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        검색결과 17

        3.
        2018.04 구독 인증기관·개인회원 무료
        The tobacco cutworm, Spodoptera litura(Fabricius) is serious pest that hurts tomato crops, actives long time of the year. Without pesticide applications, sex pheromone delta traps through experiment first and second half setting during cultural seasons in glasshouse and greenhouse. We investigated captured number of S. litura both in and out side of the two type of tomato cultivated greenhouse. As a result of investigation, captured number of S. litura showed the wave and three high peak typed graph throughout 10 months experiment. First time expression of S. litura was late April in outside installed traps and after that occurrence rate increased gradually until late August. In september, the rate decreased remarkably to middle November in both in and out side treated traps. The result also expressed that captured average number of S. litura in inside of the greenhouse were 8~10 units, and were 15~20units in outside treated traps. Simultaneous installation of internal and external sex pheromone traps succeeded in eliminating a considerable number of S. litura male moths, and the number of larvae was expected to be considerably reduced. Consequently in the experiment, captured male number of S. litura were about 220 units in outside, on the other about 80 of S. litura captured in inside installed traps.
        7.
        1997.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We have identified the candidates for the primordial galaxies in the process of formation in the Hubble Deep Field (hereafter HDF). In order to select these objects we have removed objects brighter than 29-th magnitude in the HDF images and smoothed the maps with the Gaussian filters with the FWHM of 0.8' and 4' to obtain the difference maps. This has enabled us to find. very faint diffuse structures close to the sky level. Peaks are identified in the difference map for each of three HDF chips with three filters (F450W, F606W, and F814W). They have the apparent AB magnitudes typically between 29 and 31. The objects identified in different wavelengths filters have a strong cross-correlations. The correlation lengths are about 0.8'. This means that an object found in one filter can be also found as a peak within 0.8' separation in another filter, thus telling the reality of the identified objects. This angular scale is also the size of the primordial galaxies which have strong color fluctuations on their surfaces. Their large-scale distribution quite resembles that of nearby galaxies, supporting the idea that these objects are ancestors of the present bright galaxies forming at statistically high density regions. Inspections on individual objects show that these primordial galaxy candidates have tiny multiple glares embedded in diffuse backgrounds. Their radial light distributions are quite different from that of nearby bright galaxies. We may be now looking at the epoch of galaxy formation.
        4,300원
        8.
        2017.12 KCI 등재 서비스 종료(열람 제한)
        Ascidian embryos have become an important model for embryological studies, offering a simple example for mechanisms of cytoplasmic components segregation. It is a well-known example that the asymmetric segregation of mitochondria into muscle lineage cells occurs during ascidian embryogenesis. However, it is still unclear which signaling pathway is involved in this process. To obtain molecular markers for studying mechanisms involved in the asymmetric distribution of mitochondria, we have produced monoclonal antibodies, Mito-1, Mito-2 and Mito-3, that specifically recognize mitochondriarich cytoplasm in cells of the ascidian Halocynthia roretzi embryos. These antibodies stained cytoplasm like reticular structure in epidermis cells, except for nuclei, at the early tailbud stage. Similar pattern was observed in vital staining of mitochondria with DiOC2, a fluorescent probe of mitochondria. Immunostaining with these antibodies showed that mitochondria are evenly distributed in the animal hemisphere blastomeres at cleavage stages, whereas not in the vegetal hemisphere blastomeres. Mitochondria were transferred to the presumptive muscle and nerve cord lineage cells of the marginal zone in the vegetal hemisphere more than to the presumptive mesenchyme, notochord and endoderm lineage of the central zone. Therefore, it is suggested that these antibodies will be useful markers for studying mechanisms involved in the polarized distribution of mitochondria during ascidian embryogenesis.
        9.
        2015.09 서비스 종료(열람 제한)
        In animal development, the mechanisms by which localized factors and organelles in egg cytoplasm were exactly distributed into each daughter cell are essential for formation of various cell types. During ascidian Halocynthia roretzi embryogenesis, ooplasmic mitochondria were mainly segregated into muscle and neural precursor cells. At the 32-cell stage, localized mitochondria in the B6.2 blastomeres were preferentially distributed into the B7.4 muscle precursors compared with the B7.3 mesenchyme/ notochord precursors. When the B6.2 blastomeres were isolated from the early 32-cell stage embryos and then allowed to divide 2 times of cell division, the resultant partial embryos showed symmetric distribution of mitochondria, and the partial embryos were composed of equal size cells. In normal development, cell fates of the B7.3 blastomere were correlated with the unequal cleavage of B6.2 lineage cells that normally occurs in the next two-cell division stages to produce a large B8.5 mesenchyme and a small B8.6 notochord cell. Mitochondria are distributed asymmetrically in both cells. When embryos were treated with FGF receptor inhibitor SU5402 and MEK inhibitor U0126 between the 32-cell and the early 64-cell stages, the resultant embryos showed equal cleavage pattern and symmetric distribution of mitochondria in daughter cells of the B6.2 blastomeres. However, blocking of Nodal and Notch signaling did not affect the cell division pattern and mitochondrial distribution in the B6.2 lineage blastomeres between the 32-cell and 110-cell stages. Therefore, it is likely that FGF/MEK signaling is involved in asymmetric distribution of mitochondria and unequal cleavage of the B6.2 lineage blastomeres in ascidian embryo.