270 research outputs found
Evolution and expression of the highly variable cell adhesion molecule Dscam in the crustacean Daphnia and other arthropods
No full textThe Down syndrome cell adhesion molecule (Dscam) family, is within the cell adhesion molecules, a
family whose members are characterized by being composed of immunoglobulin (Ig) and fibronectin
domains and which are known to play an essential role in the development of the nervous system in both
vertebrates and invertebrates.
In insects, one member of the Dscam family diversified extensively due to internal exon duplications
and a sophisticated mechanism of mutually exclusive alternative splicing (AS). This enables a single
individual to generate somatically thousands of Dscam isoforms which differ in half of two Ig domains
and in another complete Ig domain. That creates a high diversity of adhesion properties which are used by
nervous cells and also by immune cells (hemocytes).
How this situation evolved is best understood my means of comparative studies. I have studied aspects
of the evolution and expression of this diversified member of the Dscam family mainly in the brachiopod
crustacean Daphnia magna and to lesser extent, in other representatives of the arthropod phyla. I have
shown that like in insects, a highly variable Dscam gene evolved in crustaceans, which also express
Dscam diversity in nervous and in immune cells. Additionally I could demonstrate that not only Dscam’s
ectodomains are diversified but that several cytoplasmic tails with different signal transduction capacities
can also be expressed. The comparison between Daphnia and insects revealed furthermore that there is
high amino acid conservation among distantly related species for most Dscam domains except for the Ig
regions that are coded by the multiple exons, suggesting that the latter evolved under different selective
constraints.
Dscam has been proposed as an exciting candidate molecule for mediating specific immune responses
in arthropods. Nevertheless, the involvement of Dscam in immunity remains largely elusive. I tested the
effect of parasite infection on the expression of total Dscam and on the diversity of some duplicated exons
at the RNA level and found no significant effect. Yet, hemocytes expressed reduced transcript diversity
relative to the brain, but each transcript was likely more abundant. This would be consistent with a
function in the immune system given that each Dscam isoform would be present in higher concentrations
which would increase their functional capacity.
Dscam isoforms engage in dimer formation with other identical isoforms, promoting cell-cell
recognition. It has been demonstrated that the variable parts of Dscam coded by the duplicated exons
mediate dimer formation. The genetic diversification caused by exon duplication and AS has thus direct
functional implications. I estimated signatures of selection on some of the regions involved in dimer
formation by comparing sequences from different Daphnia magna populations and from different species
of Daphnia and Drosophila. The results indicated that diversity created by duplication followed by
divergence is maintained by purifying selection against new mutations and against new gene conversion
events. That is consistent with the essential role of Dscam diversity in the nervous system. Contrastingly, I
found that some parts of the variable regions which are not involved in dimer formation and are oriented
towards the dimer’s external environment, may evolve under positive selection, which would be consistent
with an immune function.
To understand the evolutionary history of the molecule, I searched for Dscam related genes in
representatives of chelicerates (Ixodes scapularis) and myriapodes (Strigamia maritima), two other groups
of arthropods. In both myriapodes and chelicerates, Dscam diversified extensively by whole gene
duplications and by duplications of some internal exons coding for one Ig domain region, but not several,
like in insects and crustaceans. Similar duplications could have provided the raw material from which the
highly diverse Dscam evolved uniquely in the ancestors of crustaceans and insects. I propose a speculative
scenario under which the evolution of this remarkable gene might have occurred
A BRITES DE JÚLIA NERY: UMA POSSIBILIDADE TRANSGRESSORA EM MEIO AO DISCURSO FICCIONAL
No full textEste artigo faz uma leitura do livro Crônica de Brites, de Júlia Nery, a partir dos conceitos de gênero e de performance, os quais trabalham com a premissa basilar de que gênero é construção. A partir da análise de alguns excertos do romance, e à luz dessas teorias de gênero, objetivamos mostrar como a autora, ao dialogar com o passado histórico de Portugal por meio da personagem Brites de Almeida, constrói uma obra transgressora e crítica, que desnuda alguns mecanismos que procuram engendrar os sujeitos em realidades fixas e “naturalmente” imutáveis.This paper makes a lecture of Crônica de Brites, by Júlia Nery. The lecture is based on the concept of gender and performance, where the gender is built, as the basal assumption. Merging any analysis of the romance excerpts and gender theories, we show how the author builds a critical and transgressive essay. The author makes a dialogue with the historical past of Portugal through the personage of Brites de Almeida which reveals some mechanisms that yield the subjects in fixed and “naturally” immutable realities
Landscape Settlement and Way of Life / Povoamento, Paisagem e Modo de Habitar
No full textIl testo descrive quattro casi di intervento, in territori fragili, esemplari per la capacità di ricomposizione della dinamica di evoluzione della relazione tra insediamento e paesaggio. Gli autori, nell'ambito di un percorso di ricerca internazionale sul paesaggio in Europa, individuano, ciascuno dal proprio punto di vista, storie e percorsi progettuali rivolti al perseguimento di una armoniosa ricomposizione della relazione tra insediamento e paesaggio.
