Research on analogies in science education has focussed on student interpretation of teacher and textbook analogies, psychological aspects of learning with analogies and structured approaches for teaching with analogies. Few studies have investigated how analogies might be pivotal in students’ growing participation in chemical discourse. To study analogies in this way requires a sociocultural perspective on learning that focuses on ways in which language, signs, symbols and practices mediate participation in chemical discourse. This study reports research findings from a teacher-research study of two analogy-writing activities in a chemistry class. The study began with a theoretical model, Third Space, which informed analyses and interpretation of data. Third Space was operationalized into two sub-constructs called Dialogical Interactions and Hybrid Discourses. The aims of this study were to investigate sociocultural aspects of learning chemistry with analogies in order to identify classroom activities where students generate Dialogical Interactions and Hybrid Discourses, and to refine the operationalization of Third Space. These aims were addressed through three research questions. The research questions were studied through an instrumental case study design. The study was conducted in my Year 11 chemistry class at City State High School for the duration of one Semester. Data were generated through a range of data collection methods and analysed through discourse analysis using the Dialogical Interactions and Hybrid Discourse sub-constructs as coding categories. Results indicated that student interactions differed between analogical activities and mathematical problem-solving activities. Specifically, students drew on discourses other than school chemical discourse to construct analogies and their growing participation in chemical discourse was tracked using the Third Space model as an interpretive lens. Results of this study led to modification of the theoretical model adopted at the beginning of the study to a new model called Merged Discourse. Merged Discourse represents the mutual relationship that formed during analogical activities between the Analog Discourse and the Target Discourse. This model can be used for interpreting and analysing classroom discourse centred on analogical activities from sociocultural perspectives. That is, it can be used to code classroom discourse to reveal students’ growing participation with chemical (or scientific) discourse consistent with sociocultural perspectives on learning.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv., 2002. / Härtill 6 uppsatser.

Lic. -avh. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 3 uppsatser.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 214-243).

Sistemas poliméricos para a liberação de fármacos associados à terapêutica periodontal convencional têm sido desenvolvidos e aplicados com algumas vantagens em comparação ao debridamento mecânico isolado. Um dispositivo de liberação lenta para uso em bolsas periodontais contendo metronidazol como princípio ativo, foi desenvolvido e testado quanto à sua eficácia no tratamento de pacientes com periodontite crônica. Dezesseis pacientes foram selecionados e aleatoriamente alocados aos seguintes tratamentos com 8 indivíduos por grupo: 1) raspagem e alisamento radicular (controle ativo) ou 2) raspagem e alisamento radicular + aplicação de gel contendo metronidazol a 15% (experimental). Os efeitos dos tratamentos foram avaliados pelo acompanhamento longitudinal de parâmetros clínicos (profundidade do sulco gengival à sondagem e nível clínico de inserção) e microbiológicos (análise da microbiota subgengival pela técnica da hibridização DNA-DNA Checkerboard). O monitoramento das concentrações de metronidazol no fluido gengival colhido dos pacientes que receberem o gel foi realizado pela cromatografia líquida de alta eficiência. Os resultados da análise das concentrações de metronidazol na bolsa periodontal demonstraram que o gel só pôde ser detectado em concentrações efetivas até uma hora depois da aplicação. Em relação à análise microbiológica, foi observada diferença significante entre os grupos, nos três tempos de avaliação (antes, 7 e 30 dias depois do tratamento). A análise intragrupos indicou redução significante na contagem bacteriana somente para o grupo tratado com o gel de metronidazol, após 7 dias do tratamento. Embora tenha sido detectada diferença entre os grupos nenhum deles foi capaz de eliminar ou reduzir com significância as espécies periodontopatogênicas. No que se refere aos parâmetros clínicos, ambas as terapias foram eficazes em promover a redução na profundidade à sondagem e o ganho no nível de inserção, sem benefício significante para o emprego do gel de metronidazol. / Polymeric systems for drug delivery have been developed and implemented with several advantages compared to conventional therapy. A slow-release device for use in periodontal pockets containing metronidazole as active principle, was developed and tested for its efficacy in treating patients with chronic periodontitis. Sixteen patients were randomly allocated to treatments with eight subjects per group: 1) scaling and root planing (active control) or 2) scaling and root planing + application of 15% metronidazole gel (experimental). Treatment effects were assessed by longitudinal clinical parameters (gingival sulcus depth probing and clinical attachment level) and microbiological (analysis of subgingival microbiota by the technique of checkerboard DNA-DNA hybridization). The monitoring of concentrations of metronidazole in the gingival fluid collected from the patients receiving the gel was performed by high performance liquid chromatography. The results of the analysis of concentrations of metronidazole in periodontal pockets showed that the gel could only be detected at effective concentrations until one hour after application. Regarding microbiological analysis there was significant difference between groups in the three evaluated times (before, 7 and 30 days after treatment). The intragroup analysis showed a significant decrease in bacterial count only for the group treated with metronidazole gel after 7 days of treatment. Although difference was detected between both groups, none of them was able to eliminate or significantly reduce the periodontopathogenic species. With regard to clinical parameters, both therapies were effective in promoting reduction in depth probing and gain in attachment level, without significant benefit to the use of metronidazole gel.

