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  • 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

A Concurrency and Time Centered Framework for Certification of Autonomous Space Systems

Dechev, Damian 2009 December 1900 (has links)
Future space missions, such as Mars Science Laboratory, suggest the engineering of some of the most complex man-rated autonomous software systems. The present process-oriented certification methodologies are becoming prohibitively expensive and do not reach the level of detail of providing guidelines for the development and validation of concurrent software. Time and concurrency are the most critical notions in an autonomous space system. In this work we present the design and implementation of the first concurrency and time centered framework for product-oriented software certification of autonomous space systems. To achieve fast and reliable concurrent interactions, we define and apply the notion of Semantically Enhanced Containers (SEC). SECs are data structures that are designed to provide the flexibility and usability of the popular ISO C++ STL containers, while at the same time they are hand-crafted to guarantee domain-specific policies, such as conformance to a given concurrency model. The application of nonblocking programming techniques is critical to the implementation of our SEC containers. Lock-free algorithms help avoid the hazards of deadlock, livelock, and priority inversion, and at the same time deliver fast and scalable performance. Practical lock-free algorithms are notoriously difficult to design and implement and pose a number of hard problems such as ABA avoidance, high complexity, portability, and meeting the linearizability correctness requirements. This dissertation presents the design of the first lock-free dynamically resizable array. Our approach o ers a set of practical, portable, lock-free, and linearizable STL vector operations and a fast and space effcient implementation when compared to the alternative lock- and STM-based techniques. Currently, the literature does not offer an explicit analysis of the ABA problem, its relation to the most commonly applied nonblocking programming techniques, and the possibilities for its detection and avoidance. Eliminating the hazards of ABA is left to the ingenuity of the software designer. We present a generic and practical solution to the fundamental ABA problem for lock-free descriptor-based designs. To enable our SEC container with the property of validating domain-specific invariants, we present Basic Query, our expression template-based library for statically extracting semantic information from C++ source code. The use of static analysis allows for a far more efficient implementation of our nonblocking containers than would have been otherwise possible when relying on the traditional run-time based techniques. Shared data in a real-time cyber-physical system can often be polymorphic (as is the case with a number of components part of the Mission Data System's Data Management Services). The use of dynamic cast is important in the design of autonomous real-time systems since the operation allows for a direct representation of the management and behavior of polymorphic data. To allow for the application of dynamic cast in mission critical code, we validate and improve a methodology for constant-time dynamic cast that shifts the complexity of the operation to the compiler's static checker. In a case study that demonstrates the applicability of the programming and validation techniques of our certification framework, we show the process of verification and semantic parallelization of the Mission Data System's (MDS) Goal Networks. MDS provides an experimental platform for testing and development of autonomous real-time flight applications.
122

Επίδραση των πολυαμινών στη δομή και λειτουργία του 5s ριβοσωματικού RNA

Γερμπανάς, Γεώργιος 30 July 2007 (has links)
Η ΒΥΠ διαθέτει αντίτυπο της διατριβής σε έντυπη μορφή στο βιβλιοστάσιο διδακτορικών διατριβών που βρίσκεται στο ισόγειο του κτιρίου της. / Στα βακτήρια, η μεγάλη ριβοσωματική υπομονάδα αποτελείται από δύο είδη RNA, το 23S και το 5S rRNA, καθώς και 33 πρωτεΐνες. Ο σχηματισμός του πεπτιδικού δεσμού και η απελευθέρωση της πεπτιδικής αλυσίδας επιτελούνται στη μεγάλη υπομονάδα, όπου εδράζεται το καταλυτικό κέντρο της πεπτιδυλοτρανσφεράσης (PTase). Εκτός αυτού, η μεγάλη υπομονάδα περιλαμβάνει το κέντρο προσδέσεως των μεταφραστικών παραγόντων, το οποίο πυροδοτεί τη GTPase δραστηριότητα των G-πρωτεϊνικών παραγόντων, που εμπλέκονται στη μετατόπιση των υποστρωμάτων και άλλες ριβοσωματικές λειτουργίες. Έχει υποτεθεί ότι το 5S rRNA παίζει ουσιώδη ρόλο στη συγκρότηση του κέντρου της PTase και στη μετάδοση σημάτων μεταξύ του καταλυτικού κέντρου και των ριβοσωματικών συστατικών που διεκπεραιώνουν τη μετατόπιση των υποστρωμάτων. Το ιοντικό περιβάλλον φαίνεται να επηρεάζει καθοριστικά τη διαμόρφωση του 5S rRNA. Για παράδειγμα, έχει βρεθεί ότι οι πολυαμίνες δεσμεύονται εκλεκτικά στο 5S rRNA και επηρεάζουν τη δραστικότητα του έναντι του διμεθυλο-θεϊκού, ενός αντιδραστηρίου-ιχνηθέτη της τριτοταγούς δομής του RNA. Αρχικά ελέγξαμε αν υπάρχουν εξειδικευμένες θέσεις πρόσδεσης των πολυαμινών στο 5S rRNA. Στη συνέχεια, με σκοπό να ελέγξουμε αν η πρόσδεση των πολυαμινών επηρεάζει τη λειτουργία του 5S rRNA, 70S ριβοσώματα προγραμματισμένα με πολύ-ουριδυλικό σχηματίσθηκαν από 50S υπομονάδες, ολικά ή εκλεκτικά φωτοσημασμένες με ένα φωτοδραστικό ανάλογο της σπερμίνης και από 30S ακατέργαστες υπομονάδες. Αυτά τα ριβοσώματα είχαν την ικανότητα να δεσμεύουν AcPhe-tRNA ελαφρώς ισχυρότερα, σε σύγκριση με ριβοσώματα συγκροτημένα από φυσικά συστατικά, μη περιέχοντα πολυαμίνες. Το γεγονός αυτό υποδηλώνει ότι η πρόσδεση πολυαμινών στο 5S rRNA επηρεάζει, σε μικρό βαθμό, τη λειτουργία του παράγοντα επιμήκυνσης EF-Tu. Συζευγμένα, όμως, τα εν λόγω ριβοσώματα με tRNAPhe στην Ε-θέση και AcPhe-tRNAστην Ρ-θέση, επέδειξαν ισχυρότερη καταλυτική δραστικότητα και αυξημένη ικανότητα για μετατόπιση των υποστρωμάτων. Τα αποτελέσματα αυτά εισηγούνται σημαντική εμπλοκή των πολυαμινών στο λειτουργικό ρόλο του 5S rRNA κατά την κατάλυση και μετατόπιση των υποστρωμάτων. / In bacteria, the large ribosomal subunit comprises two RNA species, 23S and 5S rRNA, and 33 proteins. Peptide bond formation and peptide release are catalyzed by the large subunit, where the peptidyltransferase (PTase) center is located. In addition to this center, which triggers the GTPase activities of G-protein factors involved in translocation and other ribosomal functions. It has been hypothesized that 5S rRNA plays essential role in assembling the PTase center and mediating signal transmissions between this center and the translocation machinery. Furthermore, the ionic environment seems to affect the conformation of 5S rRNA. For instance, polyamines have been found to bind specifically to 5S rRNA and influence the 5S rRNA reactivity towards dimethyl-sulfate (DMS), a chemical probe of RNA tertiary structure. Initially we examined whether there are specific sites for binding of polyamines. To test whether the binding of polyamines influence the function of 5S rRNA poly(U)-programmed 70S ribosomes were reconstituted from 50S subunits, totally or specifically photolabelled in their 5S rRNA with a photoreactive analogue of spermine, and native 30S subunits. These ribosomes were found to enzymatically bind AcPhe-tRNA better than ribosomes reconstituted from native components. This means, that furnishing 5S rRNA with spermine slightly influences the elongation factor EF-Tu function. However, equipped with tRNAPhe at the A-site and AcPhe-tRNA at the P-site, these ribosomes exhibited higher catalytic activity and enhanced tRNA translocation efficiency. These results suggest an essential impact of polyamines on the functional role of 5S rRNA in catalysis and translocation of translation substrates.
123

