O empreendedorismo. O perfil do empreendedor da Ilha de Santiago Cabo Verde

Este trabalho apresenta um estudo qualitativo, desenvolvido através de pesquisa exploratória, bibliográfica e de campo, feito a trezentos e noventa e nove empreendedores e empresários da Ilha de Santiago, tendo em consideração o cenário económico actual e a preocupação à volta do sector privado. Procurou-se através de pesquisa junto às empresas activas, e cujo número de pessoas ao seu serviço não ultrapassa vinte, identificar três pontos fundamentais relacionados com os empreendedores: investigar os factores que levaram as pessoas a tornarem-se empreendedores; investigar as características principais do empreendedor de sucesso; identificar as características imprescindíveis para se atingir o sucesso empresarial relacionadas com o conhecimento, competências, atitude e talento, sequenciadas por ordem de importância. Para um melhor entendimento destas questões foi utilizado um referencial teórico que aborda o empreendedorismo. A pesquisa de campo foi realizada através de utilização de questionários – entrevistas às empresas estabelecidas nesta ilha, e o método de recolha de dados foi o de entrevista directa. Os resultados obtidos mostraram que os empreendedores enfatizam a importância dos factores comportamentais no sucesso das pequenas e médias empresas e evidenciaram que os factores mais significativos e limitativos do sucesso dos empreendedores no Município da Praia, ilha de Santiago, se referem ao ambiente interno do negócio. Considerando todos estes factores e de acordo com as pesquisas desenvolvidas e analisadas, este trabalho recolheu informações específicas dos empreendedores de sucesso da ilha de Santiago e que podem ser úteis para os que almejam o sucesso empresarial e para eventuais programas de capacitação e formação empreendedora na ilha. This work presents a qualitative study developed through exploratory, bibliographic and field research to three hundred and ninety nine managers and entrepreneurs from Santiago Island, taking into consideration the present economical scenario and main concerns linked to private sector. Through a research in active enterprises and whose staff number doesn’t exceed twenty, the goal was to identify three main issues related to entrepreneurs: look into the factors that encouraged people to become entrepreneurs; examine the main characteristics of a successful entrepreneur and identify, sequenced by order of importance, the most critical characteristics related to knowledge, skills, attitude and talent, that allow entrepreneurial success achievement. For a better understanding of these questions, a theoretical approach to entrepreneurship was exploited. Field research was carried on through the use of questionnaires in enterprises located in Praia, and the data collection method was direct interviews. Results obtained showed that entrepreneurs emphasize the importance of behavioral factors in the success of small and medium enterprises and they evidenced that the most significant and restrictive factors of entrepreneurs’ success in Santiago Island are related to internal business environment. Considering these factors, and according to research developed and analyzed, the work has collected specific information of successful entrepreneurs in Santiago that can be useful for those, in the island, who seek entrepreneurial success and for eventual capacity building and entrepreneurial training programs.

