• Journal of Microbiology and Biotechnology
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• v.12 no.2
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• pp.183-188
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• 2002

The ohmic heating of foods for sterilization provides a shorter come-up time compared to conventional thermal processes. The electric fields as well as the heat generated by ohmic heating facilitate germicidal effects. In the present study, the effect of ohmic heating on the structure and permeability of the cell membrane of yeast cells, Saccharomyces cerevisae, isolated from Takju (a traditional Korean rice-beer), was investigated. The ohmic heating was found to translocate intracellular protein materials out of the cell wall, and the amount of exuded protein increased significantly as the electric field increased from 10 to 20 V/cm. As higher frequencies were applied, more materials were exuded. Compared to conventional heating, more amounts of proteins and nucleic acids were exuded when these cells were treated with ohmic heating. The molecular weights of the major exuded proteins ranged from 14 kDa to 18 kDa, as analyzed by Tricine-SDS PAGE. A TEM study also confirmed the leakage of cellular materials, thus indicating irreversible damage to the cell wall by ohmic heating. It was, therefore, concluded that the electric fields generated by ohmic heating induced electroporation, causing irreversible damage to the yeast cell wall and promoting the translocation of intracellular materials.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.4
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• pp.715-719
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• 1996

Dietary fibers consist mostly of complex carbohydrates such as cellulose, hemicelluloses and pectins, and also included are carbohydrate-based gums or hydrocolloids exampled as alginate, carrageenan, galactomannan xanthan, etc. Due to structural diversity, dietary fibers can be classified by various ways i.e., source, plant function, solubility, charge and topology. Understanding on the plant cell wall structure is of primary importance, since physicochemical properties of dietary fibers are dependent on the existence patterns in the cell wall. Depending on the four distinct observational dimensions, the physical parameters of dietary fibers were discussed in terms of raw sources, bulky & complex plant cell wall materials, individually separated hydrocolloid materials and specifically designed materials. Each existence state possesses the distinct physical parameters governing a variety of physiological properties of dietary fibers.

• Journal of Microbiology and Biotechnology
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• v.10 no.3
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• pp.333-337
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• 2000

An oil-degrading yeast, Yarrowia lipolytica 180, exhibits interesting cell surface characteristics under the growth on hydrocarbons. An electron microscopic study revealed that the cells grown on crude oil showed protrusions on the cell surface, and thicker periplasmic space and cell wall than the cell surface, and thicker periplasmic space and cell wall than the cells grown on glucose. Y. lipolytica cells lost its cell hydrophobicity after pronase(0.1 mg/ml) treatment. The strain produced two types of emulsifying materials during the growth on hydrocarbons; one was water-soluble extracellular materials and the other was cell wall-associated materials. Both emulsifying materials at lower concentration (0.12%) enhanced the oil-degrading activity of Moraxella sp. K12-7, which had medium emulsifying activity and negative cell hydrophobicity; however, it inhibited the oil-degrading activity of Pseudomunas sp. K12-5, which had medium emulsifying activity and cell hydrophobicity. These results suggest that the oil-degrading activity of Y. lipolytica 180 is closely associated with cell surface structure, and that a finely controlled application of Y.lipolytica 180 in combination with other oil-degrading microorganisms showed a possible enhancing efficiency of oil degradation.

• Applied Microscopy
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• v.14 no.2
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• pp.38-51
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• 1984

Fine structure of dormant and swollen conidiospore from Trichoderma koningii and the mechanism of protoplasting from the conidiospore were studied by scanning and transmission electron microscopy. The cell wall of dormant conidiospore was two-layered structure which consisted of electron dense outer layer and electron transparent inner layer. After 8.5 hrs incubation. the conidiospore was swollen and the outer layer of cell wall shown unequal thickness and partial breakage. Protoplast was released through the pore which has been formed by the breakage of outer layer and dissolution of newly synthesized cell wall for germ-tube formation. Swollen conidiospore and protoplast in releasing process contained various cell organelles and vacuoles with electron dense materials. The protoplast contained looser cytoplasm and had no cell wall materials outside of plasmamembrane.

• 보존과학연구
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• s.7
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• pp.246-264
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• 1986

Micoromorphological alterations of sea-waterlogged woods by marinemicro-oragnisms were investigated by the light and scanning electron microscopy as a part of serial investigations on the shipwrecked materials which were excavated at the sea shore of Wando-Kun, southern coast of Korea in 1984.Deterioration of sea-waterlogged wood by marine microorganisms were varied with the wood species. The degree of deterioration even in the same wood specieswas different according to the part where it was in mud of sea-water. However, the resistance of Torreya nucifera over the marine organisms was marked. Deterioration in cell wall may be classified into three types; thinning of cell wall, separation of secondary wall from compound middle lamella and tunneling of cell wall. Thinning and separation were frequently observed, while the tunneling was rare. Among the wood cell elements of hardwoods, vessel wall was the least deteriorated. The difference degree of degradation of cell wall constituents and the accumulation of inorganic substances in cell lumen indicate that some factors to be considered for the conservation treatment were discussed. The kinds of marine microorganisms invading and/or inhabiting in wrecked wooden ship were also discussed.