Using Computer-Aided Personalized System of Instruction (CAPSI) to teach Discrete-Trials Teaching (DTT) for educating children with Autism Spectrum Disorders (ASDs)

Zaragoza Scherman, Alejandra 10 September 2010 (has links)
The present study evaluated the use of a self-instructional manual supported by a computer-aided personalized system of instruction (CAPSI) for teaching Discrete-Trials Teaching (DTT) to university students. Prior to studying the manual, five participants taught three tasks, commonly taught to children with Autism Spectrum Disorders (ASD), to a confederate role-playing a child with an ASD. Using the Discrete-Trials Teaching Evaluation Form (DTTEF), the main researcher assessed the participants’ ability to perform DTT accurately. Subsequently, participants studied a self-instructional manual using CAPSI to demonstrate mastery of study questions about DTT. Finally, participants once again attempted to teach the three tasks to a confederate role-playing a child with an ASD. Overall mean baseline accuracy on the DTTEF was 54.86%, and improved to 84.73% in post-treatment, a 30% improvement. Participants’ self-recorded study time was an average of 12 hours and 48 minutes. The results suggest that CAPSI is an effective educational tool for the delivery of the self-instructional manual. Future research should investigate (1) how to make CAPSI even more effective, and (2) whether these results can be generalized to other populations such as ABA tutors, parents, and paraprofessionals working with children with ASD.
124

Mechanisms of dormancy, preharvest sprouting tolerance and how they are influenced by the environment during grain filling and maturation in wheat (Triticum aestivum L.)

Biddulph, Thomas Benjamin January 2007 (has links)
[Truncated abstract] Wheat is the main crop in Australia and there are stringent quality requirements. Preharvest sprouting induced by rainfall between maturity and harvest lowers grain quality from premium to feed grades and reduces yield. Wheat production has expanded into the southern Western Australian region where preharvest sprouting occurs in ~1 in 4 seasons and development of more preharvest sprouting tolerant genotypes is required. The main mechanism for improving preharvest sprouting tolerance is grain dormancy. There is genetic variation for dormancy based in the embryo and seed coat but dormancy is complex and is influenced by environmental conditions during grain filling and maturation. Screening and selecting for preharvest sprouting tolerance is problematic and the level of tolerance needed for regions which differ in the level of dormancy they impose, requires clarification. The research presented here aims to answer the underlying question for breeders of how much dormancy is required for preharvest sprouting tolerance in contrasting target environments of the central and coastal wheat belt regions of Western Australia. In the central and coastal wheat belt regions, field trials with modified environments were used to determine the environmental influence on dormancy. Water supply (without directly wetting the grain) and air temperature were modified during grain development in a range of genotypes with different mechanisms of dormancy to determine the influence of environment on dormancy. ... Genotypes with embryo dormancy were consistently the most preharvest sprouting tolerant, even though this dormancy was influenced by the environmental conditions in the different seasons. Pyramiding the embryo component with the specific seed coat component and/or awnless head trait removed some of the environmental variation in preharvest sprouting tolerance, but this was generally considered excessive to the environmental requirements. The methods developed here, of field imposed stresses may provide a valuable tool to further understand the influence of environment on the regulation of dormancy, as different phenotypes can be made with the same genotype. Moisture stress, sudden changes in water supply or high temperatures during the late dough stages influenced dormancy phenotype and should be considered and avoided if possible when selecting locations and running trials for screening for genetic differences in preharvest sprouting tolerance. In the Western Australian context, the embryo component of dormancy appeared to be sufficient and should be adopted as the most important trait for breeding for preharvest sprouting tolerance.
125

