• Applied Microscopy
• /
• v.34 no.4
• /
• pp.271-276
• /
• 2004

The genus of Biscogniauxia, well known wood degrading fungi, is a member of the Xylariales, which has woody to carbonaceous, brown to dark brown stromata. Daldinia concentrica and Biscogniauxia sp. isolated from heavily decayed hardwood, are precisely described under light microscopic and scanning electron microscopic level. Daldinia concentrica will be the first ultrastructural description in Korea. The unidentified species collected, having small size of ascospores $11.4\;15.6{\times}9.6\;12.0{\mu}m$ with full germ slit, are taxono-mically compared with similar species found in Korea.

• Toxicological Research
• /
• v.17 no.1
• /
• pp.33-39
• /
• 2001

To evaluate the skin toxicity oj topical toluene application, toluene (35 mg/$cm^2$) was sequentially applied to the portion rat skin for five days. The topical toluene application resulted in increased xanthine oxidase activity and CYP content, and significantly decreased superoxide dismutase and glutathione peroxidase activities at five days in rat skin. Especially catalase activity was remarkably decreased in toluene-applied rat skin. And benzylalcohol dehydrogenase activity showed also a significant decrease in toluene-applied skin. On the other hand, histopathological ultrastructural examination revealed disrupted epidermal basement membrane, rared intercellular adhensions and degenerated keratin layer due to topical toluene application. Increased deposit of cerrous perhydroxide resulted from reaction with $H_2O_2$was abserved in toluene-treated animals. These results indicate that oxygen free radical may be responsible for ultrastructural changes in skin tissue by toluene application to rat skin.

• ALGAE
• /
• v.21 no.4
• /
• pp.349-375
• /
• 2006

The application of modern ecological, ultrastructural and molecular methods, aided by the cultivation of numerous cyanobacterial morphotypes, has substantially changed our knowledge of these organisms. It has led to major advances in cyanobacterial taxonomy and criteria for their phylogenetic classification. Molecular data provide basic criteria for cyanobacterial taxonomy; however, a correct phylogenetic system cannot be constructed without combining genetic data with knowledge from the previous 150 years research of cyanobacterial diversity. Thus, studies of morphological variation in nature, and modern morphological, ultrastructural, ecophysiological and biochemical characters need to be combined in a “polyphasic” approach. Taxonomic concepts for generic and infrageneric ranks are re-evaluated in light of combined phenotypic and molecular criteria. Despite their usefulness in experimental studies, the limitations of using strains from culture collections for systematic and nomenclatural purposes is highlighted. The need for a continual revision of strain identification and proper nomenclatural practice associated with either the bacteriological or botanical codes is emphasized. Recent advances in taxonomy are highlighted in the context of prospects for understanding cyanobacterial diversity from natural habitats, and the evolutionary and adaptational processes that cyanobacteria undergo.

• Journal of Microbiology
• /
• v.34 no.3
• /
• pp.220-224
• /
• 1996

Ultrastructural organization of encysting zoospores of Allomyces macrogynus was examined using the methods of cryofixation and freeze substitution. During enxcystment, obvious changes were observed at the surface of the plasma membrane and in the structure of gamma particles. Many multivesicular bodies associated with the plasma membrane were observed at early stages of encystment. After induction of encystment, vesicles were found within the gamma particles. These vesicles appeared to leave gamma particles after forming multivesicular bodies. This study suggests that the cell wall formation during encystment is mediated by the fusion of multivesicular bodies with the plasma membrane.

• Applied Microscopy
• /
• v.19 no.2
• /
• pp.59-73
• /
• 1989

To investigate the effect of cadmium and cadmium binding protein on the electron transport system and conformational changes of rat kidney mitochondria, various cadmium concentration were treated in vitro and respiration rate, NADH-CoQ reductase activity were measured. Ultrastructural changes at state IV respiration were also observed. CdBP was isolated from the rat liver by Sephadex G-75 column fractionation and treated in vitro with cadmium. Also mitochondrial state IV respiration rate was measured. When cadmium was treated in vitro, state IV respiration and enzyme activity were decreased and ultrastructural transformation of mitochondria from a condensed to an orthodox conformation was inhibited under state IV respiration. In case cadmium and CdBP were treated together, oxygen consumption was more increased than cadmium only. Conformational changes of mitochondria from a condensed to orthodox conformation were also observed. This indicates that CdBP have a protective effect against cadmium toxicity.

