Functional analysis of String/CDC25 phosphatase in post-mitotic neurons

Cell cycle and differentiation are two highly coordinated processes during organ development. Recent studies have demonstrated that core cell cycle regulators also play cell cycle-independent functions in post-mitotic neurons, and are essential for the maintenance of neuronal homeostasis. CDC25 phosphatases are well-established CDK activators and their activity is mainly associated to proliferating tissues. The expression and activity of mammalian CDC25s has been reported in adult brains. However, their physiological relevance and the potential substrates in a non-proliferative context have never been addressed. string (stg) encodes the Drosophila CDC25 homolog. Previous studies from our group showed that stg is expressed in photoreceptors (PRs) and in lamina neurons, which are two differentiated cell types that compose the fly visual system. The aims of this work are to uncover the function of stg and to identify its potential neuronal substrates, using the Drosophila visual system as a model. To gain insight into the function of stg in a non-dividing context we used the GAL4/UAS system to promote downregulation of stg in PR-neurons, through the use of an RNAi transgene. The defects caused by stg loss-of-function were evaluated in the developing eye imaginal disc by immunofluorescence, and during adult stages by scanning electron microscopy. This genetic approach was combined with a specific proteomic method, two-dimensional difference gel electrophoresis (2D-DIGE), to identify the potential substrates in PR-cells. Our results showed that stg downregulation in PRs affects the well-patterned retina organization, inducing the loss of apical maintenance of PR-nuclei on the eye disc, and ommatidia disorganization. We also detected an abnormal accumulation of cytoskeletal proteins and a disruption of the axon structure. As a consequence, the projection of PR-axons into the lamina and medulla neuropils of the optic lobe was impaired. Upon stg downregulation, we also detected that PR-cells accumulate Cyclin B. Although the rough eye phenotype observed upon stg downregulation suggests neurodegeneration, we did not detect neuronal death during larval stages, suggesting that it likely occurs during pupal stages or during adulthood. By 2D-DIGE, we identified seven proteins which were differentially expressed upon stg downregulation, and are potential neuronal substrates of Stg. Altogether, our observations suggest that Stg phosphatase plays an essential role in the Drosophila visual system neurons, regulating several cell components and processes in order to ensure their homeostasis.

Using VEs to enhance chronological understanding of history in middle school children.

Studies with computer-experienced children in the UK and less experienced in Ukraine explored the potential for VEs in teaching historical chronology to middle-school children aged 10–12 years old. Active fly-through VEs had been previously used successfully with primary school children aged 8–9 years old (given specific training with the environment) when they were subsequently tested for their ability to order events chronologically. All VEs in the present studies included a training element and active challenge, both found previously to enhance learning in other age groups. Ukraine children were trained and tested. UK children here were trained and tested, then retrained and retested to examine savings. Unlike other age groups, no significant benefit was seen for VE training compared with PowerPoint and Text conditions in either study. Possible explanations for the ineffectiveness of VE training for children of middle school age will be discussed. Keywords: timeline, chronographics

Can virtual environments enhance the learning of historical chronology?

Historical time and chronological sequence are usually conveyed to pupils via the presentation of semantic information on printed worksheets, events being rote-memorised according to date. We explored the use of virtual environments in which successive historical events were depicted as “places” in time–space, encountered sequentially in a fly-through. Testing was via “Which came first, X or Y?” questions and picture-ordering. University undergraduates experiencing the history of an imaginary planet performed better after a VE than after viewing a “washing line” of sequential images, or captions alone, especially for items in intermediate list positions. However, secondary children 11–14 years remembered no more about successive events in feudal England when they were presented virtually compared with either paper picture or 2-D computer graphic conditions. Primary children 7–9 years learned more about historical sequence after studying a series of paper images, compared with either VE or computer graphic conditions, remembering more in early/intermediate list positions. Reasons for the discrepant results are discussed and future possible uses of VEs in the teaching of chronology assessed. Keywords: timeline, chronographics

Do challenge, task experience or computer familiarity influence the learning of historical chronology from virtual environments in 8–9 year old children?

