Genetic variation of wheat landraces in Afghanistan

Dissertação de mestrado em Ensino de Biologia e de Geologia no 3º Ciclo do Ensino Básico e no Ensino Secundário, apresentada ao Departamento de Ciências da Terra e Departamento de Ciências da VidaO presente relatório é referente ao período de Estágio Pedagógico, desenvolvido no âmbito do Mestrado em Ensino de Biologia e de Geologia no 3º Ciclo do Ensino Básico e no Ensino Secundário. O relatório descreve e analisa as atividades organizadas e desenvolvidas durante o estágio realizado na Escola Secundária D. Duarte, durante o ano letivo de 2013/2014. As práticas letivas foram circunscritas ao lecionamento supervisionado dos temas selecionados em Geologia e Biologia do 10º ano. Mais concretamente, os Métodos de estudo para o interior da geosfera e Vulcanologia e o Transporte nas plantas. Neste trabalho participaram alunos de duas turmas tendo sido lecionado o conteúdo de Geologia à turma A e o de Biologia à turma B. As estratégias e os recursos foram avaliados por intermédio de instrumentos de avaliação: diagnóstica (pré-teste e pós-teste, no início e final, respetivamente, de cada um dos períodos de lecionamento); sumativa (questões, específicas dos conteúdos selecionados, e integradas no terceiro e quinto teste sumativo); e questionários. Tanto em Geologia como em Biologia, verificou-se evolução positiva nos resultados do pré para o pós-teste. Relativamente aos testes sumativos, a avaliação foi diferenciada em procedimental e conceptual. Apesar dos resultados positivos a nível conceptual, os alunos revelaram muitas dificuldades a nível procedimental, provavelmente relacionado com o facto de a amostra ter uma média de idades inferior a 15 anos, não tendo sido preparados para o tipo de questões (itens de construção) utilizadas na avaliação procedimental. A análise dos resultados permitiu concluir que as estratégias e recursos tiveram influência na construção dos conhecimentos científicos de Geologia e Biologia. Nos questionários, os alunos também consideraram que as estratégias e recursos contribuíram para as suas aprendizagens. Neste trabalho, identificam-se as limitações das estratégias, dos recursos e dos procedimentos do docente, propondo-se possíveis alternativas e soluções.This report comprises the period of Pedagogical Training, developed within the framework of the Master in Teaching of Biology and Geology in the 3rd Cycle of Basic Education and Secondary Education. The report describes and analyzes the activities organized and carried out during the internship at D. Duarte High School, throughout the academic year of 2013/2014. The practices were confined to the supervised teaching of the selected themes in 10th grade Geology and Biology. Specifically, the Methods of study into the interior of the geosphere and Volcanology and Transport in plants. Students from two classes participated in this work, having been taught the content of Geology in class A and of Biology in class B. Strategies and resources were evaluated by means of assessment tools: diagnostic (pre-test and post-test, respectively in the beginning and end of each of the teaching periods); summative (specific questions of the selected content, and integrated in the third and fifth summative test); and questionnaires. It was ascertain, both in Biology and Geology, a positive development of the results from the pre to the post-test. Regarding summative tests, evaluation was differentiated as procedural and conceptual. Despite the positive results at the conceptual level, students revealed many difficulties in the procedural level, probably related to the fact that the age average of the sample was less than 15 years old and had not been prepared for the type of questions (building items) used in the procedural evaluation. The analysis of the results permitted to conclude that the strategies and resources influenced the construction of scientific knowledge of geology and biology. In the questionnaires, students also felt that the strategies and resources contributed to their learning. In this work are identified the limitations of the strategies, resources and teacher procedures, proposing possible alternatives and solutions

UBC13-Mediated Ubiquitin Signaling Promotes Removal of Blocking Adducts from DNA Double-Strand Breaks

Chemical modifications and adducts at DNA double-strand break (DSB) ends must be cleaned before re-joining by non-homologous end-joining (NHEJ). MRE11 nuclease is essential for efficient removal of Topoisomerase II (TOP2)-DNA adducts from TOP2 poison-induced DSBs. However, mechanisms in MRE11 recruitment to DSB sites in G1 phase remain poorly understood. Here, we report that TOP2-DNA adducts are expeditiously removed through UBC13-mediated polyubiquitination, which promotes DSB resection in G2 phase. We found that this ubiquitin signaling is required for efficient recruitment of MRE11 onto DSB sites in G1 by facilitating localization of RAP80 and BRCA1 to DSB sites and complex formation between BRCA1 and MRE11 at DSB sites. UBC13 and MRE11 are dispensable for restriction-enzyme-induced "clean" DSBs repair but responsible for over 50% and 70% of NHEJ-dependent repair of γ-ray-induced "dirty" DSBs, respectively. In conclusion, ubiquitin signaling promotes nucleolytic removal of DSB blocking adducts by MRE11 before NHEJ

