Browsing by Author "Silva, Manuela"
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- 45S rDNA external transcribed spacer organization reveals new phylogenetic relationships in Avena genusPublication . Rodrigues, Joana; Viegas, Wanda; Silva, ManuelaThe genus Avena comprises four distinct genomes organized in diploid (AA or CC), tetraploid (AABB or AACC) and hexaploid species (AACCDD), constituting an interesting model for phylogenetic analysis. The aim of this work was to characterize 45S rDNA intergenic spacer (IGS) variability in distinct species representative of Avena genome diversity±A. strigosa (AA), A. ventricosa (CvCv), A. eriantha (CpCp), A. barbata (AABB), A. murphyi (AACC), A. sativa (AACCDD) and A. sterilis (AACCDD) through the assessment of the 5' external transcribed spacer (5'-ETS), a promising IGS region for phylogenetic studies poorly studied in Avena genus. In this work, IGS length polymorphisms were detected mainly due to distinct 5'-ETS sequence types resulting from major differences in the number and organization of repeated motifs. Although species with A genome revealed a 5'-ETS organization (A-organization) similar to the one previously described in A. sativa, a distinct organization was unraveled in C genome diploid species (C-organization). Interestingly, such new organization presents a higher similarity with other Poaceae species than A-genome sequences, supporting the hypothesis of C-genome being the ancestral Avena genome. Additionally, polyploid species with both genomes mainly retain the A-genome 5'-ETS organization, confirming the preferential elimination of C-genome sequences in Avena polyploid species. Moreover, 5'-ETS sequences phylogenetic analysis consistently clustered the species studied according to ploidy and genomic constitution supporting the use of ribosomal genes to highlight Avena species evolutive pathways.
- Análise sistémica, modelização social e planificaçãoPublication . Silva, ManuelaAté hoje, a planificação, tal como se apresenta ao nível da prática dos vários países, tem consistido mais num conjunto de esforços de adequação entre meios e fins do que no desvendamento dos mecanismos de funcionamento do sistema e em formas de intervenção sobre esses mecanismos. Sem cuidar de saber que factores explicam o caminho até agora seguido, interessa, todavia, não deixar na sombra uma consequência importante ligada a esta forma de proceder. É que, polarizada na relação entre meios e fins, a prática planificadora tem ignorado ou menosprezado a complexidade das relações que caracterizam o sistema social. Assume este como se fosse um todo homogéneo, quando, na realidade, se trata de um complexo de diversificados, com suas leis próprias de funcionamento no conjunto por forma a manterem no seu interior, entre si, e com o exterior relações significativas, persistentes e de validade geral. Desnecessário se torna insistir na importância desta propriedade sistémica no caso dos sistemas sociais e, em particular, no alcance de que ela se reveste quando em a reprodução dos mesmos. Na medida em que a planificação é esforço de regulação da reprodução do sistema, não pode apreender-se sem se inserir no conjunto do sistema.
- Análise sistémica, modelização social e planificaçãoPublication . Silva, Manuelaste artigo é uma sistematização de notas de leitura das principais obras que se têm ocupado da análise de sistemas, na, sua dupla versão cognitiva e decisional, feita em função de uma problemática especifica—a modelização e a planificação social. Poderá esperar-se da démarche analítica da sistemologia um contributo decisivo para fazer recuar os limites ao nível do conhecimento e da intervenção planificadora que hoje se deparam à teoria e à política da evolução das sociedades humanas?
- Assessment of four portuguese wheat landrace diversity to cope with global warmingPublication . Tomás, Diana; Coelho, Luís Pinto; Rodrigues, José Carlos; Viegas, Wanda; Silva, ManuelaWheat is a dietary staple consumed worldwide strongly responsible for proteins and carbohydrate population intake. However, wheat production and quality will scarcely fulfill forward demands, which are compounded by high-temperature (HT) events as heatwaves, increasingly common in Portugal. Thus, landraces assume crucial importance as potential reservoirs of useful traits for wheat breeding and may be pre-adapted to extreme environmental conditions. This work evaluates four Portuguese landrace yield and grain composition through attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, particularly protein content, and their responses to HT treatment mimicking a heatwave. Landraces showed distinct yield traits, especially plant height and first spike grain number, and a similar pattern in FTIR spectra, although revealing differences in grain components’ proportions. Comparison between spectra band intensity indicates that Ardito has the highest protein-related peaks, contrary to Magueija, which appears to be the landrace with higher lipid content. In plants submitted to 1 week of HT treatment 10 days after anthesis, the first spike grain size and weight were markedly reduced in all landraces. Additionally, it was observed that a general increase in grain protein content in the four landraces, being the increment observed in Ardito and Grécia, is statistically significant. The comparative assessment of control and HT average FTIR spectra denoted also the occurrence of alterations in grain polysaccharide composition. An integrated assessment of the evaluations performed revealed that Ardito and Magueija landraces presented diverse yield-related characteristics and distinct responses to cope with HT. In fact, the former landrace revealed considerable grain yield diminution along with an increase in grain protein proportion after HT, while the latter showed a significant increase in spikes and grain number, with grain quality detriment. These results reinforce the relevance of scrutinizing old genotype diversity seeking for useful characteristics, particularly considering HT impact on grain production and quality
