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Search Results: 1 - 10 of 38067 matches for " Yin-Won Lee "
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Transmission of Fusarium boothii Mycovirus via Protoplast Fusion Causes Hypovirulence in Other Phytopathogenic Fungi
Kyung-Mi Lee,Jisuk Yu,Moonil Son,Yin-Won Lee,Kook-Hyung Kim
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0021629
Abstract: There is increasing concern regarding the use of fungicides to control plant diseases, whereby interest has increased in the biological control of phytopathogenic fungi by the application of hypovirulent mycoviruses as a possible alternative to fungicides. Transmission of hypovirulence-associated double-stranded RNA (dsRNA) viruses between mycelia, however, is prevented by the vegetative incompatibility barrier that often exists between different species or strains of filamentous fungi. We determined whether protoplast fusion could be used to transmit FgV1-DK21 virus, which is associated with hypovirulence on F. boothii (formerly F. graminearum strain DK21), to F. graminearum, F. asiaticum, F. oxysporum f. sp. lycopersici, and Cryphonectria parasitica. Relative to virus-free strains, the FgV1-DK21 recipient strains had reduced growth rates, altered pigmentation, and reduced virulence. These results indicate that protoplast fusion can be used to introduce FgV1-DK21 dsRNA into other Fusarium species and into C. parasitica and that FgV1-DK21 can be used as a hypovirulence factor and thus as a biological control agent.
A Putative Transcription Factor MYT1 Is Required for Female Fertility in the Ascomycete Gibberella zeae
Yang Lin,Hokyoung Son,Jungkwan Lee,Kyunghun Min,Gyung Ja Choi,Jin-Cheol Kim,Yin-Won Lee
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0025586
Abstract: Gibberella zeae is an important pathogen of major cereal crops. The fungus produces ascospores that forcibly discharge from mature fruiting bodies, which serve as the primary inocula for disease epidemics. In this study, we characterized an insertional mutant Z39P105 with a defect in sexual development and identified a gene encoding a putative transcription factor designated as MYT1. This gene contains a Myb DNA-binding domain and is conserved in the subphylum Pezizomycotina of Ascomycota. The MYT1 protein fused with green fluorescence protein localized in nuclei, which supports its role as a transcriptional regulator. The MYT1 deletion mutant showed similar phenotypes to the wild-type strain in vegetative growth, conidia production and germination, virulence, and mycotoxin production, but had defect in female fertility. A mutant overexpressing MYT1 showed earlier germination, faster mycelia growth, and reduced mycotoxin production compared to the wild-type strain, suggesting that improper MYT1 expression affects the expression of genes involved in the cell cycle and secondary metabolite production. This study is the first to characterize a transcription factor containing a Myb DNA-binding domain that is specific to sexual development in G. zeae.
A Putative Transcription Factor MYT2 Regulates Perithecium Size in the Ascomycete Gibberella zeae
Yang Lin, Hokyoung Son, Kyunghun Min, Jungkwan Lee, Gyung Ja Choi, Jin-Cheol Kim, Yin-Won Lee
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0037859
Abstract: The homothallic ascomycete fungus Gibberella zeae is a plant pathogen that is found worldwide, causing Fusarium head blight (FHB) in cereal crops and ear rot of maize. Ascospores formed in fruiting bodies (i.e., perithecia) are hypothesized to be the primary inocula for FHB disease. Perithecium development is a complex cellular differentiation process controlled by many developmentally regulated genes. In this study, we selected a previously reported putative transcription factor containing the Myb DNA-binding domain MYT2 for an in-depth study on sexual development. The deletion of MYT2 resulted in a larger perithecium, while its overexpression resulted in a smaller perithecium when compared to the wild-type strain. These data suggest that MYT2 regulates perithecium size differentiation. MYT2 overexpression affected pleiotropic phenotypes including vegetative growth, conidia production, virulence, and mycotoxin production. Nuclear localization of the MYT2 protein supports its role as a transcriptional regulator. Transcriptional analyses of trichothecene synthetic genes suggest that MYT2 additionally functions as a suppressor for trichothecene production. This is the first study characterizing a transcription factor required for perithecium size differentiation in G. zeae, and it provides a novel angle for understanding sexual development in filamentous fungi.