Gli interventi di valorizzazione sono espressione di un misurato e specifico gradiente progettuale che riconosce tra i segni impressi dal tempo nei luoghi i valori da conservare e che individua e realizza le trasformazioni utili a generare nuovi valori e garantire l’implementazione di nuovi usi per un adeguamento alle dinamiche di sviluppo contemporanee. I punti di vista della geografia, dell’urbanistica, della progettazione architettonica e della tecnologia si offrono come lente di possibile lettura per realtà esemplari secondo diversi piani di lettura
Implications of opposite phyllotaxis for light interception efficiency of Mediterranean woody plants. Trees – Structure and Function 19: 671–679
No full textAbstract Opposite leaves lead to a greater leaf overlapping than leaves spirally arranged along a shoot, decreasing light interception efficiency (Ea, fraction of the light reaching the plant actually intercepted by the leaves) of the crown. However, Ea results from a whole suite of morphological traits. The interplay between phyllotaxis, crown architecture, leaf morphology and Ea was explored in 12 woody species from Mediterranean-type ecosystems, where the abundance of woody species with opposite phyllotaxis is unusually high. The three-dimensional model Y-plant was used to estimate Ea in unbranched, vertical shoots of each species encompassing the natural morphological variation found from moderate shade to open light environments. Ea exhibited significant interspecific differences, ranging from 0.25 in Daphne gnidium to 0.75 in Cistus ladanifer, Olea europaea and Salvia officinalis, decreasing with leaf inclination angle and leaf area ratio (LAR), and increasing with internode-to-leaf-length ratio and supporting biomass. Species with spiral vs. opposite phyllotaxis did not differ in their mean Ea. However, the former had higher Ea than the latter at short internode lengths. The natural range of variation in internode length had a larger effect on Ea than the natural range of leaf elevation angle. Principal component analysis segregated species with opposite phyllotaxis from those with spiral leaves because of their greater self-shading for high sun elevation angles (>45 • ); they were in turn distributed in two groups, one with high Ea, large investment in supporting biomass and long internodes, and another with low Ea and large LAR. Species with spiral phyllotaxis all had intermediate or low Ea and steep leaf elevation angles. Species with opposite phyllotaxis can compensate their less efficient leaf arrangement by decreasing leaf elevation angle and increasing internode length, but they may expe-D. Brites · F. Valladares ( ) Centro de Ciencias Medioambientales C.S.I.C., Serrano 115 dpdo, Madrid, 28006, Spain e-mail: [email protected] Tel.: +34-917452500 Fax: +34-915640800 rience a real phylogenetic constraint for light interception when biomass allocation to supporting tissues (internodes and petioles) becomes very costly. This constraint could be involved in the shade intolerance of woody Mediterranean species exhibiting opposite phyllotaxis
Ajustamento emocional: a satisfação profissional e a exposição em incidentes críticos na Polícia de Segurança Pública
No full textOrientação: Joana Brites RosaNas circunstâncias sociais atuais o stress profissional é um problema frequente, em
diferentes áreas, nomeadamente em virtude das consequências que origina a nível da saúde
física e mental.
A presença em situações de perigo, crime ou outros incidentes críticos, fazem com
que o desempenho da função de Polícia seja uma atividade desencadeadora de stress e
burnout (Agolla, 2009; Blum, 2000; Manuel & Soeiro, 2010; Violanti et al., 2009).
