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        검색결과 1,964

        1401.
        2010.10 구독 인증기관·개인회원 무료
        Autographa californica nucleopolyhedrovirus (AcMNPV) has a large doublestrand DNA genome of approximately 134 kbp and harbors 156 open reading frames (ORFs). To elucidate DNA replication cascade of AcMNPV, we developed a novel baculovirus genome that can be maintained in Escherichia coli as a plasmid and can infect susceptible lepidopteran insect cells. This genome, named bAc-MK, contains a mini-F replicon and a kanamycin resistance marker. Using a convenient Tn7 transposon-based system, pPCS-S, 55 single ORF-truncated mutants were generated by random insertion into bAc-MK genome. These single ORF-truncated mutants were independently transfected into Sf9 cells, 16 of them were found affecting viral replication since they defected in producing polyhedra. Furthermore, to verify the pathogenicity of the single ORF-truncated mutants, the remaining 39 mutants were subjected to bioassay to Spodoptera exigua 3rd instar larvae. Among them, ac9-, ac49-, ac103- and ac105-knockout mutants showed higher mortality compared to that of bAc-MK. These results suggested that these ORFs could be related to pathogenicity of AcMNPV.
        1402.
        2010.10 구독 인증기관·개인회원 무료
        The Bacillus thuringiensis strain K4 was isolated from fallen leaves, sampled in a forest region of the city of Mungyeong, Korea. The flagellated vegetative cells of B. thuringiensis strain K4 were agglutinated with the H3 reference antiserum and further, agglutinated with 3b and 3d monospecific antisera but non-reactive for 3c and 3e factor sera. These results create a new serogroup with flagellar antigenic structure of 3a3b3d, designated serovar mogi. The strain K4 showed high activity against dipteran larvae, Anopheles sinensis and Culex pipiens pallens while no lepidopteran toxicity. It produced a single ovoidal-shaped parasporal crystal whose SDS-PAGE protein profile consisted of several bands ranging from 75 to 30 kDa. Through the protein identification by nano-LC-ESI-IT MS analysis, the putative peptides of Cry19Ba, Cry40ORF2, Cry27Aa and Cry20Aa were detected. In contrast to the plasmid profile of B. thuringiensis H3 serotype strains, the strain K4 contained only a large plasmid (~100 kb) and we cloned partial cry27Aa, cry19Ba and cry40ORF2 genes from it by thermal asymmetric interlaced PCR. Sequencing analysis showed 87%, 88% and 88% homologous with known cry27Aa, cry19Ba and cry40ORF2 genes, respectively. The new type strain, B. thuringiensis subsp. mogi (H3a3b3d) will be a good resource for new mosquitocidal cry genes.
        1403.
        2010.10 구독 인증기관·개인회원 무료
        In agricultural fields, the entomopathogenic fungal species have been investigated for their potential as the biological control agents due to their role of natural enemies for insects. To address the requirements of a potential South Korea based biocontrol effort using entomopathogenic fungi, we investigated the occurrence of various entomopathogenic fungi in 1080 soil samples representing from various area and locations in South Korea. Entomopathogenic fungi were isolated from soils using semiselective medium SDA-D50 contained saboraund dextrose agar, 50 ug/ml dodine, 100 ug/ml chloramphenicol and 50 ug/ml streptomycin. The isolated putative fungi were identified by the determination of internal transcribed spacer (ITS) region sequences of the nuclear ribosomal analysis. As a result, entomopathogenic fungi were found to occur in 30.8% of the soil samples studied. The most abundant species were Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metschn.) Sorok. Isolates of B. brongniartii, Cordyceps sp., Lecanicillium sp., Isaria sp. and Tolypocladium cylindrosporum were also found. The occurrence of entomopathogenic fungi was analyzed by the area and soil types. These positive entomopathogenic fungi may have potential against variety pests in agriculture and forest
        1404.
