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        검색결과 9,514

        5841.
        2008.10 구독 인증기관·개인회원 무료
        To develop an advanced baculovirus insecticide with additional advantages, such as higher toxicity and recovering to wild-type baculovirus, a novel recombinant baculovirus, NeuroBactrus was constructed. Bacillus thuringiensis crystal protein gene (cry1-5) and an insect-specific neurotoxin gene (AaIT) were introduced into Autographa californica nucleopolyhedrovirus genome by fusion of polyhedrin-cry1-5-polyhedrin under the control of poyhedrin gene promoter, and by fusion of orf603 partial genes and AaIT under the control of early promoter of ORF3006 from Cotesia plutellae bracovirus. About 150 kDa of Polyhedrin-Cry1-5-Polyhedrin fusion protein expressed by NeuroBactrus was occluded into the polyhedra, and activated as about 65 kDa of crystal protein when treated with trypsin. RT-PCR analysis indicated that transcription of AaIT gene occurs by 2 h postinfection (p.i.) and increased at 16 h p.i.. NeuroBactrus showed high toxicity against Plutella xylostella larvae and significant reduction in median lethal time (LT50) against Spodoptera exigua larvae compared to those of wild-type AcNPV. Re-recombinants derived from NeuroBactrus, NBt-Del5 (deleted cry1-5), NBt-DelA (deleted AaIT) and NBt-Del5A (deleted cry1-5 and AaIT; wild-type baculovirus) were generated in serial passages in vitro. This result showed that the NeuroBactrus could be transferred to wild-type baculovirus along with serial passages by the homologous recombination between two polyhedrin genes and two partial orf603 genes.
        5842.
        2008.10 구독 인증기관·개인회원 무료
        A new Bacillus subtilis isolate showed high anti-fungal activities (more than 80% control efficacy) against several plant diseases such as rice blast (Magnaporthe grisea), tomato gray mold (Botrytis cinerea), tomato late blight (Phytophthora infestans) and wheat leaf rust (Puccinia recondita). We tried to confer an insecticidal activity to this B. subtilis isolate for constructing a recombinant strain which has dual functions, anti-fungal and insecticidal activity. The insecticidal cry1Ac gene of B. thuringiensis was constructed under its own promoter in a minimal E. coli-B. thuringiensis shuttle vector (pHT1K-1Ac). The plasmid, pHT1K-1Ac was introduced into B. subtilis isolate by electroporation and the transformant was confirmed by PCR with cry1Ac specific primers. B. subtilis transformant produced a parasporal inclusion in the cells as in B. thuringiensis and the size of that protein was appox. 130 kDa. The insecticidal activity of the transformant was checked against lepidopteran pest, Plutella xylostella. This result suggests that this recombinant B. subtilis strain shows the possibility of controlling harmful insect pests as well as plant fungal diseases simultaneously at one crop, and both culture broth and harvested cells of this strain can be used as individual biological control agents separately for integrated crop protection.
        5843.
        2008.10 구독 인증기관·개인회원 무료
        Pine wilt disease (PWD) is one of the most serious forest tree diseases and now the damaged area covers 7,877 ha and more than 60 cities in Korea. The causal agent of PWD, Bursaphelenchus xylophilus is transmitted by the insect vectors, pine sawyers (Monochamus spp.). Spread of PWD damage and control effect for PWD are directly related to dispersal potential of Monochamus spp. vectors. Recently, harmonic radar technology has been applied as a means for tracking individual dispersal of tagged insects. Tracking insects with harmonic radar system is similar to a mark-and-recapture technique, in which an organism is tagged, released, and recaptured. Our objective is to develop a harmonic radar tracking system by using lightweight tags to investigate dispersal of Monochamus spp., insect vectors. The harmonic radar system consists of two parts: a commercially available, light-weight (1.6 kg), handheld transceiver (RECCO Rescue System) and a small tag that reflects the transceiver signal (917 ㎒) at harmonic frequencies (1,834 ㎒). A tag consists of a miniature diode (Toshiba ISS350) with wires (36-gauge tinned copper) soldered using conductive epoxy on each side to produce a dipole antenna. These tags were evaluated in an open field to assess their maximum detection range, and at tag length of 13 ㎝, the tag was detected at >100 m.
