• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 65
  • 62
  • 59
  • 21
  • 16
  • 10
  • 5
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 254
  • 116
  • 53
  • 39
  • 35
  • 33
  • 33
  • 27
  • 26
  • 24
  • 22
  • 21
  • 20
  • 20
  • 19
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Degradation of estrogenic endocrine disruptors by laccases: from estrogenicity monitoring methods to reactor design

Blavier, Julie 28 December 2015 (has links)
In the past decades, much concern has been expressed regarding organic micropollutants generating endocrine disruption. In particular, estrogenic endocrine disruptors, compounds that interfere with the estrogenic hormonal mechanisms, are in the center of environmental scien- tists attention. Numerous endocrine disrupting effects have been observed at concentrations corresponding to those found in aquatic environments, such as feminization of fauna, infertility, reproductive disturbance, cancer, or developmental disruption. Wastewater treatment plants ef- fluents have been identified as the main source of estrogenic endocrine disruptors in the aquatic environment, due to inappropriate treatment. Promising alternative treatment systems based on the use of ligninolytic enzymes (e.g. laccases) have recently emerged. This work falls within the framework of these new techniques. Althoughno environmentally safe threshold can clearly be set, focusing on the removal of global estrogenicity in water instead of concentrations of targeted estrogenic compounds seems a relevant research. To our knowledge, the use of these recently emerged enzymatic processes at an industrial scale (such as for the treatment of urban wastewater), oriented towards water overall estrogenicity, has not been implemented yet.The general objective of this work was to develop ans study a process of removal of estro- genicity by laccases from white-rot fungi, in laboratory, with the purpose of design and scale-up for industrial implementation. This work consisted of the conception, characterization, testing, study and modeling of this process.First, in order to enable the study and the scaling-up of a process of estrogenicity removal, op- timizing the technologies of quantification of estrogenicity in water was a real necessity. Therefore, a study of the methods of estrogenicity monitoring, within a treatment process framework, was conducted. Based on a wide literature review, existing methods were gathered and assessed with the aim of their use as monitoring and design tools. Fromthat review, four methods were selected and tested according to numerous criteria and their compatibility with our process: three bioassays (Yeast Estrogen Screen assay; Lyticase-assisted Yeast Estrogen Screen assay; MCF-7 cell based reporter gene assay) and one analytical method (High Performance Liquid Chromatography with UV detection, HPLC-UV). Concentration-response curves towards the reference 17β-estradiol, in several solvents, were acquired. A fitting model was developed for further expression of all measurements in Estradiol Equivalents. The methods were used to evaluate the estrogenicity of bisphenol A, triclosan and nonylphenol, along with estrogenicity of mixtures of bisphenol A and 17β-estradiol. The testing of these four methods enabled the assessment of their sensitivity, re- producibility, and implementation. Based on that experimental assessment, the Lyticase-assisted Yeast Estrogen Screen (LYES) assay was selected and systematized to be further applied, in combination with an adapted protocol of HPLC-UV analysis, to the monitoring of estrogenicity removal in two lab-scaled reactors. The LYES assay demonstrated a real methodological potential for thescale-up of an estrogenicity removal process and could be used as a design tool. For both reactors, results have indicated that HPLC-UV and LYES assay methods are completely inter- changeable in the case of bisphenol A monitoring (in the conditions used in this work). This work also highlighted the peculiar behavior of mixtures of bisphenol A and 17β-estradiol in terms of estrogenicity, and the parallel observation of an enhancement of bisphenol A estrogenicity removalin presence of 17β-estradiol.In the second part of this work, a batch reactor with laccases in solubilized form was developed and estrogenicity removal was assessed. Kinetics data for the degradation of estrogenic endocrinedisruptors were acquired with the LYES assay (estrogenicity) and the HPLC-UV method (concen- trations). Degradations were performed from several solutions of bisphenol A, 17β-estradiol, and mixtures. In the case of 17β-estradiol and mixtures, conversions reached minimum 90% within 1 hour of degradation at our conditions, with no dependency on pollutant initial concentrations. In the case of bisphenol A, conversions varied from 0 to 100% after 6 hours of degradation and were shown tobe strongly dependent on BPA initial concentrations, indicating the laccases deac- tivation by substrate. Bisphenol A byproducts of degradation were also analyzed, which indicated their absence of estrogenicity and their potential linear evolution with BPA degradation. Acquired kinetics data were exploited for the modeling of the batch degradations kinetics. At this stage of the work, no clear kinetics conclusions could be made in this part.From an industrial point of view, the use of immobilized enzymes is more cost-effective, due to the improvement of enzymes recovery and stability. Therefore, in the third part of this work, a continuous column-shaped packed-bed reactor composed of laccases immobilized on a silica support was developed. The packed-bed reactor was built and tested in laboratory. Residence time distributions, pressure drop calculations, and tracer degradations were performed on the re- actor for its characterization.Immobilization and activity measurements protocols were applied. Similar monitoring than in the batch reactor (LYES assay and HPLC-UV) were performed during continuous degradations of bisphenol A, 17β-estradiol, and mixtures in the packed-bed reactor. Acquired kinetics data were exploited to study and model the kinetics occurring in the packed-bed reactor. Mass transfer phenomena and laccases deactivation by substrate in the reactors were investigated and modeled, revealing, depending on the pollutant, the presence of slight external mass transfer limitation and the strong dependence of the kinetics on laccases deactivation. A design tool, in the form of a mathematical model for the design of a packed-bed reactor with immobilized laccases for the degradation of bisphenol A and related estrogenicity, was developed. The model was validated (simple validation) on experimental data. The model was then used, as a comparison, for the design of a reactor with similar conditions than a documented technique of bisphenol A degradation by ozone. The design resulted in a reactor twice smaller than for degradation by ozone, for the same conversion.In the current context of environmental crisis, this work proposed a first version of a promising practical solution for the treatment of environmentally problematic e-EDCs, oriented towards water overall estrogenicity monitoring and removal, and using natural biocatalysts. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished
122