Tendo este pressuposto presente pretende-se, com o presente trabalho, analisar o
ajustamento emocional, nos agentes da Polícia de Segurança Publica (PSP).
Aproveitando o estágio efetuado na Divisão de Psicologia da PSP foram-me cedidos
dados recolhidos a agentes através da utilização de instrumentos, regularmente utilizados pela
PSP: questionário presencial; Escala de Vulnerabilidade ao Stress – 23 QVS (Vaz Serra,
2000); Symptom Checklist - SCL-90- R (Derogatis, 1988, versão portuguesa Baptista, 1993);
Inventário Maslach de Burnout - MBI (Maslach, Jackson, Leiter, 1996).
Os resultados obtidos revelam que o grupo não satisfeito do ponto de vista
profissional têm indicadores de sintomas psicopatológicos e de propensão para o stress e
burnout em três dos instrumentos, por enquanto que a participação em incidentes críticos
apenas conduz a diferenças na vulnerabilidade ao stress, índice perfeccionismo e
dramatização da existência.In the current social circumstances’, professional stress is a problem regular to meet,
in the most diverse areas, mainly due to physic, and mental health, impacts that this problem
originates.
The contact with dangerous situations, crime and other critical incidents, make Police
activity to be an easy trigger to stress and burnout. (Agolla, 2009; Blum, 2000; Manuela
Soeiro, 2010; Violanti et. Al., 2009).
Considering this assumptions, in the present document the author pretend to make an
analysis of the emotional adjustment, in police officers, from Portuguese public safety police
(PSP).
Taking advantage of my academic stage, made in the Psychology Department of
PSP, we receive data collected from officers, with the use of four instruments, as a regular
procedure of PSP: survey; scale of vulnerability to stress – 23QVS (Vaz Serra, 2000);
Symptom Checklist – SCL 90R (Derogatis, 1988, Portuguese Version Batista, 1993); Maslach
Burnout Inventory – MBI (Masclach, Jackso, leiter, 1996).
The outcome achieved reveals that the no professionally satisfied group have
indicators of psychopathologic symptoms and tendency to stress and burnout in three of the
nstruments used, and the exposure to criticalincidents only drives to key alert indicators in the
stress vulnerability, mainly perfectionism and dramatization of existence
Exercício físico na gravidez e no trabalho de parto
No full textObjetivo: Descrever crítica e reflexivamente o método de aquisição de competências comuns e específicas no contexto do Enfermeiro Especialista em Enfermagem de Saúde Materna e Obstétrica.
Metodologia: Supervisão clínica em contexto do estágio, com uma descrição e reflexão acerca das situações vivenciadas, determinou uma prática baseada na evidência, através da pesquisa e aliando a reflexão á prática, através de informação recolhida em contexto clínico, salientando a temática do exercício físico no trabalho de parto.
Resultados: Obtenção de competências comuns e específicas do Enfermeiro Especialista em Enfermagem de Saúde Materna e Obstétrica, nos diferentes contextos clínicos, sendo que a exploração da temática contribuiu para desenvolver as competências no empoderamento das mulheres durante o trabalho de parto e parto no que respeita à prática de exercício.
Conclusões: Os objetivos definidos foram alcançados, as competências atingidas, contribuindo para uma tomada de decisão baseada na evidência científica promovendo a qualidade na prática dos cuidados de enfermagem; - Physical Exercise inPregnancy andLabour
Abstract:
Objective:To critically and reflexively describe the method of acquiring common and specific competences in the context of the Nurse Specialising in Maternal and Obstetric Health Nursing.
Methodology:Clinical supervision in the context of the internship, with a description of and reflection on the situations experienced, determined a practice based on evidence, through research and combining reflection with practice, through information gathered in a clinical context, highlighting the theme of physical exercise in labour.
Results:Common and specific competences of the Maternal and Obstetric Health Nurse Specialist were obtained in the different clinical contexts, and the exploration of the theme contributed to developing competences in the empowerment of women during labour and childbirth with regard to the practice of exercise.
