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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.
101

Studies on the regulation of the Napin <i>napA</i> promoter by ABI3, bZIP and bHLH transcription factors

Martin, Nathalie January 2008 (has links)
<p>The B3-domain transcription factor ABI3 is a major regulator of gene expression of seed maturation during Arabidopsis embryogenesis. The <i>napA</i> gene encodes for a <i>Brassica napus</i> 2S storage protein specifically expressed in the embryo during the early and mid-maturation phase (MAT program).The <i>napA</i> promoter contains two essential cis-sequences; the B-box, which functions as an Abscisic acid-responsive element (ABRE) and the RY/G cluster. ABI3 is known to target both these cis-sequences. Several bZIP factors expressed during seed maturation, bZIP12, bZIP38 and bZIP66, as well as a heterodimer of ABI5 and bZIP67, can bind the B-box ABRE in a yeast one-hybrid assay. Amongst them ABI3 and bZIP67 are able to activate synergistically the two cis-elements in a transient protoplast assay. We also show that bZIP67 interacts directly with ABI3 in a yeast two-hybrid assay. Therefore, we hypothesize that i)ABI3 is recruited indirectly to <i>napA</i> through molecular interaction with bZIP67 bound to the B-box ABRE, ii) ABI3 binds directly to the RY-element and interacts with bZIP67 targeted to the adjacent G-box found in the napA RY/G-cluster.</p><p>We also show that the RY/G cluster is responsible for repression of <i>napA</i> expression during the late maturation LEA program, and for repression of ABI3-mediated transactivation during germination. ABI3 from which the A1 activation domain had been removed, can bind to the <i>napA</i> RY-element in a yeast one-hybrid assay, in contrast to full-length ABI3, suggesting that ABI3 DNA-binding abilities are regulated by auto-inhibition. We propose that during late maturation ABI3 loses ability to bind RY, which results in repression of MAT genes but not of LEA genes that contain fewer RY-elements. In parallel, we show that the B3-domain VAL proteins bind to RY-elements and decrease ABI3-mediated transactivation of the <i>napA</i> RY/G and therefore act as active repressors maintaining silencing of MAT genes during vegetative growth.</p>
102

Studies on the regulation of the Napin napA promoter by ABI3, bZIP and bHLH transcription factors

Martin, Nathalie January 2008 (has links)
The B3-domain transcription factor ABI3 is a major regulator of gene expression of seed maturation during Arabidopsis embryogenesis. The napA gene encodes for a Brassica napus 2S storage protein specifically expressed in the embryo during the early and mid-maturation phase (MAT program).The napA promoter contains two essential cis-sequences; the B-box, which functions as an Abscisic acid-responsive element (ABRE) and the RY/G cluster. ABI3 is known to target both these cis-sequences. Several bZIP factors expressed during seed maturation, bZIP12, bZIP38 and bZIP66, as well as a heterodimer of ABI5 and bZIP67, can bind the B-box ABRE in a yeast one-hybrid assay. Amongst them ABI3 and bZIP67 are able to activate synergistically the two cis-elements in a transient protoplast assay. We also show that bZIP67 interacts directly with ABI3 in a yeast two-hybrid assay. Therefore, we hypothesize that i)ABI3 is recruited indirectly to napA through molecular interaction with bZIP67 bound to the B-box ABRE, ii) ABI3 binds directly to the RY-element and interacts with bZIP67 targeted to the adjacent G-box found in the napA RY/G-cluster. We also show that the RY/G cluster is responsible for repression of napA expression during the late maturation LEA program, and for repression of ABI3-mediated transactivation during germination. ABI3 from which the A1 activation domain had been removed, can bind to the napA RY-element in a yeast one-hybrid assay, in contrast to full-length ABI3, suggesting that ABI3 DNA-binding abilities are regulated by auto-inhibition. We propose that during late maturation ABI3 loses ability to bind RY, which results in repression of MAT genes but not of LEA genes that contain fewer RY-elements. In parallel, we show that the B3-domain VAL proteins bind to RY-elements and decrease ABI3-mediated transactivation of the napA RY/G and therefore act as active repressors maintaining silencing of MAT genes during vegetative growth.
103