Immunoneutralization Of Cytotoxic Abrin : Insights Into Mechanisms And Therapy

Bagaria, Shradha 07 1900 (has links) (PDF)
Type II Ribosome Inactivating Proteins (RIPs), commonly known as A/B toxins are heterodimers comprising of a catalytically active A chain, an RNA N-glycosidase which inhibits protein synthesis and a lectin-like B chain required for the binding of the toxin to the cell surface and internalization of the same. Abrin is a type II RIP obtained from the mature seeds of Abrus precatorius plant that is extremely toxic and has been shown to be 75 times more potent than its well studied sister toxin, ricin. The LD50 dose for abrin is only 2.8 µg/kg body weight of mice and its potential use in bio-warfare is a cause of major concern. Abrin has been classified as a select agent by the Centre for Disease Control and Prevention, U.S.A., because it is stable, effective at very low concentrations and easy to purify and disseminate in large amounts. In spite of abrin being a potential bio-warfare agent, there is no antidote or vaccine available against this toxin till date. The first and only neutralizing monoclonal antibody (mAb) against abrin, namely D6F10, was reported from our laboratory and has been shown to rescue toxicity of abrin in cells as well as in mice. The study reported in the thesis focuses on understanding the mechanism of neutralization of abrin by the mAb D6F10 and development of a potential vaccine candidate against the toxin. In order to map the epitope corresponding to the antibody, first, overlapping gene deletion constructs spanning the entire length, 251 amino acids, of ABA were generated and checked for binding to the mAb. Fragments shorter than 1-175 did not show immuoreactivity. Analysis of the crystal structure of abrin A chain revealed that a helix spanning the amino acids 148-167 was present at the core of the protein structure and truncation in this region of the protein possibly results in loss of conformation leading to abrogation of antibody binding. Therefore, a novel strategy of epitope mapping was adopted. Abrus precatorius agglutinin (APA) is a homologue of abrin obtained from the same plant source. The A chains of abrin and APA share 67% sequence identity and their crystal structures superimpose very well but unlike abrin the APA A chain does not bind the mAb D6F10. Chimeric constructs were generated within the region 1-175 of A chains of both ABA and APA and deletions and mutations of the ABA was then made on the APA as scaffold. It could be concluded that the amino acids of the region 75¬123 are involved in the formation of the epitope. Further, based on sequence alignment of ABA and APA A chain 13 residues in the chimera ABA1-123APA124-175 were mutated and it was found that the mutation of the residues Thr 112, Gly 114 and Arg 118 resulted in loss of binding to the antibody. Furthermore, the mAb D6F10 rescues inhibition of protein synthesis by abrin in HeLa cells by internalizing in cells along with abrin and possibly occluding the active site cleft of ABA. The antibody prevents cell attachment of abrin at higher concentrations. The observations provide novel insights into mechanisms of many known neutralizing antibodies against A/B toxins. The study also highlights that chimeric protein constructs could possibly be developed as potential vaccine candidates for neutralization of abrin intoxication.
126