        2010.10 구독 인증기관·개인회원 무료
        In a previous study, aggregation pheromone trap added with refrigerated eggs of Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) in a netted pouch was found to enhance parasitism by its egg parasitoid Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) in soybean fields. However, the eggs released in the netted pouch would not be well exploited by the egg parasitoid due to reduced encounter of the eggs and elevated inter- or intraspecific competition among the parasitoids in clumped condition of released eggs inside the pouch. To solve this problem, new trap was developed with twelve separate cells for egg placement. Efficiency of this new trap was evaluated in a soybean field in Songcheon, Andong. Newly developed trap and formerly designed trap each with 180 refrigerated eggs were placed at a distance of 15-20m in the field. The released eggs were collected every week, and the experiment was replicated for three weeks. In addition, comparison was carried out by placing eggs in different density in the cell (120 in total per trap) for three weeks. Parasitism in newly developed trap (32-35%) was higher than that in the former trap (16-20%). Parasitism in the trap where eggs were released in six cells was the highest, followed by three cells, one cell, and eggs released in the pouch. From these findings, newly developed traps is better than previous design in enhancing the parasitism in soybean fields.
        1405.
        2010.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 1997년부터 WTO 가입을 추진 중인 아제르바이잔 농업현황과 농업정책 동향을 살펴보고, 이를 바탕으로 WTO 가입 협상전략 및 향후 지속적인 농업농촌 발전을 위한 대응전략을 탐구한다. 주요 연구결과는 아래와 같다. 아제르바이잔에서 농업은 전체 GDP의 5.7%, 고용인구의 38%를 차지하고 있으며, 석유와 건설부문에 이어 제 3위의 매우 중요한 산업분야이다. 아제르바이잔의 농업은 경제성장, 산업다변화, 빈곤경감, 고용창출에 큰 기여를 해오고 있다. 즉 농업분야는 경제적 측면뿐만 아니라 국가 정치 및 사회 안정차원에서도 매우 중요하다. 하지만 WTO 가입은 향후 아제르바이잔 농업에 기회요인이자 동시에 큰 도전으로 다가설 것으로 보인다. 따라서 WTO 가입협상에서 보다 유리한 조건을 확보하기 위한 협상전략과 함께 WTO 가입 이후 농업의 지속적 성장을 위한 효과적 발전전략을 마련하는 것이 무엇보다 중요한 시점이다. WTO 가입협상 관련하여 무엇보다 중요한 것은 개도국 지위의 확보이며, 이를 통해 농가소득과 농업성장에 중요한 위치를 차지하는 민감품목에 대한 점진적이고 신축적인 시장개방이 되도록 시장접근, 국내보조 분야에서 효과적인 가입협상 전략을 마련해야 한다. 또한 아제르바이잔은 WTO 가입이후에 대비하여 밀을 비롯한 기초식량의 생산성 증대, 고부가가치 생산 및 수출의 확대, 농촌지역의 활력유지를 위한 구체적인 실천방안을 종합적으로 마련해야 할 것이다.
        4,500원
        1406.
        2010.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Nano sized SiC particles (270 nm) are easily agglomerated in nickel sulfamate electrolytic bath during a composite electrodeposition process. The agglomeration of nano particles in composite coatings can significantly reduce the mechanical properties of the composite coatings. In this study, Ni-SiC nano composite coatings were fabricated using a conventional electrodeposition process with the aid of ultrasound. Nano particles were found to be distributed homogeneously with reduced agglomeration in the ultrasonicated samples. Substantial improvements in mechanical properties were observed in the composite coatings prepared in presence of ultrasound over those without ultrasound. Ni-SiC composite coatings were prepared with variable ultrasonic frequencies ranging from 24 kHz to 78 kHz and ultrasonic powers up to 300 watts. The ultrasonic frequency of 38 kHz with ultrasonic power of 200 watt was revealed to be the best ultrasonic conditions for homogeneous dispersion of nano SiC particles with improved mechanical properties in the composite coatings. The microstructures, phase compositions, and mechanical properties of the composite coatings were observed and evaluated using SEM, XRD, Vickers microhardness, and wear test. The Vickers microhardness of composite coatings under ultrasonic condition was significantly improved as compared to the coatings without ultrasound. The friction coefficient of the composite coating prepared with an ultrasonic condition was also smaller than the pure nickel coatings. A synergistic combination of superior wear resistance and improved microhardness was found in the Ni-SiC composite coatings prepared with ultrasonic conditions.
        4,000원
        1407.