Isolation of ABA Insensitive Mutants using a Sensitized Screen

Nam, Eric Hyung-Uk 27 July 2010 (has links)
ABA insensitive mutants (abi1 - abi5) have been isolated in germination screens that use high concentrations of exogenous ABA, and this method is believed to be saturated. To overcome this problem, a sensitized screen that used much lower concentration of exogenous ABA was performed to isolate new ABA insensitive mutants. Some of the isolated mutants had defects in light or retrograde signalling. One particular mutant (18-11) developed long hypocotyls under normal light condition. Based on its response to blue, red and far-red light conditions, this mutant is likely a novel hy mutant. Genetic analysis revealed that while ABA insensitivity in this mutant is recessive, the long hypocotyl phenotype is dominant. Positional cloning is currently being carried out to identify the gene. Findings from this study supports that ABA signalling interacts with light signalling networks.
104

Isolation of ABA Insensitive Mutants using a Sensitized Screen

Nam, Eric Hyung-Uk 27 July 2010 (has links)
ABA insensitive mutants (abi1 - abi5) have been isolated in germination screens that use high concentrations of exogenous ABA, and this method is believed to be saturated. To overcome this problem, a sensitized screen that used much lower concentration of exogenous ABA was performed to isolate new ABA insensitive mutants. Some of the isolated mutants had defects in light or retrograde signalling. One particular mutant (18-11) developed long hypocotyls under normal light condition. Based on its response to blue, red and far-red light conditions, this mutant is likely a novel hy mutant. Genetic analysis revealed that while ABA insensitivity in this mutant is recessive, the long hypocotyl phenotype is dominant. Positional cloning is currently being carried out to identify the gene. Findings from this study supports that ABA signalling interacts with light signalling networks.
105

Secondary seed dormancy and the seedbank ecology of <I>Brassica napus</i> L. in western Canada

Gulden, Robert H. 08 September 2003
The release of genetically modified, herbicide tolerant canola (<I>Brassica napus</i> L.) genotypes in western Canada has increased interest in the persistence of volunteer canola. <i>B. napus</i> seed may be induced into secondary dormancy in the laboratory, however, little is known of the seedbank ecology and the role of secondary dormancy as a persistence mechanism in this species in the region. The objectives of this research were i) to determine seedbank additions at the time of harvest, ii) determine the role of secondary seed dormancy in seedbank persistence under different management systems, iii) determine the relative importance of factors contributing to secondary dormancy potential and iv) evaluate the role of abscisic acid (ABA) during secondary dormancy induction in <I>B. napus</i>. On farms, average seedbank additions during harvest were approximately 20 times the normal seeding rate of canola. High secondary seed dormancy potential prolonged seedbank persistence in fields, irrespective of tillage system. <I>B. napus</i> exhibited seedling recruitment of a typical summer annual weed where seedling recruitment was only observed in the spring. Seasonal seedling recruitment was the result of two fates: seed death in the shallow seedbank, irrespective of dormancy potential, and increased ungerminability in buried seeds which was related to secondary seed dormancy potential. Among the factors that contribute to secondary seed dormancy potential, genotype was of greatest significance. Seed size was of lesser importance, while the contributions of pre-harvest factors including seed maturity, year, and location were negligible in comparison. Differences in ABA synthesis and the response to ABA application were related to secondary seed dormancy potential and correlated well previous reports linking ABA to seed dormancy. Conclusions that emerge from this research are i) that on some farms, seedbank additions may be lowered by more diligent harvest practices, ii) seedbank persistence of <I>B. napus</i> may be reduced by growing low dormancy genotypes and avoiding seed burial for one year after seedbank establishment and iii) ABA + ABA-glucose ester (ABA-GE) and the ability of seeds to respond to ABA application after seed dormancy induction may potentially be used to identify seed dormancy potential in this species.
106

Autismpedagogik för alla? : en studie om lärares pedagogiska strategier i idrott &amp; hälsa för gymnasiesärelever med autism / Autism pedagogy for everyone? : a study of teaching strategiesin Physical Education for students with autism

