• Journal of the Korean Wood Science and Technology
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• 제28권4호
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• pp.10-16
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• 2000

Two wood decay ascomycetes fungi identified as Hypoxylon mammatum and H. truncatum were isolated from backyard of Korea Research Institute of Chemical Technology (KRICT) in Korea. Hypoxylon truncatum is newly recorded as a wood degrader in Korea. Unusual germination mechanisms of ascospores in H. mammatum and H. truncatum are described and illustrated. The differences between two species were noticed on the process of germ tube formation. In the process of germ tube formation, the fast movement to pigmented ascospores activated from their perispores was termed as spore eclosion that was only found in H. mammatum. This sophisticated recognition mechanism indicated the existence of specific eclosion and germ tube formation due to the composition of cell wall layers and their preferable host derive, based on examined two species under a genus. The observation on present study postulates different composition of wall layers of ascospore and different nutrient composition for germination.

• 대한미생물학회지
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• 제21권4호
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• pp.407-415
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• 1986

This study investigated whether a correlation exists between environmental physical and biochemical factors and adherence of Candida albicans to human buccal epithelial cells by using normal and UV-irradiated strains. The results were as follows: 1. The percentage of germ tube forming activities of normal Candida albicans was 91.5% and UV-irradiated Candida albicans was 15.0%. The $LD_{50}$ of normal strains in mice were $1.0{\times}10\;cells/ml$, but could not be observed in the UV-irradiated strains even with $1.0{\times}10\;cells/ml$. It demonstrated that the virulence is decreased in the UV-irradiated strain. 2. The adherence of normal Candida albicans to human buccal epithelial cells($166{\pm}29{\sim}207{\pm}17\;cells$/100 epithelial cells) was significantly greater than UV-irradiated Candida albicans($99{\pm}21{\sim}131{\pm}25\;cells$/100 epithelial cells). 3. Candida albicans cultured at $37^{\circ}C$ adhered to buccal epithelial cells($166{\pm}16{\sim}207{\pm}17\;cells$/100 epithelial cells) in greater numbers than cultured at $25^{\circ}C$($80{\pm}15{\sim}143{\pm}22\;cells$/100 epithelial cells). 4. On comparison of the adherence of viable and nonviable(heat-killed) Candida albicans to human buccal epithelial cells, the nonviable Candida albicans demonstrated poorer adherence than viable Candida albicans. 5. Adherence in vitro of Candida albicans to human epithelial cells appeared to be effected by the pH. The adherence ability was maximum increased at pH 7.0($187{\pm}22\;cells$/100 epithelial cells) other than experimental pH. 6. The adherence was proportional to the incubation time and the Candida cell concentration in the suspension. 7. A strong correlation was shown between germ tube forming activity and increased adherence of Candida albicans to human epithelial cells, indicating that germ tube forming activity were responsible for candidal virulence.

• 미생물학회지
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• 제16권3호
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• pp.111-121
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• 1978

About 40 temperature-sensitive mutants have been isolated as a preliminary step to study the spore germination, the cell cycle, and the control of macromolecular synthesis in Aspergillus nidulans. To obtain temperature-sensitive mutants rapidly and effectively, the selective enrichment method using antifungal antibiotic nystatin was developed. Based on the data which had applied to the concentration of auxotrophic mutants by the earlier investigators, the optimal concentration and the time of treatment at the nonpermissive temeprature were determined as 50 to 100 units per ml and 4.5 hr., respectively. Out of 41 ts mutants assigned to the strain symbol PK, thirteen that seemed to be arrested at the earlystage of spore germination were subjected to the further cytological and genetic analysis. Elght of these mutants are able to form germ tube and five not. Staining with acid fuchsin for the 5PK strains shows that one irreversible mutant, PK6 strain able to form germ tube, accumulate mitotic spindle, being arrested in mitosis. Another PK15 and PK23 strain have more than one intact nucleolus without germ tube formation at the restrictive temperature. the temperature-senstive mutation in PK12 strain, the onlystrain which is able occurred in certain gene specific for the germination of spore. All of the ts markers are recessive and complement each other in heterokaryon between two different ts markers at the restrictive temperature.

• 한국균학회지
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• 제21권3호
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• pp.224-229
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• 1993

C. dematium 과 C. gloeosporioides의 포자발아 및 발아관 신장에 알맞는 온도는 $20{\sim}30^{\circ}C$이며 부착기는 $20^{\circ}C$에서 형성이 잘 되었으나 포자의 발아는 늦었다. $30^{\circ}C$에서는 포자발아와 발아관의 신장이 양호하였으나 부착기의 형성은 낮았다. C. acutatum의 포자발아에 알맞는 온도는 $20{\sim}30^{\circ}C$이었으나 발아관의 신장이 $25^{\circ}C$에서 촉진되었다. 분생포자는 격막이 생기고 발아관 대신 $1{\sim}2$개의 딸세포가 포자화되었으며, 제2차 포자를 형성하면서 수지상(樹枝狀)으로 되었다. 부착기는 포자의 발아에 의해서 드물게 형성되었으며 알맞는 온도는 $20{\sim}30^{\circ}C$이었다. 그러나 $30^{\circ}C$에서 발아된 포자는 부착기의 형성능력이 없었다. Colletotrichum acutatum, C. dematium 및 C. gloeosporioides 등의 분생포자 발아 및 부착기 형성에 미치는 온도의 영향에 관해서 논의(論議)하였다.