O empreendedorismo. O perfil do empreendedor da Ilha de Santiago Cabo Verde

Este trabalho apresenta um estudo qualitativo, desenvolvido através de pesquisa exploratória, bibliográfica e de campo, feito a trezentos e noventa e nove empreendedores e empresários da Ilha de Santiago, tendo em consideração o cenário económico actual e a preocupação à volta do sector privado. Procurou-se através de pesquisa junto às empresas activas, e cujo número de pessoas ao seu serviço não ultrapassa vinte, identificar três pontos fundamentais relacionados com os empreendedores: investigar os factores que levaram as pessoas a tornarem-se empreendedores; investigar as características principais do empreendedor de sucesso; identificar as características imprescindíveis para se atingir o sucesso empresarial relacionadas com o conhecimento, competências, atitude e talento, sequenciadas por ordem de importância. Para um melhor entendimento destas questões foi utilizado um referencial teórico que aborda o empreendedorismo. A pesquisa de campo foi realizada através de utilização de questionários – entrevistas às empresas estabelecidas nesta ilha, e o método de recolha de dados foi o de entrevista directa. Os resultados obtidos mostraram que os empreendedores enfatizam a importância dos factores comportamentais no sucesso das pequenas e médias empresas e evidenciaram que os factores mais significativos e limitativos do sucesso dos empreendedores no Município da Praia, ilha de Santiago, se referem ao ambiente interno do negócio. Considerando todos estes factores e de acordo com as pesquisas desenvolvidas e analisadas, este trabalho recolheu informações específicas dos empreendedores de sucesso da ilha de Santiago e que podem ser úteis para os que almejam o sucesso empresarial e para eventuais programas de capacitação e formação empreendedora na ilha. This work presents a qualitative study developed through exploratory, bibliographic and field research to three hundred and ninety nine managers and entrepreneurs from Santiago Island, taking into consideration the present economical scenario and main concerns linked to private sector. Through a research in active enterprises and whose staff number doesn’t exceed twenty, the goal was to identify three main issues related to entrepreneurs: look into the factors that encouraged people to become entrepreneurs; examine the main characteristics of a successful entrepreneur and identify, sequenced by order of importance, the most critical characteristics related to knowledge, skills, attitude and talent, that allow entrepreneurial success achievement. For a better understanding of these questions, a theoretical approach to entrepreneurship was exploited. Field research was carried on through the use of questionnaires in enterprises located in Praia, and the data collection method was direct interviews. Results obtained showed that entrepreneurs emphasize the importance of behavioral factors in the success of small and medium enterprises and they evidenced that the most significant and restrictive factors of entrepreneurs’ success in Santiago Island are related to internal business environment. Considering these factors, and according to research developed and analyzed, the work has collected specific information of successful entrepreneurs in Santiago that can be useful for those, in the island, who seek entrepreneurial success and for eventual capacity building and entrepreneurial training programs.

A Importância do Empreendedorismo na Actividade Turística

Na actualidade, o empreendedorismo vem impulsionando o desenvolvimento de negócios em diferentes sectores com ênfase na qualidade dos serviços, tendo em vista não só a satisfação mas também a difícil tarefa de conquistar a lealdade dos clientes a médio e longo prazo. No mercado turístico, a satisfação do cliente é importante para que a actividade possa manter-se competitiva, uma vez que os clientes tornam-se mais exigentes à medida que vão-se tornando experientes. Neste contexto, o empreendedorismo aparece como forma de desenvolvimento do turismo, sendo que os resultados que se esperam das acções empreendedoras são a entrada em novos negócios, inovação, agregação de valor aos produtos/serviços e maior qualidade dos produtos/serviços. O objectivo central do trabalho é demonstrar a importância do empreendedorismo na actividade turística e como o mesmo contribui para agregação de valor e geração de resultados económicos. Para melhor compreensão do assunto da pesquisa, dividimos o enquadramento teórico em três momentos. No primeiro, abordamos o empreendedorismo, no segundo o turismo e, por fim, o empreendedorismo no turismo. O enquadramento teórico permitiu responder à questão: será que o empreendedorismo contribui para agregar valor e gerar resultados económicos na actividade turística? Os resultados do questionário aplicado aos proprietários das empresas turísticas evidenciaram que estes possuem características geralmente patentes nos empreendedores. No entanto, os resultados não são conclusivos quanto ao seu potencial empreendedor. In the present, time the entrepreneurship is driving the businesses development in different sector with emphasis on services quality in order not only satisfaction but also the difficult task of winning the costumers loyalty in the medium and long term. In the tourist market, the costumer’s satisfaction is important in order to remain the activity competitive, because the costumers become more demanding while they become experienced. In this context, the entrepreneurship shows up like a way to develop the tourism, because the expected results of entrepreneurial activities are entry in new businesses, innovation, the aggregation of value and more quality of the products/services. The central objective of this work is to demonstrate the importance of the entrepreneurship in to the tourism and how it contributes for adding value and generating economics results. To better understand the research’s subject, we divided the theoretical framework in three moments. At first one we approached entrepreneurship, then the tourism, and finally, we approached entrepreneurship in the tourism. The theoretical framework to allowed answer to the question: will the entrepreneurship contributes to add value and generate economics results in the tourism? The results of the questionnaire applied to the owners of tourists’ enterprises evidence that they possess the characteristics usually presented by the entrepreneurs. However, the results are not conclusive relatively to their potential entrepreneur.

