• Mycobiology
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• 제46권2호
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• pp.92-100
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• 2018

The filamentous Ascomycota Colletotrichum gloeosporioides sensu lato is a fungus that has been reported worldwide as a causal agent of anthracnose disease in avocado and other crops. In Mexico, this species affects fruits from an early stage of development in the orchard until the post-harvest stage. Although fungicides are continuously applied to control Colletotrichum species, pericarp cankers and soft rot mesocarp in fruits are still frequently observed. Considering the lack of a precise description of the causative agent, the aim of the current study was to determine the pathogens involved in this symptomatology. Twenty-four isolates were consistently obtained from the pericarp of avocado fruits cv. "Hass" collected in the central avocado-producing area of Mexico. Morphological features such as colony growth, conidia size, and mycelial appressorium were assessed. Bayesian multilocus phylogenetic analyses were performed using amplified sequences of the internal transcribed spacer region of the nuclear ribosomal DNA; actin, chitin synthase, glyceraldehyde-3-phosphate dehydrogenase partial genes; and APn2-Mat1-2 intergenic spacer and mating type Mat1-2 partial gene from the nine selected isolates. In addition, fruits were inoculated with a conidial suspension and reproducible symptoms confirmed the presence of Colletotrichum fructicola in this area. This pathogenic species can now be added to those previously reported in the country, such as C. acutatum, C. boninense, C. godetiae, C. gloeosporioides, and C. karstii. Disease management programs to reduce the incidence of anthracnose should include C. fructicola to determine its response to fungicides that are routinely applied, considering that the appearance of new species is affecting the commercial quality of the fruits and shifting the original population structure.

• 한국산업정보학회논문지
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• 제12권2호
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• pp.49-59
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• 2007

본 논문은 시맨틱 웹의 실현을 위해서는 필수적인 작업인 웹문서의 의미를 자동으로 태깅할 수 있는 시스템에 관한 것이다. 웹상의 방대한 자원을 일일이 사람이 수작업으로 의미를 태깅한다는 것은 사실상 불가능하기 때문에 한국어 웹문서를 대상으로 대량의 학습 데이터를 수집하고 자연어처리 기법과 시소러스를 이용하여 특징을 추출한 후 SVM 기계학습을 통하여 개념분류기를 구축하였다. 한국어의 특징을 파악하여 의미 태깅에 필요한 특징 정보를 추출하기 위해서 형태소 분석과 구문 분석을 하였다. 추출된 특징정보는 가도카와 시소러스의 의미코드를 이용하여 학습벡터로 구성되는데, 이는 유사한 단어나 구를 하나의 개념코드로 매핑하여 시스템의 재현율을 높이는 역할을 하게 된다. 실험결과 자동 의미 태깅 분야에서 본 접근방법의 가능성을 확인할 수 있었다.

• KSBB Journal
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• 제26권3호
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• pp.229-236
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• 2011

An efficient screening method was developed for rapid selection of a few overproducers of itaconic acid (IA) among the great many mutants derived from mother strains of Aspergillus terreus. For this purpose, an attempt was made to reveal the relationships of the growth rate and sporulation of each mutant on PDA solid medium with its IA productivity in the final liquid production-culture. As a result, it was possible to classify the mutated strains into 5 groups (from [A] to [E] group) according to theirmorphologies (i.e., growth rate and sporulation extent) on the PDA slants. Notably, most of the high-yielding mutants of IA were observed to belong to [A]group which had the properties of the highest growth rate and sporulation among the 5 groups, whereas the mutant groups of [C], [D] and [E] with the contrasting morphological features showed significant reductions in their IA productivities. From these results, it was concluded that the probability of selecting IA overproducing mutants could be remarkably enhanced when the mutated colonies showing faster growth rates are firstly selected on the PDA plate, and then further screening process is performed on the basis of the sporulation extents of the mutants selected. Consequently, through the application of the strategy developed in this study, costs and time involvedin the labor-intensive task of strain improvement could be reduced to a great extent, because the time-consuming liquid culture processes did not need to performed for the unfavorable mutants belonging to the groups other than group [A].