Öberg, Maja January 2012 (has links)
Syfte och frågeställningar: Syftet var att öka kunskapen om hur idrottslärare utformar undervisningen i idrott och hälsa för elever med diagnosen autism. Syftets två fråge- ställningar lyder: ”Vilka strategier väljer lärare, då de undervisar elever med autism i ämnet Idrott och hälsa på gymnasiesärnivå?” samt ”Varifrån får lärarna sina idéer och ambitioner till de strategier de använder sig av?”. Metod: Semi-strukturerade intervjuer med sju lärare genomfördes. Urvalet av informanter baserades på ett strategiskt urval, där kriteriet var att lärarna arbetar/har arbetat med elever med autism i gymnasiesärskolan i ämnet Idrott och hälsa i Stockholms län. Samtliga informanter hittades via personlig kännedom om de skolor som hade autistiska elever. I studien ingår även en observation, vilken enbart ingår som kompletterande informationskälla. Två undervisningsmodeller, TEACCH och ABA, har använts för att analysera informanternas pedagogiska strategier. Resultat: Lärarnas strategier bygger på struktur och tydlighet och dessa begrepp framträdersom viktiga ledord i undervisningen. Undervisningen sker i små elevgrupper med hög personaltäthet. Språket hålls kort och konkret och den fysiska miljön utformas som trygg och igenkänningsbar. Lektionerna sker enligt ett strukturerat och likartat upplägg. Hjälpmedel, såsom bilder, timerklockor och scheman, används. Som motivator används ibland elevens specialintressen eller belöningssystem.Lärarna har lärarutbildning, men ingen har en speciallärarutbildning. Några av dem har fått fortbildning inom autism genom kurser, studiedagar och föreläsningar. Lärarna finner även inspiration och lärdom hos varandra samt hos övrig personal på skolan. Utbytet mellan personal och samarbete runt eleven poängteras av lärarna. Slutsats: De intervjuade lärarna använder sig av element från TEACCH och ABA i sin undervisning, trots att få av lärarna kände till modellerna.  Detta kan innebära att viss kunskap är personburen och ej dokumenterad, vilket kan försvåra spridningen av kunskapen. Det behövs därmed fortsatt forskning som berör undervisning i idrott och hälsa i svenska skolan för elever med autism. En ytterligare reflektion från studien är att många anpassningar inom autismpedagogiken med fördel borde kunna användas även för elever utan autism. / Aim: The aim was to increase awareness of how teachers design learning environment in Physical Education (PE) for students diagnosed with autism in upper secondary school. The two research questions were: ”What strategies do teachers select when teaching students with autism in the subject Physical Education?” and ”From where do teachers get ideas for the strategies they use?”. Method: Qualitative interviews with seven teachers were used. They work/had been working with students with autism in PE in the upper secondary school in Stockholm. All informants were found through personal knowledge. One observation was performed, but only as a complementary source of information. Two teaching meodels; TEACCH and ABA, were used as analytical tools in the analysis of the informants teaching strategies. Results: Teachers' strategies are based on structure and clarity, and these concepts are emerging as key concepts in the teaching. Teaching is conducted in small groups of students with a high staff support. The language is kept clear, simple and concrete and the physical environment appears secure and familiar. The lessons take place in a structured and consistent approach. Tools such as pictures, timer clocks and schedules, are used. Sometimes special interests or a reward system is used as a motivator.The teachers are educated PE-teachers, but none of them a teacher educator in special needs. Some of them have received further training in autism through courses, seminars and lectures. Teachers also find inspiration and learn from each other and from other staff at school. The exchange between staff and cooperation concerning the pupil is emphasized by the teachers. Conclusions: The teachers used elements from the so-called TEACCH and ABA models  in their teaching, but few knew about the method. This may mean that some of the knowledge is only personally mediated and not documented, which may hamper the spread of knowledge. Continued studies on PE in Swedish schools for students with autism are needed. Hopefully this study contributes to a growing interest for further research and more extensive studies. A further reflection of the study is that adaptations within the autism education may benefit other students without autism too.
107

Secondary seed dormancy and the seedbank ecology of <I>Brassica napus</i> L. in western Canada

