• Horticultural Science & Technology
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• v.32 no.5
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• pp.607-613
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• 2014

Calcium has been associated with improved cold tolerance in many crops. The aim of this study was to investigate the changes in leaf cell $Ca^{2+}$ distribution and cell organelle ultrastructure of loquat (Eriobotrya japonica Lindl.) plants in response to cold stress at $-3^{\circ}C$, using transmission electron microscopy (TEM). Two loquat accessions, Zaozhong 6 (a commercial cultivar) and oakleaf loquat (a wild relative) were used. Cold tolerance, as measured by leaf browning rate, was higher in oakleaf plants, and calcium treatment improved cold tolerance in both species. Cold stress first induced inward transport of $Ca^{2+}$ from the intracellular space. Then, the imported $Ca^{2+}$ was aggregated around the chloroplast membrane, finally entering the chloroplast. This pattern of $Ca^{2+}$ distribution in leaf cells occurred earlier in Zaozhong 6 than in the wild loquat. With increasing time of cold exposure, the chloroplast membranes of Zaozhong 6 leaves were damaged, blurred and even disappeared, while those of wild oakleaf loquat leaves maintained their structure longer. In Zaozhong 6, cold stress induced a clear cavity between poorly structured granal thylakoids and vesicles appearing inside the chloroplast, while in oakleaf leaves cold stress had little effect on the ultrastructure of chloroplasts (although chloroplast membranes looked blurred). Loquat leaves accumulated free calcium ions around chloroplasts in response to cold stress, with earlier calcium accumulation occurring in the cold-sensitive cultivar Zaozhong 6 than in wild oakleaf loquat. These results demonstrate that these two loquat species have differences in both cold tolerance and calcium accumulation dynamics.

• Journal of Life Science
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• v.14 no.1
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• pp.45-50
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• 2004

To investigate the effect of the cell wall on the pigmentation and branching in Aspergillus nidulans, ultrastructure of cell wall in suppressor mutant of the null pigmentation (SU-NPG, SU602) has been examined. Scanning electron microgrphs (SEM) revealed that the most outer layer of conidia wall peeled off in SU-NPG on day 6 from the complete conidiation. They also showed that hyphal growth and branching were not well developed in SU-NPG. Transmission electron micrographs (TEM) showed that the plasma membrane was not crenulated and the hyphal wall was thick in SU-NPG. These results indicated that the ultrastructure of cell wall in SU-NPC might be modified. Cytochemical analysis showed that the cell wall in SU-NPG was differentiated into Cl, C3, C2 and C4 layer in conidia and H1, H3, H2 and H4 layer in hyphae. C3 layer and H3 layer existed in SU-NPG. The increment of the diameter in SU-NPG hyphae might be caused by the thickness of H3 layer. These results suggest that SU-NPG may have an immature but the differentiated structure for the pigmentation in cell wall.

• Parasites, Hosts and Diseases
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• v.33 no.3
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• pp.165-172
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• 1995

A transmission electron microscopic study was performed on the ultrastructure of the tegumental layer of GymophoLloines seoi (Digenea: Gymnophallidae) metacercarlae and adults. The metacercariae were obtained from naturally infected oysters, Crcssosoea gigas, and the adults from experimentally infected C3H mice. The tegumental layer generally revealed a small number of foldings, numerous small vacuoles, sines, and muscle bundles. Beneath the muscle layer, nuclei of the tegumental cells were located. There was little difference in the structure of the tegument between the metacercariae and adults. The oral sucker, having well-developed muscle layers, showed a similar structure to the ventral sucker except numerous foldlngs in the ventral sucker. The ventral pit was surrounded by a thin spcpiu layer, where a number of microtubules and mitochondria were seen. Around the ventral pit located well-developed circular and longitudinal muscles. The results showed that the ultrastructure of the tegumental layer of G. seoi metacercariae and adults revealed little difference from other trematodes in general. The ventral pit, a peculiar structure of this trematode, seems to function as a sphincter or an accessory adhesive organ.