Développement d'outils moléculaires standardisés pour les espèces levuriformes du clade CTG / Development of a standardized toolkit for CTG clade yeast

Defosse, Tatiana 12 December 2017 (has links)
Parmi les espèces de levures du clade CTG, certaines sont responsables de candidoses tandis que d’autres présentent des potentiels en biotechnologie. Depuis quelques années, nous assistons à une intensification des recherches sur ces levures. Cependant, leur code génétique particulier a ralenti la mise au point d’outils génétiques pour la plupart d’entre elles. Cette thèse vise à développer des outils moléculaires standardisés pour un grand nombre d’espèces de levures du clade CTG. Nous avons d’abord conçu des vecteurs d’expression adaptés à l’espèce M. guilliermondii. Par la suite, nous avons caractérisé le gène de résistance à l’acide mycophénolique IMH3.2 afin de l’utiliser comme marqueur de sélection lors de la transgénèse d’espèces du clade CTG. Enfin, nous avons mis au point une série de vecteurs permettant la manipulation génétique de ces espèces. Ce travail a conduit à la conception d’une large gamme d’outils utilisable dans un grand nombre de ces levures, pré-requis essentiel aux futurs recherches en mycologie médicale et au développement de stratégies de biologie synthétique. / The fungal CTG clade includes well-known yeasts of clinical importance and/or biotechnological potential. Thus, albeit being intensively studied over the last 30 years, their uncommon genetic code precludes the use of the widely available markers and reporter systems for genetic approaches in these microorganisms. We provide here a toolbox to genetically manipulate a wide range of CTG clade species. Firstly, we developed a new series of versatile controllable expression vectors for M. guilliermondii. After, we characterized MPA-resistant gene IMH3.2 et used it as a drug resistance marker in several yeast species. Finaly, we provide a molecular toolbox suitable to genetically manipulate a broad range of prominent species from the CTG clade. This versatile toolkit represents a new starting point for successful developments of research in medical mycology in the CTG clade but also will expedite synthetic biology strategies in these microorganisms for biotechnological applications.
123

Geneticky modifikované potraviny a jejich potenciál, rizika a etika

Ševčíková, Miroslava January 2015 (has links)
Diploma thesis is focused on the genetically modified crops and their ethical aspects. At the beginning there were summarized existing findings about transgenic crops, biotechnologies and mechanisms of modification. Next step was the evaluation of legislation, which is valid not only for the Czech Republic but also for European Union. By the comparative method there were assessed positive and negative sides of a genetically modified food, which were followed by the questionnaire survey to find out a general awareness about GMO. The hypothesis was formulated that a genetically modified food is a solution of current food crisis. The hypothesis was confirmed, but with serious reservations. Results showed that GMO are perceived rather negatively and sceptically despite its indisputable advantages and a potential perceived in the Czech Republic and EU. This view is caused by not sufficiently conclusive scientific results concerning negative effect of this food on the human health.
124

Optimisation des bioprocédés utilisant la culture de cellules animales pour la production de protéines glycosylées d'intérêt pharmaceutique

Hendrick, Vincianne Unknown Date (has links)
Doctorat en sciences médicales / info:eu-repo/semantics/nonPublished
125

Potenciál rozvoje odvětví biotechnologií v Olomouckém kraji jako faktor ovlivňující konkurenceschopnost regionu / The potential of the development of the biotechnology sector in the Olomouc Region as a factor affecting the competitiveness of the region