Evolution of Y chromosomes : lessons from mammals and amphibians

RÉSUMÉ : Le sexe des individus peut être déterminé par l'environnement ou la génétique. Lorsque la détermination du sexe est génétique, il y a dans le génome, la présence de chromosomes spécifiques qui détermineront le sexe. Dans cette thèse, j'ai étudié l'évolution des chromosomes sexuels et dans quel contexte des marqueurs sur ces chromosomes peuvent être utilisés. Pour explorer la formation du chromosome Y, nous avons étudié les caractéristiques des chromosomes sexuels chez la rainette verte, Hyla arborea. Dans un premier temps, nous avons utilisé un marqueur situé sur les chromosomes sexuels X et Y chez plusieurs espèces appartenant au groupe de la rainette verte. Cela nous a permis de révéler chez toutes ces espèces une hétérogamétie mâle. Dans un deuxième temps, nous avons tiré profit de deux autres marqueurs situés sur les chromosomes sexuels pour montrer que la recombinaison est supprimée chez les mâles mais pas chez les femelles. Pour expliquer la réduction de la variabilité sur le chromosome Y, il n'est pas nécessaire d'invoquer le balayage sélectif ou la sélection d'arrière-plan : le nombre de copies plus petit du chromosome Y dans le génome et l'absence de recombinaison suffisent à l'expliquer. Nous avons également analysé plus en détail la suppression de la recombinaison chez les mâles de H. arborea. Les modèles classiques de l'évolution des chromosomes sexuels supposent que la taille de la région non-recombinante augmente progressivement pendant l'évolution du chromosome Y, due à l'accumulation de changements structuraux. Dans cette étude, nous montrons un modèle différent, à savoir que la recombinaison est supprimée ou diminuée non seulement sur les chromosomes sexuels mais aussi sur les autosomes chez les mâles, dû à l'action de modificateurs généraux. En utilisant des marqueurs localisés sur le chromosome Y, ainsi que sur l'ADN mitochondrial et le chromosome X, nous avons étudié l'histoire évolutive de la musaraigne musette, Crocidura russula. Cette étude illustre que les analyses génétiques avec plusieurs types de marqueurs génétiques peuvent faciliter l'interprétation de l'histoire évolutive des espèces, mais que l'utilisation des marqueurs sur les chromosomes X et Y pour des études phylogéographiques est limitée par le peu de polymorphisme observé sur ces deux types de marqueurs. Le même jeu de données combiné avec des simulations a été employé pour comprendre les facteurs responsables de la faible variabilité sur le chromosome Y qui peut être expliqué, dans notre étude, par la démographie et les traits d'histoire de vie de C. russula. SUMMARY The sex of an individual is determined either by its environment or its genetics. Genetic sex determination relies on the presence of specific chromosomes that will determine the sex of their bearer. In this thesis, I studied the evolution of the sex chromosomes and the context in which markers on this type of chromosomes can be used. To explore the evolution of a Y chromosome, we studied the nascent sex chromosomes in the European tree frog Hyla arborea. First; we amplified a sex specific marker in several related species of European tree frog and found a homogeneous pattern of male heterogamety. Secondly, we used two additional sex-specific markers to show that recombination is suppressed in males but not in females. There is, therefore, no need to invoke background selection or selective sweeps to explain the reduced genetic variability on the Y chromosome, because the lower number of copies of the Y chromosomes per breeding pair and the absence of recombination are sufficient. To further analyze the suppression of recombination in male European. tree frogs, we constructed a microsatellite linkage map for this species. Classical models of sex-chromosome evolution assume that the non-recombining region expands progressively during the long-term evolution of the Y chromosome, owing to the accumulation of structural changes. Here we show a strikingly different pattern: recombination is suppressed or depressed both on sex chromosomes and autosomes in the heterogametic sex, presumably due to the action of general modifiers. We investigated the evolutionary history of the greater white-toothed shrew, Crocidura russula, using markers on both sex chromosomes and mtDNA. This study illustrates that multilocus genetic analyses facilitates the interpretation of a species' evolutionary history. It also demonstrates that phylogeographic inferences from X and Y chromosomal markers are restricted by the low levels of observed polymorphism. Combining this genetic study with simulations, we determined that the demography and the life-history traits of this species can alone be responsible for the low Y diversity. In conclusion, this thesis shows that sex chromosomes, in combination with autosomes or mtDNA, are necessary to understand the evolution of sex chromosomes and to precisely infer the population history of a species.