Función de OCP3 en la resistencia de Arabidopsis frente a hongos necrotrofos

García-Andrade Serrano, Javier 29 April 2016 (has links)
[EN] ocp3 mutant plants exhibit an accelerated and intensified callose deposition in response to infection by Botrytis cinerea or Plectosphaerella cucumerina. After phenotypic analysis of a series of double mutants ocp3 we observed that both, the increase callose deposition and resistance, require PMR4 callose synthase and hormone abscisic acid (ABA). In wild plants after infection with any of these necrotrophic fungi, ABA synthesis increases, this increase is even higher in ocp3. The greater resistance observed in ocp3 plants also requires the correct perception of jasmonic acid (JA) through COI1 receptor. However, JA is not required for the synthesis and basal callose deposition. In this way it could propose a model in which OCP3 exerts a specific control for callose deposition regulated by JA and requires, indispensably, ABA. The OCP3 protein, sequence homology, is classified as a nuclear transcription factor family member of Homeobox. However, we found that OCP3 imported and accumulates in the chloroplasts, and colocalized with pentatricopeptide repeat proteins involves in RNA editing. Specifically, OCP3 participates regulating ndhB transcript editing. ndhB encodes one subunit of the multiprotein chloroplast complex NADPH dehydrogenase (NDH). The absence of OCP3 results in a decay of ndhB editing; a fact which entails a reduction of the activity of NDH complex and therefore leads to a defect in the cyclic electron flow (CEF) around the photosystem I (PSI). We were also able to confirm that mutants having altered activity of NDH complex, as crr2 and crr21 turn have an increased resistance to infection by P. cucumerina, and show an increased callose deposition. Moreover, we note that the editing of the mRNA for other subunits encoded in the chloroplast NDH complex are also subject to regulation which is significantly altered in the presence of a pathogenic stimuli. At the same time, the stability of NDH complex also compromised after a pathogenic insult. All these results indicate that the NDH complex is subject to a subtle regulation in accordance with the changing environment. The ABA is a key player in activating plant defense against P. cucumerina infection. Moreover, hemibiotrofos pathogens such as Pseudomonas syringae DC3000 also cause increased synthesis of ABA. However, this increase leads to the suppression of defensive responses, which can be attributed a dual role. The regulation of dual role of this hormone, activator and repressor some other defenses, indicates the existence of a post-regulating hormone synthesis. In this Doctoral Thesis, it has been identified as PYR1 family member receptor ABA PYR/PYL/RCAR perceives this hormone to trigger a response to infection by a pathogen. PYR1 reduces the salicylic acid (SA) dependent response against the biotrophic pathogens attack. Thus exerts a positive control JA-dependent responses required to activate the defenses against necrotrophic pathogens. The loss of the perception of ABA through PYR1 activates the expression of SA-responsive genes, alteration of chromatin remodeling and increase in the activation of MAP kinases after the attack biotrophic pathogens. Thus, the ABA through PYR1 receptor and through an epigenetic control, have a regulatory role in plant immunity depending on the lifestyle of pathogens infecting the plant. / [ES] Las plantas mutantes ocp3, presentan una acelerada e intensificada deposición de calosa en respuesta a la infección producida por Botrytis cinerea o Plectosphaerella cucumerina. Tras el análisis fenotípico de una serie de dobles mutantes en el fondo ocp3 observamos que tanto el incremento en la deposición de calosa como de la resistencia requieren de la calosa sintasa PMR4, y de la hormona ácido abscísico (ABA). En las plantas silvestres, tras la infección por alguno de estos hongos necrotrofos, se incrementa la síntesis de ABA, incremento éste que aún es mayor en las plantas ocp3. La mayor resistencia que se observa en las plantas ocp3 también requiere de la correcta percepción del ácido jasmónico (JA) a través del receptor COI1. Sin embargo, el JA no es requerido para la síntesis y deposición de calosa basal. De esta forma se podría proponer un modelo en el que OCP3 ejerce un control específico para la deposición de calosa regulada por JA y que requiere, indispensablemente, de ABA. La proteína OCP3, por homología de secuencia, se clasifica como un factor de transcripción nuclear miembro de la familia de los Homeobox. Sin embargo, encontramos que OCP3 se importa y acumula en los cloroplastos, y se colocaliza con proteínas que contienen motivos de repetición pentatricopeptidos e implicadas en la edición de RNA. Concretamente, OCP3 participa regulando el mecanismo de edición del transcrito ndhB que codifica una de las subunidades del complejo multiprotéico NADPH deshidrogenasa (NDH) del cloroplasto. La ausencia de OCP3 se traduce en una deficiente edición de ndhB; hecho éste que conlleva un deterioro en la funcionalidad del complejo NDH y que por tanto acarrea un defecto en el flujo cíclico de electrones (CEF) alrededor del fotosistema I (PSI). También pudimos confirmar que mutantes que presentan alteraciones en la actividad del complejo NDH, como crr2 y crr21, a su vez presentan un incremento en la resistencia frente a la infección por P. cucumerina, además de mostrar una mayor deposición de calosa. Por otra parte, observamos que la edición de los mRNA para otras subunidades del complejo NDH codificadas en el cloroplasto están, también, sujetas a una regulación que se ve notablemente alterada en presencia de un estimulo patogénico. Al mismo tiempo, la estabilidad del complejo NDH también se ve comprometida tras un insulto patogénico. Todos estos resultados indicarían que el complejo NDH está sujeto a una sutil regulación en concordancia con las condiciones cambiantes del entorno. El ABA es determinante en la activación de mecanismos de defensa frente a P. cucumerina. Por otra parte, patógenos hemibiotrofos como por ejemplo Pseudomonas syringae DC3000 también provocan incremento en la síntesis de ABA. Sin embargo, este incremento acarrea la supresión de las respuestas defensivas, por lo que se le puede atribuir un papel dual. La regulación del papel dual de esta hormona, activador de unas defensas y represor de otras, indica la existencia de una regulación posterior a la síntesis de la hormona. En la presente Tesis Doctoral, se ha identificado a PYR1 como el miembro de la familia de los receptores de ABA PYR/PYL/RCAR que percibe esta hormona para desencadenar una respuesta a la infección por un patógeno. PYR1 amortigua la respuesta dependiente de ácido salicílico (SA) frente al ataque de un patógeno biotrofo. De esta forma ejerce un control positivo sobre las respuestas dependientes de JA requeridas para activar las defensas frente a patógenos necrotrofos. La pérdida de la percepción del ABA por PYR1 provoca una activación de los genes de respuesta a SA, una alteración de la remodelación de la cromatina y un incremento en la activación de las MAP quinasas tras el ataque de patógenos biotrofos. De esta forma, el ABA a través del receptor PYR1 y a través de un control epigenético, tendría un papel regulador de la inmunidad vegetal en función del / [CAT] Les plantes mutants ocp3, presenten una accelerada e intensificada deposició de calosa en resposta a la la infecció produïda per Botrytis cinerea o Plectosphaerella cucumerina. Darrere l'anàlisi d'una sèrie de dobles mutants amb ocp3, observem que tant l'increment en la deposició de calosa com de la resistència requereixen de la calosa sintasa PMR4, i de l'hormona àcid abscisic (ABA). Les plantes silvestres infectades amb algú d'aquests fongs necrotrofs, incrementen la síntesi de ABA, increment aquest que encara és major en les plantes ocp3. La major resitència que s'observa en les plantes ocp3 també requereix de la correcta percepció de l'àcid jasmonic (JA) a través del receptor COI1. No obstant això, el JA no és requerit per a la síntesi i deposició de calosa basal. D'aquesta forma, es podria proposar un model en el qual OCP3 exerceix un control especific per a la deposició de calosa regulada pel JA i que requerix, indispensablement, de l'ABA. La proteïna OCP3, per homologia de seqüència, es classifica com un factor de transcripció nuclear membre de la familia dels Homeobox. No obstant això, trobem que OCP3 s'importa i acumula en el cloroplasts, i es colocaliza amb proteïnes que contenen motius de repetició pentatricopeptids i implicades en l'edició de RNA. Concretament, OCP3 participa regulant el mecanisme d'edició del transcrit ndhB que codifica una de les subunitats del complex multiproteic NADPH deshidrogenasa (NDH) del cloroplast. L'absència d'OCP3 es tradueix en una deficient edició de ndhB; fet aquest que comporta una pèrdua de la funcionalitat del complex NDH i que per tant implica un defecte en el flux cíclic d'electrons (CEF) al voltant del fotosistema I (PSI). També vam poder confirmar que mutants que presenten alteracions en la activitat del complex NDH, com crr2 i crr21, al seu torn presenten un increment en la resistència enfront de la infecció per P. cucumerina, a més de mostrar una major deposició de calosa. D'altra banda, observem que l'edició dels mRNA per a altres subunitats del complex NDH codificades en el cloroplast estan, també, subjectes a una regulació que es ceu notablement alterada en preséncia d'un estimulo patogenic. Tots aquests resultats indicarien que el complex NDH està subjecte a una sutil regulació en concordaça amb les condicions canviants de l'entorn. El ABA es determinatn en l'activació de mecanismes de defensa enfront de P. cucumerina. D'altra banda, patògens hemibiotrofs com per exemple Pseudomonas syringae DC3000 també provoquen increment en la síntesi de ABA. No obstant això, aquest increment implica la supressió de les respostes defensives, per la qual cosa se li pot atribuir un paper dual. La regulació del paper dual d'aquesta hormona, activador d'unes defenses i repressor d'unes altres, indica l'existència d'una regulació posterior a la síntesi de l'hormona. En la present Tesis Doctoral, s'ha indentificat a PYR1 com el membre de la familia dels receptors de ABA PYR/PYL/RCAR que percep aquesta hormona per desencadenar una resposta a la infecció per un patogen. PYR1 esmorteeix la resposta dependent d'acid salicílic (SA) enfornt de l'atac d'un patogen biotorof. D'aquesta forma exerceix un control positiu sobre les respostes dependents de JA requerides per activar les defenses enfront de patògens necrotofs. La pèrdua de la percepció del ABA per PYR1 provoca una activació de les MAP quinases després de l'atac de patògens biotrofs. Així donçs, el ABA a través del receptor PYR1 i a través d'uun control epigenètic, tindria un paper regulador de la immunitat vegetal en funció de l'estil de vida del patogen que infecti a la planta. / García-Andrade Serrano, J. (2016). Función de OCP3 en la resistencia de Arabidopsis frente a hongos necrotrofos [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/63147 / TESIS
127