MYT3, A Myb-Like Transcription Factor, Affects Fungal Development and Pathogenicity of Fusarium graminearum
Yongsoo Kim, Hun Kim, Hokyoung Son, Gyung Ja Choi, Jin-Cheol Kim, Yin-Won Lee
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0094359
Abstract: We previously characterized members of the Myb protein family, MYT1 and MYT2, in Fusarium graminearum. MYT1 and MYT2 are involved in female fertility and perithecium size, respectively. To expand knowledge of Myb proteins in F. graminearum, in this study, we characterized the functions of the MYT3 gene, which encodes a putative Myb-like transcription factor containing two Myb DNA-binding domains and is conserved in the subphylum Pezizomycotina of Ascomycota. MYT3 proteins were localized in nuclei during most developmental stages, suggesting the role of MYT3 as a transcriptional regulator. Deletion of MYT3 resulted in impairment of conidiation, germination, and vegetative growth compared to the wild type, whereas complementation of MYT3 restored the wild-type phenotype. Additionally, the Δmyt3 strain grew poorly on nitrogen-limited media; however, the mutant grew robustly on minimal media supplemented with ammonium. Moreover, expression level of nitrate reductase gene in the Δmyt3 strain was decreased in comparison to the wild type and complemented strain. On flowering wheat heads, the Δmyt3 strain exhibited reduced pathogenicity, which corresponded with significant reductions in trichothecene production and transcript levels of trichothecene biosynthetic genes. When the mutant was selfed, mated as a female, or mated as a male for sexual development, perithecia were not observed on the cultures, indicating that the Δmyt3 strain lost both male and female fertility. Taken together, these results demonstrate that MYT3 is required for pathogenesis and sexual development in F. graminearum, and will provide a robust foundation to establish the regulatory networks for all Myb-like proteins in F. graminearum.
Genome-wide expression profiling shows transcriptional reprogramming in Fusarium graminearum by Fusarium graminearum virus 1-DK21 infection
Won Kyong Cho, Jisuk Yu, Kyung-Mi Lee, Moonil Son, Kyunghun Min, Yin-Won Lee, Kook-Hyung Kim
BMC Genomics , 2012, DOI: 10.1186/1471-2164-13-173
Abstract: Using a 3′-tiling microarray covering all known F. graminearum genes, we carried out genome-wide expression analyses of F. graminearum at two different time points. At the early point of growth of an infected strain as compared to an uninfected strain, genes associated with protein synthesis, including ribosome assembly, nucleolus, and ribosomal RNA processing, were significantly up-regulated. In addition, genes required for transcription and signal transduction, including fungal-specific transcription factors and cAMP signaling, respectively, were actively up-regulated. In contrast, genes involved in various metabolic pathways, particularly in producing carboxylic acids, aromatic amino acids, nitrogen compounds, and polyamines, showed dramatic down-regulation at the early time point. Moreover, genes associated with transport systems localizing to transmembranes were down-regulated at both time points.This is the first report of global change in the prominent cellular pathways in the Fusarium host containing FgV1-DK21. The significant increase in transcripts for transcription and translation machinery in fungal host cells seems to be related to virus replication. In addition, significant down-regulation of genes required for metabolism and transporting systems in a fungal host containing the virus appears to be related to the host defense mechanism and fungal virulence. Taken together, our data aid in the understanding of how FgV1-DK21 regulates the transcriptional reprogramming of F. graminearum.
A Comparison of Transcriptional Patterns and Mycological Phenotypes following Infection of Fusarium graminearum by Four Mycoviruses
Kyung-Mi Lee, Won Kyong Cho, Jisuk Yu, Moonil Son, Hoseong Choi, Kyunghun Min, Yin-Won Lee, Kook-Hyung Kim
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0100989
Abstract: Many fungi-infecting viruses, which are termed mycoviruses, have been identified, and most do not cause any visible symptoms. Some mycoviruses, however, can attenuate the virulence of the infected fungi, a phenomenon referred to as hypovirulence. To study fungus responses to virus infection, we established a model system composed of Fusarium graminearum and four mycoviruses including FgV1 (Fusarium graminearum virus 1), FgV2, FgV3, and FgV4. FgV1 and FgV2 infections caused several phenotypic alterations in F. graminearum including abnormal colony morphology, defects in perithecium development, and reductions in growth rate, conidiation, and virulence. In contrast, FgV3 and FgV4 infections did not cause any phenotypic change. An RNA-Seq-based analysis of the host transcriptome identified four unique Fusarium transcriptomes, one for each of the four mycoviruses. Unexpectedly, the fungal host transcriptome was more affected by FgV1 and FgV4 infections than by FgV2 and FgV3 infections. Gene ontology (GO) enrichment analysis revealed that FgV1 and FgV3 infections resulted in down-regulation of host genes required for cellular transport systems. FgV4 infection reduced the expression of genes involved in RNA processing and ribosome assembly. We also found 12 genes that were differentially expressed in response to all four mycovirus infections. Unfortunately, functions of most of these genes are still unknown. Taken together, our analysis provides further detailed insights into the interactions between mycoviruses and F. graminearum.
