• Korean Journal of Agricultural Science
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• v.13 no.2
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• pp.157-167
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• 1986

The study was carried out to identify several factors affecting isolation and culture of cotyledone and leaf mesophyll protoplasts of cabbage (Brassica oleraceae), petsai (B.campestris subsp. pekinensis) and rape (B.napus). High viable protoplasts could be obtained when the cotyledon and the leaf mesophyll tissue of all species were treated with enzyme solution composed of 1% macerozyme 'R-10', 1.5% Onozuka 'R-10', 10% mannitol and 50,0 mM $CaCl_22H_2O$ for 4 hours. The protoplasts which obtained from the cotyledon of all species except the cabbage and the leaf mesophyll tissue of all species were divided on NN culture medium supplemented with 9.1% mannitol, 1% glucose, 1% sucrose, $1mg/{\ell}$ 2,4-D, $0.5mg/{\ell}$ NAA and $0.5mg/{\ell}$ BA. The division of the rape leaf mesophyll protoplasts were continued and led to colony.

• Journal of Life Science
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• v.32 no.2
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• pp.161-166
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• 2022

Mitosis is a process in which a replicated genome is distributed to two daughter cells, and it is necessary for cell survival and organismal development. During mitosis, the spindle assembly checkpoint (SAC) ensures faithful chromosome segregation by monitoring the kinetochore attachment to the mitotic spindle. Although the SAC mechanism has been extensively studied over the last 30 years, the mechanism by which a single unattached kinetochore activates the SAC remains unclear. The key components of the SAC are Mad1, Mad2, Mad3 (BubR1 in higher eukaryotes), Bub1, Bub3, and Cdc20, which are all required for SAC activation. An essential step for SAC activation is the formation of the Mad2 - Cdc20 complex in the unattached kinetochore, which is kinetically disfavored. Although the mechanism by which Mad2 and Cdc20 are recruited to unattached kinetochores is well-known, it is not clear how they form a complex. Recently, a key mechanism for the formation of the Mad2 - Cdc20 complex has been identified, which is catalyzed by an unattached kinetochore. This supports the evidence that a single unattached kinetochore can activate the SAC signaling. Herein, we discuss the known key mechanism for SAC activation, review the recent studies on SAC, and conclude how their discoveries improved the understanding of mitosis.

• Journal of Plant Biology
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• v.36 no.4
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• pp.357-362
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• 1993

To elucidate the origin of secondary growth in the rhizome of B. ternaturn, the developmental changes of vascular cambium was observed in ultrastructural features. The vascular cambium was gradually differentiated from procambium as in seed plants, but the cambial activity did not persist very long so that the cambial cells became a dormant state like fossil cryptogams. Dense cytoplasm of procambial cells became progressively sparse during the growth, and the tiny vesicles were fused to form numerous small vacuoles and then a few large vacuoles. These gradual changes and the occurrence of storage materials which was associated with the developmental stages might support the progressive differentiation of the cambial cells. In addition, the cessation of cambial activity could be indicated by the facts that late vascular cambial cells accumulate large lipid bodies and show very small peripheral cytoplasm and unlikely thickened cell wall, compared to other meristematic cells. Therefore. the vascular cambium showed the characteristics of both seed plants and fossil cryptogams from the view point of cambial ontogeny and activity.tivity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.3
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• pp.297-307
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• 1995

Anatomical and physiological studies of sink tissues are required for better understanding the biological plant growth system and energy metabolism Anatomy of root growth zones of two genotypes of tall fescue (Festuca arundinacea Schreb.) receiving 50 or 200 ppm N were determined, Cross-sectional anatomy and cells responses of root growth zones were observed and examined. Rapid radial root expansion occurred within the first 1.0 mm from root apex, and then increased gradually for both genotypes and N levels. Another increase in diameter occurred at high N after cell elongation slowed near 3.0 mm. Area of the central cylinder cell increased rapidly near the root apex. However, it then decreased again about 1.0 to 1.5 mm from the apex, perhaps because of pressure from the rapid increase of root diameter due largely to an increasing proportion of cortex and epidermis or hypodermis in the distal portion of the root growth zone. Root area from the apical initial to 6.0 mm distal consisted of 10 to 18% epidermis or exodermis, 67 to 79% cortex, and 10 to 22% vascular cylinder cells containing cambium cells (6 to 20%) and xylem cells (0.8 to 2.5%). These data indicate that N application affects root growth radially by increasing mainly cortex cell area, with less effect on epidermis and central cylinder cells.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.989-992
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• 2014

Myelination using Schwann cells and neuron cells was performed in rat. Schwann cells and neuron cells from dorsal root ganglion (DRG) of rat embryos (E16) were cultured, respectively. The embryonic DRG cells purified were cultured and anti-mitotic agents were added. Purified the embryonic Schwann cells were cultured and added to the embryonic DRG cells purified. A purified population of myelination in vitro system was accomplished and identified formation of myelination using antibody of neurofilament protein.

