Extension and patterning of the vertebrate body

Dissertation presented to obrain the Ph.D degree in Biology. Developmental BiologyVertebrates exhibit an enormous diversity in body shapes. Despite this variability, they all develop by a common principle, in which new tissue is continuously added at the posterior embryonic end during development. Axial extension requires a tight balance between the maintenance of axial progenitors in an undifferentiated state and the production of cells fated to generate different body structures. Concurrently, newly formed tissues are endowed with patterning information that coordinates their differentiation.(...

Contribuição ao estudo comparativo da genitália externa em sub-famílias de Reduviidae (Hemiptera-Heteroptera)

Five representatives of the Reduviid sub-families (Microtominae, Piratinae, Ectrichodiinae, Reduvinae and Triatominae), were studied with special reference to the morphology of the male and female genitalia. Drawings were made of the Terminalia from various angles (dorsal, ventral and lateral) to facilitate future studies on comparative morphology and to show the structural modifications present in the material studied. These detailed descriptions are based on the Terminology proposed by DUPUIS (1955). Selected references on previous morphological descriptions of genitalia are given as guide to future works on the group.Cinco representantes de sub-famílias de Reduviidae (Microtominae, Piratinae, Ectrichodiinae, Reduviinae e Triatominae), foram estudados abordando-se principalmente estruturas da genitália dos machos e das fêmeas sob variados ângulos, (dorsal, ventral e de perfil), com o intuito de propiciar condições a um trabalho de morfologia comparada e mostrar as modificações estruturais existentes. É feita uma descrição pormenorizada com indicações nas figuras, usando a terminologia proposta por DUPUIS (1955) e oferecida uma indicação de trabalhos selecionados sobre morfologia da genitália

Contribuição ao conhecimento da conquiliologia, anatomia, dados biológicos e aspectos comportamentais de Thaumastus (Thaumastus) Taunaisii (Ferussac, 1822) (Mollusca, Gastropoda, Bulimulidae)

Data about shell and body morphology, geographical, distribuition, biology and behavioral aspects of the terrestrial gastropod Thaumastus (T.) taunaisii (Férussac, 1822) are given. Characterization of the sub family Bulimulinae is made. It is conduded that shell and body morphology characterize the species, separating it from Thaumastus (T) achilles (Pfeiffer, 1852), and that the study o f its behavioral aspects contributes to the knowledge of its biology.São apresentados os resultados sobre a morfologia da concha e das partes moles, de distribuição geográfica, os dados biológicos e os aspectos comportamentais do gastropóde terrestre Thaumastus (T.) taunaisii (Férussac, 1822). E comentada a caracterização da subfamília Bulimulinae. Conclui-se que a morfologia da concha e das partes moles caracterizam a espécie separando-a de Thaumastus (T.) achilles (Pfeiffer, 1852) e que o estudo dos aspectos comportamentais fornecem subsídios para o conhecimento da biologia da espécie

<i>Schistosoma mansoni</i> cercariae experience influx of macromolecules during skin penetration

We have observed that when cercariae penetrate the skin of mice, there is influx into their tissues of Lucifer Yellow and certain labelled molecules of up to 20 kDa molecular weight. This observation was made using a variety of fluorescent membrane-impermeant compounds injected into the skin before the application of cercariae. This unexpected phenomenon was investigated further by transforming cercariae in vitro in the presence of the membrane-impermeant compounds and examining the distribution by microscopy. In schistosomula derived from this procedure, the nephridiopore and surface membrane were labelled while the pre- and post-acetabular glands were not labelled. The region associated with the oesophagus within the pharyngeal muscle clearly contained the fluorescent molecules, as did the region adjacent to the excretory tubules and the germinal mass. We used cercariae stained with carmine to aid identification of regions labelled with Lucifer Yellow. Although the mechanism of this influx is unclear, the observation is significant. From it, we can suggest an hypothesis that, during skin penetration, exposure of internal tissues of the parasite to external macromolecules represents a novel host-parasite interfac

Visões de ciências de jovens universitários: um estudo de caso sobre a influência dos nichos sociocultural e de pesquisa

Partindo-se de visões sobre ciência e sua filosofia no mundo moderno, este é um estudo de caso que reflete acerca das contribuições dos nichos de pesquisa na construção de uma natureza da ciência dos alunos de Ciências Biológicas Modalidade Médica, um curso de graduação, na Universidade Federal do Rio de Janeiro, que tem por objetivo formar pesquisadores. Foram entrevistados 117 alunos. A análise foi estruturada com base em um questionário fechado que continha questões como “O que é fazer ciência?”, “Como se dá o progresso da ciência?”, “Por que você escolheu esse curso?”. Os resultados mostram as visões de ciência desses alunos: romântica, técnica e social e como essas visões são construídas ao longo da graduação

