• Journal of Microbiology and Biotechnology
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• 제5권6호
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• pp.359-363
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• 1995

The antigenic variation of B. thuringiensis subsp. satto have been investigated for 120 hours during sporulation and crystallization by using SDS-PAGE and Western blot. Most antigens of a vegetative cell were found to disappear as it was in sporulation and crystallization, but protein antigens of 46, 29, 27, and 21 kDa continued to be expressed. The new protein bands of 293, 138, 119, 75, and 68 kDa appeared on days 2 through 5 in modified GYS medium. They were thought to be involved in sporulation and crystallization. The protein of 138 kDa was found to be a major protein of both crystal and spore. The expression patterns were immunologically analyzed by Western blot. The polyclonal antisera against the intact crystal showed strong immunoreactivity to proteins with molecular masses of 293, 138, 68, and 46 kDa. The polyclonal antisera against the spore recognized proteins of 293, 138, 68, and 46 kDa. Both crystals and spores appeared to express the common protein antigens.

• Applied Microscopy
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• 제46권2호
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• pp.83-88
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• 2016

Structural differentiation of the connective stalk in giant duckweed, Spirodela polyrhiza, was examined to reveal the anatomical and ultrastructural characteristics within reduced shoot. The study focuses primarily on structural features of the connective stalk (CT), which connect offspring to their mother fronds. Photoautotrophic offspring fronds remained connected by stalks to mother fronds in the reproductive pockets until separation. The CT originated from the meristematic region of the abaxial frond and joined the fronds laterally with two abscission layers. The most notable features of the CT were polymorphic mitochondria, random occurrences of fibrillar structures in intercellular spaces, and great variability in cell wall thickness. Vascular tissues in CTs were highly reduced, demonstrating only a central vascular strand. Grana with 2 to 4 thylakoids and starch grains were found in the chloroplasts. A chlorophyll assay indicated high chlorophyll concentrations in daughter fronds and low concentrations in CTs. The frond and CT, while physically connected to each other, functioned independently. Despite great reduction in S. polyrhiza, the CT has proven to be very efficient for separating offspring from the mother frond, which lends to its capacity for rapid vegetative reproduction. The ultrastructural aspects of CTs in S. polyrhiza were characterized for the first time in this study.

• Journal of Microbiology and Biotechnology
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• 제9권4호
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• pp.475-481
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• 1999

The study of lignin, a major component of secondary cell wall, has been partly focused on its removal from the woody part in the kraft pulping industry. Cinnamyl alcohol dehydrogenase (CAD; EC 1.1.l95) catalyzes the synthesis of cinnamyl alcohols from corresponding cinnamaldehydes. A cDNA clone, MdCADl, encoding putative CAD from apples (Malus domestica Borkh. cv Fuji) was characterized in this study. The clone contains an open reading frame of 325 amino acid residues, which shows a greater than 80％ identity with Eucalyptus CADl. MdCADl mRNA was detectable in vegetative tissues and was strongly expressed in the fruit. The expression pattern of MdCADl mRNA in the fruit peel after light exposure was also examined. The mRNA was rapidly increased until 1 day after light exposure and remained stable thereafter, suggesting that MdCADl is light inducible. The inducibility of the MdCADl gene was examined using several environmental stresses. Mechanical wounding of leaves increased the MdCADl mRNA level and the induction was further increased by salicylic acid. Southern blot hybridization showed that there is either one or a few copies of CAD genes in apples. To our knowledge, it is believed that MdCADl is the first CAD clone expressed predominantly in fruit.

• The Plant Pathology Journal
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• 제35권2호
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• pp.91-99
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• 2019

Mitogen-activated protein kinase (MAPK) cascades in fungi are ubiquitously conserved signaling pathways that regulate stress responses, vegetative growth, pathogenicity, and many other developmental processes. Previously, we reported that the AbSte7 gene, which encodes a mitogen-activated protein kinase kinase (MAPKK) in Alternaria brassicicola, plays a central role in pathogenicity against host cabbage plants. In this research, we further characterized the role of AbSte7 in the pathogenicity of this fungus using ${\Delta}AbSte7$ mutants. Disruption of the AbSte7 gene of A. brassicicola reduced accumulation of metabolites toxic to the host plant in liquid culture media. The ${\Delta}AbSte7$ mutants could not efficiently detoxify cruciferous phytoalexin brassinin, possibly due to reduced expression of the brassinin hydrolase gene involved in detoxifying brassinin. Disruption of the AbSte7 gene also severely impaired fungal detoxification of reactive oxygen species. AbSte7 gene disruption reduced the enzymatic activity of cell walldegrading enzymes, including cellulase, ${\beta}$-glucosidase, pectin methylesterase, polymethyl-galacturonase, and polygalacturonic acid transeliminase, during host plant infection. Altogether, the data strongly suggest the MAPKK gene AbSte7 plays a pivotal role in A. brassicicola during host infection by regulating multiple steps, and thus increasing pathogenicity and inhibiting host defenses.