        5844.
        2008.10 구독 인증기관·개인회원 무료
        To find effective native natural enemies of spider mites in the surrounding vegetation of citrus orchards, we investigated the species composition and seasonal occurrence of phytoseiid mites on Podocarpus macrophyllus, which is one of the major windbreak tree species surrounding citrus orchards in Japan, in Nagasaki prefecture, south-western Japan, from 2006 to 2007. Six species were found: Amblyseius eharai, Euseius sojaensis, Okiseius subtropicus, Typhlodromus vulgaris, T. kishimotoi, and Typhlodromus sp. Amblyseius eharai was the most dominant species and formed more than 60% of the phytoseiid species collected in both years. Typhlodromus vulgaris was the second most dominant species. The other species were rare, except that Okiseius subtropicus was abundant in February in 2006. The density of A. eharai showed two peaks in late June and from late August to early September. The density of T. vulgaris also peaked in late June. However, the density declined thereafter, and remained low, unlike the seasonal occurrence of A. eharai. Podocarpus macrophyllus blooms from early to mid-June and produces a great deal of pollen. Both A. eharai and T. vulgaris developed and oviposited well when they were reared on pollen of Podocarpus macrophyllus as food. Therefore, the increase of these phytoseiid species in June was thought to be due to the supply of pollen of Podocarpus macrophyllus as food.
        5845.
        2008.10 구독 인증기관·개인회원 무료
        In order to establish artificial indoor rearing techniques for the black soldier fly (BSF), we developed indoor rearing instructions and collection manual for each developmental stage of the fly. The fly collection was conducted between June and October at 1 month interval. Calf feed and food waste were most effective to attract adults. Collection efficiency is higher from the trap installed in a shady spot than that in an open spot. It was highest to collect flies in August and September. As the egg-laying medium for the artificial egg collection, calf feed and food waste were most effective. The optimal number of the medium (W*D*H=60*40*15cm) was 8 for 2000 adults (male:Female=1:1) in the egg-laying net (W*D*H=4*2*2m). Flower foams and wooden blocks with holes were used as egg-laying sites. Adult females preferred the holes on average 3~5mm in diameter and 7~10mm in depth for oviposition. Larvae reared in low density (2~4 individuals/㎠) showed superior practical traits than those reared in an overcrowded environment (6~10 individuals/㎠). It is important to place the fly pupae in moist sawdusts (humidity: 20~40%), since a pupa tends to hide in a refuge. Adult insects should be employed for laying eggs for food waste processing immediately after emergence. When treated at 10℃ for 10 days after pupation, emergence rate of the insect was still 93.3%. By keeping pupae at the low temperature, emergence timing could be manipulated with about 10 day flexibility.
        5846.
        2008.10 구독 인증기관·개인회원 무료
        Terrestrial animals are widely considered to be well protected from damage caused by ambient UV radiation, and thus the direct effects of solar UV-B radiation on arthropods have not attracted a great deal of attention. However, if plant-dwelling arthropods have evolved behavioral adaptations to solar UV-B radiation, but not morphological or physiological adaptations, the resources available to them would be strongly limited. Tetranychus urticae and their dominant natural enemies, phytoseiid mites, usually stay on the lower leaf surfaces. Because of the accumulation of UV-B-absorbing compounds such as flavonoids in the leaves, the upper and lower leaf surfaces provide different UV environments. We tested whether UV irradiation affects survival and reproduction of T. urticae and, if so, whether staying on the lower leaf surfaces is beneficial for their performance in solar UV radiation. Consequently, we observed lethal effects of artificial UV-B irradiation and solar UV radiation on T. urticae. However, by remaining on lower leaf surfaces, the mites could avoid such deleterious effects. These suggest that staying on the lower leaf surfaces is a behavioral adaptation of T. urticae to avoiding harmful solar UV-B radiation. Lethal effects of UV-B irradiation also exerted strong deterrent effects on the hatchability of phytoseiid mites. Additionally, preliminary experiments suggested that phytoseiid mites avoided and quickly escaped from a place irradiated by solar UV. Therefore, solar UV-B radiation may strongly affect the diurnal and spatial patterns of distribution or migration of mite communities on host plant canopies.
