A polo-like kinase modulates cytokinesis and flagella biogenesis in Giardia lamblia

Background: Polo-like kinases (PLKs) are conserved serine/threonine kinases that regulate the cell cycle. To date, the role of Giardia lamblia PLK (GlPLK) in cells has not been studied. Here, we report our investigation on the function of GlPLK to provide insight into the role of this PKL in Giardia cell division, especially during cytokinesis and flagella formation. Methods: To assess the function of GIPLK, Giardia trophozoites were treated with the PLK-specific inhibitor GW843286X (GW). Using a putative open reading frame for the PLK identified in the Giardia genomic database, we generated a transgenic Giardia expressing hemagglutinin (HA)-tagged GlPLK and used this transgenic for immunofluorescence assays (IFAs). GlPLK expression was knocked down using an anti-glplk morpholino to observe its effect on the number of nuclei number and length of flagella. Giardia cells ectopically expressing truncated GlPLKs, kinase domain + linker (GlPLK-KDL) or polo-box domains (GlPLK-PBD) were constructed for IFAs. Mutant GlPLKs at Lys51, Thr179 and Thr183 were generated by site-directed mutagenesis and then used for the kinase assay. To elucidate the role of phosphorylated GlPLK, the phosphorylation residues were mutated and expressed in Giardia trophozoites RESULTS: After incubating trophozoites with 5 μM GW, the percentage of cells with > 4 nuclei and longer caudal and anterior flagella increased. IFAs indicated that GlPLK was localized to basal bodies and flagella and was present at mitotic spindles in dividing cells. Morpholino-mediated GlPLK knockdown resulted in the same phenotypes as those observed in GW-treated cells. In contrast to Giardia expressing GlPLK-PBD, Giardia expressing GlPLK-KDL was defective in terms of GIPLK localization to mitotic spindles and had altered localization of the basal bodies in dividing cells. Kinase assays using mutant recombinant GlPLKs indicated that mutation at Lys51 or at both Thr179 and Thr183 resulted in loss of kinase activity. Giardia expressing these mutant GlPLKs also demonstrated defects in cell growth, cytokinesis and flagella formation. Conclusions: These data indicate that GlPLK plays a role in Giardia cell division, especially during cytokinesis, and that it is also involved in flagella formation.ope

VvpM induces human cell death via multifarious modes including necroptosis and autophagy

VvpM, one of the extracellular metalloproteases produced by Vibrio vulnificus, induces apoptotic cell death via a pathway consisting of ERK activation, cytochrome c release, and activation of caspases-9 and -3. VvpM-treated cells also showed necrotic cell death as stained by propidium iodide (PI). The percentage of PI-stained cells was decreased by pretreatment with Necrostatin-1, indicating that VvpM-mediated cell death occurs through necroptosis. The appearance of autophagic vesicles and lipidated form of light-chain-3B in rVvpM-treated cells suggests an involvement of autophagy in this process. Therefore, the multifarious action of VvpM might be one of the factors responsible for V. vulnificus pathogenesis.ope

RNA-sequencing Profiles of Cell Cycle-Related Genes Upregulated during the G2-Phase in Giardia lamblia

To identify the component(s) involved in cell cycle control in the protozoan Giardia lamblia, cells arrested at the G1/S- or G2-phase by treatment with nocodazole and aphidicolin were prepared from the synchronized cell cultures. RNA-sequencing analysis of the 2 stages of Giardia cell cycle identified several cell cycle genes that were up-regulated at the G2-phase. Transcriptome analysis of cells in 2 distinct cellcycle stages of G. lamblia confirmed previously reported components of cell cycle (PcnA, cyclin B, and CDK) and identified additional cellcycle components (NEKs, Mad2, spindle pole protein, and CDC14A). This result indicates that the cell cycle machinery operates in this protozoan, one of the earliest diverging eukaryotic lineages.ope

Functional Identification of a Nuclear Localization Signal of MYB2 Protein in Giardia lamblia

MYB2 protein was identified as a transcription factor that showed encystation-induced expression in Giardia lamblia. Although nuclear import is essential for the functioning of a transcription factor, an evident nuclear localization signal (NLS) of G. lamblia MYB2 (GlMYB2) has not been defined. Based on putative GlMYB2 NLSs predicted by 2 programs, a series of plasmids expressing hemagglutinin (HA)-tagged GlMYB2 from the promoter of G. lamblia glutamate dehydrogenase were constructed and transfected into Giardia trophozoites. Immunofluorescence assays using anti-HA antibodies indicated that GlMYB2 amino acid sequence #507-#530 was required for the nuclear localization of GlMYB2, and this sequence was named as NLSGlMYB2. We further verified this finding by demonstrating the nuclear location of a protein obtained by the fusion of NLSGlMYB2 and G. lamblia glyceraldehyde 3-phosphate dehydrogenase, a non-nuclear protein. Our data on GlMYB2 will expand our understanding on NLSs functioning in G. lamblia.ope