AbaA Regulates Conidiogenesis in the Ascomycete Fungus Fusarium graminearum
Hokyoung Son, Myung-Gu Kim, Kyunghun Min, Young-Su Seo, Jae Yun Lim, Gyung Ja Choi, Jin-Cheol Kim, Suhn-Kee Chae, Yin-Won Lee
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0072915
Abstract: Fusarium graminearum (teleomorph Gibberella zeae) is a prominent pathogen that infects major cereal crops such as wheat, barley, and maize. Both sexual (ascospores) and asexual (conidia) spores are produced in F. graminearum. Since conidia are responsible for secondary infection in disease development, our objective of the present study was to reveal the molecular mechanisms underlying conidiogenesis in F. graminearum based on the framework previously described in Aspergillus nidulans. In this study, we firstly identified and functionally characterized the ortholog of AbaA, which is involved in differentiation from vegetative hyphae to conidia and known to be absent in F. graminearum. Deletion of abaA did not affect vegetative growth, sexual development, or virulence, but conidium production was completely abolished and thin hyphae grew from abnormally shaped phialides in abaA deletion mutants. Overexpression of abaA resulted in pleiotropic defects such as impaired sexual and asexual development, retarded conidium germination, and reduced trichothecene production. AbaA localized to the nuclei of phialides and terminal cells of mature conidia. Successful interspecies complementation using A. nidulans AbaA and the conserved AbaA-WetA pathway demonstrated that the molecular mechanisms responsible for AbaA activity are conserved in F. graminearum as they are in A. nidulans. Results from RNA-sequencing analysis suggest that AbaA plays a pivotal role in conidiation by regulating cell cycle pathways and other conidiation-related genes. Thus, the conserved roles of the AbaA ortholog in both A. nidulans and F. graminearum give new insight into the genetics of conidiation in filamentous fungi.
A Phenome-Based Functional Analysis of Transcription Factors in the Cereal Head Blight Fungus, Fusarium graminearum
Hokyoung Son equal contributor,Young-Su Seo equal contributor,Kyunghun Min,Ae Ran Park,Jungkwan Lee,Jian-Ming Jin,Yang Lin,Peijian Cao,Sae-Yeon Hong,Eun-Kyung Kim,Seung-Ho Lee,Aram Cho,Seunghoon Lee,Myung-Gu Kim,Yongsoo Kim,Jung-Eun Kim,Jin-Cheol Kim,Gyung Ja Choi,Sung-Hwan Yun,Jae Yun Lim,Minkyun Kim,Yong-Hwan Lee,Yang-Do Choi,Yin-Won Lee
PLOS Pathogens , 2011, DOI: 10.1371/journal.ppat.1002310
Abstract: Fusarium graminearum is an important plant pathogen that causes head blight of major cereal crops. The fungus produces mycotoxins that are harmful to animal and human. In this study, a systematic analysis of 17 phenotypes of the mutants in 657 Fusarium graminearum genes encoding putative transcription factors (TFs) resulted in a database of over 11,000 phenotypes (phenome). This database provides comprehensive insights into how this cereal pathogen of global significance regulates traits important for growth, development, stress response, pathogenesis, and toxin production and how transcriptional regulations of these traits are interconnected. In-depth analysis of TFs involved in sexual development revealed that mutations causing defects in perithecia development frequently affect multiple other phenotypes, and the TFs associated with sexual development tend to be highly conserved in the fungal kingdom. Besides providing many new insights into understanding the function of F. graminearum TFs, this mutant library and phenome will be a valuable resource for characterizing the gene expression network in this fungus and serve as a reference for studying how different fungi have evolved to control various cellular processes at the transcriptional level.
Development and Evaluation of Korean Nurses’ Core Competency Scale (KNCCS)  [PDF]
Won-Hee Lee, Sanghee Kim, Jihyoun An
Open Journal of Nursing (OJN) , 2017, DOI: 10.4236/ojn.2017.75045
Abstract: Purpose: The purpose of this study was to develop and evaluate a Korean Nurses’ Core Competency Scale (KNCCS). Methods: This methodological research was conducted over two major steps. The first step involved developing a preliminary 70-item KNCCS based on an extensive literature review and the standards and criteria proposed by the Korean Accreditation of Nursing. The second step involved evaluating validity and reliability of the KNCCS. 528 newly graduated nurses recently employed in nine major hospitals were participated in this research for validation. Results: The final KNCCS consisted of 70 items. The exploratory factor analysis identified five subscales under which each item could be categorized: 1) human understanding and communication skills; 2) professional attitudes; 3) critical thinking and evaluation; 4) general clinical performance; and 5) specific clinical performance. Conclusion: The KNCCS shows good reliability and validity. However, the test of both criterion and construct validity were recommended further.
No Null-Helix Mannheim Curves in the Minkowski Space
Jae Won Lee
International Journal of Mathematics and Mathematical Sciences , 2011, DOI: 10.1155/2011/580537
Abstract: We study a null Mannheim curve with time-like or space-like Mannheim partner curve in the Minkowski 3-space 31. We get the characterization of a null Mannheim curve. Then, we investigate there is no null-helix Mannheim curve in 31.
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