Budding yeast ATM/ATR control meiotic double-strand break (DSB) levels by down-regulating Rec114, an essential component of the DSB-machinery

An essential feature of meiosis is Spo11 catalysis of programmed DNA double strand breaks (DSBs). Evidence suggests that the number of DSBs generated per meiosis is genetically determined and that this ability to maintain a pre-determined DSB level, or "DSB homeostasis", might be a property of the meiotic program. Here, we present direct evidence that Rec114, an evolutionarily conserved essential component of the meiotic DSB-machinery, interacts with DSB hotspot DNA, and that Tel1 and Mec1, the budding yeast ATM and ATR, respectively, down-regulate Rec114 upon meiotic DSB formation through phosphorylation. Mimicking constitutive phosphorylation reduces the interaction between Rec114 and DSB hotspot DNA, resulting in a reduction and/or delay in DSB formation. Conversely, a non-phosphorylatable rec114 allele confers a genome-wide increase in both DSB levels and in the interaction between Rec114 and the DSB hotspot DNA. These observations strongly suggest that Tel1 and/or Mec1 phosphorylation of Rec114 following Spo11 catalysis down-regulates DSB formation by limiting the interaction between Rec114 and DSB hotspots. We also present evidence that Ndt80, a meiosis specific transcription factor, contributes to Rec114 degradation, consistent with its requirement for complete cessation of DSB formation. Loss of Rec114 foci from chromatin is associated with homolog synapsis but independent of Ndt80 or Tel1/Mec1 phosphorylation. Taken together, we present evidence for three independent ways of regulating Rec114 activity, which likely contribute to meiotic DSBs-homeostasis in maintaining genetically determined levels of breaks

Conformational landscapes of bimesogenic compounds and their implications for the formation of modulated nematic phases

The twist-bend phase (NTB) is most commonly observed in materials with a gross-bent shape: dimers; bent-cores; bent-oligomers. We had suggested previously that the bend-angle of such systems effectively dictates the relative thermal stability of the NTB phase. However, our earlier paper relied on the use of a single energy-minimum conformer and so failed to capture any information about flexibility and conformational distribution. In the present work, we revisit our hypothesis and examine a second set of dimers with varying linking groups and spacer composition. We have improved on our earlier work by studying the conformational landscape of each material, allowing average bend-angles to be determined as well as the conformer distribution. We observe that the stability of the NTB phase exhibits a strong dependence not only on the Boltzmann-weighted average bend-angle (rather than just a static conformer), but also on the distribution of conformers. To a lesser extent, the flexibility of the spacer appears important. Ultimately, this work satisfies both theoretical treatments and our initial experimental study and demonstrates the importance of molecular bend to the NTB phase

Physical properties of Centaur (60558) 174P/Echeclus from stellar occultations

The Centaur (60558) Echeclus was discovered on March 03, 2000, orbiting between the orbits of Jupiter and Uranus. After exhibiting frequent outbursts, it also received a comet designation, 174P. If the ejected material can be a source of debris to form additional structures, studying the surroundings of an active body like Echeclus can provide clues about the formation scenarios of rings, jets, or dusty shells around small bodies. Stellar occultation is a handy technique for this kind of investigation, as it can, from Earth-based observations, detect small structures with low opacity around these objects. Stellar occultation by Echeclus was predicted and observed in 2019, 2020, and 2021. We obtain upper detection limits of rings with widths larger than 0.5 km and optical depth of $\tau$ = 0.02. These values are smaller than those of Chariklo's main ring; in other words, a Chariklo-like ring would have been detected. The occultation observed in 2020 provided two positive chords used to derive the triaxial dimensions of Echeclus based on a 3D model and pole orientation available in the literature. We obtained $a = 37.0\pm0.6$ km, $b = 28.4 \pm 0.5$ km, and $c= 24.9 \pm 0.4$ km, resulting in an area-equivalent radius of $30.0 \pm 0.5$ km. Using the projected limb at the occultation epoch and the available absolute magnitude ($\rm{H}_{\rm{v}} = 9.971 \pm 0.031$), we calculate an albedo of $p_{\rm{v}} = 0.050 \pm 0.003$. Constraints on the object's density and internal friction are also proposed.Comment: Corrected and typeset versio