A Study on the Secondary Color Terms of Achromatic Color Category in Accordance with Material

This study aimed to clarify the usual color names of achromatic color category with the highest product sales rate based on material. To collect diverse color names, the range of the characteristic idiomatic phrases for each material was drawn based on diverse materials universally shown in the actual products by collecting the secondary color terms of achromatic color category shown in domestic/foreign industrial areas(automobile, nail, eye-shadow). It aimed to increase the clear use of secondary color terms on material by providing a research to users making color names in the actual industry. In foreign countries, most of the secondary color terms are composed in English, so that it was based on the Anglosphere. Selecting the top ten brands in the industrial area, total 837 secondary color terms of achromatic color category were collected. The secondary color terms of each industrial area were analyzed in category, and the repetitive secondary color terms were extracted from each industry. Producing the idiomatic phrases of total 59 drawn secondary color terms with four stages of achromatic colors and four diverse materials, total 16 samples were applied to subjects. The results of this study on the idioms for secondary color terms of achromatic color category in accordance with material are like below. First, three industrial areas showed the most secondary color terms in 'adjective', which showed that the idiomatic phrases expressing visual image were used more. Second, the most secondary color terms were shown in 'material' for the automobile area, and in 'unrelatedness' for nail and eye-shadow area. However, in the whole three industrial areas, 'material' showed the most secondary color terms. Third, generally, people had more common visual image language in pearly material than glossy material. Fourth, ‘cotton’ was universally used for white-matte material while 'dove’ was universally used for gray-matte material. Fifth, among domestic/foreign secondary color terms of achromatic color, 'Sparkling', 'Pixie Dust', 'Mirrorball', 'Crystal', and 'Shine' were the terms much influenced by pearl regardless of chromatic color and achromatic color. Especially, ‘Crystal’ was appeared in the ‘white’ and ‘black’ of secondary color terms of the car industry, the term can be interpreted as pearl material in the car industry. On the other hand, 'Galaxy', 'Aurora', 'Moonlight', 'Dress', 'Diamond', and 'Space' were the idioms that could be universally used for achromatic color and pearl. The results of this study showed the current status of secondary color terms of achromatic color category shown in domestic/foreign industrial area, and also the range of characteristic idiomatic phrases shown for each material.;본 연구는 제품 판매율이 가장 높은 무채색의 관용색명을 재질을 기준으로 범위를 명확히 하고자 하였다. 다양한 색명을 수집하기 위해 국내외 산업분야 (자동차, 네일, 아이섀도우)에서 나타나는 무채색 범주의 관용색명을 수집하여 실제 제품에서 보편적으로 나타나는 다양한 재질을 기준으로 재질별 특성 관용구 범위를 도출하였다. 실제 산업에서 색명을 만드는 사용자들에게 연구를 제공하여 재질에 대한 관용색명의 명확한 사용을 높이려고 하였다. 해외는 대부분의 관용색명이 영어로 구성되어 있어 영미권을 기준으로 하였다 산업분야 상위 1-10위 브랜드를 선정하여 무채색 범주의 관용색명을 총 837개를 수집하였다. 각 산업분야 관용색명을 카테고리로 분석하고 반복 관용색명을 산업별로 추출하였다. 도출된 총 59개의 관용색명의 관용구를 4단계의 무채색과 4개의 다양한 재질로 제작하여 총 16개 샘플을 피험자에게 실험하였다. 재질에 따른 무채색 범주의 관용색명 관용어의 연구의 결과는 다음과 같다. 첫째, 3개 산업분야는 ‘형용사’에서 가장 많은 관용색명이 나타나고 있는데 이는 시각적 이미지를 표현하는 관용구가 더욱 많이 사용되고 있음을 알 수 있었다. 둘째, 자동차분야에서는 ‘재질’, 네일과 아이섀도우 산업에서는 ‘관련없음’ 카테고리에서 가장 많은 관용색명이 나타나지만 전체 3개 산업분야에서는 ‘재질’에서 가장 많은 관용색명이 나타났다. 셋째, 일반적으로 사람들은 광택 재질보다 펄 재질에서 더욱 공통된 시각적 이미지 언어를 가지고 있음을 알 수 있었다. 넷째, ‘면(Cotton)’은 흰색-무광재질, ‘비둘기(Dove)’는 회색-무광재질 범위에서 보편적으로 사용할 수 있는 것으로 나타났다. 다섯 번째, 국내외 무채색 관용색명 중 ‘반짝거리는(Sparkling)’, ‘요정가루(Pixie Dust)’, ‘미러볼(Mirrorball)’, ‘크리스탈(Crystal)’, ‘빛나는(Shine)’는 유채색과 무채색에 관계없이 펄에 영향을 많이 받는 관용어로 나타났다. 특히 ‘크리스탈(Crystal)’은 실제 자동차 산업 분야 관용색명에서 ‘흰색’과 ‘검정’에서 동일하게 반복 빈도 관용어로 나타났는데 이는 ‘크리스탈(Crystal)’이 실제 산업에서도 펄 재질을 가진다는 관용어로 쓰였다고 유추할 수 있다. 반면 무채색과 펄에서 보편적으로 사용할 수 있는 관용어는 ‘은하수(Galaxy)’, ‘오로라(Aurora)’, ‘달빛(Moonlight)’, ‘드레스(Dress)’,‘다이아몬드(Diamond)’, ‘우주(Space)’로 나타났다. 이를 통해 국내외 산업분야에서 나타나는 무채색 범주의 관용색명의 현황을 알 수 있었으며 재질별로 보여지는 특징 관용구의 범위에 대해 알 수 있었다.Ⅰ. 서론 1 A. 연구배경 및 목적 1 B. 연구범위 및 방법 3 Ⅱ. 이론적 배경 5 A. 무채색의 및 분류 5 B. 재질에 대한 정의 및 언어적 연관성 6 C. 관용색명의 정의 및 특성 7 Ⅲ. 무채색 범주의 관용색명 현황 및 분석 16 A. 조사대상 선정 및 방법 16 1. 분야별 브랜드 선정 범위 16 2. 색채 및 관용색명 분류 및 분석 방법 17 B. 산업 분야 관용색명 관용어 현황 및 분석 21 1. 자동차 산업 분야 무채색 관용색명 현황 및 분석 21 2. 네일 산업 분야 무채색 관용색명 현황 및 분석 31 3. 아이섀도우 산업 분야 무채색 관용색명 현황 및 분석 42 C. 소결론 50 Ⅳ. 재질에 따른 무채색 범주 관용색명 실험 51 A. 제 1차 실험 연구 설계 및 방법 51 B. 제 1차 실험 결과 54 1. 무채색 빈도 분석 54 2. 재질별 빈도 분석 58 C. 제 2차 실험 연구 설계 및 방법 66 D. 제 2차 실험 결과 67 Ⅴ. 결론 및 한계점 70 참고문헌 72 부록1. 설문지 77 부록2. 자동차 산업 분야 관용색명 78 부록3. 네일 산업 분야 관용색명 80 부록4. 아이섀도우 산업 분야 관용색명 83 ABSTRACT 8

