Submitted by Marta Toyoda (1144061@mackenzie.br) on 2017-01-17T16:35:22Z No. of bitstreams: 2 Cícera Rosa Segredo Yamamoto.pdf: 1238755 bytes, checksum: 6b4136cbb81cad58ebe0909372716319 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Aline Amarante (1146629@mackenzie.br) on 2017-02-07T21:06:55Z (GMT) No. of bitstreams: 2 Cícera Rosa Segredo Yamamoto.pdf: 1238755 bytes, checksum: 6b4136cbb81cad58ebe0909372716319 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-02-07T21:06:55Z (GMT). No. of bitstreams: 2 Cícera Rosa Segredo Yamamoto.pdf: 1238755 bytes, checksum: 6b4136cbb81cad58ebe0909372716319 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-03-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Manoel de Barros is a poet and as defines itself, "word of poet", whose poems are closely related to the Pantanal (South) of Mato Grosso, putting on display the close relationship between the work and the context. We search to answer along the thesis, three questions: if the "poetic inspiration" by Manoel de Barros transcends his personal experience in his books, or the place and time where pronounced are so present in the works that ultimately enroll them autobiography traces; if the traits that make up the poetic writer can do (or not) identify in their works a poet "local" or a universalizing poetic; such as (South) Mato Grosso writer, chronologically enrolled in the "45 generation" articulates tradition and innovation in his poetic construction. Confirming or deconstructing "truths" published on the poetics of the author and searching new constructs and aesthetic effects that literary production, we have the following objectives: identify regularities and dispersions in the form and content of the poems; discuss the relationship between local and universal, between tradition and modernity, between memory and invention and among selves / others who live in the works; search identifying traits of poetic writer. To this end, we elected as corpus of research two works of Manoel de Barros: Poemas concebidos sem pecados (1937), the first book of the writer, and Memórias inventadas: A terceira infância (2008), searching to bridge the gap between the first and one of the last books the poet. Compliance with the proposed objectives requires, however, in addition to "face" the work, to provide himself with a theoretical foundation. Thus, we use of Candido (2000) to treat the issue of the location of the dialectic and universal literary decolonization, as well as the relationship of author-work-public. To clarify concepts or principles "technical" essential to the analysis, such as "tradition," "influence" and "intertextuality", we called to Nitrini (2000), to whom we add Bakhtin (2011), mainly to treat style, aesthetics and exotopy, and Paz (1972; 1991). For understanding the concept of identity, the support came from Hall (2011) and other invited authors to the reflections on identity and memory, as Gusdorf (1951, 1990, 1991), Bergson (2006), Halbwachs (2003), Ricoeur (2007) and Candau (2014). In addition to these authors, some others will emerge in due course, because indispensable to poetry reading Manoel de Barros. We found that Barros excluded from his poetry any purpose of describing landscapes or historicizing costumes, putting on display the dialogue, rapprochement and the gap between the selves, times and spaces. Barros attributed his lyricism to "a desert in the eye" and to express it, took a seemingly autobiographical format, just like the invention feature because sang "what was not," but what had missing "for not having been "revealing us exotopy spoken by Bakhtin (2011). From our reading, the memory was not as "representation" but as "eye divination" in tone and unmistakable verses of Manoel de Barros. / Manoel de Barros é poeta e, como se autodefine, “poeta da palavra”, cujos poemas guardam íntima relação com o Pantanal (sul-)mato-grossense, pondo à mostra a estreita relação entre a obra e o contexto. Procuramos responder, ao longo da tese, a três questões: se a “inspiração poética” de Manoel de Barros transcende sua experiência pessoal nos seus livros, ou se o lugar e o tempo de onde se pronuncia são tão presentes nas obras que acabam por inscrever nelas traços de autobiografia; se os traços que constituem o fazer poético do escritor podem (ou não) identificar em suas obras um poeta “do local”, ou uma poética universalizante; como o escritor mato-grossense, cronologicamente inscrito na “geração de 45”, articula tradição e inovação em sua