• Mycobiology
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• 제51권5호
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• pp.273-280
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• 2023

The nucleolus is the largest, membrane-less organelle within the nucleus of eukaryotic cell that plays a critical role in rRNA transcription and assembly of ribosomes. Recently, the nucleolus has been shown to be implicated in an array of processes including the formation of signal recognition particles and response to cellular stress. Such diverse functions of nucleolus are mediated by nucleolar proteins. In this study, we characterized a gene coding a putative protein containing a nucleolar localization sequence (NoLS) in the rice blast fungus, Magnaporthe oryzae. Phylogenetic and domain analysis suggested that the protein is orthologous to Rrp8 in Saccharomyces cerevisiae. MoRRP8-GFP (translational fusion of MoRRP8 with green fluorescence protein) co-localizes with a nucleolar marker protein, MoNOP1 fused to red fluorescence protein (RFP), indicating that MoRRP8 is a nucleolar protein. Deletion of the MoRRP8 gene caused a reduction in vegetative growth and impinged largely on asexual sporulation. Although the asexual spores of DMorrp8 were morphologically indistinguishable from those of wild-type, they showed delay in germination and reduction in appressorium formation. Our pathogenicity assay revealed that the MoRRP8 is required for full virulence and growth within host plants. Taken together, these results suggest that nucleolar processes mediated by MoRRP8 is pivotal for fungal development and pathogenesis.

• Molecules and Cells
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• 제38권6호
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• pp.506-517
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• 2015

Arabidopsis Shaggy-like protein kinases (ASKs) are Arabidopsis thaliana homologs of glycogen synthase kinase 3/SHAGGY-like kinases (GSK3/SGG), which are comprised of 10 genes with diverse functions. To dissect the function of $ASK{\beta}$ (AtSK32), $ASK{\beta}$ antisense transgenic plants were generated, revealing the effects of $ASK{\beta}$ down-regulation in Arabidopsis. Suppression of $ASK{\beta}$ expression specifically interfered with pollen development and fertility without altering the plants' vegetative phenotypes, which differed from the phenotypes reported for Arabidopsis plants defective in other ASK members. The strength of these phenotypes showed an inverse correlation with the expression levels of $ASK{\beta}$ and its co-expressed genes. In the aborted pollen of $ASK{\beta}$ antisense plants, loss of nuclei and shrunken cytoplasm began to appear at the bicellular stage of microgametogenesis. The in silico analysis of promoter and the expression characteristics implicate $ASK{\beta}$ is associated with the expression of genes known to be involved in sperm cell differentiation. We speculate that $ASK{\beta}$ indirectly affects the transcription of its co-expressed genes through the phosphorylation of its target proteins during late pollen development.

• 한국식품저장유통학회지
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• 제10권1호
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• pp.70-74
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• 2003

벼의 산지 및 품종별로는 중온 및 고온성 세균의 분포에 큰 차이가 없었으며, 도정도가 낮을수록 저장기간이 길수록 각각의 균들이 많이 존재하였다. 전기밥솥에서 고온성 세균의 증식은 75$^{\circ}C$이하에서 보온온도가 낮을수록 빠르게 나타났으며, 보온 초기에는 나타나지 않았으나 18∼24시간 사이에 증식속도가 빨라지는 경향을 나타내었다. 전기밥솥 밥의 고온성 세균수와 이상취 발생의 상관성은 있었으며, 고온성 세균수는 오븐내 밥의 표면중앙이 중심이나 밑바닥에 비하여 약간 많게 나타났다. 백미밥의 휘발성 성분은 보온초기에는 쌀로부터 유래되는 hexanal이 주성분이었으며, 장시간보온 후는 이상취를 나타내는 furan을 포함한 고비점 물질이 많았다.