Análisis funcional del gen OCP3

Ramirez Garcia, Vicente 19 May 2009 (has links)
El gen OCP3 codifica un factor de transcripción de la familia Homeobox. En trabajos anteriores se ha demostrado que la pérdida de función de este gen en Arabidopsis thaliana causa un notable incremento de la resistencia a infecciones por hongos necrotrofos como Botrytis cinerea o Plectosphaerella cucumerina. Además esa resistencia es dependiente de la correcta señalización mediada por ácido jasmónico (JA), una de las fitohormonas más ampliamente relacionadas con el establecimiento de las respuestas defensivas en plantas junto con el ácido salicílico (SA). A través del balance entre las señalizaciones de estos dos reguladores (JA y SA), la planta es capaz de disparar la respuesta defensiva más apropiada dependiendo del tipo de patógeno que la ataca. Así pues, el estudio de las interrelaciones entre JA y SA y los componentes que transducen las respectivas señales es de gran utilidad para desentramar la compleja red de regulación que compone la respuesta inmune de las plantas. Mediante el estudio de dobles mutantes, se ha demostrado un nuevo papel de OCP3 en la interconexión entre SA y JA en respuesta a Pseudomonas syringae e Hyaloperonospora arabidopsidis, dos patógenos de tipo biotrofo. Además se propone a OCP3 como un nuevo componente de la denominada Resistencia Sistémica Inducida (ISR). Existe cierto grado de solapamiento entre las respuestas de las plantas frente a estreses bióticos y abióticos. La identificación de los componentes comunes a estas dos rutas es de gran valor para conocer cómo las plantas se adaptan ante situaciones de estrés diferentes. Mediante un rastreo por doble híbrido en levadura, se identificaron cuatro proteínas que interaccionan con OCP3. Todas ellas están implicadas en la señalización mediada por ABA, una fitohormona que regula, entre otros procesos, la respuesta frente al estrés hídrico. En el presente trabajo se aportan numerosas evidencias que indican que OCP3 regula el cierre estomático promovido por ABA, y con ello la tolerancia a / Ramirez Garcia, V. (2008). Análisis funcional del gen OCP3 [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/4683 / Palancia
128

Regulation of ABA signaling through degradation of clade A PP2Cs by the RGLG1 and CRL3 BPM E3 ligases