Pospíšil, David January 2009 (has links)
Biotechnologies are nowadays considered to be crucial for the transition to a knowledge-based economy and their development has a positive effect on the competitive strength of countries and regions. The aim of this diploma thesis is to assess, in a complex way, the biotechnology sector development potential in a particular region -- in the Olomouc Region. The theoretical part provides a general theoretical framework for the subject matter and a general description of the sector. The complex assessment of the development potential of biotechnologies is based on several partial analyses. The thesis analyzes the general characteristics of the innovation environment in the Olomouc Region, the education and research facilities that are present in this region, the biotechnology business sector and their mutual cooperation. Thesis also maps the current projects in the area of biotechnology and the key personalities in terms of the development of biotechnologies in the Olomouc Region.
126

Analýza vybraných průmyslových sektorů v ČR a v SRN a komparace jejich konkurenceschopnosti jako podklad pro strategická rozhodování / The analysis of selected industrial sectors in the Czech republic and Germany and the comparison of their competitiveness as a base for strategic decision making

Rybička, Miloš January 2012 (has links)
The goal of this Masters Thesis is to analyze three selected industry sectors in the Czech Republic and in Germany. Concretely the industries in focus are engineering, motor vehicle manufacturing and finally pharmacy along with bio- and nanotechnology. Furthermore, factors limiting but also supporting the industry development are identified and described in the Thesis. In the Thesis, analytical instruments will be used, especially the SWOT analysis and benchmarking. The Thesis is mainly intended for managers, employees, consultants and all other direct or indirect interest groups of both Czech and German industry companies and their suppliers but also for potential investors who are deciding whether to enter a market in the CEE region.
127

Comunicação, Bioarte e Bioidentidades: discursos estéticos sobre as corporeidades contemporâneas

Ferreira, Hamilton de Paulo 25 March 2015 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2015-12-16T10:25:54Z No. of bitstreams: 1 hamiltondepauloferreira.pdf: 1124273 bytes, checksum: 5f98e1a7126a46d51020f211591e1b55 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2015-12-16T11:20:18Z (GMT) No. of bitstreams: 1 hamiltondepauloferreira.pdf: 1124273 bytes, checksum: 5f98e1a7126a46d51020f211591e1b55 (MD5) / Made available in DSpace on 2015-12-16T11:20:18Z (GMT). No. of bitstreams: 1 hamiltondepauloferreira.pdf: 1124273 bytes, checksum: 5f98e1a7126a46d51020f211591e1b55 (MD5) Previous issue date: 2015-03-25 / O crescente desenvolvimento no campo científico e tecnológico impulsiona a sociedade a viver de outra forma, trazendo para nossas vidas a assimilação tecnológica, em um momento que pode ser chamado de biocontemporaneidade, marcado pelas construções identitárias fortalecidas pela imagem do corpo, a bioidentidade. A presente pesquisa visa ressaltar os discursos biológicos da contemporaneidade presentes no movimento da Bioarte e sua relação de proximidade com as biotecnologias. Destas se utilizam métodos e técnicas a fim de construir propostas estéticas artísticas ligadas ao corpo e às suas fragmentações, que se espalham pelo contexto social criando novas possibilidades de subjetivação. A tríade arte, ciência e tecnologia alimenta os questionamentos sobre o cenário que ocupa o corpo frente às possibilidades por ele instaurados. A hipótese norteadora é a de que a fragilidade que apresenta o corpo nesse contexto, como matéria passiva, o coloca em evidência e crise simultaneamente, em um questionamento emergente sobre o assujeitamento na aderência às biotecnologias. Partindo da contextualização do corpo no século XX, aliada aos conceitos de Biopoder descritos por Michael Foucault, bem como à descrição de movimentos artísticos – como as performances e a Body Art – e aos novos meios – como o cinema e a fotografia – inaugurados nesse período, e à contextualização de artistas e obras inseridos no discurso bioartístico, constitui-se um panorama em que o corpo encontra-se sob uma nova ótica social e estética. / The increasing development in science and technology pushes society to live in another manner, bringing technological assimilation to our lives at a time that can be referred to as biocontemporaneity, marked by identity constructions strengthened by the image of the body, that is, bioidentity. This research aims to highlight the biological discourses of contemporaneity, which can be found in the Bioart movement and its close relationship with biotechnology. These methods and techniques are applied in order to build artistic aesthetic applications, linked to the body and its fragmentation, spreading through the social context and creating new possibilities of subjectivity. The triad - arts, science and technology - feeds the questions about the scenario that occupies the body in face of the possibilities opened by it. The hypothesis which guides us, is that the weakness, which shows the body, in this context, as passive matter, simultaneously places it in highlight and crisis, through an emerging questioning on the acquiesce hence the adherence of biotechnologies. Opening in the contextualization of the concept of body in the twentieth century, beside the concept of Biopower, described by Michael Foucault, as well as the description of artistic movements - such as performances and Body Art - and the new media - such as film and photography initiated in this period - and the contextualization of artists and works inserted in a bio-artistic speech, constitutes a panorama in which the body is under a new social and aesthetical perspective.
128