• The Plant Pathology Journal
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• 제32권1호
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• pp.1-7
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• 2016

Responses of Botryosphaeria dothidea to interrupted wetness periods were investigated under in vivo and in vitro conditions. Conidia of B. dothidea were allowed to germinate on apple fruits under wetting condition at $25^{\circ}C$ for 5 hr. They were air-dried for 0, 1, 2 or 4 hr, and then rewetted at $25^{\circ}C$ for 5 hr. Following an initial wetness period of 5 hr, 83% of the conidia germinated. The percent conidial germination increased to 96% when wetting was extended continuously another 5 hr. However, no further conidial germination was observed when wetting was interrupted by dry periods of 1, 2 and 4 hr, resulting in 83, 81 and 82%, respectively. The mean length of the germ tubes was $37{\mu}m$ after 5 hr of wetting and elongated to $157{\mu}m$ after 10 hr of continuous wetting. On the other hand, interruption of wetting by a dry period of 1 hr or longer after the 5 hr of initial wetting arrested the germ tube elongation at approximately $42{\mu}m$ long. Prolonged rewetting up to 40 hr did not restore germ tube elongation on slide glasses under substrate treatments. Model simulation using weather data sets revealed that ending infection periods by a dry period of at least 1 hr decreased the daily infection periods, avoiding the overestimation of infection warning. This information can be incorporated into infection models for scheduling fungicide sprays to control apple white rot with fewer fungicide applications.

• The Plant Pathology Journal
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• 제39권1호
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• pp.123-135
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• 2023

Previously, Pseudomonas plecoglossicida YJR13 and Pseudomonas putida YJR92 from a sequential screening procedure were proven to effectively control Phytophthora blight caused by Phytophthora capsici. In this study, we further investigated the anti-oomycete activities of these strains against mycelial growth, zoospore germination, and germ tube elongation of P. capsici. We also investigated root colonization ability of the bacterial strains in square dishes, including cell motility (swimming and swarming motilities) and biofilm formation. Both strains significantly inhibited mycelial growth in liquid and solid V8 juice media and M9 minimal media, zoospore germination, and germ tube elongation compared with Bacillus vallismortis EXTN-1 (positive biocontrol strain), Sphingomonas aquatilis KU408 (negative biocontrol strain), and MgSO₄ solution (untreated control). In diluted (nutrient-deficient) V₈ juice broth, the tested strain populations were maintained at >10⁸ cells/ml, simultaneously providing mycelial inhibitory activity. Additionally, these strains colonized pepper roots at a 10⁶ cells/ml concentration for 7 days. The root colonization of the strains was supported by strong swimming and swarming activities, biofilm formation, and chemotactic activity towards exudate components (amino acids, organic acids, and sugars) of pepper roots. Collectively, these results suggest that strains YJR13 and YJR92 can effectively suppress Phytophthora blight of pepper through direct anti-oomycete activities against mycelial growth, zoospore germination and germ tube elongation. Bacterial colonization of pepper roots may be mediated by cell motility and biofilm formation together with chemotaxis to root exudates.

• 한국유기농업학회지
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• 제28권2호
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• pp.223-233
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• 2020

본 연구에서는 친환경 농가에서 사용되고 있는 바이오 황(Bio-S, bio-sulfur)을 이용하여 감귤 더덩이병(Citrus scab)에 대한 발병 억제 효과를 알아보고자 수행되었다. 바이오 황이 감귤 더뎅이병의 발아관 생장 억제 효과는 감귤 더뎅이병균을 PDB와 Agar 배지에서 배양하여 발아관을 관찰한 결과 접종 40시간과 88시간 모두 바이오 황 500배, 1,000배, 2,000배 처리구에서 발아관 형성이 억제되었으며, 4,000배 이상 희석배수가 높아질수록 발아관은 형성되었으나 무처리구에 비해 생장이 억제되었다. 포장에서 감귤 봄순 잎에 대한 더뎅이병의 발병 억제 효과는 무처리구 이병율은 40.3%였으며, 화학농약인 Imibenconazole 수화제 이병율이 5.3%을 보였으며, 친환경 농업에 사용하는 석회보르도액 2-4식과 6-6식은 모두 10.3%, 바이오 황 500배 12.3%, 석회유황합제 15.3%로 비슷한 경향을 나타냈으며, 반면 바이오 황 1,000배에서는 24.0%로 비교적 높은 이병율을 보였다. 감귤 과실에 대한 시험결과 무처리구 이병율은 79.3%였으며, Imibenconazole 수화제 이병율은 4.0%을 보였으며, 석회보르도액 2-4식 33.8%, 6-6식 42.0%, 바이오 황 500배 43.3%, 석회유황합제 44.8%로 비슷한 효과를 나타냈으며, 반면 바이오 황 1,000배에서는 78.0%로 비교적 높은 이병율을 보였다. 따라서 감귤 더뎅이병은 봄순이 전개되는 5월부터 감귤의 잎에 발생하기 때문에 봄순이 전개되기 전인 4월 중하순부터 예방방제를 시작하여 예찰을 통해 방제하면 높은 방제율과 노동력 및 영농비용 등을 절감할 수 있을 것으로 생각된다.