        5847.
        2008.10 구독 인증기관·개인회원 무료
        Population density of the citrus red mite, Panonychus citri (McGregor), in Japanese pear orchards remained low until mid-August, even after inoculation of pear leaves with a considerable number of adult female P. citri from May onwards. This raised the possibility that pear leaves contain a natural compound that suppresses an increase of P. citri populations. The rate of development from larva to adult was significantly lower on leaves collected in July than on leaves collected earlier or later, in several years. The population suppression was caused by molting inhibition and ovicidal activity, according to our close observation in the laboratory [Gotoh and Kubota (1997) Exp. Appl. Acarol. 21: 343-356]. To clarify whether a natural pear compound caused this molting inhibition, a methanol crude extract of pear leaves was isolated and added to a newly developed artificial diet, consisting of sodium caseinate, sucrose, levulose, glucose and inositol. The compound extracted from pear leaves resulted in the molting inhibition as observed on pear leaves. Based on infrared and NMR spectral analysis, the compound extracted from pear leaves closely resembled the synthetic acaricide hexythiazox. Furthermore, the LC50-values of the compound extracted from pear leaves for ovicidal activity of P. citri eggs and for inhibition of molting to protonymphs were similar to those of hexythiazox. These results strongly suggest that the molting deterrent extracted from pear leaves was in fact hexythiazox, an acaricide in use on pear trees, rather than a natural product. This suggestion becomes even stronger, considering that the molting inhibition was observed in a hexythiazox-spray year, but not in a non-spray year.
        5848.
        2008.10 구독 인증기관·개인회원 무료
        We analyzed a portion of mitochondrial COI gene sequences (658 bp) to investigate the genetic diversity and geographic variation of the swallowtail butterfly, Papilioxuthus L., and the cabbage butterfly, Pieris rapae (Lepidoptera: Papilionidae). P. xuthus showed a moderate level of sequence divergence (0.91% at maximum) in 15 haplotypes, whereas P. rapae showed a moderate to high level of sequence divergence (1.67% at maximum) in 30 haplotypes, compared with other relevant studies. Analyses of population genetic structure showed that most populations are not genetically differentiated in both species. The distribution pattern of both species appears to be consistent with category IV of the phylogeographic pattern sensu Avise (Avise et al. 1987): a phylogenetic continuity, an absence of regional isolation of mtDNA clones, and extensive distribution of close clones. The observed pattern of genetic diversity and geographic variation of the two butterfly species seems to reflect the abundant habitats, abundant host plants, and flying abilities in connection with the lack of historical biogeographic barriers.
        5849.
        2008.10 구독 인증기관·개인회원 무료
        The 15,338-bp long complete mitochondrial genome (mitogenome) of the Japanese oak silkmoth, Antheraeayamamai (Lepidoptera: Saturniidae) was determined. This genome has a gene arrangement identical to those of all other sequenced lepidopteran insects, but differs from the most common type, as the result of the movement of tRNAMet to a position 5’-upstream of tRNAIle. No typical start codon of the A. yamamai COI gene is available. Instead, a tetranucleotide, TTAG, which is found at the beginning context of all sequenced lepidopteran insects was tentatively designated as the start codon for A. yamamai COI gene. Three of the 13 protein-coding genes (PCGs) harbor the incomplete termination codon, T or TA. All tRNAs formed stable stem-and-loop structures, with the exception of tRNASer(AGN), the DHU arm of which formed a simple loop as has been observed in many other metazoan mt tRNASer(AGN). The 334-bp long A+T-rich region is noteworthy in that it harbors tRNA-likestructures, as has also been seen in the A+T-rich regions of other insect mitogenomes. Phylogenetic analyses of the available species of Bombycoidea, Pyraloidea, and Tortricidea bolstered the current morphology-based hypothesis that Bombycoidea and Pyraloidea are monophyletic (Obtectomera). As has been previously suggested, Bombycidae (Bombyxmori and B.mandarina) and Saturniidae (A.yamamai and Caligula boisduvalii) formed a reciprocal monophyletic group.
        5850.