Gulden, Robert H. 08 September 2003 (has links)
The release of genetically modified, herbicide tolerant canola (<I>Brassica napus</i> L.) genotypes in western Canada has increased interest in the persistence of volunteer canola. <i>B. napus</i> seed may be induced into secondary dormancy in the laboratory, however, little is known of the seedbank ecology and the role of secondary dormancy as a persistence mechanism in this species in the region. The objectives of this research were i) to determine seedbank additions at the time of harvest, ii) determine the role of secondary seed dormancy in seedbank persistence under different management systems, iii) determine the relative importance of factors contributing to secondary dormancy potential and iv) evaluate the role of abscisic acid (ABA) during secondary dormancy induction in <I>B. napus</i>. On farms, average seedbank additions during harvest were approximately 20 times the normal seeding rate of canola. High secondary seed dormancy potential prolonged seedbank persistence in fields, irrespective of tillage system. <I>B. napus</i> exhibited seedling recruitment of a typical summer annual weed where seedling recruitment was only observed in the spring. Seasonal seedling recruitment was the result of two fates: seed death in the shallow seedbank, irrespective of dormancy potential, and increased ungerminability in buried seeds which was related to secondary seed dormancy potential. Among the factors that contribute to secondary seed dormancy potential, genotype was of greatest significance. Seed size was of lesser importance, while the contributions of pre-harvest factors including seed maturity, year, and location were negligible in comparison. Differences in ABA synthesis and the response to ABA application were related to secondary seed dormancy potential and correlated well previous reports linking ABA to seed dormancy. Conclusions that emerge from this research are i) that on some farms, seedbank additions may be lowered by more diligent harvest practices, ii) seedbank persistence of <I>B. napus</i> may be reduced by growing low dormancy genotypes and avoiding seed burial for one year after seedbank establishment and iii) ABA + ABA-glucose ester (ABA-GE) and the ability of seeds to respond to ABA application after seed dormancy induction may potentially be used to identify seed dormancy potential in this species.
108

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.
109

Genes, hormones and signalling pathways implicated in plant defence to Leptosphaeria maculans /

Kaliff, Maria, January 2007 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2008. / Härtill 4 uppsatser.
110

A regulatory role for N-acylethanolamine metabolism in Arabidopsis thaliana seeds and seedlings.

Teaster, Neal D. 05 1900 (has links)
N-Acylethanolamines (NAEs) are bioactive acylamides that are present in a wide range of organisms. Because NAE levels in seeds decline during imbibition similar to ABA, a physiological role was predicted for these metabolites in Arabidopsis thaliana seed germination and seedling development. There is also a corresponding increase of AtFAAH (fatty acid amide hydrolase), transcript levels and activity, which metabolizes NAE to ethanolamine and free fatty acids. Based on whole genome microarray studies it was determined that a number of up-regulated genes that were responsive to NAE were also ABA responsive. NAE induced gene expression in these ABA responsive genes without elevating endogenous levels of ABA. It was also determined that many of these NAE/ABA responsive genes were associated with an ABA induced secondary growth arrest, including ABI3. ABI3 is a transcription factor that regulates the transition from embryo to seedling growth, the analysis of transcript levels in NAE treated seedlings revealed a dose dependent, inverse relationship between ABI3 transcript levels and growth, high ABI3 transcript levels were associated with growth inhibition. Similar to ABA, NAE negatively regulated seedling growth within a narrow window of early seedling establishment. When seedlings are exposed to NAE or ABA within the window of sensitivity, the induction of genes normally associated with the ungerminated desiccation tolerant state resumed. The NAE tolerant FAAH overexpressor and the NAE sensitive FAAH knockout both had a NAE/ABA sensitive window similar to the wild type A. thaliana. The abi3-1 ABA insensitive mutant does not undergo growth arrest upon exposure to ABA, but NAE did induce growth arrest when treated within the sensitivity window. This evidence showed that although NAE functions within an ABA dependent pathway, it also functions in an ABA independent signaling pathway. The FAAH overexpressor is tolerant to NAE through its ability to quickly metabolize NAE from the growth media, yet it is hypersensitive to ABA. The FAAH overexpressor also displayed hypersensitivity to GA, which improved its delayed germination in non-stratified seed, while the FAAH knock out showed GA insensitivity. Overall, these results showed that NAE functions as a negative regulator of germinating seed and seedling growth in ABA dependent and independent signaling pathways, and that altered NAE metabolism may interfere with ABA/GA perception in germinating seed.

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