13,080,581 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
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
<i>No se sabe</i>: entrevista a Lucas Gagliardi
No full textEntrevista al Licenciado y Profesor en Letras (UNLP) Lucas Gagliardi. Se especializa en literatura en lengua inglesa y en crítica genética. Se desempeña como profesor en la Universidad Pedagógica (UNIPE), en institutos de formación docente y escuelas secundarias. Ha participado en proyectos de investigación sobre archivos de escritores, publicaciones impresas. Participa en el programa de voluntariado universitario de la Facultad de Trabajo Social (UNLP) en articulación con la Biblioteca Ambulante del Hospital de Niños dictando talleres de lectura y escritura.Al hacer clic en el enlace que figura en "Documentos relacionados", pueden accederse a todos los trabajos de Lucas Gagliardi presentes en el repositorio.Radio Universidad Nacional de La Plat
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Se Hyeuk Kim
No full text학위논문(박사)--아주대학교 일반대학원 :분자과학기술학과,2014. 2CONTENTS
LIST OF TABLES…………...……………………...........................…..….……...i
LIST OF FIGURES……………………...……..…………………….……………ii
ABSTRACT…………………………………………………………………..……iv
Chapter 1. General Introduction………………………………………………..1
1.1 Introduction…………………….……………………..…………………...2
1.2 MEP pathway………………………………………………..………………5
1.3 MEV pathway……………………….…………………….…………………6
1.4 Microbial production of carotenoids………………………………….……..8
1.5 Aims of This study ………………………………….………………………9
Chapter 2. Astaxanthin dirhamnoside biosynthesis pathway in Sphingomonas lacus PB304T…………………………………………..………………………….12
2.1 Abstract……………………………………………………….……………13
2.2 Introduction………………..…………………..…………………………14
2.3 Materials and Methods……………………………………………………..17
2.3.1. Bacterial strains, plasmids, and growth conditions……………..….17
2.3.2. Phylogenetic analysis of 16S rRNA………………………………….17
2.3.3. Recombinant DNA techniques…………………………….…………18
2.3.4. Fosmid library construction…………………………….……………18
2.3.5. Colony hybridization………………………………….……………..19
2.3.6. Gene cloning…………………………………………………………20
2.3.7. Carotenoid isolation and structural analysis………………..………20
2.4 Results…………………………………………………………………..…24
2.4.1. Taxonomic analysis of the isolated strain PB304……………….……24
2.4.2. Carotenoid profile of Sphingomonas lacus PB304T and structural assignment of the major Sphingomonas lacus PB304T carotenoid…24
2.4.3. Identification of CrtZ, CrtB, CrtI, and CrtY…………………………28
2.4.4. Identification of CrtW and CrtX…………………………………….30
2.4.5. Functional analysis of the putative carotenogenic enzymes from Sphingomonas lacus PB304T………………………………………32
2.4.6. Phylogenetic analysis of Sphingomonas lacus PB304T CrtX………...35
2.5. Discussion……………………………………………………..…………37
Chapter 3. Functional expression and extension of the staphylococcal staphyloxanthin biosynthetic pathway in Escherichia coli…..40
3.1. Abstract…………………………………………..…………………….…41
3.2. Introduction…………….………………………………..………………42
3.3. Materials and Methods…………………………………………………….46
3.3.1. Cloning and synthetic module construction……………….…………46
3.3.2. Culture growth for carotenoid production……………………………47
3.3.3. Isolation of carotenoids………………………………………………47
3.3.4. Preparation of carotenoids for LC/MS……………..………………48
3.3.5. Allelic replacement…………………………………………………48
3.3.6. Analysis of carotenoids………………………………………………49
3.4. Results …………………………………………………………………….52
3.4.1. Reconstruction of a partial staphyloxanthin biosynthetic pathway in E. coli………………………………………………………………….52
3.4.2. Identification of the sixth enzyme in the staphyloxanthin biosynthetic pathway of S. aureus…………………………………………………55
3.4.3. Identification of an enzyme catalyzing the oxidation of carotenoid aldehyde to carboxylic acid in S. carnosus…………………………60
3.4.4. Functional verification of 4,4′-diaponeurosporen-aldehyde dehydrogenase (AldH) in S. aureus using allelic replacement.……61
3.4.5. Expression of the complete staphyloxanthin pathway in E. coli and characterization of staphyloxanthin-like compounds produced in engineered E. coli……………………………………………………65
3.5. Discussion………………………………………………………………71