        2008.10 구독 인증기관·개인회원 무료
        Sclerodermus harmandi populations were collected from 6 Korean regions (Seoul, Gangwon, Chungcheong, Jeolla, Gyeonasang and Jeju provinces), 1 Chinese region (Nanjing) and 1 Japanese region (Tokyo). Above all was identified as the same species based on morphological characteristics. In present study, we compared the intra-specific characteristics of regional isolated populations of S. harmandi based on nucleotide and amino acid sequences of variant genomic and mitochondrial loci: the full length of internal transcribed spacer 1 and 2 (ITS1 & ITS2), the complete cytochrome oxidase subunit I and II (COI & COII) and tRNA genes for aspartate and lysine and 5'end of ATPase 8 genes. There were no significant differences among the analysed 9 populations regardless of regional segregation. The nucleotide and translated amino acid sequences similarities were significantly high, despite some sequence differences were found in same loci. This result support the report based on the morphological characteristics. However, we are conducting further study to identify whether sequence differences in specific loci are the characteristics of individual level in population or population level and to analyse the full sequences of mitochondrial DNA by regional segregation.
        5851.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cellulose nanofibers from microfibril cellulose (MFC) was prepared by hydrobromic acid (HBr) treatment at different concentrations. Polyvinyl alcohol (PVA) composite films at various loading level of nanofibers were manufactured by a film casting method. The analysis of degree of polymerization (DP), crystallinity (Xc) and molecular weight (Mw) of cellulose after acid treatment was conducted. The mechanical and thermal properties of the cellulose nanofibers reinforced PVA films were characterized using tensile tests and thermogravimetric analysis (TGA). The DP and Mw of MFC by HBr hydrolysis considerably decreased, but Xc showed no significant change. After acid hydrolysis, the diameter of cellulose nanofibers was in the range of 100 to 200 nm. The thermal stability of the films was steadily improved with the increase of nanofiber loading. There was a significant increase in the tensile strength of PVA composite films with the increase in MFC loading. Finally, 5 wt.% nanofiber loading exhibited the highest tensile strength and thermal stability of PVA composite films.
        4,000원
        5853.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        4,000원
        5854.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        폴리스티렌-폴리히드록시에틸 아크릴레이트(PS-b-PHEA) 디블록 공중합체와 폴리비닐알콜(PVA)을 1 : 1 무게비로 블렌딩하여 수소 이온 전도성 가교형 고분자 전해질막을 개발하였다. 특히 술포석시닉산(SA)를 사용하여 디블록 공중합체의 PHEA 블록과 PVA와 가교반응을 시켰고, 이를 FT-IR 분광법을 이용하여 분석하였다. 이온교환능(IEC)은 SA 함량이 증가함에 따라 계속하여 증가하여 0.95 meq/g까지 도달하였고, 이는 전해질막에 이온 그룹수가 증가하기 때문이다. 하지만, 함수율은 SA 함량이 20 wt%까지는 증가하다 그 이상에서는 감소하였다. 또한 수소 이온 전도도도 SA 함량에 따라 증가하여 20 wt% SA농도에서 0.024 S/cm의 최대값을 나타내었다. 함수율과 수소이온전도도의 이러한 경향은 SA 함량이 증가함에 따라 이온 그룹의 수가 증가하는 효과와 가교가 증가하는 효과가 서로 경쟁적으로 일어나기 때문으로 생각된다.
        4,000원
        5855.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, alterations in whole proteome expression patterns in the head of Japanese medaka (Oryzias latipes) was investigated following acute or chronic exposure to benzo(a)pyrene (BaP) (25 μg L-1) for 48 hrs and 15 days, respectively. The
        4,000원
        5856.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A taxonomic survey of the dinoflagellate genus Ceratium Schrank was conducted on 17 locations off the coast of Korea. A total of sixteen species and four varieties have been collected, of which Ceratium arcticum, C. longirostrum, C. praelongum, C. tripos
        4,000원
        5857.