• Mycobiology
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• v.29 no.1
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• pp.15-18
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• 2001

Protoplast fusion is a useful technique for establishing fungal hybrids to overcome the natural barriers. The ultrastructure of protoplast and its fusion process were observed using a scanning electron microscopy(SEM) and a transmission electron microscopy(TEM). The protoplasts were variable in size from $0.5{\sim}15{\mu}m$ in diameter, and the mean diameter was about $3{\sim}5{\mu}m$. It was impossible to discriminate protoplasts of Lentinula edodes from protoplasts of Coriolus versicolor by size and surface structure. Big aggregates of the dehydrated protoplasts were observed, after polyethylene glycol 4000 treatment. Nucleus, mitochondria, lipid granules and various vesicles having granules were scattered in the cytoplasm. The vesicles were heterogeneous in size and vary from one protoplast to another. The fused membrane layer of the two protoplasts was observed. Time protoplast membrane contact and reorganization of membrane components were essential condition for protoplast fusion. Transmission electron micrograph showed fused protoplasts and flattening of the cells in the area of the membrane contact. We hope that our electron microscopic observations provide some insights into the understanding of the fusion process of protoplast in fungi.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.4
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• pp.283-292
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• 2005

This study investigated the effects of naringin, and chitosan in rabbits' corneas. Naringin, a glycone of naringenin, is a widely distributed bioflavonoid in the grapefruit and citrus peel, and it has already been reported as an antioxidant, antimicrobial, and anticancer agent. It has been used as a food preservatives and cosmetics. One of the natural preservatives, chitosan has also used in food preservatives, health drinks, and teas. Chitosan is distributed in the epithelium of crustacea, insects, and fungi. Naringin and chitosan have no harmful effects of cytotoxicity in the human body and they are recognized as an antibacterial for various forms of bacteria. The purpose of this study is to search for the ideal percentage of natural products to substitute the chemical preservatives occuring within the cornea and conjunctiva cytotoxicity and inflammations as wearing on soft contact lens. The present study compared the morphology of corneal epithelium and endothelium observed by light microscopy (LM) and transmission electron microscopy (TEM). In vivo methods, We investigated the effects of natural preservatives on soft contact lens. We inserted 3-4 drops of the naringin and chitosan, directly on rabbits' corneas 4 times per a day during one week. After enucleation of cornea, morphorgical damages of the epithelium and endothelium were observed by LM and TEM. In view of ultrastructure, chitosan caused siginficant damage on the epithelium and endothelium of cornea. The damage of cells was higher in chitosan treated cornea than 0.01, 0.1, and 1% of naringin. The 1% of naringin also expressed cell damage seriously. The results suggest that the most important thing is to use the reasonable percentage of preservatives for contact lens solutions.

• Korean Journal of Environmental Biology
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• v.37 no.3
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• pp.260-267
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• 2019

Two aerophytic cyanobacteria from the rockwall of Haje port located in Geum river, Korea, were isolated in unialgal cultures and submitted to polyphasic evaluation. The filaments of the populations presented solitary or several to many parallel arranged. The straight trichomes were not attenuated with rounded apical cell. Phylogenetic analyses based on 16S rDNA sequences indicated that these populations formed the same clade with Wilmottia murrayi and had 99% or greater DNA similarity. Through the ultrastructure of the TEM, these populations showed parietal thylakoid arrangement, which coincides with family Coleofasciculaceae. From the above results, we reported the newly recorded genus Wilmottia, and species W. murrayi in Korea.

• Korean Journal of Veterinary Research
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• v.31 no.1
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• pp.89-97
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• 1991

For the ultrastructural observation on Babesia gibsoni(B gibsoni), the protozoa were challenged experimentally to splectomized dog. To examine the ultrastructure of the B gibsoni in the erythrocyte, the infected erythrocytes were collected at the cephalic or jugular vein of the dog. The results obtained by TEM(transmission electron microscopy) were as follows; 1. The sizes of protozoa in erythrocytes are $0.92{\pm}0.36{\mu}m{\times}0.67{\pm}0.21{\mu}m$, the sizes of nucleus of the protozoa are $0.55{\pm}0.24{\mu}m{\times}0.38{\pm}0.26{\mu}m$, and sizes of rhoptries in plasma of the protozoa are $0.33{\pm}0.05{\mu}m{\times}0.25{\pm}0.07{\mu}m$, respectively. 2. The tropozoite membrane in the erythrocyte was one, and it's nuclear membrane was made up of double. But the protozoa of initial stage in infected erythrocyte had double clear mambranes, and distinguished from plasma membrane of red blood cell. 3. The mitochondrialike structures covered with two membranes were observed in the protozoa. 4. Mitochondria and vesicles of the reticulocyte were observed near protozoa in the erythrocyte. 5. There are rhoptry, coiled structure and single nucleous in the merozoite. 6. The shape of rhoptry was round or ovoid form and in occasionally, the content of rhoptry was lost partially. 7. There was able to observe the dividing process of the protozoa. 8. Maurer's cleft-like structure was observed.