Chapter 4. Investigation of biological activity of natural and non-natural C30 carotenoids ………………...……………………………….……….73
4.1. Abstract…………………………………………………………………….74
4.2. Introduction……………………………………………………..………75
4.3. Materials and Methods……………………………………………………79
4.3.1. Bacterial strains, plasmids, and growth conditions………………….79
4.3.2. Gene cloning and construction of C30 carotenogenic gene module…79
4.3.3. Isolation of carotenoids………………………………………………80
4.3.4. Analysis of carotenoids………………………………………………80
4.3.5. 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenge assay……81
4.3.7. Cytotoxicity tests and neurogenesis of rBMSCs……………………82
4.4. Results……………………………………………………………………85
4.4.1. Manipulation of C30 acyclic carotenoid biosynthesis pathway………85
4.4.2. Manipulation of C30 monocyclic carotenoid biosynthesis……………87
4.4.3. Manipulation of bicyclic C30 carotenoids pathway………………….90
4.4.4. Radical scavenging activity measurement of various structures of C30 carotenoids……………………….…………………………………..93
4.4.5. Neuronal differentiation of rat Bone Marrow Mesenchymal stem cells (rBMSCs) induced by 4,4’-diapotorulene……………………………96
4.5. Discussion…………………………………………………………………99
Chapter 5. Proposed anticancer mechanisms of two major saffron carotenoids, crocin and crocetin, on cancer cell lines…………………………102
5.1. Abstract…………………………………………………………………103
5.2. Introduction………………………………………………………………104
5.3. Materials and Methods…………………………………………………106
5.3.1. Reagents……………………………………………………………106
5.3.2. Cell culture……………………………………………………….…106
5.3.3. Cell viability - MTT assay…………………………………………106
5.3.4. Western blot analysis………………………………………………107
5.3.5. Reverse transcriptase PCR (RT-PCR)…………………………...…108
5.3.6. Reporter assay………………………………………………………108
5.3.7. Detection of ROS………………………………………..…………109
5.3.8. LDH activity assay…………………………………………………109
5.3.9. Statistical analysis…………………………………………………110
5.4. Results……………………………………………………………….….111
5.4.1. Cytotoxicity of crocin and crocetin on 5 human cancer cell lines…111
5.4.2. Intracellular ROS levels in crocin/crocetin-treated HeLa cells……114
5.4.3. ROS-associated cytotoxicity of crocin/crocetin…………………….114
5.4.4. Crocin/crocetin-mediated Nrf2 activation…………………………118
5.4.5. Inhibitory activity of crocin and crocetin on the expression of LDHA in HeLa cells…………………….……………………………………120
5.5. Discussion……………………………………………………………....122
Chapter 6. Simultaneous transcriptional and translational regulation for tuning protein expression level in Escherichia coli ……………126
6.1. Abstract…………………………………………………………………127
6.2. Introduction…………………………………………………………….128
6.3. Materials and Methods…………………………………………………130
6.3.1. Bacterial strains, plasmids, and growth conditions ………………130
6.3.2. Recombinant DNA techniques …………………………………....130
6.3.3. Construction of reporter plasmid …………………………………..130
6.3.4. β-Galactosidase assay …………………………………….………131
6.4. Results…………………………………….……………………………..134
6.4.1. Construction of synthetic expression cassette (SEC) library...…….134
6.4.2. Screening of SEC library with β-galactosidase assay ……………137
6.4.3. Sequence analysis of the SEC library.…..…………………………140
6.5. Discussion………………………………………………………………142
7. Conclusion……………….…………………………………………………144
8. References……………………...……………….……………………………146
ABSTRACT IN KOREAN………………………………..…….…………….…169
ACKNOWLEDGEMENTS………………..………………….…………....……172MasterIncreasing demand on the development of sustainable processes is raising importance of the microbial production of natural products, chemicals, and fuels. This trend has driven recent research on the production of isoprenoids such as terpenoids and carotenoids in heterologous hosts. In particular diverse structures of carotenoids, natural isoprenoid pigments, were produced in engineered heterologous microorganisms due to their beneficial functions to humans. As an attempt to engineer diverse structures of carotenoids of biological significances, 1) biochemical and genetic elucidation of biosynthesis pathways of carotenoids, 2) heterologous production of various novel structures of C30 carotenoids, 3) mechanism studies on biological activities of carotenoids, and 4) regulatory engineering for fine-controlling pathway enzyme expression have been carried out.