Studies examined the potential use of Virtual Environments (VEs) in teaching historical chronology to 127 children of primary school age (8–9 years). The use of passive fly-through VEs had been found, in an earlier study, to be disadvantageous with this age group when tested for their subsequent ability to place displayed sequential events in correct chronological order. All VEs in the present studies included active challenge, previously shown to enhance learning in older participants. Primary school children in the UK (all frequent computer users) were tested using UK historical materials, but no significant effect was found between three conditions (Paper, PowerPoint and VE) with minimal pre-training. However, excellent (error free) learning occurred when children were allowed greater exploration prior to training in the VE. In Ukraine, with children having much less computer familiarity, training in a VE (depicting Ukrainian history) produced better learning compared to PowerPoint, but no better than in a Paper condition. The results confirmed the benefit of using challenge in a VE with primary age children, but only with adequate prior familiarisation with the medium. Familiarity may reduce working memory load and increase children’s spatial memory capacity for acquiring sequential temporal-spatial information from virtual displays. Keywords: timeline, chronographics

Human-Centric Chronographics:Making Historical Time Memorable

A series of experiments is described, evaluating user recall of visualisations of historical chronology. Such visualisations are widely created but have not hitherto been evaluated. Users were tested on their ability to learn a sequence of historical events presented in a virtual environment (VE) fly-through visualisation, compared with the learning of equivalent material in other formats that are sequential but lack the 3D spatial aspect. Memorability is a particularly important function of visualisation in education. The measures used during evaluation are enumerated and discussed. The majority of the experiments reported compared three conditions, one using a virtual environment visualisation with a significant spatial element, one using a serial on-screen presentation in PowerPoint, and one using serial presentation on paper. Some aspects were trialled with groups having contrasting prior experience of computers, in the UK and Ukraine. Evidence suggests that a more complex environment including animations and sounds or music, intended to engage users and reinforce memorability, were in fact distracting. Findings are reported in relation to the age of the participants, suggesting that children at 11–14 years benefit less from, or are even disadvantaged by, VE visualisations when compared with 7–9 year olds or undergraduates. Finally, results suggest that VE visualisations offering a ‘landscape’ of information are more memorable than those based on a linear model. Keywords: timeline, chronographics

Bottom-up regulation of phytoplankton in the Guadiana estuary

Tese dout., Ciências do Mar (Ecologia Marinha), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2010

Evolution of matrix and bone gamma-carboxyglutamic acid proteins in vertebrates

The evolution of calcified tissues is a defining feature in vertebrate evolution. Investigating the evolution of proteins involved in tissue calcification should help elucidate how calcified tissues have evolved. The purpose of this study was to collect and compare sequences of matrix and bone γ-carboxyglutamic acid proteins (MGP and BGP, respectively) to identify common features and determine the evolutionary relationship between MGP and BGP. Thirteen cDNAs and genes were cloned using standard methods or reconstructed through the use of comparative genomics and data mining. These sequences were compared with available annotated sequences (a total of 48 complete or nearly complete sequences, 28 BGPs and 20 MGPs) have been identified across 32 different species (representing most classes of vertebrates), and evolutionarily conserved features in both MGP and BGP were analyzed using bioinformatic tools and the Tree-Puzzle software. We propose that: 1) MGP and BGP genes originated from two genome duplications that occurred around 500 and 400 million years ago before jawless and jawed fish evolved, respectively; 2) MGP appeared first concomitantly with the emergence of cartilaginous structures, and BGP appeared thereafter along with bony structures; and 3) BGP derives from MGP. We also propose a highly specific pattern definition for the Gla domain of BGP and MGP. Previous Section Next Section BGP1 (bone Gla protein or osteocalcin) and MGP (matrix Gla protein) belong to the growing family of vitamin K-dependent (VKD) proteins, the members of which are involved in a broad range of biological functions such as skeletogenesis and bone maintenance (BGP and MGP), hemostasis (prothrombin, clotting factors VII, IX, and X, and proteins C, S, and Z), growth control (gas6), and potentially signal transduction (proline-rich Gla proteins 1 and 2). VKD proteins are characterized by the presence of several Gla residues resulting from the post-translational vitamin K-dependent γ-carboxylation of specific glutamates, through which they can bind to calcium-containing mineral such as hydroxyapatite. To date, VKD proteins have only been clearly identified in vertebrates (1) although the presence of a γ-glutamyl carboxylase has been reported in the fruit fly Drosophila melanogaster (2) and in marine snails belonging to the genus Conus (3). Gla residues have also been found in neuropeptides from Conus venoms (4), suggesting a wider prevalence of γ-carboxylation.