construção poética. Ratificando ou desconstruindo “verdades” publicadas sobre a poética do autor e buscando novos construtos e efeitos estéticos nessa produção literária, temos como objetivos específicos: identificar regularidades e dispersões na forma e conteúdo dos poemas; discutir a relação entre local e universal, entre tradição e modernidade, entre memória e invenção e entre os eus/outros que convivem nas obras; buscar traços identificadores da poética do escritor. Para tanto, elegemos como corpus da pesquisa duas obras de Manoel de Barros: Poemas concebidos sem pecado (1937), primeiro livro do escritor, e Memórias inventadas: terceira infância (2008), procurando fazer uma ponte entre o primeiro e um dos últimos livros do poeta. O cumprimento dos objetivos propostos requer, no entanto, além de “enfrentar” a obra, munir-se de uma fundamentação teórica. Assim, valemonos de Candido (2000) para tratar da questão da dialética do local e do universal na descolonização literária, bem como da relação autor-obra-público. Para esclarecer conceitos ou princípios “técnicos” essenciais à análise, como tradição, influência e intertextualidade, recorremos a Nitrini (2000), a quem agregamos Bakhtin (2011), sobretudo para tratarmos de estilo, estética e exotopia, e Paz (1972; 1991). Para a compreensão do conceito de identidade, o apoio veio de Hall (2011) e de outros autores convocados para as reflexões sobre identidade e memória, como Gusdorf (1951, 1990, 1991), Bergson (2006), Halbwachs (2003), Ricoeur (2007) e Candau (2014). A esses autores de referência, alguns outros emergem oportunamente, porque indispensáveis à leitura da poesia de Manoel de Barros. Verificamos que Barros excluía de sua poesia qualquer propósito de descrever paisagens ou historiar costumes, pondo à mostra o diálogo, a aproximação e o distanciamento entre os eus, os tempos e os espaços. Barros atribuía seu lirismo a “um ermo dentro do olho” e, para expressálo, adotou um formato aparentemente autobiográfico, apenas como recurso de invenção, pois cantou “o que não fora”, mas do que tinha saudade “por não ter sido”, revelando-nos a exotopia de que fala Bakhtin (2011). De nossa leitura, ficou a memória não como representação, mas como "olho divinatório", em tom e versos inconfundíveis de Manoel de Barros.

The research presented in this thesis focuses on the study of the reaction between boronic acids and diols and its evaluation as a possible "click" reaction, possibly applicable in bioconjugation and drug delivery. A key feature of this reaction is its reversibility at acidic pH, which could allow the release of a diol-containing drug from a bioconjugate in the acidic environment of late endosome/lysosome, possibly after undergoing receptor mediated endocytosis. Over the last two decades various studies have focused on the study of the conjugation of boronic acids to diols using Alizarin Red S as a fluorescence reporter. In this research we have presented an alternative method based on the batochromic shifts of Alizarin Red S absorbance; this method is particularly advantageous in complex systems with an elevated scattering, such as colloidal dispersions or for binding to complexed active compounds. We have therefore demonstrated that this method allows the determination of equilibrium constants between diols (e.g. catecholamines) and boronic acids. We have also demonstrated that the method allows to follow the kinetics of enzymatic reactions involving catechols; in particular, we have focused on cytochrome P450-mediated reactions such as the conversion of estradiol to 2-hydroxyestradiol using CYP1A2, or the demethylation of 3-methoxytyramine to dopamine using CYP2D6. Once we have established a reliable method for following this reaction on low molecular weight compounds, we have applied it to polymeric bioconjugates. Specifically, we have selected hyaluronic acid (HA) as a biocompatible and biodegradable polymeric backbone and produced derivatives containing boronic acids, catechols and dimethylated catechols (as negative controls). The resulting polymers where characterised via UV-Vis, 1H NMR and SLS, also qualitatively evaluating their cytotoxicity and enzymatic degradability. The conjugates with boronic acids showed the lowest cytotoxicity, and the highest degradability. The complexation of HA-boronic derivatives was then studied; using the same library of diols previously used with low molecular weight compounds, evaluating the effect of the presence of the polysaccharidic macromolecular chain.