O Brasil é o segundo maior produtor de feijão, sendo a espécie mais cultivada o Phaseolus vulgaris L. Entre as três possíveis safras exploradas no Brasil, aquela que gera a maior produção é a da seca. Por outro lado, como a maioria das lavouras emprega pouca tecnologia, um dos problemas desta cultura é o estresse hídrico, que leva a uma redução na produtividade. Dessa forma, a identificação de genes que controlam os mecanismos de defesa e adaptação do feijoeiro à falta de água seria de grande utilidade. Nos últimos anos, muitas informações ômicas do feijoeiro foram geradas, criando uma visão integrada deste organismo e oferecendo uma complexa rede de interações entre genes e seus produtos. Este trabalho teve como objetivo central à identificação de genes diferencialmente expressos no sistema radicular de um genótipo de feijoeiro resistente ao estresse hídrico (BAT 477), quando submetido a uma interrupção de irrigação durante seu desenvolvimento. Foi construída uma biblioteca subtrativa de cDNA (SSH), que representou os genes diferencialmente expressos no genótipo resistente, utilizando-se como driver o genótipo Carioca 80SH (suscetível a seca). Foram obtidos 1572 reads válidos, sendo 931 destes singletons e 189 contigs com uma média de seis reads por cluster. A anotação das sequências foi conduzida via BLASTX, sendo consideradas para anotação somente os melhores resultados dos produtos gênicos similares com E- Value \'<OU=\' 10-5. A classificação funcional foi feita tendo-se como base modelos descritos para plantas (modelo CS e MIPS) e os resultados foram agrupados em seis classes funcionais distintas. As análises de bioinformática ajudaram na identificação de genes descritos como envolvidos na resposta da planta ao estresse hídrico. Entre eles: proteínas do grupo LEA; fatores de transcrição como DREB, NAC e proteínas ricas em leucina; enzimas sintetizadoras de carboidratos incluindo trehalose, sacarose e rhamnose; proteínas ricas em prolina; receptores de hormônios (ABA, etileno); aquaporinas; chaperonas; ubiquitinas; nodulinas; e proteínas associadas à fotossíntese e à respiração. A fim de se obter a validação das ESTs anotadas, foi conduzido um experimento de PCR em tempo real confrontando os padrões de expressão de 15 genes sob quatro tratamentos: ambos os genótipos sob estresse e respectivos controles. Três replicatas biológicas foram adotadas e dois genes de referência (act e skip2) foram escolhidos para normalização interna dos dados. Os padrões de expressão gênica obtidos confirmam a hipótese de que tais genes são mesmo mais expressos no genótipo resistente, embora não sejam exclusivos já que uma quantidade menor de tais transcritos também foi detectada no genótipo suscetível / Brazil is the second biggest producer of common bean, being Phaseolus vulgaris L. the most cultivated species. Among the three possible harvests exploited in Brazil, drought is the one which generates the greatest production. On the other hand, as the majority of the households employees low technology, one of the problems of this culture is drought stress that leads to a reduction in the productivity. So, the identification of gene that controls the mechanisms of defense and adaptation of common bean to the lack of water would be very useful. In the past years, many omics information of common bean have been generated, creating an integrated view of this organism and providing a complex network between genes and its products. The main goal of this work was the identification of differentially expressed genes in a genotype of common bean resistant to drought stress (BAT 477), when submitted to a interruption of irrigation during its development. It was build a cDNA suppression subtractive hybridization library (SSH), which represented the differentially expressed genes, on the resistant genotype, having as driver the genotype Carioca 80SH (susceptible to drought). It was obtained 1572 valid reads, being 931 singletons and 189 contigs, with the average of 6 reads per cluster. The sequences annotation was conducted via BLAST X, considering only the best similarity results with E value \'<OU=\' 10-5. The functional classification was done adopting models described for plants (CS and MIPS) and the results were grouped into six different functional classes. Bioinformatic analyses contribuited to the identification of genes described as involved on plants response to drought stress. Among them: LEA proteins; transcription factors like DREB, NAC and leucine-rich proteins; carbohydrates synthesizers enzymes like the ones for trehalose, sucrose and rhamnose; proline-rich proteins; hormone receptors (ABA and ethylene); aquaporins; chaperones; ubiquitins; nodulins; and proteins associated with photosynthesis and respiration. In order to validate the ESTs annotated, a RT-qPCR experiment was conducted comparing the expression patterns of 15 genes under four treatments: both genotypes under stress and their respective controls. Three technical replicates were used and two reference genes (act and skip2) were chosen for intern data normalization. The gene expression patterns obtained confirm the hypothesis that such genes are more expressed on the resistant genotype although they are not exclusive since a lower levels of these transcripts were also detected in the susceptible genotype