Red tape and delayed entry

Does cutting red tape foster entrepreneurship in industries with the potential to expand? We address this question by combining the time needed to comply with government entry procedures in 45 countries with industry-level data on employment growth and growth in the number of establishments during the 1980s. Our main empirical finding is that countries where it takes less time to register new businesses have seen more entry in industries that experienced expansionary global demand and technology shifts. Our estimates take into account that proxying global industry shifts using data from only one country or group of countries with similar entry regulations will in general yield biased results.

Human capital and regional development

We investigate the determinants of regional development using a newly constructed database of 1569 sub-national regions from 110 countries covering 74 percent of the world s surface and 97 percent of its GDP. We combine the cross-regional analysis of geographic, institutional, cultural, and human capital determinants of regional development with an examination of productivity in several thousand establishments located in these regions. To organize the discussion, we present a new model of regional development that introduces into a standard migration framework elements of both the Lucas (1978) model of the allocation of talent between entrepreneurship and work, and the Lucas (1988) model of human capital externalities. The evidence points to the paramount importance of human capital in accounting for regional differences in development, but also suggests from model estimation and calibration that entrepreneurial inputs and possibly human capital externalities help understand the data.

Increased mobility of major histocompatibility complex I-peptide complexes decreases the sensitivity of antigen recognition.

CD8(+) cytotoxic T lymphocytes (CTL) can recognize and kill target cells expressing only a few cognate major histocompatibility complex (MHC) I-peptide complexes. This high sensitivity requires efficient scanning of a vast number of highly diverse MHC I-peptide complexes by the T cell receptor in the contact site of transient conjugates formed mainly by nonspecific interactions of ICAM-1 and LFA-1. Tracking of single H-2K(d) molecules loaded with fluorescent peptides on target cells and nascent conjugates with CTL showed dynamic transitions between states of free diffusion and immobility. The immobilizations were explained by association of MHC I-peptide complexes with ICAM-1 and strongly increased their local concentration in cell adhesion sites and hence their scanning by T cell receptor. In nascent immunological synapses cognate complexes became immobile, whereas noncognate ones diffused out again. Interfering with this mobility modulation-based concentration and sorting of MHC I-peptide complexes strongly impaired the sensitivity of antigen recognition by CTL, demonstrating that it constitutes a new basic aspect of antigen presentation by MHC I molecules.

Improving Transition Outcomes: CASE (Career And Self Exploration): Replication Template

Replication Template for Improving Transition Outcomes CASE (Career And Self Exploration) Prototype. This concise document explains how your team can implement CASE and the corresponding entrepreneurship component.

Lack of Smad3 signaling leads to impaired skeletal muscle regeneration.

