• 미생물학회지
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• 제40권4호
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• pp.282-285
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• 2004

Zoosporic fungi의 일종인 Blastocladiella emersonii에서는, 적은 수의 핵을 포함하는 작은 크기의 sporangium의 형성을 유도할 수 있다. 이들의 단축된 포자형성과정에서, sporangium내에 존재하던 일부 핵들의 소멸이 관찰되었다. 이 결과는 핵의 소멸이 포자형성과정의 필수적인 부분과정이라는 가설을 뒷받침해준다. 핵의 소멸과정은 형태적으로 세포질의 autophagy와 유사하였으며, autophagy의 형태적인 발달과정을 연구하기 위한 좋은 모델 시스템이 될 것으로 생각한다.

• ALGAE
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• 제33권1호
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• pp.1-19
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• 2018

Members of the family Parviluciferaceae (Alveolata, Perkinsozoa) are the well-known dinoflagellate parasitoids along with Amoebophrya ceratii species complex and parasitic chytrid Dinomyces arenysensis and contain six species across three genera (i.e., Parvilucifera infectans, P. sinerae, P. rostrata, and P. corolla, Dinovorax pyriformis, and Snorkelia prorocentri) so far. Among Parvilucifera species, the two species, P. infectans and P. sinerae, are very similar or almost identical each other morphologically and genetically, thereby make it difficult to distinguish between the two. The only main difference between the two species known so far is the number of sporangium wall (i.e., 2 layers in P. infectans vs. 3 layers in P. sinerae). During sampling in Masan bay, Korea during the spring season of 2015, the dinoflagellate Akashiwo sanguinea cells infected by the parasite Parvilucifera were observed and this host-parasite system was established in culture. Using this culture, its morphological and ultrastructural features with special emphasis on the variation in the number of sporangium wall over developmental times, were investigated. In addition, the sequences of rDNA regions and ${\beta}-tubulin$ genes were determined. The result clearly demonstrated that the trophocyte at 36 h was covered with 4 layers, and then outer layer of the sporocyte gradually degraded over time, resulting in wall structure consisting of two layers, with even processes being detached from 7-day-old sporangium with smooth surface, indicating that the difference in the number of layers seems not to be an appropriate ultrastructural character for distinguishing P. infectans and P. sinerae. While pairwise comparison of the large subunit rDNA sequences showed 100% identity among P. infectans / P. sinerae species complex, genetic differences were found in the small subunit (SSU) rDNA sequences but the differences were relatively small (11-13 nucleotides) compared with those (190-272 nucleotides) found among the rest of Parvilucifera species (P. rostrata and P. corolla). Those small differences in SSU rDNA sequences of P. infectans / P. sinerae species complex may reflect the variations within inter- strains of the same species from different geographical areas. Taken together, all morphological, ultrastructural, and molecular data from the present study suggest that they are the same species.

• 한국응용곤충학회지
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• 제20권2호
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• pp.107-111
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• 1981

고추 역병균의 균사생장 및 유주자낭 형성에 미치는 광선 및 pH의 효과를 조사하기 위하여 PC7971외 2균주를 공시하여 다음과 같은 결과를 얻었다. 1. 역병균의 생육적온은 $25^{\circ}C$ 내외이었고, 2. 생육적정 pH는 6.0부근이었다. 3. 유주자낭 형성에는 광이 필요했으며 $20^{\circ}C$에서는 2,000Lux의 광도가 유주자낭 형성에 가장 효과적이었고, 4. 광처리후 56시간까지 급속한 형성을 보였다. 5. Oat meal배지와 V-8 Juice 배지가 Bean meal배지보다 현저히 많은 유주자낭을 형성하였다.

• 한국식물병리학회지
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• 제14권2호
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• pp.115-119
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• 1998

Root rot of carnation caused by isolates of Phytophthora was found at Kongju, 1996. Infected plants appeared symptoms of wilting, brown discoloration on collar area and consequently led to death. The causal pathogen was identified as Phytophthora nicotianae based on morphological, cultural and physiological characteristics. Mycelium was grown to rosette colony pattern on corn meal agar and the growth was 10.2 mm/day on 10% clarified V8 medium at $25^{\circ}C$. Swelling with radiating hyphae was formed in water and on agar within 7 days. Chlamydospores were abundantly produced on agar within 7 days. Sporangium was prominent papillate, 2~3 apex, 1.2 : 1 l/b ratio, lateral attacment on sporangiospore and was rarely produced on solid media but produced in water. The shape of sporangium was spherical or ovoid, and the size was 34~73$\times$32~60 (av. 33$\times$66.5) ${\mu}{\textrm}{m}$ in dimension. The isolates were heterothallic, and mating type A2. Oogonium was spherical, ovoid, 26~36 (av. 36 ${\mu}{\textrm}{m}$) in diameter, and antheridium was amphygynious to oogonia. The fungus was able to grow 10~35$^{\circ}C$, and optimal temperature was 27$^{\circ}C$.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.273-276
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• 2000

Marine fungus, Thraustochytrium aureum ATCC 34034, was incubated in artificial sea water media in order to produce docosahexaenoic acid(DHA). Cultures were performed at $24^{\circ}C$ in light for 13 days with orbital shaker at 100rpm. Maximum cell productivity of 1.34g/L and DHA yield of 41.4 mg/L were obtained by using this method, which is almost the twice level of DHA yield obtained for the strains reported previously. This strain did produce much more DHA after sporangium disruption.