Since the dawn of the nuclear age, radioactive technetium (Tc)-99 has been released into the environment from nuclear weapons testing, spent fuel reprocessing facilities, and other nuclear activities. Quantifying the measurement, effect, and risk of trace concentrations of Tc-99 is paramount to understanding the isotope’s behaviour in human-environment systems. Ground state Tc-99 decays by beta emission (Emax — 292 keV) with a half-life (t1/2= 2.11 x 105 y), while the metastable isomer Tc-99m (t1/2 = 6.0 h) decays rapidly by emitting a gamma photon. Technetium-99 is present in the environment in mobile pertechnetate (TcO4−) form. Tc-99 is used as an oceanographic tracer to investigate seawater movement and coastal pollution using seaweed as a bioindicator. The purpose of this study is to develop a sample preparation method to measure low concentrations, down to femtogram levels, of Tc-99 in environmental samples such as seaweed, water and medical Tc-99m waste using an accelerator mass spectrometer (AMS). When present in its soluble form, Tc (VII)can be reduced to Tc (IV) in the presence of a strong reducing agent such as SnCl2, then precipitated out of solution as an iron hydroxide by the addition of an iron carrier. Using AMS to measure precipitates prepared through a simple one-step co-precipitation method show high levels of isobaric interferences by Ruthenium-99 (Ru-99) and impurities by the co-precipitation of other hydroxides. A double-step co-precipitation method was determined to be efficient at reducing interferences of impurities present in the final precipitate. Using Tc-99m as a chemical tracer, the efficiencies of different oxidizing- reducing agents were compared to optimize the yield of Tc-99. The aims and objectives of the study are first: to develop a method for the separation and purification of Tc-99 from Ru-99 by ARS-II with ABEC column. Second: to develop methods for the removal of interferences and extraction of Tc-99 from iii environmental small size samples, and third: to develop a method to analyze Tc-99 by low energy AMS. Concentrations of Tc-99 were measured in seaweed samples with a newly developed oxidation-reduction method using Tc-99m as a yield tracer. The detection of Tc-99 from seaweed samples follows a two-step procedure. The first step is the oxidation of technetium from Tc (IV) to Tc (VII) oxidation state with H2O2 followed by iron hydroxide precipitation. The second step is the reduction of Technetium from Tc (VII) to the Tc (IV) oxidation state with SnCl2 followed by iron hydroxide co-precipitate. The co-precipitate contains the Tc (IV) and is dried at 80oC and then at 200oC to remove excess water, then mixed with PbF2 to produce TcF5– in the AMS ion source. The purification and separation of Ru-99 from Tc-99 is done by ARS-II with ABEC column and measure by AMS. Currently, the most sensitive practical choice for Tc-99 is ICP-MS, with typical LOD at picogram (pg.) levels. This translates to 10-100s of litres required for a seawater sample. AMS has shown potential <10 fg LOD, which translates to volume requirement of sub-litre to litres for seawater samples, this would make the AMS quantification of Tc-99 an incredibly useful and competitive alternative.

Our work is closely connected with the problem of splitting of separatrices (breaking of homoclinic orbits) in a singularly perturbed model describing gravity water waves on a surface of finite depth. The singularly perturbed model is a family of singularly perturbed fourth-order nonlinear ordinary differential equations, parametrized by an external parameter (in addition to the small parameter of the perturbations). It is known that in general separatrices will not survive a singular perturbation. However, it was proven by Tovbis and Pelinovsky that there is a discrete set of exceptional values of the external parameter for which separatrices do survive the perturbation. Since our family of equations can be written in the Hamiltonian form, the question is whether or not survival of separatrices implies integrability of the corresponding equation. The complete integrability of the system is examined from two viewpoints: 1) the existence of a second first integral in involution (Liouville integrability), and 2) the existence of single-valued, meromorphic solutions (complex analytic integrability). In the latter case, a singular point analysis is done using the technique given by Ablowitz, Ramani, and Segur (the ARS algorithm) to determine whether the system is of Painlevé-type (P-type), lacking movable critical points. The system is shown by the algorithm to fail to be of P-type, a strong indication of nonintegrability.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2019-02-28T12:55:45Z No. of bitstreams: 1 Osni Packer_.pdf: 1793483 bytes, checksum: 5cc829d986439756b57cd5aa164fff68 (MD5) / Made available in DSpace on 2019-02-28T12:55:45Z (GMT). No. of bitstreams: 1 Osni Packer_.pdf: 1793483 bytes, checksum: 5cc829d986439756b57cd5aa164fff68 (MD5) Previous issue date: 2018-10-31 / UNIDAVI- Centro Universitário para o Desenvolvimento do Alto Vale do Itajaí / O Governo do Estado de Santa Catarina implementou uma reforma administrativa, estabelecendo a descentralização da estrutura de governo, com a criação das Agências de Desenvolvimento Regional (ADRs), cujo objetivo é possibilitar a execução de diversos projetos e ações na sua região de inserção. O objetivo deste estudo foi analisar o funcionamento de uma ADR, a partir dos fluxos de comunicação, interação estratégica, autorizações e/ou aprovações técnicas de projetos, e das posições de poder e influência de seus atores. Para estudar essa nova realidade, selecionou-se a 12.