Conclusions:The objectives set were achieved, the competences attained, contributing to decision-making based on scientific evidence and promoting quality in the practice of nursing care
A new nomenclature for the livestock-associated Mycobacterium tuberculosis complex based on phylogenomics
No full textFigure 1 - Distribution of the raw pairwise SNP distances between and within main La1 groups.
Table 1 – Accession numbers and metadata associated with the 839 WGS used of La1, La2 and La3.
Table 2 - Accession numbers and metadata associated with the 1,226 WGS used as representatives of the whole MTBC.
Table 3 – Spoligotypes patterns inferred from the WGS and used to complement the geographic distribution of La1 sublineages.
Table 4 – Single nucleotide polymorphisms (SNPs) specific to livestock-associated MTBC lineages and sublineages. Coordinates based on the M. tuberculosis H37Rv annotation (NC_000962.3) are given (Position_ref), and the lineage and or sublineage classification (PhylogeneticSNP). Additionally, the gene-based position is indicated (Position_gene) as well as the kind of mutation based on SnpEff annotation [40]. SNPs used to create the new KvarQ testsuite are indicated.
Table 5 – KvarQ results of lineage and sublineage typing done with the new testsuite implemented
The nature and evolution of genomic diversity in the Mycobacterium tuberculosis complex
No full textThe Mycobacterium tuberculosis Complex (MTBC) consists of a clonal group of several mycobacterial lineages pathogenic to a range of different mammalian hosts. In this chapter, we discuss the origins and the evolutionary forces shaping the genomic diversity of the human-adapted MTBC. Advances in whole-genome sequencing have brought invaluable insights into the macro-evolution of the MTBC, and the biogeographical distribution of the different MTBC lineages, the phylogenetic relationships between these lineages. Moreover, micro-evolutionary processes start to be better understood, including those influencing bacterial mutation rates and those governing the fate of new mutations emerging within patients during treatment. Current genomic and epidemiological evidence reflect the fact that, through ecological specialization, the MTBC affecting humans became an obligate and extremely well-adapted human pathogen. Identifying the adaptive traits of human-adapted MTBC and unraveling the bacterial loci that interact with human genomic variation might help identify new targets for developing better vaccines and designing more effective treatments
Somatic and germline diversification of a putative immunoreceptor within one Phylum: dscam in arthropods
No full textArthropod Dscam, the homologue of the human Down Syndrome cell adhesion molecule, is a receptor used by the nervous and immune systems. Unlike in vertebrates, evolutionary pressure has selected and maintained a vast Dscam diversity of isoforms, known to specifying neuronal identity during the nervous system differentiation. This chapter examines the different modes of Dscam diversification in the context of arthropods' evolution and that of their immune system, where its role is controversial.In the single Dscam gene of insects and crustaceans, mutually exclusive alternative splicing affects three clusters of duplicated exons encoding the variable parts of the receptor. The Dscam gene produces over 10,000 isoforms. In the more basal arthropods such as centipedes, Dscam diversity results from a combination of many germline genes (over 80) with, in about half of those, the possibility of alternative splicing affecting only one exon cluster. In the even more basal arthropods, such as chelicerates, no splicing possibility is detected, but there exist dozens of germline Dscam genes. Compared to controlling the expression of multiple germline genes, the somatic mutually alternative splicing within a single gene may offer a simplified way of expressing a large Dscam repertoire. Expressed by hemocytes, Dscam is considered a phagocytic receptor but is also encountered in solution. More information is necessary about its binding to pathogens, its role in phagocytosis, its possible role in specifying hemocyte identity, its kinetics of expression, and the regulation of its RNA splicing to understand how its diversity is linked to immunity
Old and new selective pressures on Mycobacterium tuberculosis
No full textTuberculosis (TB) has been affecting humans for millennia. There is increasing indication that human-adapted Mycobacterium tuberculosis complex (MTBC) has been co-evolving with different human populations. Some of the most important drivers of MTBC evolution have been the host immune response and human demography. These old selective forces have shaped many of the features of human TB we see today. Two new selective pressures have emerged only a few decades ago, namely HIV co-infection and the use of anti-TB drugs. Here we discuss how the emergence of HIV/TB and drug resistance could impact the long-term balance between MTBC and its human host, and how these changes might influence the future evolutionary trajectory of MTBC
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