Smad3 is a key intracellular signaling mediator for both transforming growth factor-β and myostatin, two major regulators of skeletal muscle growth. Previous published work has revealed pronounced muscle atrophy together with impaired satellite cell functionality in Smad3-null muscles. In the present study, we have further validated a role for Smad3 signaling in skeletal muscle regeneration. Here, we show that Smad3-null mice had incomplete recovery of muscle weight and myofiber size after muscle injury. Histological/immunohistochemical analysis suggested impaired inflammatory response and reduced number of activated myoblasts during the early stages of muscle regeneration in the tibialis anterior muscle of Smad3-null mice. Nascent myofibers formed after muscle injury were also reduced in number. Moreover, Smad3-null regenerated muscle had decreased oxidative enzyme activity and impaired mitochondrial biogenesis, evident by the downregulation of the gene encoding mitochondrial transcription factor A, a master regulator of mitochondrial biogenesis. Consistent with known Smad3 function, reduced fibrotic tissue formation was also seen in regenerated Smad3-null muscle. In conclusion, Smad3 deficiency leads to impaired muscle regeneration, which underscores an essential role of Smad3 in postnatal myogenesis. Given the negative role of myostatin during muscle regeneration, the increased expression of myostatin observed in Smad3-null muscle may contribute to the regeneration defects.

Entrepreneurial success and failure: Confidence and fallible judgement

Excess entry or the high failure rate of market-entry decisions is often attributed tooverconfidence exhibited by entreprene urs. We show analytically that whereas excess entryis an inevitable consequence of imperfect assessments of entrepreneurial skill, it does notimply overconfidence. Judgmental fallibility leads to excess entry even when everyone isunderconfident. Self-selection implies greater confidence (but not necessarilyoverconfidence) among those who start new businesses than those who do not and amongsuccessful entrants than failures. Our results question claims that entrepreneurs areoverconfident and emphasize the need to understand the role of judgmental fallibility inproducing economic outcomes.

Excess entry, ambiguity seeking and competence: An experimental investigation

Excess entry refers to the high failure rate of new entrepreneurial ventures. Economic explanations suggest 'hit and run' entrants and risk-seeking behavior. A psychological explanation is that people (entrepreneurs) are overconfident in their abilities (Camerer & Lovallo, 1999). Characterizing entry decisions as ambiguous gambles, we alternatively suggest following Heath and Tversky (1991) that people seek ambiguity when the source of uncertainty is related to their competence. Overconfidence, as such, plays no role. This hypothesis is confirmed in an experimental study that also documents the phenomenon of reference group neglect. Finally, we emphasize the utility that people gain from engaging in activities that contribute to a sense of competence. This is an important force in economic activity that deserves more explicit attention.

Managing Social-Business Tensions: A Review and Research Agenda for Social Enterprise

In a world filled with poverty, environmental degradation, and moral injustice, social enterprises offer a ray of hope. These organizations seek to achieve social missions through business ventures. Yet social missions and business ventures are associated with divergent goals, values, norms, and identities. Attending to them simultaneously creates tensions, competing demands, and ethical dilemmas. Effectively understanding social enterprises therefore depends on insight into the nature and management of these tensions. While existing research recognizes tensions between social missions and business ventures, we lack any systematic analysis. Our paper addresses this issue. We first categorize the types of tensions that arise between social missions and business ventures, emphasizing their prevalence and variety. We then explore how four different organizational theories offer insight into these tensions, and we develop an agenda for future research. We end by arguing that a focus on social-business tensions not only expands insight into social enterprises, but also provides an opportunity for research on social enterprises to inform traditional organizational theories. Taken together, our analysis of tensions in social enterprises integrates and seeks to energize research on this expanding phenomenon.