• 한국미생물·생명공학회지
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• 제47권3호
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• pp.465-472
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• 2019

Candida albicans는 기회감염을 유발하는 주요한 병원성 진균 중의 하나이다. 캔디다증 치료과정에서 항진균제에 대한 내성이 흔히 발견되는데, 그 이유는 Candida가 바이오필름을 형성할 수 있기 때문이다. 이전의 연구에서 우리는 단삼(Salvia miltiorriza)의 에탄올추출물이 세포막의 투과성을 변화시키고 세포벽 합성을 저해하여 항캔디다 활성을 나타냄을 밝혔다. 본 연구에서는 10개 C. albicans 임상균주가 형성한 초기단계의 바이오필름을 대상으로 XTT 환원분석법으로 대사활성을 측정하니, $78{\mu}g/ml$ 단삼 에탄올추출물에 의해 바이오필름의 대사활성이 평균 51.3% 감소되었다. C. albicans 세포들이 폴리스티렌 표면에 부착하거나 germ tube를 형성하는 과정에서의 단삼 에탄올추출물의 영향을 현미경으로 분석하니, $39{\mu}g/ml$ 단삼 에탄올추출물에 의해 부착된 세포의 밀도는 현저하게 감소하였으나 germ tube 형성은 거의 억제하지 못했다. 단삼 에탄올추출물이 C. albicans SC5314 세포의 균사에 특이적인 유전자 발현에 미치는 영향을 qPCR로 분석한 결과, EAP1은 34.7% (p < 0.001), ALS1은 45.0% (p < 0.001), ALS3는 48.1% (p < 0.001), ECE1은 21.3% (p = 0.006) 억제하였다. 결론적으로 단삼의 에탄올추출물은 초기단계의 C. albicans 바이오필름 발달을 효율적으로 저해하며, 이는 EAP1, ALS1, ALS3 유전자의 발현억제에 따른 세포부착 억제와 관련이 있다. 더불어 단삼 에탄올추출물의 C. albicans 세포막 기능저해와 세포벽 합성억제에 의한 구조변화 또한 세포부착단계에서의 바이오필름 발달억제에 기여할 것으로 추정된다.

• 한국응용곤충학회지
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• 제5_6권
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• pp.19-26
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• 1968

휴지상태에 있는 성숙한 도열병균 포자 1,000개를 관찰한 결과 각 세포에 단핵을 가지는 포자비율이 $95\%$로 단연 많았고 또 미숙회자인 1세포 1핵 포자로부터 출발하여 3세포 3핵인 성숙포자가 형성됨을 관찰할 수 있었다. 분열 중인 핵은 배열된 염색체로서 관찰할 수 있었으며, 염색체수는 n=3,4,5,6개로 나타났으나, n=5개가 가장 많았다. 핵이 발아관으로 이동하는 방법은 첫째로 휴지상태에 있던 핵이 분열하여 2핵이 되고 그 중 1핵이 발아관에 이동하고 1핵은 세포내에 머무는 것과$(43\%)$, 둘째 방법은 핵분열 없이 직접 세포내의 1핵이 발아관을 따라 이동하는 것들이 $(57\%)$ 있다. 또 부착기내의 핵을 염색하여 관찰한 결과 무핵의 부착기가 상당히 많았으나 핵질을 가진 500개의 부착기 중에 단핵이 476개로서 $95.2\%$였다(Chromosome 으로 관찰된 4부착기는 제외). 이상의 결과로서 도열병균은 전생활환을 통하여 단핵을 함유한다는 것을 인정할 수 있으며, 도열병균포자가 다세포일지라도 Homokaryon이라고 생각되므로 단포자분리균을 도열병에 관한 모든 시험에 공시하는 것은 합당하다고 할 수 있다.

• 한국어업기술학회:학술대회논문집
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• 한국어업기술학회 2002년도 추계 수산관련학회 공동학술대회발표요지집
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• pp.175-176
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• 2002

Rice blast, caused by Pyricularia oryzae (P. oryzae), is generally considered to be the most serious fungal disease of rice by its widespread distribution and destructiveness (Manandhar et al., 1998). The pathogenic fungus directly penetrates into the rice plant from a cellular structure called an appressorium that is formed at the tip of the germ tube. And the fungus can attack any aerial part of the rice plant, including seeds, in which the fungus may overwinter for several years. (omitted)