1,720,966 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Úloha anillinu v růstovém kónu neuronů
No full textDuring embryonal development, axons of newly differentiated neurons need to properly interconnect and create a functional neuronal network. To achieve this, the cell requires a growth cone. The growth cone is a highly dynamic structure at the end of growing axons that serves both as the navigator and the propeller. Crosstalk between actin and microtubules is vital for proper axonal pathfinding. But the exact mechanism of this cooperation remains unknown. This diploma thesis investigates the possible role of a candidate scaffolding protein called anillin in this process. Anillin has been studied in two human cell lines. SH-SY5Y neuroblastoma cell line was used for overexpression and siRNA knock-down experiments. Anillin overexpression led to perturbed neurite morphology and growth cone dynamics in SH-SY5Y cells, whereas cells with lower anillin expression had fewer neurites. Next, neurons differentiated from human iPSC (induced pluripotent stem cells) expressing endogenous fluorescently tagged anillin were studied. Local dynamic high concentration spots of anillin have been observed at the base of cell protrusions of differentiating neurons. These anillin flares appeared during cell migration, early neurite initiation, and in newly created growth cones. These results suggest that anillin plays a...Axony nově vznikajících neuronů se musí během embryonálního vývoje správně propojit, aby vytvořily fungující neurální síť. Pro tento účel slouží růstový kónus, vysoce dynamická struktura na konci rostoucích axonů, která zajišťuje navigaci i samotný pohyb. Pro správné hledání cesty je nutná komunikace mezi aktinem a mikrotubuly. Přesný mechanismus takové kooperace však dosud není objasněn. Tato diplomová práce studuje možnou roli proteinu anillinu v tomto procesu. Anillin byl studován ve dvou lidských buněčných liních. V SH-SY5Y neuroblastomové linii byla provedena transgenní overexprese a siRNA knock-down. Zvýšení exprese anillinu v SH-SY5Y buňkách vedlo k vzniku poškozených neuritů, zatímco buňky se sníženou expresí tvořily méně neuritů. Dále byly studovány neurony diferencované z lidských iPSC (indukované pluripotentní kmenové buňky), ve kterých se exprimuje endogenní fluorescenčně značený anillin. Zde byly pozorovány lokální dynamické shluky anillinu na bázi dynamických výběžků diferencujících se neuronů. Shluky se objevovaly zejména během migrace, iniciace nových neuritů, ale také v čerstvě vzniklých růstových kónech. Tyto výsledky nasvědčují tomu, že anillin hraje roli v zakládání neuritů lidských neuronů. Pro odhalení přesné funkce anillinu v těchto buňkách bude třeba další práce.Katedra buněčné biologieDepartment of Cell BiologyFaculty of SciencePřírodovědecká fakult
Functional characterization of selected microtubule regulatory
No full textMicrotubules (MTs) play crucial roles in intracellular organization and transport, cell polarity, motility, signalling, division and differentiation. MTs form complex arrays, which are, due to their highly dynamic nature, capable of rapid reorganization in response to cellular requirements. Dynamics, stability and spatial organization of MTs are regulated by many factors including MT regulatory proteins. In the presented study we functionally characterized three selected MT regulatory proteins: Ca2+ -sensor STIM1, MT severing protein spastin and γ-tubulin that is essential for MT nucleation. We found out that activation of bone marrow mast cells (BMMCs) leads to the formation of plasma membrane protrusions containing MTs. Formation of these MT protrusions is dependent on an influx of extracellular Ca2+ regulated by protein STIM1, located in endoplasmic reticulum. STIM1 associates with MTs and its depletion prevents formation of MT protrusions. This indicates that Ca2+ ions might be involved in MT regulation. Since STIM1 depletion also causes defects in chemotaxis, we propose that MT protrusions might be involved in sensing of external signals recognized by BMMCs. Glioblastoma multiforme is the most common and most aggressive malignant primary brain tumor in humans. We demonstrated that MT severing..