• Korean Journal of Ichthyology
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• v.12 no.2
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• pp.111-117
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• 2000

There were observed the histomorphological alterations such as chloride cell hyperplasia, branchial lamellar epithelial separation, the increased cellular turnover of chloride cells, glomerular shrinkage and blood congestion in rainbow trout (Oncorhynchus mykiss) during the seawater adaptation. The ultrastructure by scanning electron microscope (SEM) indicated that the gill secondary lamella of rainbow trout exposed to seawater, were characterized by rough convoluted surfaces during the adaptation. There were observed a large number of mitochondria with the elongate and well-developed cristae in chloride cells exposed to seawater by transmission electron microscope (TEM). The presence of two mitochondria- rich cell types is discussed with regard to their possible role in the hypoosmoregulatory changes which occur during seawater-adaptation. Glomerulus shrinkage and blood congestion were occurred higher in nephrons of seawater-adapted fish than those living in freshwater. Our findings demonstrated that rainbow trout tolerated moderately saline environment and the increased body weight living in seawater was relatively higher than that living in freshwater in spite of histopathological changes.

• ALGAE
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• v.28 no.4
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• pp.331-341
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• 2013

Rhinomonas reticulata var. atrorosea G. Novarino is a photosynthetic marine flagellate that is known to have typical characteristics of cryptomonads. We examined the flagellar apparatus of R. reticulata var. atrorosea by transmission electron microscopy. The major components of the flagellar apparatus of R. reticulata var. atrorosea consisted of four types of microtubular roots (1r, 2r, 3r, and mr), a non-keeled rhizostyle (Rhs), mitochondrion-associated lamella (ML), two connections between basal bodies, a striated fibrous root (SR) and a striated fiber-associated microtubular root (SRm). Four types of microtubular roots originated near the ventral basal body and extended toward the left side of the basal bodies. The non-keeled Rhs originated at the Rhs-associated striated fiber, which was located between two basal bodies and extended into the middle of the cell. The ML was a plate-like fibrous structure associated with mitochondria and originating from a Rhs-associated fiber. It split into two parts and extended toward the dorsal-posterior of the cell to a mitochondrion. The SR and SRm extended parallel to the anterior lobe of the cell. The overall configuration of the flagellar apparatus in R. reticulata var. atrorosea was similar to the previously reported descriptions of those of Cryptomonas paramecium, C. pyrenoidifera, C. ovata, Hanusia phi, Guillardia theta, and Proteomonas sulcata. However, the flagellar apparatus system of R. reticulata var. atrorosea was more complex than those of other cryptomonad species due to the presence of an additional microtubular root and other distinctive features, such as a rhizostyle-associated striated fiber and large ML.

• Parasites, Hosts and Diseases
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• v.35 no.2
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• pp.79-86
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• 1997

Toxoplasmn gonnii, an intracellular protozoan infecting many kinds of eukaryotic cells, has been used to experimentally infect macrophages, epithelial cells, fibroblasts, and various cancer cells, but rarely T and B Iymphocytes or granulocytes. The present study was performed to determine the susceptibility of murine (BALB/c or CBA) splenic T and B llrnphocytes, and granulocytes to infection trio T. gondii RH tachyzoites. The ultrastructure of the infected host cells was observed by TEM, and the degree of intracellular parasite proliferation was quantified using 3H-uracil uptake assay. At 24 hrs post-culture, the host cell cytoplasm was found to contain 1 or 2, or a maximum of 7-8 tachyzoites. Infected T Iymphocytes demonstrated a peripherally displaced nucleus, a parasitophorous vacuole enveloping the parasite, and an increased number of mitochondria. In B Iymphocytes infected with tachyzoites, RER was not well developed compared to uninfected B Iymphocytes. Uninfected granulocytes contained many electron dense granules, but T. gondii-infected granulocytes demonstrated a decreased number of granules. Based on the 3H-uracil uptake assay. the susceptibility of T and B Iymphocytes, and granulocytes, to infection with T. gonnii tachyzoites was fairly high irrespective of cell type and strain of mouse. This strongly suggests deterioration in the functioning of infected host immune cells.