- Assessment of high temperature effects on grain yield and composition in bread wheat commercial varietiesPublication . Tomás, Diana; Rodrigues, José Carlos; Viegas, Wanda; Silva, ManuelaWheat is one of the most important cereals for food and feed, and it is, therefore, necessary to determine the e ects of short-term high temperature events (heatwaves) during grain filling. These heatwave events are increasingly common, especially in Portugal. In this work, seven commercial varieties recommended for production in Portugal were submitted to one-week high temperature (HT) treatment ten days after anthesis to evaluate heat e ects on grain yield and quality. Grain yield parameters, such as grain number and weight, were evaluated as well as grain composition through attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Variation in HT response between varieties was detected. Grain number and weight tended to decrease in most varieties analyzed. However, two varieties proved to be more resilient since grain number and weight remain unaltered in the Bancal variety, which is the one with better yield results, and even increased in the Pata Negra variety. Regarding grain composition, the comparison between ATR-FTIR spectra of milled grains from control and HT plants revealed alterations in peaks assigned to polysaccharides and proteins. Additionally, a model was built based on nitrogen elemental analysis to predict protein content in flour samples through spectral data that corroborated the di erences identified by spectra profile comparison. Moreover, both analyses showed that the intervarietal diversity observed in control conditions was significantly reduced in HT treated plants. The results obtained highlight the intervarietal diversity of wheat response to HT, regarding grain yield parameters, grain composition, and particularly, protein content
- Assimetrias espaciais do progresso no continente portuguêsPublication . Silva, ManuelaNo termo de dois planos de fomento, é inteiramente justificada e oportuna uma avaliação dos resultados obtidos. Nas observações que seguem, temos presentes apenas os efeitos de ordem social, designadamente sobre as assimetrias da repartição da riqueza nacional e do grau de satisfação dos indivíduos. Por outras palavras, é nosso intuito -analisar as variações que se registaram nas condições sociais e qual o sentido dessas variações. Uma vez que se prepara novo programa para a política governamental de desenvolvimento económico, será de toda a oportunidade que se considere a possibilidade de, através do novo Plano, se garantir a melhor difusão do progresso por todas as regiões e bem assim de se corrigirem as assimetrias observadas. Será ainda de esperar que o novo Plano venha a dar resposta a necessidades fundamentais das populações mais desfavorecidas e integrá-las no processo geral, de promoção material e espiritual que é o objectivo último de todo o desenvolvimento.
- Bases de um processo de desenvolvimento comunitárioPublication . Silva, ManuelaAs técnicas clássicas de desenvolvimento não se mostraram eficientes para promover o crescimento de certas zonas, conhecidas por isso pela designação de «regiões-problema». A técnica de desenvolvimento comunitário, apresentando a vantagem de aproveitar dados da Economia e da Psicologia, procura vir ao encontro dessa dificuldade e baseia-se fundamentalmente na adesão das populações e sua participação efectiva em todas as fases do processo de desenvolvimento.
- Child poverty and deprivation in Portugal: a national case studyPublication . Silva, ManuelaThis paper examines the. characteristics and the scope of child poverty in Portugal and the impact of economic growth and social po1icy on the well-being of children within the context of the structural and institutional problems of the Country. Fluctuations in the welfare of children are therefore to policy issues. The study encompasses the almost 40 years: between 1950 and 1988. This period has been broken down. into three subperiods which are characterized by substantially different approaches in. economic and social policy: 1950-74: the period of the dictatorship; 1974-85: a period. of revolution, socialist reform, consolidation and economic crisis; and 1985 and beyond: the period of the entry into. the European Economic Community and the economic “takeoff” of the country. Overall, Portuguese children are still not assured of the benefits of economic growth, and they are not protected from the risks of misdirected development. Indeed, there are reasons to fear that poverty and social deviance may increase in the near future to the detriment of children. The need is well demonstrated for local and; national policies which can help prevent poverty among children and improve child well-being.
- Chromosomal locus rearrangements are a rapid response to formation of the allotetraploid Arabidopsis suecica genomePublication . Silva, Manuela; Viegas, Wanda; Pontes, Olga; Neves, Nuno; Lewis, Michelle S.; Madlung, Andreas; Comai, Luca; Pikaard, CraigAllopolyploidy is a significant evolutionary process, resulting in new species with diploid or greater chromosome complements derived from two or more progenitor species. We examined the chromosomal consequences of genomic merger in Arabidopsis suecica, the allotetraploid hybrid of Arabidopsis thaliana and Arabidopsis arenosa. Fluorescence in situ hybridization with centromere, nucleolus organizer region (NOR), and 5S rRNA gene probes reveals the expected numbers of progenitor chromosomes in natural A. suecica, but one pair of A. thaliana NORs and one pair of A. arenosa-derived 5S gene loci are missing. Similarly, in newly formed synthetic A. suecica-like allotetraploids, pairs of A. thaliana NORs are gained de novo, lost, and or transposed to A. arenosa chromosomes, with genotypic differences apparent between F3 siblings of the same F2 parent and between independent lines. Likewise, pairs of A. arenosa 5S genes are lost and novel linkages between 5S loci and NORs arise in synthetic allotetraploids. By contrast, the expected numbers of A. arenosa-derived NORs and A. thaliana-derived 5S loci are found in both natural and synthetic A. suecica. Collectively, these observations suggest that some, but not all, loci are unstable in newly formed A. suecica allotetraploids and can participate in a variety of alternative rearrangements, some of which resemble chromosomal changes found in nature.
- Combined multi-omics and physiological approaches to elucidate drought-response mechanisms of durum wheatPublication . Arriagada, Osvin; Meneses, Claudio; Pedreschi, Romina; Núñez-Lillo, Gerardo; Maureira, Carlos; Reveco, Samantha; Villarroel, Valentina; Steinfort, Úrsula; Albornoz, Francisco; Cabas-Lühmann, Patricia; Silva, Manuela; Matus, Iván; Schwember, Andrés R.