Julián Valenzuela, Jose 24 February 2020 (has links)
[ES] La ubiquitinación inducida por hormonas desempeña un papel crucial en la vida media de los reguladores negativos clave de la propia señalización hormonal. En la señalización por ABA, los reguladores negativos clave son las PP2Cs del clado A, como PP2CA o ABI1, y su degradación es un mecanismo complementario a la inhibición de su actividad mediada por PYR/PYL/RCAR. El ABA promueve la degradación de ABI1 a través de las E3 ligasas PUB12/13, y PP2CA a través de las E3 ligasas RGLG1/5. Sin embargo, se predice que otras E3 ligasas no identificadas también regularán la vida media de las PP2Cs del clado A. En pasos posteriores de la señalización por ABA, el ABA también induce la regulación positiva de los niveles de transcrito y proteína de las PP2Cs como un mecanismo de retroalimentación negativa. Por lo tanto, restablecer la señalización de ABA también requiere la degradación de las PP2Cs para evitar su acumulación excesiva inducida por el propio ABA. En este trabajo identificamos las proteínas BTB/POZ AND MATH DOMAIN (BPM), adaptadores del sustrato de las E3 ligasas multiméricas CULLIN3-RING E3 (CRL3), como proteínas que interactúan con las PP2Cs. BPM3 y BPM5 interactúan en el núcleo con PP2CA, así como con ABI1, ABI2 y HAB1. Además, BPM3 y BPM5 aceleran la degradación de las PP2Cs de una manera dependiente del ABA y su sobreexpresión conduce a una mayor sensibilidad al ABA. Además, las plantas mutantes bpm3 bpm5 mostraron una mayor acumulación de PP2CA, ABI1 y HAB1, lo que conduce a una sensibilidad global disminuida al ABA. Finalmente, utilizando ensayos bioquímicos y genéticos, demostramos que las BPM aumentaban la ubiquitinación de PP2CA. Dado que la formación de los complejos ternarios receptor-ABA-fosfatasa se ve notablemente afectada por la abundancia de sus componentes proteicos y la concentración de ABA, revelamos que las BPM y las E3 ligasas multiméricas CRL3 son moduladores importantes de los niveles del correceptor PP2C para regular la señalización temprana de ABA, así como durante los consiguientes pasos de restablecimiento. Al contrario que con PUB12/13, no se sabe cómo el ABA aumenta la degradación de PP2CA a través de RGLG1/5. En el caso de RGLG1, esta proteína se encuentra predominantemente en la membrana plasmática, mientras que PP2CA se encuentra predominantemente en el núcleo. Nosotros demostramos que el ABA modifica la localización subcelular de RGLG1, promoviendo la interacción nuclear con PP2CA. En primer lugar, encontramos que RGLG1 está miristoilado in vivo, lo que facilita su unión a la membrana plasmática, sin embargo, el ABA inhibe esta miristoilación. El ABA también regula negativamente a N-myristoyltransferase 1, la enzima activa y central en la miristoilación de proteínas, esto puede ayudar a promover la translocación de RGLG1 al núcleo. Allí, RGLG1 puede interactuar con ciertos receptores monoméricos del ABA, como PYL8. El reclutamiento nuclear de la E3 ligasa también fue promovido por el aumento de los niveles de proteína PP2CA y por la formación de complejos RGLG1-PYL8-PP2CA en presencia de ABA. Además, nosotros encontramos que RGLG1Gly2Ala, mutada en el sitio de miristoilación N-terminal, muestra localización nuclear constitutiva y provoca una respuesta más sensible al ABA y al estrés salino y osmótico. En resumen, proporcionamos evidencia de que una ligasa E3 puede reubicarse dinámicamente en respuesta al ABA, el estrés salino y osmótico, y el aumento de los niveles de su sustrato, lo que revela un mecanismo para explicar cómo el ABA mejora la interacción RGLG1-PP2CA y, por lo tanto, la degradación de PP2CA. / [CAT] L' ubiquitinació induïda per hormones té un paper crucial en la vida mitjana dels reguladors negatius clau de la pròpia senyalització hormonal. En la senyalització per ABA, els reguladors negatius clau són les PP2Cs del clado A, com PP2CA o ABI1, i la seva degradació és un mecanisme complementari a la inhibició de la seva activitat mediada per PYR/PYL/RCAR. El ABA promou la degradació de ABI1 a través de les E3 lligases PUB12/13, i PP2CA per mitja de les E3 lligases RGLG1/5. No obstant això, es prediu que altres E3 lligases no identificades també regularan la vida mitjana de les PP2Cs del clado A. En passos posteriors de la senyalització per ABA, l'ABA també indueix la regulació positiva de nivells de transcrit i proteïna de les PP2Cs com un mecanisme de retroalimentació negativa. Per tant, restablir la senyalització d'ABA també requereix la degradació de les PP2Cs per evitar la seva acumulació excessiva induïda pel propi ABA. En aquest treball identifiquem les proteïnes BTB/POZ AND MATH DOMAIN (BPM), adaptadors del substrat de les E3 lligases multimèriques CULLIN3-RING E3 (CRL3), com proteïnes que interactuen amb les PP2Cs. BPM3 i BPM5 interactuen en el nucli amb PP2CA, així com amb ABI1, ABI2 i HAB1. A més, BPM3 i BPM5 acceleren la degradació de les PP2Cs d'una manera dependent del ABA i la seva sobreexpressió porta a una major sensibilitat al ABA. A més, les plantes mutants bpm3 bpm5 van mostrar una major acumulació de PP2CA, ABI1 i HAB1, el que porta a una sensibilitat global disminuïda a ABA. Finalment, utilitzant assajos bioquímics i genètics, aconseguint que les BPM augmentaven l' ubiquitinació de PP2CA. Atès que la formació dels complexos ternaris receptor-ABA-fosfatasa es veu notablement afectada per l'abundància