^{**},\;'82:r=-0.918^{**}$). It is considered that larval mortality mainly caused by antibiosis and larval mortality 20 days after infestation on rice seedlings is ideal for evaluating the varietal resistance to rice stem maggot. Resistant varieties are Nagdongbyeo, Jinjubyeo and Chucheongbyeo susceptible varieties, Keumgangbyeo, Milyang 23, Baigyangbyeo and Milyang 30.

• Journal of Life Science
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• v.25 no.6
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• pp.715-723
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• 2015

Insects represent the largest class within the animal kingdom in terms of species number. Humans had been utilized insect in the broad area, including food, agriculture, industry, pharmaceuticals and so on. At present, insects are emerging as a leading group for identifying and extracting novel bioactive substances due to enormous number and a high nutritional value. Insects rely on a suite of systemic response to resist infection such as immune cells, hemocytes, activation of enzymes cascades, and antimicrobial peptide/protein. Among the substances, antimicrobial peptides (AMPs) are main components of potent antimircrobial innate defense system into the insect hemolymph. AMPs raise influential candidate as avenue to resolve the development of antibiotic-resistant microbial organism. Insect AMPs are classified into four main classes: cecropins, insect defensins, glycine/proline-rich peptides. Insect AMPs have been purified, over 150. In this review, AMPs derived from several insects were summarized including honey bee, dung beetle, butterfly and longicorn beetle. These peptides almost exhibited potent antimicrobial activities against human microbial pathogens without causing remarkable hemolysis to erythrocytes excluding melittin, and their mode of action(s) are based on disruption of the plasma membrane or fungal apoptosis. Therefore, study of insect AMPs is expected to be useful for designing novel therapeutic antimicrobial applications.

• Weed & Turfgrass Science
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• v.3 no.3
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• pp.165-173
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• 2014

This review study was conducted to recommend the effective use of herbicide mixtures in Korea. The herbicide ingredients by Herbicide Resistancce Action Committee (HRAC) was classified into 23 groupes according to the mode of action (acetyl CoA carboxylase inhibitors, acetolactate synthase, photosystem I and II inhibitors, protoporphyrinogen oxidase inhibitors, carotenoid biosynthesis inhibitors, enolpyruvyl shikimate-3-phosphate synthase inhibitors, glutamine synthetase inhibitors, dihydropteroate synthetase inhibitors, mitosis inhibitors, cellulose inhibitors, oxidative phosphorylation uncouplers, fatty acid and lipid biosynthesis inhibitors, synthetic auxins, auxin transport inhibitors and potential nucleic acid inhibitors or non-descript mode of action). The rice herbicide mixtures registered in Korea were classified based on the guideline of HRAC. Accordingly, such a classification system for resistance management can help to avoid continuous use of the herbicide having the same mode of action in the same field.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.247-252
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• 2006

오염 퇴적물내 중금속의 방출과 이에 따른 생이용성(bioavalability)은 기존의 가역 평형관계로써 설명하기에 불충분한 것으로 알려져 있다. 최근 연구결과에 의하면 이러한 탈착 저항성을 설명하기 위한 비가역적 모델에 의해 퇴적물내 중금속의 탈착저항성 부분이 존재함이 밝혀졌다. 탈착저항성에 대해서는 아직 충분한 규명이 이루어지지 않았으나, 오염물질의 노화(aging)에 의해 일단 탈착저항성을 띠게 되면 생이용성(bioavailability)이 감소되는 것으로 알려져 있다. 본 연구에서는 노화(aging)가 연안 퇴적물 내 납과 카드뮴의 흡/탈착 특성에 미치는 영향을 알아보기 위해 연속 탈착실험과 biphasic 탈착모델을 적용함으로써 납과 카드뮴의 탈착저항성을 규명하고자 하였다. 그리고 연속 추출 실험을 통해서 노화(aging)에 따른 퇴적물 내 납과 카드뮴의 흡착 기작을 규명하고자 하였다. 연속탈착 실험 결과 시간이 경과함에 따라 탈착저항성부분의 크기가 증가하였으며, 연속추출 실험 결과 납의 경우 carbonate fraction에서 추출된 납이 가장 많았으며, 노화(aging) 따라 exchangeable fraction에서 추출된 납이 감소하는 반면 reducible, organic material, residual fraction에서 추출된 납의 양이 증가하였다. 카드뮴의 경우 가장 많은 양이 추출된 단계는 exchangeable fraction이였으며, organic material fraction에서는 카드뮴이 추출되지 않았다. 노화(aging) 따라 reducible fraction과 residual fraction에서의 추출량이 증가하는 경향을 보였으나 그 양은 매우 적은 것으로 나타났으며, 노화(aging)에 따른 exchangeable fraction과 carbonate fraction에서의 추출량은 큰 변화가 없었다. 대해서는 북한지역의 분포상황을 밝혔다.것을 알 수 있었으며, 크롬과 비소의 경우는 초기에 많이 용출되고, 구리의 경우는 꾸준히 용출되는 것을 알 수 있었다. 3년 된 통나무집이 8년 된 통나무집보다. 용출양이 더 컸으며, 이는 CCA성분이 초기에 많이 용출된다는 것을 의미한다. 억제 효과를 나타내었고 Hep3B에서는 부탄을 분획물 (1 mg/mL)에서 82%의 비교적 높은 성장억제효과를 나타내었다.as a "front" and "back". Thus, Germany′s private space may face a genuine public space and street, which is rare in the Korean housing. Although the layout of indoor space in the korean housing tends to be open, such an openness may be outstanding in living and dining spaces, kitchen and various accesses to rooms. In the case of Germany, such indoor spaces are usually closed to each other. Thus corridors act to separate these spaces. Such differences are analysed to be due to the different perceptions of interpersonal and socio-cultural attributes as intra-family and inter-neighbor relationships or communications. 알 수 있었다.도 질소와 인산처럼 토양지지대가 있는 경우가 낮은 함량을 유지하였다.pe from the daily life, to fantasize and daydre

• Journal of Life Science
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• v.15 no.1 s.68
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• pp.112-117
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• 2005

Plants living riverside show diverse resistance responses to submergence. The promoted petiole elongation of semi-aquaitc plants, e.g., such as Ranunculus sceleratus and Rumex palustris, is one of the adaptive responses mediated by the plant hormone ethylene. The gaseous hormone is trapped in submerged plant tissues and enhances the petiole growth by increasing sensitivity of the tissues to some plant hormones including auxin. Due to the stimulated growth of petioles, the leaves finally reach the water surface and can respirate again. At the water surface, the accumulated ethylene diffuses out from the tissues to the air. As a result, the increased hormone sensitivity decreases again, and thus the growth rate reduces to the basal level as before. The increased auxin sensitivities by ethylene observed in Ranunculus sceleratus, revealed by the changes in the auxin dose-response curves, indicate the increase of affinities of the receptors to auxin. However, the molecular mechanism of the affinity regulation remains still largely unknown, because the identity of the auxin receptor is still unclear.