• The Plant Pathology Journal
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• v.25 no.2
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• pp.113-120
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• 2009

Microscopic study of chili pepper (Capsicum annuum L.) infected with Phytophthora capsici, causing Phytophthora blight of chili pepper, was conducted to compare histological and cytological characteristics in the root and stem of susceptible (C. annuum cv. Bugang) and resistant (C. annuum cv. CM334) pepper cultivars. The susceptible pepper roots and stems were extensively penetrated and invaded by the pathogen initially into epidermal cells and later cortical and vascular cells. Host cell walls adjacent to and invaded by the infecting hyphae were partially dissolved and structurally loosened with fine fibrillar materials probably by cell wall-degrading enzymes of the pathogen. In the resistant pepper, the pathogen remained on root epidermal surface at one day after inoculation, embedded and captured in root exudation materials composed of proteins and polysaccharides. Also the pathogen appeared to be blocked in its progression at the early infection stages by thickened middle lamellae. At 3 days after inoculation, the oomycete hyphae were still confined to epidermal cells of the root and at most outer peripheral cortical cells of the stem, resulting from their invasion blocked by wound periderms formed underneath the infection sites and/or cell wall appositions bounding the hyphal protrusions. All of these aspects suggest that limitation of disease development in the resistant pepper may be due to the inhibition of the pathogen penetration, infection, invasion, and colonization by the defense structures such as root exudation materials, thickened middle lamellae, wound peridems and cell wall appositions.

• The Plant Pathology Journal
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• v.27 no.1
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• pp.8-13
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• 2011

The induced resistance of cucumber leaves treated with oligochitosan to the infection of the cucumber powdery mildew, Sphaerotheca fuliginea, was investigated using transmission electron microscopy. The results showed that when the plants were treated with oligochitosan and challenged with inoculum, a significant decrease of the disease occurred. The mycelial development in the treated leaves was markedly inhibited. The cytoplasm of the powdery mildew mycelium was aggregated, with its organelles disintegrated and the cytoplasm collapsed. The protoplasm in haustoria became electron-dense. Haustoria became malformed, their organelles disintegrated, the hausterial wall thickened and eventually the whole complex necrotized. The host cells produced defence structures and materials associated with infection and a hypersensitive response. The host cell wall was thickened and deeply stained; several layers of papilla structure were produced under the cell wall; dark materials were deposited between the cell wall and plasmalemma; extrahaustorial plasmalemma was deeply stained and extrahaustorial matrix appositions had large deposits of electron-dense material; the cytoplasm was disordered, host organelles disintegrated and eventually the whole host cell disintegrated and necrotized.

• Journal of Powder Materials
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• v.27 no.2
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• pp.119-125
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• 2020

One of the promising candidates for accident-tolerant fuel (ATF), a ceramic microcell fuel, which can be distinguished by an unusual cell-like microstructure (UO₂ grain cell surrounded by a doped oxide cell wall), is being developed. This study deals with the microstructural observation of the constituent phases and the wetting behaviors of the cell wall materials in three kinds of ceramic microcell UO₂ pellets: Si-Ti-O (STO), Si-Cr-O (SCO), and Al-Si-Ti-O (ASTO). The chemical and physical states of the cell wall materials are estimated by HSC Chemistry and confirmed by experiment to be mixtures of Si-O and Ti-O for the STO; Si-O and Cr-O for SCO; and Si-O, Ti-O, and Al-Si-O for the ASTO. From their morphology at triple junctions, UO₂ grains appear to be wet by the Si-O or Al-Si-O rather than other oxides, providing a benefit on the capture-ability of the ceramic microcell cell wall. The wetting behavior can be explained by the relationships between the interface energy and the contact angle.

• Applied Microscopy
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• v.28 no.2
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• pp.159-170
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• 1998

The glandular secretory system of the capitate gandular trichomes in leaf of Thymus quinquecostatus Celakovsky was examined by transmission electron microscope. The glandular trichome was consisted of three cell layers; an basal cell layer, a stalk cell with single-celled intermediate layer and a discoid secretory layer with thickened cuticle. The secretory cell was dense, rich in mitochondria, rER, plastds, Golgi complex and had many vesicular structure. Typical plastids with reticulate body and plastoglobule were present in glandular trichome. The tytoplasm of secretory cell was filled with osmiophilic secretory materials. The secretory vesicles, originated from Golgi complex, appeared as membrane bounded vesicles and secreted to the outer wall surface. The presences of well developed rER, mitochondria, Golgi complex, and membrane-bounded vesicles fused with plasmalemma in the secreting cells indicate that the granulocrine mechanism of secretion was occurring in T. quinquecostatus. Subcuticular cavity was developed between the cuticular layer and the secretory cell wall, and it formed above the secretory cell upon separation of cuticle-wall.

• Korean Journal of Pharmacognosy
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• v.45 no.4
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• pp.346-353
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• 2014

This study was performed to investigate the effects of cell-wall broken spores of Ganoderma lucidum on the lipid accumulation and body weight reduction in C57BL/6J mice. Six-week-old C57BL/6J mice were randomly divided into 5 groups and assigned to one of these groups; normal chew diet(Nor) group, high-fat diet(HFD) group, HFD plus spores of Ganoderma lucidum 800 mg/kg/day (HFD + GS/B) group, HFD plus cell-wall broken spores of Ganoderma lucidum 400 mg/kg/day (HFD + BGS/A) group and finally HFD plus cell-wall broken spores of Ganoderma lucidum 800mg/kg/day (HFD + BGS/B). The experimental groups which were treated oral co-administration with cell-wall broken(or original) spores of Ganoderma lucidum and HFD significantly attenuated accumulative body weight gain, compared with HFD group. Administration of these experimental materials also resulted in significant reduction not only the serum levels of total cholesterol, homocysteine but also the lipid accumulation in liver tissue. But in the almost of results the cell-wall broken spores of Ganoderma lucidum were evaluated superior than the original one. These results indicate that cell-wall broken spores of Ganoderma lucidum may inhibit the lipid accumulation in blood as well as liver tissue. Therefore it may be a valuable candidate for the therapy preventing obese induced hyperlipidemic symptoms.