• Korean Journal Plant Pathology
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• v.10 no.2
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• pp.144-147
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• 1994

About 450 phytopathogenic fungal cultures were stored in sterile distilled water ar room temperature by the sterile water storage method, which has been known as a simple, convenient, and long-term storage method of microorganisms. After 12 months, viability and pathogenicity of the stored isolates were tested. Among 205 tested, 175 isolates (84.5%) survived. Of these, Rhizoctonia solani, Botrytis cinerea, Pyricularia oryzae, Phytophthora infestans, and Sclerotinia sclerotiorum showed relatively lower survival rate; 92%, 74.1%, 62.5%, 45.8%, and 30%, respectively. Twenty seven isolates belonging to seven important phytopathogenic fungi were tested for pathogenicity, and all isolates tested maintained pathogenicity until at least 12 months after storage.

• Parasites, Hosts and Diseases
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• v.21 no.2
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• pp.234-240
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• 1983

The pathogenicity of free-living amoeba, Waegleria fcwleri, is influenced according to the strain, cultural condition and host (Culbertson et at., 1968; Carter, 1970; Wong et at., 1975), Phillips (1973) demonstrated that Entamoeba histolytica became avirulent after more than 2 year maintenance in axonic culture in vitro. This study was carried out to compare the difference in pathogenicity between two strains of N. fowleri, one of a prolonged maintenance in arsenic medium and the other one obtained by serial brain passage in mice. The 0 strain was that N. fowleri had cultivated axenically more than 7 years in CGVS medium. The 2-1 strain was obtained from the brain of mouse inoculated intranasally with a strain, which was from the mouse brain infected with 0 strain, and cultured for 15 weeks until the beginning of this experiment. White male mice weighing 18-22 g were used. Mice were anesthetized by an intraperitoneal injection of about 1 mg secobarbital, and inoculated intranasally with $10{\times}$10^4 live N. fowleri trophoBoites in a $5{\;}{\mu}l$ cell suspension. Sluggish behaviour, nervousness, rotation and leg paralysis were developed earlier and more frequently in the 2-1 experimental group than the control 0 group. Pathological changes such as inflammatory and necrotic lesion were observed in the olfactory and anterior portion of brain, and these changes were more extensive in the 2-1 group. The edematous and inflammatory changes in lung were demonstrated in mice died after 13th day post-inoculation. The experimental mice of 2-1 group began to die suddenly from 7th day post-inoculation, and the survival time in 2-1 group mice was shorter than 0 group mice. The typical primary amoebic meningoencephalitis was developed in the mice inoculated intranasally with N. fowleri. The prolonged maintenance of N. fowleri amoebae in axonic CGVS medium was observed to have lost their original pathogenicity for mice, but their pathogenicity was restored by serial brain passage in mice.

• The Korean Journal of Mycology
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• v.43 no.4
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• pp.286-289
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• 2015

Clubroot, caused by the obligate parasite Plasmodiophora brassicae, is a severe soilborne disease of Brassicaceae. Storage of clubroot gall is important for studies on pathogenicity and race identification. As the current storage method has been used for more than 100 years, a new storage method should be developed and the most efficient way maintaining pathogenicity should be determined. Effects of storage conditions with different storage periods on pathogenicity in galls of kimchi cabbage were examined in a greenhouse. The experiments were performed under six conditions and four temperatures in order to determine the most effective storage conditions for maintenance of pathogenicity. The most effective conditions for clubroot gall storage was the storage of whole gall at $-70^{\circ}C$ or storage of filtrate at the same temperature through eight layers of gauze after homogenization of the galls.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.11a
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• pp.65-73
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• 1996

LPS/LOS, the compound found only in gram-negative bacterial outer membrane, plays important roles in bacterial maintenance as well as its pathogenesis. We isolated and characterized several genes required for NTHi 2019 LOS biosynthesis, which encode enzymes required for sugar substrate synthesis or the transfer of substrates to receptor molecules. The htrB gene, however, appears to have more complex role. It has acryltransferase activity as well as various other activity, which may control regulation of LOS biosynthesis as well as its pathogenicity. Evidences supporting the latter come from the observations that the lipid A of the B29 induced significantly less TNF ${\alpha}$ from macrophages than that of the wild type LOS (unpublished data). H. influenzae A2-htrB mutant strain was also significantly less invasive than the wild type strain. The structural similarities of the enterobacterial LPS and the Haemophilus LOS enabled us to isolate the NTHi 2019 genes involved in LOS biosynthesis genes by using the S. typhimurium LPS deep core mutants. While a similar approach has been used for E. coli, this technique for selection of an LPS phenotype has not been applied to nonenterobacterial species. The difficulties inherent in the molecular manipulation of organism such as Neisseria and Haemophilus species make this approach particularly attractive in the identification and cloning LOS genes. Studies on genetic features of LPS/LOS biosynthesis would be useful for understanding bacterial pathogenesis as well as for developing vaccines for these gram-negative pathogenic bacteria.

• Parasites, Hosts and Diseases
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• v.41 no.3
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• pp.147-154
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• 2003

Toxoplasma gondii tachyzoites were isolated from the blood of an ocular patient, and have been successfully passaged in the laboratory, for over a year, by peritoneal inoculation in mice. The isolated parasite was designated the Korean Isolate-1 (KI-1) and its characteristics were compared with those of the RH strain, a well-known virulent strain originating from a child who suffered from encephalitis. The morphology, pathogenicity, infectivity and cell culture characteristics of the KI-1 were similar to those of the RH strain. Both RH and KI-1 antigens were detected by an anti-T gondii monoclonal antibody (mAb), Tg563, against the major surface protein SAG1 (30 kDa), whereas no reaction was observed against an anti-Neospora caninum mAb, 12B4. The KI-1 was confirmed as an isolate of T. gondii. A long-term laboratory maintenance and characterization of a local T gondii isolate is reported for the first time in the Republic of Korea.

• Korean journal of applied entomology
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• v.18 no.2 s.39
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• pp.73-76
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• 1979

Two different isolates of Xanthomonas oryzae, KB 7785 of pathotype I and JN 7721 of pathotype III, that had been the most virulent isolates in the previous inoculation test, were reisolated from cultivar 'Milyang 23' and serially transferred to 10 times. They were inoculated to the 3 cultivars; 'Milyang 23' in Kinmaze group, 'Yushin' in Kogyoku group and 'Tongil' in Rantai-emas group cultivars. It was observed that the virulence of the isolate JN 7721 was more attenuated by the serial transfer on the Wakimoto's agar than the isolate KB 7785. The attenuation of virulence of the isolate JN 7721 was more significant at the cultivar 'Milyang23' than at the other cultivars. This suggests that the host-pathogen interactions and differences of the pathogenicity-maintenance ability among the pathogenic strains may be involved.