Structural fragment clustering reveals novel structural and functional motifs in α-helical transmembrane proteins

Schroeder, Michael, Marsico, Annalisa, Henschel, Andreas, Winter, Christof, Tuukkanen, Anne, Vassilev, Boris, Scheubert, Kerstin 27 November 2015 (has links)
Background A large proportion of an organism's genome encodes for membrane proteins. Membrane proteins are important for many cellular processes, and several diseases can be linked to mutations in them. With the tremendous growth of sequence data, there is an increasing need to reliably identify membrane proteins from sequence, to functionally annotate them, and to correctly predict their topology. Results We introduce a technique called structural fragment clustering, which learns sequential motifs from 3D structural fragments. From over 500,000 fragments, we obtain 213 statistically significant, non-redundant, and novel motifs that are highly specific to α-helical transmembrane proteins. From these 213 motifs, 58 of them were assigned to function and checked in the scientific literature for a biological assessment. Seventy percent of the motifs are found in co-factor, ligand, and ion binding sites, 30% at protein interaction interfaces, and 12% bind specific lipids such as glycerol or cardiolipins. The vast majority of motifs (94%) appear across evolutionarily unrelated families, highlighting the modularity of functional design in membrane proteins. We describe three novel motifs in detail: (1) a dimer interface motif found in voltage-gated chloride channels, (2) a proton transfer motif found in heme-copper oxidases, and (3) a convergently evolved interface helix motif found in an aspartate symporter, a serine protease, and cytochrome b. Conclusions Our findings suggest that functional modules exist in membrane proteins, and that they occur in completely different evolutionary contexts and cover different binding sites. Structural fragment clustering allows us to link sequence motifs to function through clusters of structural fragments. The sequence motifs can be applied to identify and characterize membrane proteins in novel genomes.
129

Early Events in Foamy Virus - Host Interaction and Intracellular Trafficking

Lindemann, Dirk, Berka, Ursula, Hamann, Martin Volker 18 December 2015 (has links)
Here we review viral and cellular requirements for entry and intracellular trafficking of foamy viruses (FVs) resulting in integration of viral sequences into the host cell genome. The virus encoded glycoprotein harbors all essential viral determinants, which are involved in absorption to the host membrane and triggering the uptake of virus particles. However, only recently light was shed on some details of FV’s interaction with its host cell receptor(s). Latest studies indicate glycosaminoglycans of cellular proteoglycans, particularly heparan sulfate, to be of utmost importance. In a species-specific manner FVs encounter endogenous machineries of the target cell, which are in some cases exploited for fusion and further egress into the cytosol. Mostly triggered by pH-dependent endocytosis, viral and cellular membranes fuse and release naked FV capsids into the cytoplasm. Intact FV capsids are then shuttled along microtubules and are found to accumulate nearby the centrosome where they can remain in a latent state for extended time periods. Depending on the host cell cycle status, FV capsids finally disassemble and, by still poorly characterized mechanisms, the preintegration complex gets access to the host cell chromatin. Host cell mitosis finally allows for viral genome integration, ultimately starting a new round of viral replication.
130

Vývoj minibioreaktoru pro mikrobiální biotechnologie / Development of microbioreactor for microbial biotechnology

Jakešová, Michaela January 2021 (has links)
This master thesis deals with the development of a minibioreactor for microbial biotechnologies. The AlgaTox system – an analytical photobioreactor from BVT Technologies – was the default unit of the new device. The working volume of the new minibioreactor is in the range of 4 to 8 ml. The minibioreactor was composed of a minithermostat, a reaction vessel, an oxygen electrode, a temperature and pH probe, accessories for the supply of air to the liquid and an insertion for the transport of liquid from / to the reactor. The functionality of the assembled device and its characteristics were measured. Furthermore, an operating procedure for the decontamination process using a hydrogen peroxide mist was developed for the new equipment. An operating procedure for culturing microorganisms in a minibioreactor was also set up. Pilot cultivations of Halomonas halophila were demonstrated in the prepared equipment. In these cultivations, three assemblies for air supply to the liquid were tested. However, none of the assemblies was able to provide a sufficient supply of oxygen to cell culture – the dissolved oxygen value always dropped to 0%. For the further development, a new assembly was designed for the supply of air to the liquid - an aeration ring from a membrane tube.

Page generated in 0.0772 seconds