        2008.09 구독 인증기관 무료, 개인회원 유료
        Thrombospondins (TSP-1, TSP-2) are secretory extracellular glycoproteins that are involved in a variety of physiological processes such as tumor cell adhesion, invasion, and metastasis. The present study was undertaken to elucidate the involvement of thrombospondins in the adhesion of osteoblast-like cells using the TSP-1 or TSP-2 antisense MG63 and MC3T3-E1 cell lines. For downregulation of TSPs expression, we prepared antisense constructs for TSP-1 and TSP-2 using the pREP4 an episomal mammalian expression vector, which be able to produce the specific antisense oligonucleotides around chromosome. MG63 and MC3T3-E1 osteoblast-like cells were transfected with the antisense constructs and nonliposomal Fugene 6, and then selected under hygromycin B (50 μM/mℓ) treatment for 2 weeks. Western blot analysis revealed that expression of the TSP proteins was downregulated in the antisense cell lines. The cell adhesion assay showed that adhesive properties of TSP-1 and TSP-2 antisense MG63 cells on the polystyrene culture plate were reduced to 17% and 21% of the control cells, respectively, and those of the TSP-1 and TSP-2 antisense MC3T3-E1 cells also decreased to 19% and 27% of control, respectively. Adhesion of TSP-1 and TSP-2 antisense MC3T3-E1 cells on Type I collagen-coated culture plate decreased to 27% and 76%, respectively. These results indicate that TSP-1 and TSP-2 proteins may have an important role in adhesion of osteoblast-like cells to extracellular matrix.
        4,000원
        5858.
        2008.09 구독 인증기관 무료, 개인회원 유료
        Embryonic stem cells have a pluripotency and a potential to differentiate to all type of cells. In our previous study, we have shown that embryonic stem cells (ESCs) lines can be generated from murine parthenogenetic embryos. This parthenogenetic ESCs line can be a useful stem cell source for tissue repair and regeneration. The defect in full-term development of parthenogenetic ESCs line enables researchers to avoid the ethical concerns related with ESCs research. In this study, we presented the results demonstrating that parthenogenetic ESCs can be induced into osteogenic cells by supplementing culture media with ascorbic acid and β-glycerophosphate. These cells showed morphologies of osteogenic cells and it was proven by Von Kossa staining and Alizarin Red staining. Expression of marker genes for osteogenic cells (osteopontin, osteonectin, alkaline phosphatase, osteocalcin, bone-sialoprotein, collagen type1, and Cbfa1) also confirmed osteogenic potential of these cells. These results demonstrate that osteogenic cells can be generated from parthenogenetic ESCs in vitro.
        4,000원
        5859.
        2008.09 구독 인증기관 무료, 개인회원 유료
        We tested the effects of roasted and non-roasted Zizyphi Spinosi Semen (ZSS) hot water extracts on pentobarbital-induced sleeping behavior, pentylentetrazole-induced convulsions, and locomotor activity in mice. Both ZSS extracts decreased locomotor activity and pentylentetrazole-induced convulsions. Both extracts alos dose-dependently shortened the sleep onset and prolonged the sleep time induced by pentobarbital, with roasted extract being more potent. In addition, chemical constituents in HPLC also were different. Thus, both roasted and non-roasted ZSS extracts potentiate the sleep onset and the sleeping time induced by pentobarbital, decrease locomotor activity, and reduce pentylentetrazole-induced convulsions, with roasting improving extract potency.
        4,000원
        5860.
        2008.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In an attempt of clarifying the connection between the photospheric abundance anomalies and the stellar rotation as well as of exploring the nature of “normal A” stars, the abundances of seven elements (C, O, Si, Ca, Ti, Fe, and Ba) and the projected rotational velocity for 46 A-type field stars were determined by applying the spectrum-fitting method to the high-dispersion spectral data obtained with BOES at BOAO. We found that the peculiarities (underabundances of C, O, and Ca; an overabundance of Ba) seen in slow rotators efficiently decrease with an increase of rotation, which almost disappear at ve sin i > 100 km s−1. This further suggests that stars with sufficiently large rotational velocity may retain the original composition at the surface without being altered. Considering the subsolar tendency (by several tenths dex below) exhibited by the elemental abundances of such rapidly-rotating (supposedly normal) A stars, we suspect that the gas metallicity may have decreased since our Sun was born, contrary to the common picture of galactic chemical evolution.
        4,900원