dels seus components proteics i la concentració d'ABA, revelem que les BPM i les E3 lligases multimèriques CRL3 són moduladors importants dels nivells del coreceptor PP2C per regular la senyalització primerenca de ABA, així com durant els consegüents passos de restabliment. Al contrari que amb PUB12/13, no se sap com el ABA augmenta la degradació de PP2CA a través d'RGLG1/5. En el cas de RGLG1, aquesta proteïna es troba predominantment en la membrana plasmàtica, mentre que PP2CA es troba predominantment en el nucli. Nosaltres vam demostrar que l'ABA modifica la localització subcelular de RGLG1, promovent la interacció nuclear amb PP2CA. En primer lloc, trobem que RGLG1 està miristoilado in vivo, el que facilita la seva unió a la membrana plasmàtica, però, el ABA inhibeix aquesta miristoilación. El ABA també regula negativament N-myristoyltransferase 1, l' enzim actiu i central en la miristoilación de proteïnes, això pot ajudar a promoure la translocació de RGLG1 al nucli. Allà, RGLG1 pot interactuar amb certs receptors monomèrics de l'ABA, com PYL8. El reclutament nuclear de l'E3 lligasa també va ser promogut per l'augment dels nivells de proteïna PP2CA i per la formació de complexos RGLG1-PYL8-PP2CA en presència d'ABA. A més, nosaltres trobem que RGLG1Gly2Ala, mutada en el lloc de miristoilació N-terminal, mostra localització nuclear constitutiva i provoca una resposta més sensible al ABA i l'estrès salí i osmòtic. En resum, proporcionem evidència que una ligasa E3 pot reubicar dinàmicament en resposta al ABA, l'estrès salí i osmòtic, i l'augment dels nivells de la seva substrat, el que revela un mecanisme per explicar com el ABA millora la interacció RGLG1-PP2CA i, per tant, la degradació de PP2CA. / [EN] Hormone-induced ubiquitination plays a crucial role to determine the half-life of key negative regulators of hormone signaling. In case of ABA signaling, the key negative regulators are the clade-A PP2Cs, such as PP2CA or ABI1, and their degradation is a complementary mechanism to PYR/PYL/RCAR-mediated inhibition of their activity. ABA promotes the degradation of ABI1 through the PUB12/13 E3 ligases, and PP2CA through the RGLG1/5 E3 ligases. However, other unidentified E3 ligases are predicted to regulate clade A PP2Cs half-life as well. At later steps of ABA signaling, ABA also induces upregulation of PP2C transcripts and protein levels as a negative feedback mechanism. Therefore, resetting of ABA signaling also requires PP2C degradation to avoid excessive ABA-induced accumulation of PP2Cs. In this work we identified BTB/POZ AND MATH DOMAIN proteins (BPMs), substrate adaptors of the multimeric CULLIN3-RING E3 ligases (CRL3s), as PP2C-interacting proteins. BPM3 and BPM5 interact in the nucleus with PP2CA as well as with ABI1, ABI2 and HAB1. Additionally, BPM3 and BPM5 accelerate the turnover of PP2Cs in an ABA-dependent manner and their overexpression leads to enhanced ABA sensitivity. Moreover, bpm3 bpm5 mutant plants showed increased accumulation of PP2CA, ABI1 and HAB1, which leads to global diminished ABA sensitivity. Finally, using biochemical and genetic assays we demonstrated that BPMs enhance the ubiquitination of PP2CA. Given the formation of receptor-ABA-phosphatase ternary complexes is markedly affected by the abundance of protein components and ABA concentration, we reveal that BPMs and multimeric CRL3 E3 ligases are important modulators of PP2C co-receptor levels to regulate early ABA signaling as well as the subsequent resetting steps. In contrast to PUB12/13, it was not known how ABA enhances the degradation of PP2CA by RGLG1/5. RGLG1 is predominantly found in the plasma membrane whereas PP2CA is predominant in the nucleus. We demonstrate that ABA modifies the subcellular localization of RGLG1, promoting nuclear interaction with PP2CA. Firstly, we found that RGLG1 is myristoylated in vivo, which facilitates its attachment to the plasma membrane, nevertheless, ABA inhibits its myristoylation. ABA also downregulates N-myristoyltransferase 1, the central active enzyme of protein myristoylation, which may help to promote RGLG1 translocation to the nucleus. There, RGLG1 can interact with certain monomeric ABA receptors, as PYL8. Enhanced nuclear recruitment of the E3 ligase was also promoted by increasing PP2CA protein levels and the formation of RGLG1-PYL8-PP2CA complexes in the presence of ABA. Additionally, we found that RGLG1Gly2Ala protein, mutated at the N-terminal myristoylation site, shows constitutive nuclear localization and causes an enhanced response to ABA and salt and osmotic stresses. In summary, we provided evidence that an E3 ligase can dynamically relocalize in response to ABA, salt and osmotic stress, and increased levels of its target, which reveals a mechanism to explain how ABA enhances RGLG1-PP2CA interaction and hence PP2CA degradation. / Julián Valenzuela, J. (2020). Regulation of ABA signaling through degradation of clade A PP2Cs by the RGLG1 and CRL3 BPM E3 ligases [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/137777 / TESIS
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Occupational Stress, Burnout and Teacher efficacy in teachers, special educators and habilitation professionals with and without formal ABA training / Yrkesstress, utbrändhet och Teacher efficacy (lärareffektivitet) hos lärare, specialpedagoger och habiliteringspersonal med och utan formell TBA-utbildning

