• 대한의생명과학회지
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• 제16권3호
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• pp.139-149
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• 2010

The present study was carried out to elucidate whether an environmental strain of Cryptococcus neoformans (environmental C. neoformans) isolated from an environmental source in a park of Busan has an acute pathophysiological effect in rats. On the second day after peritoneal inoculation of environmental C. neoformans, adverse effects occurred from the viewpoint of hematology and biochemistry. Eosinophil damages and crystal formations were found in the blood. Disturbances in cytokines production were observed in the cerebral and pulmonary tissues. Fungal budding existed in the brain, lung, liver and kidney. Tissue injury findings such as inflammation, leukocyte infiltration, bleeding, or degeneration were found in the brain, lung, liver and kidney. The present data suggest that the environmental C. neoformans can cause systematically harmful effects even for short periods of infection (two days of cryptococcal infection) and the adverse effects are summarized as immune derangements and biochemical and/or histological dysfunction and injury on major organ such as the brain, lung, liver and kidney in the immunocompetent hosts. Further studies should be focused on comparing the differences between environmental and clinical strains of C. neoformans.

• 미생물학회지
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• 제42권4호
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• pp.257-264
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• 2006

한국의 임상검체와 자연환경에서 분리된 Cryptococcus neoformans 58주에 대한 혈청형과 세포외효소 생성능에 관한 셍물학적 특성을 조사하였다. 환자로부터 분리된 임상균주 51주 중 48주는 혈청형 A (94.1%) 였으며 2주는 혈청형 B (3.92%),그리고 나머지 1주는 혈청형 D (1.96%)였다. 자연환경에서 분리된 7주는 비둘기 분변에서 분리된 것들이며 모두 혈정형 A였다. 모든 균주는 proteinase와 phnospholipase를 생성하였고, 또한 API-ZYM system을 이용한 19종류의 효소생성능 시험에서는 alkaline phosphatase, esterase (C4), esterase lipase (C8), leucine arylamidase, acid phosphatase, naphthol-AS-BI-phosphohydrolase, $\alpha$-glucosidase, 그리고 $\beta$-glucosidase를 생성하였으나, N-acetyl-$\beta$-glucosarninidase는 39주 (67.2%)에서만 생성하였다. 혈청형 B로 동정된 2주와 혈청형 A로 동정된 균주중 1주는$\beta$-glucuronidase를 생성하였다. 본 연구에 사용된 총21종류의 효소 생성능 시험을 기초로 하여 생물형을 구분하였는데, 모두 4가지의 유형을 나타내었고, 또한 임상과 환경균주에서 혈정형과 생물형 특성간의 유의한 상관성를 나타내었다.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2007년도 International Meeting of the Microbiological Society of Korea
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• pp.120-122
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• 2007

All living organisms use numerous signal-transduction pathways to sense and respond to their environments and thereby survive and proliferate in a range of biological niches. Molecular dissection of these signalling networks has increased our understanding of these communication processes and provides a platform for therapeutic intervention when these pathways malfunction in disease states, including infection. Owing to the expanding availability of sequenced genomes, a wealth of genetic and molecular tools and the conservation of signalling networks, members of the fungal kingdom serve as excellent model systems for more complex, multicellular organisms. Here, we employed Cryptococcus neoformans as a model system to understand how fungal-signalling circuits operate at the molecular level to sense and respond to a plethora of environmental stresses, including osmoticshock, UV, high temperature, oxidative stress and toxic drugs/metabolites. The stress-activated p38/Hog1 MAPK pathway is structurally conserved in many organisms as diverse as yeast and mammals, but its regulation is uniquely specialized in a majority of clinical Cryptococcus neoformans serotype A and D strains to control differentiation and virulence factor regulation. C. neoformans Hog1 MAPK is controlled by Pbs2 MAPK kinase (MAPKK). The Pbs2-Hog1 MAPK cascade is controlled by the fungal "two-component" system that is composed of a response regulator, Ssk1, and multiple sensor kinases, including two-component.like (Tco) 1 and Tco2. Tco1 and Tco2 play shared and distinct roles in stress responses and drug sensitivity through the Hog1 MAPK system. Furthermore, each sensor kinase mediates unique cellular functions for virulence and morphological differentiation. We also identified and characterized the Ssk2 MAPKKK upstream of the MAPKK Pbs2 and the MAPK Hog1 in C. neoformans. The SSK2 gene was identified as a potential component responsible for differential Hog1 regulation between the serotype D sibling f1 strains B3501 and B3502 through comparative analysis of their meiotic map with the meiotic segregation of Hog1-dependent sensitivity to the fungicide fludioxonil. Ssk2 is the only polymorphic component in the Hog1 MAPK module, including two coding sequence changes between the SSK2 alleles in B3501 and B3502 strains. To further support this finding, the SSK2 allele exchange completely swapped Hog1-related phenotypes between B3501 and B3502 strains. In the serotype A strain H99, disruption of the SSK2 gene dramatically enhanced capsule biosynthesis and mating efficiency, similar to pbs2 and hog1 mutations. Furthermore, ssk2, pbs2, and hog1 mutants are all hypersensitive to a variety of stresses and completely resistant to fludioxonil. Taken together, these findings indicate that Ssk2 is the critical interface protein connecting the two-component system and the Pbs2-Hog1 pathway in C. neoformans.