        2010.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Human gingival fibroblasts (hGFs) were reported to play an important role in inflammatory reactions to lipopolysaccharide (LPS) from P.gingivalis in the periodontal connective tissue. Although the biostimulatory effects of hyperbaric oxygen therapy, such as anti-inflammatory activity, have been reported, the pathological mechanism is not completely understood. This study examined the changes in the inflammatory cytokine profiles, which are produced after exposure to hyperbaric oxygen in P.gingivalis LPS-treated human gingival fibroblasts, and subsequently to examine the mitogen activated protein kinase (MAPK) pathway involved in cytokine production. Gingival fibroblasts with or without P.gingivalis LPS were exposed to hyperbaric oxygen, and the cytokine profiles in the supernatant were observed using a human inflammation antibody array. The expression of cyclooxyginase-2 (COX-2) protein, phosphorylation of extracellular signal-regulated kinase (ERK1/2), p38, and c-Jun-N-terminal kinase (JNK) MAPK by western blot analysis, and the amount of prostaglandin E2 (PGE2) in the supernatant by an enzyme-linked immunoassay were determined. COX-2 protein expression and PGE2productionwereincreasedsignificantlyintheP. gingivalis LPS-treated group, and were decreased by treating P. gingivalis LPS with hyperbaric oxygen. Treatment of P. gingivalis LPS in the gingival fibroblasts led an increase in the amount of pro-inflammatory-related cytokines interleukin-6 (IL-6) and IL-8 released, whereas hyperbaric oxygen inhibits the irrelease. Ananalysis of the MAPK signal transduction showed that hyperbaric oxygen induced a significant decrease in the level of P38 phosphorylation regardless of the presence or absence of LPS. In addition, hyperbaric oxygen promoted JNK phosphorylation, significantly in the presence of LPS. Hyperbaric oxygen can inhibit pro-inflammatory cytokines and mediate the MAPK signal pathway, and appears to be useful as an anti-inflammatory tool.
        4,300원
        1408.
        2010.06 구독 인증기관 무료, 개인회원 유료
        The discovery of antibiotics has helped to save the lives of an uncountable number of people. Antibiotics have been grouped in different classes based on their origin, structure, and mechanism of action. An intrinsic and acquired mechanism of antimicrobial resistance has been identified in many bacterial strains that are of high clinical importance. This has seriously jeopardized the use of antibiotics and has also caused the spread of microbes that are resistant to effective first-choice, or “first-line” drugs. Thus, sensible use of antibiotics and the search for effective alternative measures are of high importance in order to minimize the effect due to existing and emerging antimicrobial resistant microbes.
        4,900원
        1409.
        2010.05 구독 인증기관·개인회원 무료
        The porcine reproductive and respiratory syndrome virus (PRRSV) has three major structural proteins which designated as GP4, GP5, and M. They have been considered very important to arouse the humoral and cellular immune responses against PRRSV infection and proposed to be the excellent candidate proteins in the design of PRRS bioengineering vaccine. However, the PRRSV structural proteins are produced in low levels in the infected cells because it forms insoluble protein and possesses several transmembrane regions. To overcome this problem, we fused the GP4, GP5, and M with SUMO (Small ubiquitin-related modifier), and expressed the fused gene in Bm5 cells and silkworm larvae. Expression of the proteins were analyzed by 12% SDS-PAGE and western blotting using 6xHis tag and porcine anti-PRRSV antibodies. In results, SUMO fused proteins were expressed at a high level in Bm5 cells. The levels of protein using the silkworm larvae is higher than that using Bm5 cells. The fused protein was purified by Ni-NTA affinity chromatography. This study demonstrated that SUMO, when fused with PRRSV structural proteins, was able to promote its soluble expression. This may be a better method to produce PRRSV structural proteins for vaccine development.
        1410.
        2010.05 구독 인증기관·개인회원 무료
        In agricultural fields, the entomopathogenic fungal species have been investigated for their potential as the biological control agents due to their role of natural enemies for insects. To address the requirements of a potential South Korea based biocontrol effort using entomopathogenic fungi, we investigated the occurrence of various entomopathogenic fungi in 1080 soil samples representing from various area and locations in South Korea. Entomopathogenic fungi were isolated from soils using semiselective medium SDA-D50 contained saboraund dextrose agar, 50 ug/ml dodine, 100 ug/ml chloramphenicol and 50 ug/ml streptomycin. The isolated putative fungi were identified by the determination of internal transcribed spacer (ITS) region sequences of the nuclear ribosomal analysis. As a result, entomopathogenic fungi were found to occur in 30.8% of the soil samples studied. The most abundant species were Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metschn.) Sorok. Isolates of B. brongniartii, Cordyceps sp., Lecanicillium sp., Isaria sp. and Tolypocladium cylindrosporum were also found. The occurrence of entomopathogenic fungi was analyzed by the area and soil types. These positive entomopathogenic fungi may have potential against variety pests in agriculture and forest
        1411.