First, the biosynthesis pathway of astaxanthin dirhamnoside of novel species, Sphingomonas lacus PB304T, was elucidated genetically and biochemically. Two gene clusters, crtZBIY and crtWX, encoding six astaxanthin dirhamnoside biosynthesis enzymes were discovered from a fosmid library, and six genes were annotated by blast analysis. Complementation of each gene of S. lacus PB304T with carotenogenic gene modules of Pantoea agglomerans in E. coli assigned the function of each gene except for rhamnosyltransferase, CrtX.
Second, a missing enzyme, 4,4’-diaponeurosporen-aldehyde dehydrogenase (AldH), that is involved in the biosynthesis of staphyloxanthin in Staphylococcus aureus was identified. Through heterologous expression of biosynthesis pathway of staphyloxanthin in E. coli and knockout strategy in S. aureus, the new function of AldH was assayed, and AldH was found to be an essential enzyme in the biosynthesis of staphyloxanthin. Heterologous expression of complete pathway enzymes of staphyloxanthin in E. coli resulted in biosynthesis of a few staphyloxanthin-like compounds, which have altered fatty acid acyl chains, indicating functional expression and coordination of the six staphyloxanthin pathway enzymes in a heterologous host E. coli.
Third, nine novel structures of C30 carotenoids using in vitro evolved 4,4’-diapophytoene desaturase (CrtN) and lycopene cyclase (CrtY) was created by extending 4,4’-diaponeurosporene, 4,4’-diapotorulene, and 4,4’-diapo-β-carotene pathway enzymes in E. coli. Two acyclic, three monocyclic, and four bicyclic C30 carotenoids were produced. 4,4’-diapolycopen-dial exhibited the highest radical scavenging activity (4.4 fold compare with DL-α-tocopherol), and 4,4’-diapotorulene induced neuronal cells-like morphological changes to rat bone marrow mesenchymal stem cells (rBMSCs), demonstrating potential uses of novel C30 carotenoids.
Fourth, anticancer activities of two major glycosylated (crocin) and carboxylic (crocetin) carotenoids were investigated on 5 human cancer cell lines, and their possible anticancer mechanisms were proposed. Crocetin showed a 7-fold higher cytotoxicity than crocin, suggesting that structural differences account for the different efficacies between them. It was further proved by higher induction of intracellular ROS in HeLa cells monitored by FACS analysis. Induction of nuclear factor E2-related factor 2 (Nrf2) was also monitored, and inhibitory effect of crocin and crocetin on lactate dehydrogenase A (LDHA), one of the targets for chemoprevention in cancer cells, was measured. Crocetin showed higher effect on induction of Nrf2 and inhibition of LDHA, indicating crocetin and crocin have different mechanisms for the observed cytotoxicity in cancer cell lines.
Finally, synthetic expression cassettes (SEC) were constructed for fine-tuning pathway enzyme expression. Sequences of promoter and ribosomal binding regions were simultaneously randomized and screened based on the β-galactosidase activity. The strength of SEC was adjusted between 5 to 8500 Miller Unit (MU) based on the activity level. However, no significant features were found from sequence analysis and in silico calculation of translation initiation rate.
In conclusion, through systematic studies on heterologous biosynthesis of diverse structures of carotenoids by using synthetic expression modules and combinatorial biosynthesis, 2 new biosynthetic pathways were identified and characterized genetically and biochemically, over 10 novel structures of carotenoids were created, and their biological activities and cellular mechanisms were investigated. These results with SECs and other engineering tools will be served invaluable information for further application and engineering of isoprenoids including carotenoids
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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