ª ADR de Rio do Sul. Para isso escolheram-se a metodologia de análise de redes sociais (ARS) e a abordagem quantitativa. Mensuraram-se diversas propriedades estruturais em nível de rede e de ator, elaborando-se sociogramas para cada uma das relações estabelecidas. Concluiu-se que a rede se apresenta com uma densidade baixa e pouco coesa. É bastante concentrada em determinados atores identificados com o poder e a influência; e há muitos atores periféricos. A baixa conexão entre os atores resulta em uma quantidade também baixa de poder na rede. Os atores que concentraram maior poder e influência foram o Secretário Executivo Regional, seguidos do Gerente de Administração, Finanças e Contabilidade, o Gerente de Educação e o Consultor Jurídico nas trocas de informações quanto na busca por interação, e nas autorizações e/ou aprovações de projetos aparecem o Secretário Executivo Regional, o Consultor Jurídico e o Controle Interno. Comparada à concepção da ADR, constatou-se que o funcionamento da Agência, na prática, possui fragilidades e, por ser uma rede esparsa, cujo funcionamento se concentra em poucos atores, e os atores periféricos não contribuírem relevantemente para seu desempenho, apresenta dificuldades principalmente na operacionalização dos projetos. Sugere-se reestruturação que congregue os atores periféricos em todos os fluxos ou uma estrutura com menor número de atores para maior agilidade. Este estudo proporciona parâmetros para gestores públicos analisarem as administrações voltadas para uma nova estrutura e para a governança. Para a academia, o estudo contribuiu para o crescimento do conhecimento sobre o campo estudado, a partir da perspectiva das redes sociais. / The Government of the State of Santa Catarina implemented an administrative reform, establishing the decentralization of the government structure, with the creation of Regional Development Agencies (ADRs), whose objective is to enable the execution of several projects and actions in its region of insertion. The purpose of this study was to analyze the functioning of an ADR, based on communication flows, strategic interaction, technical approvals and / or approvals of projects, and the positions of power and influence of its actors. In order to study this new reality, the 12th ADR of Rio do Sul was selected. The methodology of social network analysis (ARS) and the quantitative approach were chosen. Several structural properties were measured at network and actor level, and sociograms were elaborated for each of the relationships established. It was concluded that the network presents a low density and little cohesion. It is rather concentrated on certain actors identified with power and influence; and there are many peripheral actors. The low connection between the actors results in a very low amount of power in the network. The actors who concentrated the greatest power and influence were the Regional Executive Secretary, followed by the Administration, Finance and Accounting Manager, the Education Manager and the Legal Adviser in the exchange of information as to the search for interaction, and in the authorizations and / or approvals of projects include the Regional Executive Secretary, the Legal Adviser and the Internal Control. Compared with the concept of ADR, it has been found that the functioning of the Agency in practice is fragile and, because it is a sparse network whose operation is concentrated in few actors, and the peripheral actors do not contribute significantly to its performance, presents difficulties mainly in the operationalization of the projects. It is suggested a restructuring that brings together the peripheral actors in all the flows or a structure with smaller number of actors for greater agility. This study provides parameters for public managers to analyze administrations focused on a new structure and governance. For the academy, the study contributed to the growth of knowledge about the field studied, from the perspective of social networks.

Made available in DSpace on 2015-05-14T12:40:01Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1053252 bytes, checksum: a973be809a979b5319cfa651d5150b33 (MD5) Previous issue date: 2009-08-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Ce travail étudie les lettres de Machado de Assis, en les vérifiant par les contraintes rhétoriques de l´ars dictaminis, en démontrant leurs thématiques les plus expressives. L´importance de cet étude c´est due, surtout, à deux grandes raisons: 1) les lettres sont analisées tandis que appartenantes à une tradition épistolaire, avec les prescriptions qui leurs sont inhérentes, et pas seulement comme des écrits qui fournissent des donnés tantôt subjectifs tantôt objectifs à propos de la biographie de l´auteur; 2) Machado de Assis est étudié à partir d´un aspect pas connu ou peu valorisé par la critique et par l´historiographie littéraire brésilienne. Après analiser la place de la lettre dans le scénario de la littérature au Brésil et de sillonner ce qui a été déjà dit ou ce qui a été laissé