        2010.05 구독 인증기관·개인회원 무료
        Entomopathogenic fungi are widely available as biological control agents for controlling insect pests in agriculture and forestry. The fungal culture broth contains various pathogenesis-related components such as blastospores, mycelium and insecticidal enzymes such as chitinase, Pr1- and Pr2-proteases, which have been reported to play an important role in penetrating insect cuticles. In this study, we tried to evaluate the utility of culture broth from Beauveria bassiana SFB-205 to control lepidopteran pests. High level of insecticidal activity correspond to over 90% of mortality were observed when the culture broth of B. bassiana SFB-205 was inoculated to the Spodoptera litura larvae together with the B. thuringiensis K1. The freeze-dried culture broth showed synergistic effects in insecticidal activity against larvae of S. exigua and S. litura when treated with corresponding baculoviruses, SeNPV and SlNPV. Active ingredient of the B. bassiana SFB-205 culture broth was identified to chitinase, which have truncated form by insertional mutation compared to previously reported chitinases.
        1412.
        2010.05 구독 인증기관·개인회원 무료
        Bacillus thuringiensis 1-3 (Bt 1-3) which was isolated from a Korean soil sample showed high insecticidal activity against Aedes aegypti as well as Plutella xylostella. The isolate was determined to belong to ssp. aizawai (H7) type by an H antiserum agglutination test and produced bipyramidal-shaped crystal proteins with a molecular weight of 130 kDa. PCR analysis with cry gene specific primers showed that Bt 1-3 contained cry1Aa, cry1Ab, cry1C, cry1D and cry2A gene, differing from spp. aizawai (reference strain) which contains cry1Aa, cry1Ab, cry1C and cry1D. We modified the plasmid capture system (PCS) to clone plasmid from Bt 1-3 through in vitro transposition. Fifty-three clones were acquired and their sizes were approximately 10 kb. Based on the sequence analysis, they were classified according to similarities with four known Bt plasmids, pGI3, pBMB175, pGI1 and pGI2, respectively. One of pGI3-like clones, named as pBt1-3, was fully sequenced and its 20 putative open reading frames (ORFs), Rep-protein, double-strand origin of replication (dso), single-strand origin of replication (sso), have been identified. The structure of pBt1-3 showed high similarity with pGI3 which is one of rolling-circle replication (RCR) group VI family.
        1413.
        2010.05 구독 인증기관·개인회원 무료
        Through an application of plasmid capture system (PCS) to Bacillus thuringiensis plasmid DNAs, we acquired 21 polymorphic clones of putative genomic DNA of bacteriophage. The genome size of phage 1-3 (PhBT1-3) was determined to be 46,517 base pairs (bp) with 35.43% G + C content and 83% coding region. Sixty-five putative open reading frames (ORFs) with more than 50 codons were found in the new phage genome. In accordance with this genome finding, the phage particles and its DNA were confirmed from the supernatant of B. thuringiensis 1-3. Morphological characterization and infectivity assay demonstrated that PhBT1-3 belongs to the family Siphoviridae and it showed infectivity to three B. thuringiensis type strains, galleriae, entomocidus, and morrisoni. Based on these results, we screened the existence of phages in B. thuringiensis type strains by PCR with terminase small subunit-specific primers. Ten of 67 type strains showed PCR products and the similarity of those putative amino acids was more than 70%. Furthermore, we verified the existence of various shaped phages from the supernatants of 10 B. thuringiensis type cultures. In conclusion, we characterized a putative genome of phage, PhBT1-3 from B. thuringiensis 1-3, and confirmed the distribution of phages in the group of 67 B. thuringiensis type strains.
        1414.
        2010.05 구독 인증기관·개인회원 무료
        A new Bacillus thuringiensis isolate 19-22 (Bt 19-22) exhibited high anti-fungal activity against barley powdery mildew (Blumeria graminis f. sp. hordei). The cry gene content of Bt 19-22 comprised cry1Aa, cry1Ab, cry1Ac and cry1D which have high insecticidal activity against lepidopteran larvae. We tried to confer a dipteran insecticidal activity to Bt 19-22 for constructing a recombinant strain which has multiple functions, anti-fungal and dual insecticidal activity. The insecticidal cry11Aa gene of B. thuringiensis was constructed under cry1Ac promoter in an E. coli-B. thuringiensis shuttle vector (pPro11A). The plasmid, pPro11A was introduced into Bt 19-22 isolate by electroporation and four transformants which had different cry gene contents were identified by PCR with cry11Aa and cry1-type specific primers. Among them, a Bt 19-22 transformant (11A/19-22 No. 7) expressed Cry11A protein (approximately 70 kDa) successfully without change of its inherent characteristics such as Cry protein expression and antifungal activity. The insecticidal activity of 11A/19-22 No. 7 was checked against Plutella xylostella and Culex pipiens. These results suggests that the recombinant strain shows dual insecticidal activity against lepidopteran and dipteran larvae as well as antifungal activity.