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Funkční charakterizace vybraných proteinů regulujících mikrotubuly
Get PDFMicrotubules (MTs) play crucial roles in intracellular organization and transport, cell polarity, motility, signalling, division and differentiation. MTs form complex arrays, which are, due to their highly dynamic nature, capable of rapid reorganization in response to cellular requirements. Dynamics, stability and spatial organization of MTs are regulated by many factors including MT regulatory proteins. In the presented study we functionally characterized three selected MT regulatory proteins: Ca2+ -sensor STIM1, MT severing protein spastin and γ-tubulin that is essential for MT nucleation. We found out that activation of bone marrow mast cells (BMMCs) leads to the formation of plasma membrane protrusions containing MTs. Formation of these MT protrusions is dependent on an influx of extracellular Ca2+ regulated by protein STIM1, located in endoplasmic reticulum. STIM1 associates with MTs and its depletion prevents formation of MT protrusions. This indicates that Ca2+ ions might be involved in MT regulation. Since STIM1 depletion also causes defects in chemotaxis, we propose that MT protrusions might be involved in sensing of external signals recognized by BMMCs. Glioblastoma multiforme is the most common and most aggressive malignant primary brain tumor in humans. We demonstrated that MT severing...SOUHRN Mikrotubuly (MTs) hrají zásadní roli ve vnitřní organizaci buňky a vnitrobuněčném transportu, v regulaci polarity, pohyblivosti a přenosu signálů i v buněčném dělení a diferenciaci. MTs vytvářejí složité struktury, které jsou díky jejich dynamické povaze schopné rychlé reorganizace dle potřeb buňky. Dynamika, stabilita a prostorové uspořádání MTs jsou regulovány mnoha faktory. Jedním z nich jsou proteiny regulující MTs. V této práci jsme se zabývali funkční charakterizací tří proteinů regulujících MTs: Ca2+ -senzoru STIM1, spastinu, proteinu štěpícího MTs, a γ-tubulinu, který je zásadní pro nukleaci MTs. Zjistili jsme, že aktivace žírných buněk kostní dřeně (BMMCs) vede ke tvorbě výběžků cytoplasmatické mebrány, které obsahují MTs. Tvorba těchto MT výběžků je závislá na transportu extracelulárních Ca2+ iontů do buňky, který je řízen proteinem STIM1 lokalizovaným na endoplasmatickém retikulu. STIM1 se váže na MTs a potlačení jeho exprese zabraňuje tvorbě MT výběžků. To naznačuje, že Ca2+ ionty mohou hrát roli při regulaci MTs. Jelikož snížení exprese STIM1 způsobuje také poruchy chemotaxe, popsané MT výběžky mohou být hypoteticky důležité pro vnímání vnějších signálů. Glioblastoma multiforme je nejčastější a nejagresivnější maligní primární nádor mozku u člověka, jehož možnosti léčby jsou dosud velmi...Department of Cell BiologyKatedra buněčné biologieFaculty of SciencePřírodovědecká fakult
Kinases regulating AP2 complex phosphorylation in Caenorhabditis elegans
No full textHeterotetrameric adaptor protein 2 complex (AP2) is a fundamental component of clathrin-coated pits playing a part in every step of clathrin-coated vesicle generation. Although the mechanism of AP2 function has been extensively studied for no less than 20 years, the exact role of the regulatory phosphorylation on T156 of its μ2 subunit remains unclear. The main kinase responsible for the T156 phosphorylation in mammals is AAK1; however, many observations suggest that other kinases collaborate on this event. The aim of this project is to shed light on the importance of AP2 phosphorylation in Caenorhabditis elegans and elucidate the function of SEL-5/AAK1 kinase. To determine the relationship between SEL-5/AAK1, AP2 phosphorylation, and the function of endocytosis, we used a combination of phenotype analysis of C. elegans transgenic lines and in vitro assays. We showed that DPY-23, the C. elegans μ2 subunit, is phosphorylated analogously to its human orthologue. We confirmed that DPY-23 phosphorylation depends on SEL-5, yet we were not able to prove the kinase activity of SEL-5 directly. Interestingly, our results further revealed that DPY-23 phosphorylation is dispensable for the endocytosis of a model cargo, and we also showed that interaction motifs located outside the kinase domain of SEL-5 are..