As comunidades imigrantes em Cabo Verde: os chineses em São Vicente e a sua participação no desenvolvimento do comércio

Esta investigação insere-se na temática do Empreendedorismo Imigrante e do Comércio Étnico. Trata-se de uma pesquisa que se debruça sobre a imigração para Cabo Verde, com destaque para a análise da imigração chinesa, sobretudo dedicada ao comércio na ilha de São Vicente. O objectivo geral deste trabalho prende-se com a identificação do contributo da comunidade imigrante supracitada no processo de desenvolvimento de São Vicente, através da instalação e da prática de actividades comerciais. Para concretização deste objectivo foi desenvolvido, durante 5 meses, um trabalho de terreno em Cabo Verde (Santiago e São Vicente). O trabalho empírico socorreu-se de entrevistas formais à presidente da Câmara Municipal de São Vicente e a personalidades da Embaixada de China em Cabo Verde , e informais efectuadas aos comerciantes chineses e seus funcionários, bem como aos comerciantes locais. Foram ainda aplicados inquéritos a todos os comerciantes chineses na ilha de São Vicente, processo que permitiu obter a informação necessária para a caracterização da comunidade chinesa e das actividades comerciais por ela aqui desenvolvidas. Os resultados destes questionários foram armazenados numa base de dados informática, com recurso ao SPSS- Statistical Package for Social Sciences, também utilizado como instrumento de tratamento da informação, assim como a folha de cálculo Excel. Dos resultados da nossa investigação, ressalta que o comércio chinês tem dinamizado muito o tecido comercial sãovicentino, contribuindo para a criação de novos postos de trabalho, diversificando as ofertas e estabilizando ou levando mesmo à redução do preço dos produtos, o que vem generalizar as possibilidades de consumo a segmentos da população menos solventes, que até então tinham muita dificuldade em comprar bens como brinquedos ou certos artigos para o lar. De realçar também que, entre o comércio chinês e o comércio local, existe para além da concorrência como é óbvio, uma certa complementaridade. Esta relação recíproca é estabelecida através de aquisição e revenda de produtos diversificados adquiridos aos comerciantes locas, permitindo assim oferecer assim mais produtos e de melhor qualidade aos seus clientes. Todavia, conclui-se que o comércio chinês, com todas as implicações que trás, ainda não constitui um vector central do desenvolvimento da ilha, designadamente se entendermos o desenvolvimento numa perspectiva abrangente e integral, que incorpora dimensões culturais, sociais e ecológicas que ultrapassam a esfera económica. Contudo, pode-se dizer que a presença do comércio chinês na ilha tem sido bastante positiva, uma vez que coloca no mercado uma diversidade de produtos a preços razoavelmente acessíveis, contribuindo para melhorar a qualidade de vida dos São Vicentinos.

Poor, hungry and ignorant: Numeracy and the impact of high food prices in industrializing Britain, 1780-1850

This paper uses the ability to recall one s age correctly as an indicator of numeracy.We show that low levels of nutrition impaired numeracy in industrializing England, 1780-1850.Numeracy declined markedly among those born during the war years, especially where wheatwas dear. England s nascent welfare state mitigated the negative effect of high food prices oncognitive skills. Nutrition during early development mattered for labor market outcomes:individuals born in periods or countries with high age heaping were more likely to sort intooccupations with limited intellectual requirements.

Functional analysis of human POT1 and RPA : insights into the role of single stranded DNA binding proteins at telomeres