        1415.
        2010.05 구독 인증기관·개인회원 무료
        Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) and Gryon japonicum (Ashmead) (Hymenoptera: Scelionidae) are major egg parasitoids of Riptortus pedestris (Fabricius) (Hemiptera: Alydidae), a mobile pest on several crops in Korea and Japan. We compared the sensitivity of the two parasitoids to different temperature and relative humidity (RH) conditions to understand their phenological relations. Less than 6 hours old naïve female adult O. nezarae and G. japonicum were individually kept in 50 ml tubes without food and water sources. The tubes were placed in three humidity conditions (50-55, 70-75, and 90-95% RH) in desiccators. These desiccators were then maintained at 20, 25, and 30°C. In each temperature and RH combination 75-76 individuals were assessed for the mortality every 8 hours. G. japonicum was found to survive longer (37-116 hours) in all the temperature and RH combinations than O. nezarae (31-103 hours). Both the two parasitoids survived better in higher RH in all temperatures. The reduced sensitivity to lower humidity by G. japonicum compared to O. nezarae may explain the earlier occurrence of G. japonicum in the spring. The relations with seasonal occurrence of the two parasitoids were discussed.
        1416.
        2010.05 구독 인증기관·개인회원 무료
        Chrysanthemum flower model trap developed by modifying an artificial yellow chrysanthemum flower was reported to be more attractive to flower thrips than a commercial yellow sticky trap. The installation of the traps (20 traps per 50 m2 plot), especially, reduced the seasonal populations of Frankliniella intonsa Trybom (Thysanoptera: Thripidae) on strawberry flowers in greenhouse by 82% compared to the untreated control. In this study, we tested if the installation of the flower model traps can reduce thrips population on a red pepper field located in Seokdong, Andong. The pepper field was treated two times with pesticides during the period of experiment. The traps were installed in plant canopy at different densities (0, 5, 10, 20 traps) in 20 plots (3×5 m2 each) using a completely randomized design. Population of thrips was examined on the collected pepper flowers from 1 July to 29 July in 2009. Thrips found on the flowers were all F. intonsa. Significance effect of treatment and sampling date was found from repeated-measure analysis of variance. The highest density of traps significantly reduced female and male F. intonsa population by 60% and 46% compared to the control, respectively. However, no difference in immature population was found among the treatments. These results indicate flower model trap can be an additional tool for the management of flower thrips on field red pepper.
        1417.
        2010.05 구독 인증기관·개인회원 무료
        Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) causes losses in several crops in Korea. Release of non-viable refrigerated eggs of R. pedestris is known to enhance natural parasitism by Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) and Gryon japonicum (Ashmead) (Hymenoptera: Scelionidae) in soybean fields. In this study, we conducted an experiment of cage-exclusion design to verify the former results in more manipulative approach in a soybean field. Agakong field (45×26 m2) located at Songcheon, Andong was divided into 15 plots (10×6 m2) with each experimental arena of 3×2 m2 in the center. There were three treatments: (1) release of refrigerated eggs of R. pedestris, (2) release of refrigerated eggs with one time spray of thiamethoxam, and (3) untreated control. A fine mesh cloth with iron poles was used to encircle the arenas. Refrigerated eggs of R. pedestris were released (100/arena) twice before sampling. One-day old eggs of R. pedestris were released (60/arena) in all the experimental arenas at an interval of 6 days, and 30 eggs from each were collected to record parasitism. We found no significant difference in the eggs and nymphs population of R. pedestris among the treatments. However, adult density was significantly reduced in the treated plots during final two sampling days compared to the control. We found significantly higher parasitism by G. japonicum on the eggs collected from treated plots (9-25%) compared to the control plots (1-9%). It is verified that releasing non-viable eggs of R. pedestris help to enhance natural parasitism in soybean field.
        1418.
        2010.04 구독 인증기관·개인회원 무료