• 한국버섯학회지
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• 제13권1호
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• pp.41-49
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• 2015

표고(Lentinula edodes)는 우리나라의 주요 임산버섯으로 최근 표고 톱밥재배가 정착됨에 따라 급속도로 확산되고 있으나 국내 환경에 적합하고 재배시기를 다변화 할 수 있는 균주의 육성이 시급하다. 따라서 9개의 균주를 시험재배하여 생산성이 높고 자실체 특성이 우수한 4개 균주(SANJO701HO, FMRI2534, FMRI2337, FMRI2613)를 모균주로 선발하였고 균주당 각각 20개씩 총 80개의 단핵균주를 분리하여 117개의 교배균주를 육성하였다. 그중 산조701호와 FMRI2337의 교배조합이 다른 조합의 교배균주들보다 평균생장속도가 10% 가량 낮았으며 이들 교배균주의 배양 및 생리적 특성을 비교 조사하였다. 따라서 본 연구는 우수한 톱밥재배용 품종개발의 기반조성을 마련하고자 하였으며, 차후 교배균주에 대한 생산성 검정의 연구가 필요하다.

• Molecules and Cells
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• 제43권10호
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• pp.848-855
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• 2020

Cells assemble stress granules (SGs) to protect their RNAs from exposure to harmful chemical reactions induced by environmental stress. These SGs release RNAs, which resume translation once the stress is relieved. During stem cell differentiation, gene expression is altered to allow cells to adopt various functional and morphological features necessary to differentiate. This process induces stress within a cell, and cells that cannot overcome this stress die. Here, we investigated the role of SGs in the progression of stem cell differentiation. SGs aggregated during the neuronal differentiation of human bone marrow-mesenchymal stem cells, and not in cell lines that could not undergo differentiation. SGs were observed between one and three hours post-induction; RNA translation was restrained at the same time. Immediately after disassembly of SGs, the expression of the neuronal marker neurofilament-M (NF-M) gradually increased. Assembled SGs that persisted in cells were exposed to salubrinal, which inhibited the dephosphorylation of eukaryotic translation initiation factor 2 subunit 1 (eIF2α), and in eIF2α/S51D mutant cells. When eIF2α/S51A mutant cells differentiated, SGs were not assembled. In all experiments, the disruption of SGs was accompanied by delayed NF-M expression and the number of neuronally differentiated cells was decreased. Decreased differentiation was accompanied by decreased cell viability, indicating the necessity of SGs for preventing cell death during neuronal differentiation. Collectively, these results demonstrate the essential role of SGs during the neuronal differentiation of stem cells.

• ALGAE
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• 제20권2호
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• pp.141-150
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• 2005

To make a preliminary identification of the gracilarioid plant attached to cultivation ropes of Undaria pinnatifida and establish a method of cultivating this plant, the first taxonomic and cultivation studies on this species in Korea were conducted. This gracilarioid plant was identified from its morphological and anatomical features, as Gracilaria chorda. Growth tests using the 10, 20, and 30 cm cuttings of axes of G. chorda were performed twice, from May 3 to August 21, 2002 and from December 15, 2002 to April 3, 2003 in Ihoijin aquafarm, Hoijin, Jangheung, Jeollanamdo, Korea. In the first growing test, the thallus length of the 10, 20, and 30 cm cuttings increased twelve-fold, ten-fold, and seven-fold; the wet weight increased 81-fold, 60-fold, and 41-fold; the numbers of more than 10 cm-long branches increased 3.8-fold, 5.2-fold, and 6.1-fold, respectively. In the second growth test, the thallus length of the 10, 20, and 30 cm cuttings increased seven-fold, 5.5-fold, and four-fold; the wet weight increased 81-fold, 53-fold and 36-fold; the number of branches increased 3.8-fold, 7.3-fold, and 6.6-fold, respectively. The cultivation of G. chorda by vegetative regeneration using cuttings of thallus axes was successful for the first time in Korea.

• Parasites, Hosts and Diseases
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• 제56권5호
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• pp.463-475
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• 2018

The present study was performed to observe histopathological effects of Oculotrema hippopotami Stunkard, 1924 infection in the eye of Hippopotamus amphibius, as well as to reveal new details of morphology and structural features of this monogenean and its comparison between 2 age stages of the parasite. This was done using both light and scanning electron microscopy, energy dispersive X-ray analysis (EDXA) and histopathology. The presence of a mixture of different generations (adult and sub-adult) in one host individual is common for Oculotrema Stunkard, 1924 in contrast to Polystoma Zeder, 1800. New metrical and graphical information obtained for adults and sub-adults compared with the previous studies. Here we show the presence of genital papillae in adults, metrical data on the distal part of the vas deferens. SEM micrographs of sperm ejaculatory structures and information about the flattened dorsal side of the body provided for the first time. Histopathological changes, such as necrosis and hemorrhage in host tissues as a result of O. hippopotami attachment structures are described. Structural analysis of different body parts of O. hippopotami of both age groups are also included. We show qualitative differences in the presence of hardening ions (S, P, Ca) in attachment structures (oral and haptor suckers) that increase with the age of the worm. The presence of sub-adults and adults on the same host, together with high levels of infection without high pathogenicity may account for Oculotrema being one of the most successful parasites among the Monogenea.