Abstract Telomeres, the natural ends of chromosomes, need to be protected from chromosome end fusions, aberrant homologous recombination and degradation. In humans, chromosome ends are specified through arrays of tandemly repeated 5'-TTAGGG-3' hexamers, ending in a 3' overhang. A complex formed by the six proteins TRF1, TRF2, hRap1, TIN2, TPP1 and POT1 specifically assocìates with and protects telomeres. Telomeres are maintained by semiconservative DNA replication and by a specialized reverse transcriptase, telomerase, that carries an RNA subunit which templates new telomeric repeat synthesis. The telomeric single stranded (ss) DNA binding protein POT1 protects the telomeric 3' overhang and modulates telomerase-mediated telomere elongation. It is possible that POT1 also influences DNA synthesis during semiconservative DNA replication, which is initiated by the DNA polymerase alpha-primase complex. The heterotrimeric ss DNA-binding protein RPA plays essential roles during DNA replication. RPA binds to ss DNA with high affinity in order to stabilize ss DNA and facilitate nascent strand synthesis at the replication fork. Here we investigate how the two proteins RPA and POT1 contribute to telomere maintenance by regulating semi-conservative DNA replication and telomerase. Using chromatin immunoprecipitation experiments, we show that RPA associates with telomeres during S-phase. Analysis of telomere structure in cells shRNA-depleted for RPA and POT1 reveals that loss of RPA and POT1 causes exposure of single-stranded DNA at telomeres, suggestive of incomplete DNA replication. Biochemical experiments using purified recombinant POT1 and RPA show that saturating telomeric oligonucleotides with POT1 or RPA reduces the primase activity of the DNA polymerase alpha-primase complex and the overall activity of telomerase. POT1 and RPA also increase the primer extension by DNA polymerase alpha-primase complex and the processivity of telomerase under certain conditions, although POT1 increases the activities to a greater extent than RPA. We propose that POT1 is required for proper replication of the lagging strand of telomeres and that some phenotypes observed in POT1-depleted cells may stern from incomplete DNA replication rather than de-protection of the single-stranded overhang. Résumé Les télomères, les extrémités normales des chromosomes linéaires, doivent être protégés des fusions chromosomiques, d'événements de recombinaison homologue aberrants et de phénomènes de dégradation. Chez l'Homme, les extrémités des chromosomes sont constitués d'ADN double brin répétitif de séquence 5'-TTAGGG-3', d'une extension simple brin 3' sortante et d'un complexe protéique formé des six facteurs TRF1, TRF2, hRap1, TIN2, TPP1 et POT1 qui, s'associant à cette séquence, protègent l'ADN télomèrique. Les télomères sont maintenus par la télomérase, une transcriptase inverse capable d'allonger l'extension 3' sortante télomérique. POT1 lie l'ADN simple brin télomérique et module l'élongation des télomères par la télomérase. POT1 pourrait en théorie également influencer la réplication semi-conservative de l'ADN. L'ADN-polymérase Pal alpha-primase amorce et initie la synthèse d'ADN. Pendant la réplication, l'ADN simple brin est stabilisé par RPA, un complexe hétérotrimèrique qui lie l'ADN simple brin. RPA facilite la synthèse du brin naissant à la fourche de réplication. Ici nous avons étudié comment ces deux protéines qui lient l'ADN simple brin, RPA et POT1, régulent la réplication des télomères par la télomérase et la machinerie classique de réplication de l'ADN. Par immunoprécipitation de chromatine (ChIP), nous montrons que RPA est localisé aux télomères lors de la phase S du cycle cellulaire. De plus, l'analyse de la structure des télomeres indique que !a perte de RPA ou de POT1 conduit à l'apparition d'ADN simple brin télomérique, suggérant une réplication incomplète de l'ADN télomérique in vivo. Par une approche complémentaire biochimique utilisant les protéines POT1 et RPA recombinantes purifiées, nous montrons également que la liaison de POT1 ou de RPA à des oligonucléotides télomériques bloque l'activité primase du complexe polymérase alpha/primase et réduit l'activité télomérase sur ces substrats. En revanche, leur liaison augmente l'activité ADN-polymérase du complexe polymérase alpha/primase, ainsi que fa processivité de la télomérase dans certaines conditions, POT1 étant le plus efficace des deux facteurs. Nous proposons que POT1 est nécessaire à la réplication du brin retardé au niveau des télomères, ce qui suggère que certains phénotypes des cellules déplétés en POT1 puissent résulter d'une réplication incomplète de l'ADN télémétrique plutôt que d'une déprotection de l'extrémité sortante des télomères.