Kinázy regulující fosforylaci AP2 komplexu u Caenorhabditis elegans
Get PDFHeterotetrameric adaptor protein 2 complex (AP2) is a fundamental component of clathrin-coated pits playing a part in every step of clathrin-coated vesicle generation. Although the mechanism of AP2 function has been extensively studied for no less than 20 years, the exact role of the regulatory phosphorylation on T156 of its μ2 subunit remains unclear. The main kinase responsible for the T156 phosphorylation in mammals is AAK1; however, many observations suggest that other kinases collaborate on this event. The aim of this project is to shed light on the importance of AP2 phosphorylation in Caenorhabditis elegans and elucidate the function of SEL-5/AAK1 kinase. To determine the relationship between SEL-5/AAK1, AP2 phosphorylation, and the function of endocytosis, we used a combination of phenotype analysis of C. elegans transgenic lines and in vitro assays. We showed that DPY-23, the C. elegans μ2 subunit, is phosphorylated analogously to its human orthologue. We confirmed that DPY-23 phosphorylation depends on SEL-5, yet we were not able to prove the kinase activity of SEL-5 directly. Interestingly, our results further revealed that DPY-23 phosphorylation is dispensable for the endocytosis of a model cargo, and we also showed that interaction motifs located outside the kinase domain of SEL-5 are...Heterotetramerní adaptorový proteinový komplex 2 (AP2) je podstatnou součástí klatrinových jamek hrající roli v každém kroku procesu tvorby klatrinového váčku. Přestože je mechanismus funkce AP2 intenzivně studován již více než 20 let, přesná role regulační fosforylace na T156 jeho podjednotky μ2 zůstává nejasná. Hlavní kinázou zodpovědnou za fosforylaci T156 u savců je AAK1, nicméně mnohá pozorování naznačují, že se této události účastní i další kinázy. Cílem této práce je popsat důležitost fosforylace AP2 u Caenorhabditis elegans a objasnit funkci kinázy SEL-5/AAK1. Ke studiu vztahu mezi SEL-5/AAK1, fosforylací AP2 a funkčností endocytózy jsme využili kombinaci analýzy fenotypů transgenních linií C. elegans s in vitro přístupy. Ukázali jsme, že DPY-23, podjednotka μ2 u C. elegans, je fosforylována analogicky ke svému ortologu u člověka, nebyli jsme však schopni přímo prokázat kinázovou aktivitu SEL-5, přestože jsme potvrdili, že fosforylace DPY-23 na SEL-5 závisí. Naše výsledky dále odhalily, že fosforylace DPY-23 je postradatelná pro endocytózu modelového karga, a ukázali jsme, že interakční motivy ležící mimo kinázovou doménu SEL-5 jsou důležité pro její funkci. Pro určení vazebných partnerů SEL-5/AAK1, pro které jsou tyto motivy klíčové, a procesu, který s touto spoluprací souvisí, je však...Katedra buněčné biologieDepartment of Cell BiologyFaculty of SciencePřírodovědecká fakult
The role of anillin in the growth cone of neurons
No full textDuring embryonal development, axons of newly differentiated neurons need to properly interconnect and create a functional neuronal network. To achieve this, the cell requires a growth cone. The growth cone is a highly dynamic structure at the end of growing axons that serves both as the navigator and the propeller. Crosstalk between actin and microtubules is vital for proper axonal pathfinding. But the exact mechanism of this cooperation remains unknown. This diploma thesis investigates the possible role of a candidate scaffolding protein called anillin in this process. Anillin has been studied in two human cell lines. SH-SY5Y neuroblastoma cell line was used for overexpression and siRNA knock-down experiments. Anillin overexpression led to perturbed neurite morphology and growth cone dynamics in SH-SY5Y cells, whereas cells with lower anillin expression had fewer neurites. Next, neurons differentiated from human iPSC (induced pluripotent stem cells) expressing endogenous fluorescently tagged anillin were studied. Local dynamic high concentration spots of anillin have been observed at the base of cell protrusions of differentiating neurons. These anillin flares appeared during cell migration, early neurite initiation, and in newly created growth cones. These results suggest that anillin plays a..
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