Browsing by Issue Date, starting with "2022-03-24"
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- Transcriptional regulation of Synaptonemal complex assembly and disassembly during meiosisPublication . Marques, Bruno Filipe Pinheiro; Martinho, Rui Gonçalo; Bragança, JoséHuman female meiosis can take several decades to be concluded, as the oocytes enter meiosis before birth and stay arrested in prophase I in a dormant state until puberty. We aim to better understand the mechanisms responsible for the correct awakening of the oocyte, and the way they ensure successful meiotic progression and oocyte maturation. We and others showed that the prophase I-arrested Drosophila oocyte is transcriptionally quiescent for approximately 36 hours, and similarly to human oocytes, its reactivation is associated with a poorly understood global remodelling of its chromatin architecture. A screen for endogenously GFP-tagged transcription factors allowed the identification of Polycomb as being highly enriched in the oocyte chromatin and we will present our ongoing work related with the function of this protein complex and our attempts to visualize oocyte reactivation using live-cell imaging techniques. Additionally, the synaptonemal complex (SC) is a proteinaceous scaffold that is assembled between the paired homologous chromosomes during the onset of meiosis. The SC stabilizes chromosome pairing and is important for crossovers formation, recombination and accurate segregation of meiotic chromosomes. Timely expression of SC genes is essential for SC assembly and successful meiosis. However, SC components have an intrinsic tendency to self-organize into alternative repetitive structures (polycomplexes), being potentially deleterious for meiosis and gametogenesis. In this work, we show that Sfmbt, is required to avoid excessive expression of SC genes during prophase I and consequently formation of polycomplexes during SC disassembly. Overexpression of Corona and depletion of other Polycomb group proteins are similarly associated to polycomplexes formation during SC disassembly. These polycomplexes are highly dynamic and have a well-defined periodic structure. Further confirming the importance of Sfmbt for female gametogenesis, germ line depletion of this protein is associated to significant metaphase I defects and a reduction of female fertility.
- Encarregados de educação em contexto de pandemia - COVID 19: práticas e desafiosPublication . Felícia, Paula Alexandra Correia; Borges, Maria LeonorEm pleno século XXI, onde a medicina está claramente avançada, desenvolvida e tecnologicamente evoluída, nada indicaria que uma pandemia viesse alterar as rotinas pessoais diárias de uma forma tão intensa. E foi devido a estas alterações forçadas que a questão de partida deste estudo surge no sentido de saber como os Encarregados de Educação (EE) se reajustaram à nova realidade de pandemia Covid-19. Emerge assim, como seu principal objetivo: Conhecer e analisar o papel dos EE no apoio ao ensino aprendizagem dos seus educandos e na relação com a escola, durante o período de confinamento e pandemia acompanhado por diversos objetivos específicos. Desenvolveu-se o estudo, de cariz exploratório, de natureza qualitativa, descritiva e interpretativa, sustentado em dados quantitativos e qualitativos, na forma de estudo de caso, num agrupamento de escolas do Algarve. Para a recolha de dados, realizámos inquéritos por questionário, aos educadores (ED), aos titulares de turma (TT), aos diretores de turma (DT), num total de 23 docentes, e aos pais e EE (n=73) e, ainda, dois grupos focais, um para os docentes com 8 intervenientes e outro para EE onde participaram 7 pais. A análise dos resultados obtidos revela que o papel dos EE é de extrema importância no apoio ao processo de ensino aprendizagem em qualquer contexto, sendo que, em contexto pandémico, a sua importância foi imprescindível e fundamental. Sem o apoio dos EE não era possível ter existido E@D.
- Optimizing the nutritional composition of commercial diets for flatfish larvaePublication . Valente, Afonso Manuel Roberto; Conceição, Luís Eugénio da Castanheira; Coutinho, Wilson Gabriel PoseiroAquaculture industry is the food sector with higher contribution to recent growth in global food supply. Atlantic salmon (Salmo salar) is the most commercialized species in Europe. Mediterranean aquaculture is dominated by seabass (Dicentrarchus labrax) and seabream (Sparus aurata). Senegalese sole (Solea senegalensis) and turbot (Scophthalmus maximus) are two flatfish identified with potential in aquaculture whose production recently increased significantly in Portugal, Spain and France especially due to research effort made for these countries, in subjects such as weaning strategy, larvae nutrition and disease control. There are important improvements still needed for these species because they are cultivated in recirculation systems and water quality should be kept under control. It is necessary to find formulations that comply with larval necessary nutritional requirements and allow reduce nutrient leaching into the water and adapted to the flatfish species-specific feeding behaviour. The type of binder and/or binding process selected in a diet formulation and feed production technology will influence the leaching and physical characteristics of the pellets. Ingredients that provide microdiets a higher capacity of sinking of the pellets are more suitable for Senegalese sole that feed on the bottom, while binders that will slow-down sinking should be used for turbot diets that feeds on the water column. This thesis aims to perform adaptations in microdiets formulation in order to improve their physical properties and leaching and evaluate how the new ingredients affect the Senegalese sole larvae growth performance. New binders and different combinations of them were used to reduce Turbot microdiets nutrient leaching, adjust the dispersion and sinking capacity and also correlate with the biological efficiency which was evaluated in two trials. On trial 1 Senegalese sole larvae were fed with four different microdiets. The used diets were a commercial microdiet as control, and 3 diets with different ingredients. B/C was a diet with high benefit/cost ratio composed of high quality fish and squid meals and a mixture of plant-proteins including wheat gluten and pea protein concentrates, LFAT a diet with a similar composition to diet B/C, but where the reduction of the crude fat content was targeted, and PL was a diet also with a similar composition to diet B/C, but where the inclusion of a higher phospholipid content was targeted. The growth performance from all treatments was not significantly different except on LFAT which had a significantly lower growth performance, but regarding the microdiets properties PL was the diet with lower protein leaching, B/C and PL were the diets with higher sinking capacity and B/C was the diet with higher dispersion capacity. Furthermore, the results suggest that PL and B/C can be considered the best treatments used on trial 1 essentially due to the growth performance results which are similar to the control treatment and represent a higher benefit/cost ratio, but because they also fulfil important requirements on physical properties. On the second trial four different microdiets were tested in Turbot larvae, a diet used as control and three experimental diets. CTRL was a commercial-like diet, being composed of high quality fish and squid meals and plant-proteins including wheat gluten. MIX was produced with a similar composition to CTRL but using a mixture of binders in its dietary composition, LOW was produced with a similar composition to CTRL, but using a novel binder at a low inclusion level, and HIGH was produced with a similar composition to CTRL, but using a novel binder at a high inclusion level. At the end of trial CTRL and HIGH were the diets with best results for growth performance. Despite HIGH and CTRL does not have the best results on leaching reduction and the physical properties tests were not the ones who best fit into the Turbot feeding behaviour, the growth performance obtained with this dietary treatment was higher than the remaining treatments. When compared with other treatments, MIX can be a good solution to reduce leaching but will result in a with lower growth performance. CTRL and HIGH were, therefore, the most advantageous solutions. In summary, B/C and PL microdiet for Senegalese sole was the best solution due to it high benefit/cost ratio, combined with a good growth performance and reduced protein leaching, regarding Turbot, the best treatments were CTRL and HIGH due to its best growth performance results.