• ALGAE
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• 제21권1호
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• pp.109-124
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• 2006

Responses to various types of mechanically induced wounding were followed in the giant-celled Caulerpalean species, Derbesia tenuissima, using time-lapse video-microscopy. Gametophyte vesicle cells. Puncture wounding: the gametophyte cell seals the puncture in 5 min. This is followed by cycles of ruptures and sealing, ending with full recovery in 24 hrs. Cut wounding: the protoplast immediately retracts away from the wall and reforms an intact, deflated protoplast that expands to fill the original cell within 21 hrs. Crush wounding (internal). When retained within the cell wall many protoplast fragments condense, round up, and coalesce; the reconstituted protoplast expands until it attains complete recovery, filling the original cell shape in 12 hrs. Crush wounding (external). Protoplast fragments extruded from the crushed cell are more numerous and smaller taking longer to recover. Most fragments become spherical, transforming into small viable cells capable of reproduction in several days. Sporophyte filaments. Crush wounding creates many small fragments that initially condense, coalesce and then expand within the wall to restore a complete filament with normal cytoplasmic streaming within 5 hrs. Reproduction: gametophyte. Our culture isolates produce more females than males (30:1). Gametangia develop one day before discharge that occurs explosively (1/6 sec) at first morning light. The vesicle cell forms successive gametangia every 14 days. Sporophyte. Each sporangium develops on a lateral branch that becomes isolated by the creation of successive basal plugs. After cytoplasmic cleavage and differentiation the stephanokont spores are discharged. The spores settle quickly and germinate forming gametophyte cells.

• 한국환경농학회지
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• 제16권3호
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• pp.212-215
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• 1997

Metalaxyl과 streptomycin sulfate(SM) 내성 획득여부를 알아보기위해 감자역병균의 모균주와 단일 포자낭에서 얻은 $F_1$세대에 대한 반응을 조사하였다. 모균주 KM10, U6, CDB6은 metalaxyl에 내성을 보였으며, F827, DNC303, DN107 균주는 SM에 내성을 나타냈다. 약제에 노출시킨 단일 포자낭에서 얻은 $F_1$세대는 모균주보다 생육이 양호하였다. 특히, F817, CDB6, JD1의 $F_1$세대는 metalaxyl 처리배지에서 대조구보다 51%이상 신장하였고, KM10, U6, JD1의 $F_1$세대는 모균주보다 SM처리에서 51%이상 신장하였다. 이것들은 본 실험의 표준에 의하면 내성을 획득하였다. 또 모균주와 $F_1$세대간에는 약제저항성에 정의 상간관계가 있었다. Metalaxyl의 경우 SM의 경우보다 준내성 이상을 보인 모균주로부터 얻은 $F_1$세대의 내성획득 정도가 더 큰 경향을 보였다.

• The Plant Pathology Journal
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• 제36권3호
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• pp.244-254
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• 2020

Gom-chwi (Ligularia fischeri) is severely infected with Phytophthora drechsleri, the causal organism of Phytophthora root rot, an economically important crop disease that needs management throughout the cultivation period. In the present study, Phytophthora root rot was controlled by using bacterial isolates from rhizosphere soils collected from various plants and screened for antagonistic activity against P. drechsleri. A total of 172 bacterial strains were isolated, of which, 49 strains showed antagonistic activities by dual culture assay. In the seedling assay, six out of the 49 strains showed a predominant effect on suppressing P. drechsleri. Among the six strains, the ObRS-5 strain showed remarkable against P. drechsleri when treated with seed dipping or soil drenching. The ObRS-5 strain was identified as Enterobacter asburiae based on 16S ribosomal RNA gene sequences analysis. The bacterial cells of E. asburiae ObRS-5 significantly suppressed sporangium formation and zoospore germination in P. drechsleri by 87.4% and 66.7%, respectively. In addition, culture filtrate of E. asburiae ObRS-5 also significantly inhibited sporangium formation and zoospore germination by 97.0% and 67.6%, respectively. Soil drenched bacterial cells, filtrate, and culture solution of E. asburiae ObRS-5 effectively suppressed Phytophthora root rot by 63.2%, 57.9%, and 81.1%, respectively. Thus, E. asburiae ObRS-5 could be used as a potential agent for the biological control of Phytophthora root rot infecting gom-chwi.

• 한국식물병리학회지
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• 제14권6호
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• pp.714-719
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• 1998

Obligate bacterial parasite attacking Heterodera glycines was firstly found from Chungju soybean field in Korea. Diameters of sporangium and central body were 5.6 ${\mu}{\textrm}{m}$ and 1.9 ${\mu}{\textrm}{m}$ under light microscopy (LM), and 3.9 ${\mu}{\textrm}{m}$ and 1.8 ${\mu}{\textrm}{m}$ under transmission electron microscopy (TEM). Endospore showed cup-shaped with smooth-type exosporium without peg-like thickening in polar area under SEM and TEM. Bacteria completed its life cycle in female of soybean cyst nematode after adhering on cuticle of second-stage juvenile. From these results, the Pasteuria found from Chungju was identified with P. nishizawae.

• Journal of Plant Biology
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• 제28권4호
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• pp.317-327
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• 1985

Floral morphology of Magnoliaceae and Illiciaceae in Korea is investigated. Magnoliaceae has long and elongate floral axis where numerous stamens and pistils are pistils are spirally arranged, whereas Illiciaceae has short floral axis and pistils are arranged in a single whorl on the axis. The stamens are basically similar in both families; winged and broad filament, prominant connective, long sporangium, and no clear limitation between fertile and sterile parts, which are primitive characters in stamen. The ovaries are the conduplicate type, in both, with decurrent stigma, stigmatic surface confined to stylar position, and no distinct style. Magnoliaceae has one locule and two ovules, whereas Illiciaceae has one locule and one ovule. The ovule is anatropous or hemianatropus, and has bitegmic integument and crassinucellate nucellus.