• 한국약용작물학회지
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• 제16권5호
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• pp.287-293
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• 2008

This study was conducted to determine the characteristics of fertilization process and embryo development of Astragalus membranaceus Bunge (Astragali Radix) to provide basic data needed in its breeding. A. membranaceus showed poor seed setting when self-pollination was induced. When artificial pollination was induced, it showed less than 5% bearing in late August, but more than 13% bearing from the beginning of September 4th. The flower size was about $17.0\;mm{\times}4.0\;mm$ and pistils and stamens had the same length of 15.0mm at flowering stage. When self-pollination or cross-pollination was induced, pollen tubes extended to an ovule. While pollen tube was extending to the ovule, reproductive cell split and formed two male generative nuclei and a vegetative nucleus. In the case of self-pollination, fertilized embryo was not observed, but was formed in the case of cross-pollination. A. membranaceus is noted to have zygote self-incompatibility. In the case of cross-pollination, fertilization was observed in 6 to 8 h after pollination, where apical cell derivatives split after fertilization. A spherical pro-embryo was then formed three days after fertilization. The seed attained full shape with a seed coat showing its distinctive contour 15 days after fertilization. Thus, A. membranaceus in Leguminosae family is found to have zygote selfincompatibility although its flower shape is shown to match the self-compatibility plant.

• Molecules and Cells
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• 제28권1호
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• pp.57-65
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• 2009

CDC48 is a member of the AAA ATPase superfamily. Yeast CDC48 and its mammalian homolog p97 are implicated in diverse cellular processes, including mitosis, membrane fusion, and ubiquitin-dependent protein degradation. However, the cellular functions of plant CDC48 proteins are largely unknown. In the present study, we performed virus-induced gene silencing (VIGS) screening and found that silencing of a gene encoding a tobacco CDC48 homolog, NgCDC48, resulted in severe abnormalities in leaf and shoot development in tobacco. Furthermore, transgenic tobacco plants (35S:anti-NgCDC48), in which the NgCDC48 gene was suppressed using the antisense RNA method, exhibited severely aberrant development of both vegetative and reproductive organs, resulting in arrested shoot and leaf growth and sterile flowers. Approximately 57-83% of 35S:anti-NgCDC48 plants failed to develop mature organs and died at early stage of development. Scanning electron microscopy showed that both adaxial and abaxial epidermal pavement cells in antisense transgenic leaves were significantly smaller and more numerous than those in wild type leaves. These results indicate that NgCDC48 is critically involved in cell growth and development of tobacco plants. An in vivo targeting experiment revealed that NgCDC48 resides in the endoplasmic reticulum (ER) in tobacco protoplasts. We consider the tantalizing possibility that CDC48-mediated degradation of an as-yet unidentified protein(s) in the ER might be a critical step for cell growth and expansion in tobacco leaves.

• 생명과학회지
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• 제13권6호
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• pp.814-821
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• 2003

Heme 합성의 중간체이며 또한 광수용체로도 작용하는 protoporphyrin IX의 세포 내 농도 및 성장 배지에 존재하는 농도가 야생형 M. xanthus DK1622 균주로부터 측정되었다. Protoporphyrin IX의 세포 내 농도는 배양 시간이 경과함에 따라 계속 증가하여, 안정기에 최고치에 이르는 것으로 나타났다 안정기에 도달한 세포 내에는 6.4 picomoles/mg of protein의 protoporphrin IX이 존재하는 것으로 밝혀졌다. Protoporphyrin IX은 대수기 중간 시기부터 세포외로 분비가 시작되어, 안정기에 도달한 세포의 배양액에서는 세포의 단백질 대비하여 3.0 picomoles/mg of protein이 존재하는 것으로 측정되었다. 영양분의 고갈에 기인하여 형성된 포자에서도 protoporphyrin IX의 농도는 6.5 picomoles/mg of protein이 존재하는 것으로 관찰되었다. Succinylacetone을 $500\muM$ 농도로 성장 배지에 첨가하였을 경우에 protoporphyrin IX의 생산은 검출이 불가능할 정도로 방해를 받았으며, 세포성장이 저해되고 세포 성장은 정상의 절반 수준인 약 100 Klett unit에서 정지하는 것으로 나타났다. 하지만 포자의 형성은 succinylacetone의 첨가에 관계없이 89-100%의 생성율을 보였음으로 정상 농도의 protoporphyrin IX가 M. xanthus의 성장을 위해서는 중요하지만, 포자 형성 과정에 필수적인 것으로 보이지는 않는다. 안정기 세포에서 나타나는 photolysis 현상도 succinylacetone의 첨가 여부에 관계없이 유사한 수준으로 관찰되었다.