• Parasites, Hosts and Diseases
• /
• v.47 no.1
• /
• pp.65-68
• /
• 2009

Excretory-secretory products of Toxocara canis larvae have been considered as a major functional antigen in immune responses against toxocariasis. We studied ultrastructural localization of T. canis second-stage larval antigen using a seropositive human serum under immunogold electron microscopy. High-density gold particles were observed in the secretory cells, excretory duct, intestinal epithelium, and cuticle of the larval worm sections. The distribution of the positive reactions in the larval worms suggests that the nature of the antigen is excretory-secretory antigen including waste metabolites and secretory enzymes.

• Korean Journal of Veterinary Research
• /
• v.24 no.1
• /
• pp.64-68
• /
• 1984

Undifferentiated leiomyosarcomas were encountered in two dogs, and an ultrastructural study was carried out. The results of this study were summarized as follows; 1. The nuclei of mosts tumor cells showed bilobate appearance. 2. Most cells of the tumors had not a distinct basement membrane. 3. Most cells of the tumors had a degenerative rough endoplasmic reticulum. 4. Intercellular matrix contained some amounts of collagen. 5. Attachment areas between tumor cells were not apparent, but a few tight junction were clearly seen. 6. Myofibrils were present in bipolor end area.

• Applied Microscopy
• /
• v.21 no.1
• /
• pp.27-45
• /
• 1991

To study the effects of dietry methionine level on lipid peroxidation of rats, rats were fed vitamin E, selenium and methionine - deficient diet or the same diet supplemented with various levels(0.3%, 0.6%, 0.9%) of methionine for 6 weeks. The biochemincal and mophological changes in the rat liver were investigated. Lipid peroxide levels in plasma and hepatic mitochondrial fraction of MF rats were more increased than those of control rats. However, supplementation with 0.6% methionine modified this increment. Catalase activity was decreased in hepatic mitochondrial fraction from rats fed MF diet. Methionine supplementation did not induce this enzyme. The ultrastructural evidence for lipid peroxidation was found in plasma membranes facing sinusoids. The most striking changes in including disruption and loss of microvilli and development of numerous lipid droplets occurred in rats fed MF diet. These changes were not effectively prevented by the same diet supplemented with 0.3% or 0.9% methionine, but supplementation with 0.6% methionine modulated more or less the changes.

• The Korean Journal of Malacology
• /
• v.20 no.1
• /
• pp.7-16
• /
• 2004

Histochemical and ultrastructural studies on the salivary gland and salivary duct of a land snail Nesiohelix samarangae were conducted to observe structural characteristics and function. The salivary gland consisted of one type of epithelial cell, one type of supporting cell, and six types of gland cells. Four out of six gland cell types were histochemically identified on these secretions. The one secreted acid mucopolysaccharide and the other three secreted neutral mucopolysaccharide. The salivary duct epithelium had only one type of columnar cell with microvilli on its luminal surface. The basal protoplasmic membranes of the epithelial cells were deeply infolded so many times all along the cell bases.

• The Korean Journal of Zoology
• /
• v.39 no.2
• /
• pp.139-146
• /
• 1996

A studv on the ultrastructural changes of the hermaprodite duct epithelium in spring and summer specimens of a Korean slug Incirovia fruhstorferi was conducted. In spring specimen, the hermaphrodite duct was 0.3 H 0.2 mm in diameter and seemed to be a little bit abnormal feature, due to shrinkage. The epithelium of the duct was composed of cells containing various-sized vacuoles and their cytoplasm showed high electron density. In summer specimen, the hermaphrodite duct was 0.4 $\times$ 0.23 mm in diameter and seemed to be more voluminous than that of the spring specimen. The lumen of the duct in the summer specimen was lined by a epithelium composed of several cell types such as ciliated cuboidal, pseudostratified cuboidal, ciliated columnar and irregular cells. Phasocvtotic activities of the duct epithelium are observed only in the summer specimen. Both of the duct epithelia in the spring and summer specimens were surrounded by connective tissues at their bases. The results obtained suggest that the duct epithelia of the slugs experience seasonal variation in relation to their reproductive cycles.