• 대한예방의학회:학술대회논문집
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• 대한예방의학회 1994년도 교수 연수회(환경)
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• pp.585-595
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• 1994

The region of the respiratory tract where inhaled particles deposit can have important implications for the causation of local or systemic toxic effects. For most aerosols of occupational importance, respiratory tract deposition can be predicted from the aerodynamic diameter of the particles. With the advent of cascade impactors, particularly those of personal sampler size, the determination of the aerodynamic diameters of aerosols has become more common. Some limitations of cascade impactor use are well recognized (e.g., particle bounce and substrate overloading) and are generally correctable. However, two important limitations of the instruments may not be receiving adequate attention: relative humidity effects on potentially hygroscopic aerosols and the collection characteristics of fibrous aerosols as compared to their actual deposition site potential. The results of this study, when compared to results of previous controlled laboratory trials, suggest that, while potentially hygroscopic lead aerosols from lead acid battery plant operations do not appear to be affected by changes in plant environmental humidity levels, the potential - exists for significant size changes upon inhalation. Secondly, fibers were detected in aerodynamic size ranges that would be associated with deep lung deposition; however, upon microscopic examination, these same fibers would actually be predicted to deposit in the upper airways. This study suggests that the physicalchemical properties and morphological features of an aerosol should be carefully considered by industrial hygienists before cascade impactors are used in attempts to predict the effects of inhaled aerosols.

• 대한수의학회지
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• 제29권3호
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• pp.215-222
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• 1989

In order to investigate the morphological characteristics of epididymal duct of the squirrel, the histological and histochemical studies were carried out. The results obtained were summarized as follows: The epididymal duct can be divided into 9 segments by histological and histochemical features. Segments 1 to 5 were located in the head, segments 6 and 7 in the body, and segments 8 and 9 in the tail of the epididymis. The apical cells were numerous in the segment 1. Clear cells which has a compact, deeply staining nucleus and a characteristically clear cytoplasm were scattered in the epithelium throughout the duct. Interepithelial clear cells which had PAS-positive granules tended to increase in number caudally. Strong PAS-positive reaction was detected at the intralumen of the segments 3,8 and 9. Acid phosphatase activity was relatively high in the basal cytoplasm of the segment 7, and then in the supranuclear region of the segments 8 and 9. Alkaline phosphatase activity was weakly positive or negative except the segments 3 and 4. ATPase activity was strong in the free surface of the epithelium in the head and the entire cytoplasm in the body and tail, a,nd SDH activity was generally weak except for the body where it was more intense.

• 한국재료학회지
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• 제26권4호
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• pp.207-211
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• 2016

Ti films were deposited on glass substrates under various preparation conditions in a chamber of two-facing-target type dc sputtering; after deposition, the electric resistivity values were measured using a conventional four-probe method. Crystallographic orientations and microstructures, including the texture and columnar structure, were also investigated for the Ti films. The morphological features, including the columnar structures and surface roughness, are well explained on the basis of Thornton's zone model. The electric resistivity and the thermal coefficient of the resistivity vary with the sputtering gas pressure. The minimum value of resistivity was around 0.4 Pa for both the $0.5{\mu}m$ and $3.0{\mu}m$ thick films; the apparent tendencies are almost the same for the two films, with a small difference in resistivity because of the different film thicknesses. The films deposited at high gas pressures show higher resistivities. The maximum of TCR is also around 0.4 Pa, which is the same as that obtained from the relationship between the resistivity and the gas pressure. The lattice spacing also decreases with increasing sputtering gas pressure for both the $0.5{\mu}m$ and $3.0{\mu}m$ thick films. Because they are strongly related to the sputtering gas pressures for Ti films that have a crystallographic anisotropy that is different from cubic symmetry, these changes are well explained on the basis of the film microstructures. It is shown that resistivity measurement can serve as a promising monitor for microstructures in sputtered Ti films.