A evolução da indústria petrolífera mundial e os impactos no comércio internacional de petróleo do século XXI após o início da exploração de fontes não convencionais pelos Estados Unidos

Observa o processo de desenvolvimento da indústria do petróleo ao redor do mundo até os dias atuais. Após essa análise, são introduzidos os determinantes do comércio internacional dessa commoditty, até chegar a seu objetivo final que é apresentar as interações entre os principais players do mercado internacional de petróleo durante o século XXI a partir da análise dos fluxos comerciais entre esses países anterior a exploração de fontes não convencionais dessa commodity e depois, as alterações, que o início da exploração dessas fontes ditas não convencionais, sobretudo por parte dos Estados Unidos, ocasionaram no comércio internacional desse produto

Sede de vida

Fotolivro que articula sentimentos próprios da modernidade, e principalmente do universo feminino, como autoconhecimento, solidão, insegurança e amor. Tudo isso decorre em forma poética, buscando a redenção do eulírico, que é apresentada tanto nas poesias contidas, quanto na coloração fotográfica

Compartment-dependent activities of Wnt3a/β-catenin signaling during vertebrate axial extension

Extension of the vertebrate body results from the concerted activity of many signals in the posterior embryonic end. Among them, Wnt3a has been shown to play relevant roles in the regulation of axial progenitor activity, mesoderm formation and somitogenesis. However, its impact on axial growth remains to be fully understood. Using a transgenic approach in the mouse, we found that the effect of Wnt3a signaling varies depending on the target tissue. High levels of Wnt3a in the epiblast prevented formation of neural tissues, but did not impair axial progenitors from producing different mesodermal lineages. These mesodermal tissues maintained a remarkable degree of organization, even within a severely malformed embryo. However, from the cells that failed to take a neural fate, only those that left the epithelial layer of the epiblast activated a mesodermal program. The remaining tissue accumulated as a folded epithelium that kept some epiblast-like characteristics. Together with previously published observations, our results suggest a dose-dependent role for Wnt3a in regulating the balance between renewal and selection of differentiation fates of axial progenitors in the epiblast. In the paraxial mesoderm, appropriate regulation of Wnt/β-catenin signaling was required not only for somitogenesis, but also for providing proper anterior-posterior polarity to the somites. Both processes seem to rely on mechanisms with different requirements for feedback modulation of Wnt/β-catenin signaling, once segmentation occurred in the presence of high levels of Wnt3a in the presomitic mesoderm, but not after permanent expression of a constitutively active form of β-catenin. Together, our findings suggest that Wnt3a/β-catenin signaling plays sequential roles during posterior extension, which are strongly dependent on the target tissue. This provides an additional example of how much the functional output of signaling systems depends on the competence of the responding cells.Fundação para a Ciência e a Tecnologia: (PTDC/BIA-BCM/110638/2009, PTDC/SAU-BID/110640/2009, SFRH/BD/33562/2008, SFRH/BD/51876/2012)

Estudo da genitália externa masculina de duas espécies de Opisthacidius Berg, 1879 (Hemiptera, Reduviidae, Reduviinae)

In order to stablish new taxonomic characters for the genus Opisthcidius a detailed comparative study of the male external genitalia was performed in O. rubropictus (H. Shaeffer, 1848), the type species, and O. pertinax (Breddin, 1903), mantioned as predators of triatomines. The most representative phallic structures were: the median process of pygophore, the phallosoma struts and the vesica process

Switching Axial Progenitors from Producing Trunk to Tail Tissues in Vertebrate Embryos

The vertebrate body is made by progressive addition of new tissue from progenitors at the posterior embryonic end. Axial extension involves different mechanisms that produce internal organs in the trunk but not in the tail. We show that Gdf11 signaling is a major coordinator of the trunk-to-tail transition. Without Gdf11 signaling, the switch from trunk to tail is significantly delayed, and its premature activation brings the hindlimbs and cloaca next to the forelimbs, leaving extremely short trunks. Gdf11 activity includes activation of Isl1 to promote formation of the hindlimbs and cloaca-associated mesoderm as the most posterior derivatives of lateral mesoderm progenitors. Gdf11 also coordinates reallocation of bipotent neuromesodermal progenitors from the anterior primitive streak to the tail bud, in part by reducing the retinoic acid available to the progenitors. Our findings provide a perspective to understand the evolution of the vertebrate body plan.Fundação para a Ciência e a Tecnologia grants: (PTDC/BIA-BCM/110638/2009, PTDC/SAU-BID/110640/2009); FCT PhD fellowships: (SFRH/BD/33562/2008, SFRH/BD/51876/2012, SFRH/BD/51879/2012)