Entomofauna associated with the olive tree in southern Portugal

Since 2004 several studies have been carried out in order to identify the main insect species that usually inhabiting the olive ecosystem. The field trials have taken place in two olive groves, one situated in Olhão and the other one in Loulé, both in Algarve and also under Integrated Pest Management (IPM). The sampling techniques used differ according to their purpose (sticky traps, pheromone traps, pitfall traps and samples of aerial parts of the trees such as inflorescences, leaves, fruits and branches). Results showed that the main insect pests of olive tree in southern Portugal were the olive fruit fly Bactrocera oleae Gmelin (Diptera: Tephritidae) and the olive moth Prays oleae Bernard (Lepidoptera: Hyponeumetidae). Other insect pests were also found in our olive groves namely the olive psyllid Euphyllura olivina Costa (Homoptera: Psyllidae), the olive dark beetle Phloeotribus scarabaeoides Bernard (Coleoptera: Curculionidae), the mediterranean black scale Saissetia oleae (Olivier) (Homoptera: Coccidae) and the olive thrip Liothripes oleae Costa (Thysanoptera: Phlaeothripidae). Concerning the auxiliary insects that were found in our olives groves they belong to the following orders and families: Diptera (Syrphidae), Coleoptera (Carabidae, Coccinelidae and Staphylinidae), Hemiptera (Anthocoridae and Miridae), Neuroptera (Chrysopidae) and Hymenoptera (Braconidae, Encyrtidae, Eulophidae, Formicidae and Trichogrammatidae).

Valorização de resíduos carbonosos de gasificação como precursores de materiais para adsorção de poluentes em fase aquosa

Tese de doutoramento, Energia e Ambiente (Energia e Desenvolvimento Sustentável), Universidade de Lisboa, Faculdade de Ciências, 2014

Design and Qualitative/Quantitative Analysis of Multi-Agent Spatial Simulation Library

Thesis (Master's)--University of Washington, 2012

Graffiti composition: screenplay

Ongoing collaboration with Christian Marclay. ‘Graffiti Composition’ and ‘Screenplay’ are two related works consisting of live musical improvisation and performance. They are part of an ongoing collaboration with the artist Christian Marclay. 'Graffiti Composition' involved Beresford directing an invited orchestra of improvising musicians. The work focuses on making music from the random compositional acts of strangers. Prior to realization, Marclay fly-posted several hundred sheets of blank manuscript paper, collecting the sheets some days later, after passers-by had written on them – using either traditional music notation or more transgressive interference modes (colour-blocks, torn holes in or abstract graphic symbols on the paper) – and sending photographs of them to Beresford. Beresford’s directorial decisions helped these random graffiti become music via simple formal processes – restricting each musician to a handout of two MS each, or stipulating a mini-concerto for each player. Beresford’s contribution explores the paradox of improvisation stipulated by strangers and controlled, however loosely, by the structuring agency of a musical director. ‘Screenplay’ extended this collaborative process between Marclay and Beresford. Beresford and other musicians responding to a visual track comprising found and public domain moving images manipulated by Marclay – gunfight scenes from a TV Western; running water; racing cars morphing into crying children, and so on, in black-and-white, with single-colour blocks appearing and developing as lines, spots, and other suggestive ‘notation’. The elliptical, surprising, humorous nature of the images at times is hyperexplicated by the improvised music, and at others challenged, ignored or contradicted by the musicians’ interaction. ‘Graffiti Composition’ was performed by the LSO at St. Luke’s, London, March 22, 2005. ‘Screenplay’ premiered in Dundee in 2006, and toured Europe during 2007. Reviewed in the Herald (21 Feb 06) and Times (24 March 07). Beresford’s work as improviser, composer and performer was profiled in The Wire (April 2002, May 2005).

Discrete Gaussian Sampling for Low-Power Devices

Thesis (Master's)--University of Washington, 2015

Sistema de fundações para postes de catenária com betão com pré-colocação de agregados (PAC)

Trabalho de Projecto de natureza científica para obtenção do grau de Mestre em Engenharia Civil

ECO-betão com adição de resíduo da indústria petrolífera

Dissertação de natureza Científica para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização em Edificações