Lundin, Fredrik January 2021 (has links)
Research suggests a correlation between high levels of stress and burnout, and low levels of self- efficacy, in school and habilitation professionals. These findings are also prominent in practitioners in Applied Behavior Analysis (ABA) such as teachers, psychologists and Board-Certified Behavior Analysts (BCBAs). This current study aimed to examine the levels in self-reported stress, burnout, and self-efficacy reported in the Ohio State Teacher Efficacy Scale (OSTES), in a Swedish-speaking sample consisting of sixty-seven participants based in school settings, and twenty-five participants based in habilitation settings. All participants were divided into two subgroups: one group who have stated participation in formal post-graduate ABA-training (n = 31), and a group without formal ABA training (n = 61). The hypotheses formulated from previous research were: 1) Teacher Efficacy levels are higher in professionals with ABA-training; 2) Stress-levels are lower in professionals with ABA- training; 3) Burnout levels are lower in professionals with ABA-training; 4) Stress-levels are lower in professionals working in habilitation settings; 5) Burnout levels are lower in professionals working in habilitation settings. Analyzes showed that stress correlated highly positive with burnout, and that teacher efficacy had a negative correlation with stress and burnout. Furthermore, no differences in stress and burnout levels were found between participants from school and habilitation, but the levels in Self-reported Stress and Self-reported Burnout were lower in the ABA group, which therefore confirmed the predictions. Reported OSTES-levels were higher in the ABA-group, but at non- significant levels (except in the sub-item “Efficacy for instructional strategies” where significant levels were found). The conclusion was that educators high in teacher efficacy may be less likely to suffer from stress and burnout, than low-efficacy educators. To address the growing problem of stress-related diseases among Swedish school and habilitation staff, the current teacher efficacy-levels in these occupations must be further highlighted. / Forskning tyder på en korrelation mellan höga nivåer av stress och utbrändhet, och låga nivåer av self- efficacy hos personal i skola och habilitering. Dessa forskningsresultat är också framträdande gällande utövare av tillämpad beteendeanalys (TBA), såsom lärare, psykologer och certifierade beteendeanalytiker (BCBA). Den aktuella studien syftade till att undersöka nivåerna i självrapporterad stress, utbrändhet och self-efficacy baserat på Teacher efficacy-skalan Ohio State Teacher Efficacy Scale (OSTES), gällande ett urval av svensktalande deltagare bestående av sextiosju personer som arbetar inom skolan och tjugofem personer som arbetar inom habiliteringen. Samtliga deltagare delades in i två undergrupper: en grupp som tidigare genomfört en formell TBA-utbildning (n = 31) och en grupp utan formell TBA-utbildning (n = 61). Hypoteserna utifrån tidigare forskning var: 1) Teacher efficacy-nivåerna är högre hos yrkesverksamma med TBA-utbildning; 2) Stressnivåerna är lägre hos professionella med TBA-utbildning; 3) Utbrändhetsnivåerna är lägre hos professionella med TBA-utbildning; 4) Stressnivåerna är lägre hos yrkesverksamma som arbetar inom habiliteringsyrken; 5) Utbrändhetsnivåerna är lägre hos professionella som arbetar inom habiliteringsyrken. Analyserna visade att stress korrelerade mycket positivt med utbrändhet och att Teacher efficacy-nivåerna hade en negativ korrelation med stress och utbrändhet. Vidare hittades inga skillnader i stress- och utbrändhetsnivåerna mellan deltagare från skola och habilitering, men nivåerna i självrapporterad stress och självrapporterad utbrändhet var lägre i TBA-gruppen, vilket därför bekräftade denna förutsägelse. Nivåerna erhållna i OSTES-skalan var högre i TBA-gruppen, men på icke-signifikanta nivåer (förutom i underkategorin “Efficacy for instructional strategies” där signifikanta nivåer hittades). Slutsatsen var att lärare med hög Teacher efficacy kan vara mindre benägna att drabbas av stress och utbrändhet än lärare med låg Teacher efficacy. För att ta itu med det växande problemet med stressrelaterade sjukdomar bland svensk skol- och habiliteringspersonal måste de aktuella nivåerna av Teacher efficacy i dessa yrken belysas ytterligare.
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The Use of School-Wide Positive Behavior Support at a Rural High School to Decrease Disruptive Behavior for Both Typical Students and Students Identified with Special Needs.

Blevins, Leia Dowdy 15 December 2007 (has links) (PDF)
There is ever-increasing pressure on school officials to provide a safe school environment that is conducive to learning. There is also a growing concern from teachers and administrators that many students are unrecognized for their continual appropriate behavior(s), in part, because of the attention consumed by both challenging students and students with exceptional talents and abilities. In response, a School-Wide Positive Behavior Support (SWPBS) approach is growing in popularity to address both of these issues. SWPBS is implemented across an entire school population and involves all individuals whether they are challenging, exceptional, or typical. The initial research shows encouraging results and supports the effectiveness of a School-Wide Positive Behavior Support program. This study focused on the development, implementation, and results of a SWPBS program at a rural high school. Data collected included office daily referrals, suspensions, expulsions, attendance, and the number of reinforcers (Mo-Bucks) distributed by staff. Outcome data indicated that compared to the year prior to the SWPBS program's implementation, there was a reduction in office daily referrals, a reduction in expulsions, and an increase in attendance. The results of this 3-year study supported the effectiveness of SWPBS as an intervention for reducing disruptive behaviors at the high school level for typical students as well as for students with special needs.

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