형질전환 애기장대에서 페튜니아 PhADF 유전자의 조직 특이적 발현에 미치는 인트론의 효과

학위논문(석사)--서울대학교 대학원 :생명과학부,2002.Maste

과학 영재 프로그램의 학습 목표, 과학적 모형, 과학탐구의 인지 과정 : 서울대학교 과학 영재 프로그램을 중심으로

학위논문(석사)--서울대학교 대학원 :과학교육과 지구과학전공,2004.Maste

VvpM, an extracellular metalloprotease of Vibrio vulnificus, induces apoptotic death of human cells.

A pathogenic bacterium, Vibrio vulnificus produces various extracellular proteases including the elastolytic metalloprotease, VvpE. In silico analysis of its genome revealed a VvpE-homologous protease, VvpM whose proteolytic activity was abolished by specific inhibitors against metalloproteases. To investigate whether this newly identified protease has pathogenic role in host interaction in addition to proteolytic role, human cell lines were incubated with recombinant VvpM (rVvpM). rVvpM-challenged cells showed typical morphological changes found in cells under apoptosis. Apoptotic cell death was further evidenced by estimating the Annexin V-stained cells, whose proportions were dependent upon the concentrations of rVvpM treated to human cells. To elucidate the signaling pathway for VvpM-induced apoptosis, three MAPKs were tested if their activation were mediated by rVvpM. ERK1/2 was phosphorylated by treatment of rVvpM and rVvpM-induced cell death was blocked by a specific inhibitor against ERK1/2. In rVvpM-treated cells, the cytosolic levels of cytochrome c were increased in a VvpM concentration-dependent manner, while the levels of cytochrome c in mitochondria were decreased. Cell deaths were accompanied by apparent cleavages of procaspases-9 and -3 to the active caspases-9 and -3, respectively. Therefore, this study demonstrates that an extracellular metalloprotease of V. vulnificus, VvpM induces apoptosis of human cells via a pathway consisting of ERK activation, cytochrome c release, and then activation of caspases-9 and -3.ope

Features of the 8th grade students` asking question, planning method, analyzing data, and drawing conclusion generated for conducting self-directed, open-ended scientific inquiry

학위논문(박사)--서울대학교 대학원 :과학교육과(지구과학전공),2008.2.Docto