It has been well documented that mRNA is associated with the cytoskeleton, and that this relationship is involved in translation and mRNA sorting. The molecular components involved in the attachment of mRNA to the cytoskeleton are only poorly understood. The objective of this thesis was to directly visualize the interaction of mRNA with the cytoskeleton, with sufficient resolution to identify the filament systems and structures involved. This work required the development of novel in situ hybridization methods for use with electron microscopy. This allowed resolution to visualize single mRNA molecules and individual filaments. The development of a silver enhancement methodology for both the light and electron microscopic detection of biotinated oligo-dT probes permitted a synoptic view of the intracellular distribution of poly(A) mRNA. At the light microscope, the distribution of poly(A) mRNA did not resemble the individual distribution patterns of microfilaments, intermediate filaments or microtubules. Ultrastructural examination revealed that poly(A) mRNA was not uniformly distributed along cytoskeletal filaments, but clustered at their intersections. The composition of these mRNA containing structures was investigated by both morphologic and in situ hybridization analysis using antibodies to cytoskeletal proteins. In thin sections, polysomes were observed attached to both microfilaments and intermediate filaments. To permit the simultaneous detection of oligo-dT hybridization and specific cytoskeletal proteins, a double labelling method using colloidal gold conjugated antibodies was developed. The majority of poly(A) mRNA was associated with the actin cytoskeleton, with 72% of the hybridization localized within 5nm of a labelled microfilament. Within the actin cytoskeleton, poly(A) mRNA was localized to intersections of orthogonal networks. Greater than 50% of poly(A) colocalized with the actin crosslinking proteins, filamin and α-actinin, but not vinculin. A significant amount of poly(A) mRNA was found to be associated with intermediate filaments. The double label gold analysis demonstrated that 33% of the hybridization signal localized within 5nm of labelled vimentin filaments. Prior disorganization of the actin cytoskeleton using cytochalasin did not disrupt the association of mRNA with vimentin. These observations are consistent with our morphologic results of polysome-intermediate filament associations, and indicate that microfilaments are not the only filament system to which mRNA is bound. Furthermore, a small amount of hybridization signal (12%) consistently was observed along microtubules, providing an additional cytoskeletal network to distribute mRNA. To further characterize the spatial organization of mRNA within the cytoskeleton, ultrastructural methods were developed to directly visualize individual mRNA molecules. First, oligonucleotide probes chemically modified with a single hapten and directly conjugated primary reagents were used to permit detection of an individual hybridized probe molecule by a single gold particle. Second, biotin and digoxigenin labelled oligonucleotide probes were used to simultaneously visualize the intermolecular and intramolecular relationships of two nucleic acid sequences. Third, reverse transcriptase was used to extend hybridized primers in situ which permitted visualization of the poly(A) sequence concomittant with the conformation of an mRNA molecule. These methods have permitted analysis of how single mRNA molecules may be positioned with respect to each other within the cytoskeleton. The ultrastructural visualization of mRNA within its structural environment has demonstrated heterogeneous interactions with the cytoskeleton. Future work will be needed to further characterize the mechanism of mRNA attachment. The proteins which bridge nucleic acid sequences to specific intersections can be identified. It will be interesting to learn how the identified mRNA-cytoskeletal interactions might be involved in the regulation of both mRNA translation and intracellular location. Lastly, and perhaps the most challenging goal, is to investigate whether the identified mRNA-cytoskeletal interactions are used by the cell to influence its own shape, polarity and architecture.