• Horticultural Science & Technology
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• v.32 no.1
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• pp.33-40
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• 2014

This study was carried out to understand the physiological characteristics of early-matured 'Hanareum' (Pyrus pyrifolia Nakai) pears through anatomical structure and fruit characteristics and also the changes according to gibberellin (GA) treatment. The pericarp at full bloom consists of outer epidermis, hypodermis, parenchyma cell, and inner epidermis from the exterior and five types of vascular bundle tissues. Cork cell layer was formed at 70 days after full bloom (DAFB) in non-treated fruits and formed at 60 DAFB in GA treated fruits. Cell division period was from full bloom (FB) to 40 DAFB and then fruit enlargement was accomplished by the cell growth. Comparison of the fruit enlargement and fruit structure development by GA treatment or non-treatment showed that cell division of 'Hanaerum' fruits did not affect the GA treatment but fruit enlargement was affected cell growth. Fruit stalk of GA treatment fruits was larger than non-treated fruits from 40 DAFB which correspond to the period of the stop of cell division and 'Hanareum' was regarded GA treatment expedite of vascular bundle tissue growth and relatively increased nutrient transport to fruit. In addition to, average fruit quality between the non-treatment and GA treatment showed that fruit weight was higher in fruits treated by GA but firmness was lower and probably was effected fruit storing in 'Hanareum' pear.

• Environmental Mutagens and Carcinogens
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• v.16 no.1
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• pp.1-5
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• 1996

Fumonisin B$_1$ is hepatotoxic in all species, but liver carcinogenic and nephrotoxic in rat. Our objective was to investigate the effects of multiple iv dose of FB$_1$. Male Sprague-Dawley rats were injected intravenously (iv) with FB$_1$ at 1 mg/kg singly (T1), or daily for 2 (T2) or 3 (T3). T1 rats did not show any cytotoxicity in both liver and kidney. However, the most dramatic change occurred in this group was mitotic figures in liver, which increased 5.5-fold to that of control. Hepatotoxic effects were shown in T3, based on histopathology and serum chemistry. A few scattered single cell deaths occurred primarily in the centrilobular area of the liver in T2. Similar but more lesions in liver and a small number of degenerating cells with hypereosinophilic cytoplasm in outer stripe of medulla of kideny were found in T3 rats. Serum chemical profiles included liver enzymes increased, in which cholesterol was very sensitive. This study suggests that multiple exposure of low dose FB$_1$ cause cytotoxic in the liver earlier time point than kideny. FB$_1$$ also stimulates mitosis in liver that may be associated with carcinogenesis.

• Horticultural Science & Technology
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• v.18 no.3
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• pp.368-372
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• 2000

The fruit structure of 'Fuji' apples from full bloom to maturing was observed from 1997 to 1998. Cell division period of the fruit was found to be 4 to 5 weeks after full bloom. Vascular bundles in the inner part of the fruit skin which were not described in the books illustrating apple fruit structure was observed, as they were tentatively named as outer vascular bundles (OVB), and another vascular bundles were also observed newly in periphery of locules, as they were tentatively named as inner vascular bundles (IVB). In the observation of the inner epidermis (IE) in the inner part of the locules on 2 days prior to full bloom, the guard cells were observed and these were disappeared in the observation made 2 days later, i.e. on full bloom. The formation of fruit skin was observed at the microscope 65 days after full bloom and the number of cell which organized the fruit skin did not change from this time to maturation period. Tannin which is mainly in the fruit skin changing from continuously during fruit growth, specially the tannin of epidermis disappeared completely 100 days after full bloom stage, and then constituted again. Starch was not almost found out in cell division period of fruit from full bloom stage after this time it constituted much at flesh part and decreased at maturation period. Epidermis was developed by uniform cells of a layer the cell of epidermis constituted irregularity after pigmentation stage, the organization of fruit was not close because the very big intercellular space constituted at hypodermis and flesh structure.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.2
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• pp.135-141
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• 2015

Cell senescence can be identified by cellular changes that occur as a result of intrinsic aging and/or diseases. In case of skin cells, aging and cell senescence caused by external factors results in cessation of cell proliferation and cellular malfunction, which, in turn, accelerates skin aging. In this study, inhibition of cell senescence and enhancement of cell function were studied using cordycepin to evaluate the potential for skin anti-aging agent. By comparing with the number of senescence associated with ${\beta}$-galactosidase (SA-${\beta}$-gal) positive cells in young and replicative aged human fibroblasts, it was found that replicative aged cells showed higher expression of ${\beta}$-galactosidase. Treatment of cordycepin - known as an anti-oxidative and anti-inflammatory agent - reduced ${\beta}$-galactosidase expression in senescent cells and enhanced cell survival in serum-free culture condition. Cordycepin also showed superb inhibition of ROS, which is another indicator of cell senescence. The results of this study proved the anti-aging effect of cordycepin on human fibroblasts and also proposed a possibility of its use as an anti-aging cosmetic ingredient.

• Korean Journal of Microbiology
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• v.44 no.1
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• pp.80-84
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• 2008

We constructed the null mutants of fission yeast Schizosaccharomyces pombe spDbp5 gene that is homologous to DEAD-box RNA helicase DBP5 in budding yeast Saccharomyces cerevisiae, which plays important roles in mRNA export out of nucleus. A null mutant in an $h^+/h^+$ diploid strain was constructed by replacing the spDbp5-coding region with an $ura4^+$ gene using one-step gene disruption method. Tetrad analysis showed that the spDbp5 is essential for vegetative growth. The haploid spDbp5 null mutants harboring pREP81X-spDbp5 plasmid showed extensive $poly(A)^+$ RNA accumulation in the nucleus and decrease in the cytoplasm after repression of spDbp5 expression. These results suggest that spDbp5 is also involved in mRNA export from the nucleus.