d´être dit critiquement par rapport à l´écriture épistolaire Machadienne, le présent travail démontre quelques absences thématiques et leurs possibles raisons, au même temps qui souligne le caractère rhétorique de la persona epistolar, et qui remarque les sujets les plus récurrents de ces textes. Il émerge des lettres un eu-missivista gêné par la vieillesse et par les maladies, en se rapportant pas rarement à la solitude et à l´imminence de la mort, en marmottant de l´excès de travail, au même temps que les lettres figurent l´image de l´auteur comme un homme discret, sérieux, travailleur, amant des lettres, chargé de conduire la crítica-amiga d´un groupe de compères écrivains. À la fin, la recherche présente les références metalinguistiques remarquées dans le discours épistolaire de Machado, lesquelles suggèrent des pratiques et des significations de l´écriture des lettres particulières de l´époque de l´auteur. / Este trabalho estuda as cartas de Machado de Assis, enfocando-as pelo viés da retórica da ars dictaminis, bem como levantando as temáticas mais expressivas das epístolas. O estudo mostra-se relevante, entre outros aspectos, devido a dois grandes motivos: 1º) as cartas são analisadas enquanto pertencentes a uma tradição epistolar, com prescrições que lhe são inerentes, e não apenas como escritos que fornecem dados subjetivos ou objetivos à biografia do autor; 2º) Machado de Assis é estudado sob um ângulo desconhecido ou pouco valorizado pela crítica e pela historiografia literária brasileira. Após analisar o lugar da carta no cenário da literatura no Brasil e fazer um mapeamento do que já foi dito ou deixou de ser dito criticamente sobre a epistolografia machadiana, o presente trabalho mostra algumas ausências temáticas, com seus supostos motivos, o caráter retórico da persona epistolar, bem como os assuntos mais recorrentes dos textos. Emerge das cartas um eu-missivista incomodado com a velhice e as enfermidades, referindo-se não raramente à solidão e à iminência da morte, resmungando do excesso de trabalho, ao mesmo tempo em que as cartas constroem uma imagem do autor como um homem discreto, sério, trabalhador, amante das letras, liderando a crítica-amiga de uma roda de compadres literatos. Por fim, apresentam-se referências metalinguísticas contidas no discurso epistolar de Machado, que sugerem práticas e significados da escrita de cartas na época do escritor.

Orientador: Carlos Eduardo Ornelas Berriel / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Estudos da Linguagem / Made available in DSpace on 2018-08-15T23:39:17Z (GMT). No. of bitstreams: 1 MoraesJunior_HelvioGomes_D.pdf: 21905328 bytes, checksum: 58b7b44cf41f7b4ea55f583df1f1ec9b (MD5) Previous issue date: 2010 / Resumo: Esta tese apresenta a tradução comentada dos Dez Diálogos da História de Francesco Patrizi da Cherso, uma ars histórica publicada em Veneza em 1560. Tal tradução e acompanhada de um estudo que busca colocar em evidencia aqueles que, para nos, são os aspectos mais relevantes deste texto: a revisão critica das principais idéias humanistas sobre a historia, essencialmente embasadas nos postulados de auctoritates como Cícero e Luciano, e a proposta de uma nova concepção historiográfica, de forte inspiração neoplatônica, que prescreve a união entre conhecimento histórico e filosófico como instrumentos úteis para a finalidade ultima da comunidade política, a felicidade civil. Também são trazidas para a cena dialógica as contribuições do pensamento político florentino da primeira metade do Cinquecento, que se aliam a defesa da tradição política veneziana (plasmada sobre um pano de fundo utópico), promovendo uma espécie de fusão que dara a esta ars histórica um perfil único entre os vários escritos que compõem o gênero. / Abstract: This thesis presents the Portuguese commented translation of Francesco Patrizi's Della historia diece dialoghi, an ars historica published in Venice in 1560. It is complemented by a study which is aimed at emphasizing the most relevant aspects of this text: a critical review of the main humanistic ideas on history, essentially founded on the statements pronounced by auctoritates like Cicero and Lucian, and the proposal of a union of historical and philosophical knowledge as useful means to the ultimate end of the political community, the civil happiness. The dialogical scene also brings the contributions from the Florentine political thought of the first half of the Cinquecento, sided with the defense of Venetian political tradition (formulated in a utopian background), and the result is a kind of fusion that gives this ars historica a unique profile among the many works which belong to this literary genre. / Doutorado / Historia e Historiografia Literaria / Mestre em Teoria e História Literária

Univ., Diss.--Wien, 2003.

In der eukaryotischen Ontogenese ist die Etablierung differenzierungsspezifischer Genexpression eng an die Unterteilung des Genoms in funktionell getrennte Domänen gekoppelt. Solche Domänen lassen entweder erhöhte transkriptionelle Aktivität zu oder unterdrücken sie und werden Eu- bzw. Heterochromatin genannt. Heterochromatin enthält spezielle Proteine, die zur Ausbildung dieser repressiven Chromatinstruktur beitragen. Eine der Hauptfragen in der Heterochromatinbiologie ist, wie solche Proteine rekrutiert werden. Dieser Prozess ist entscheidend damit einzelnde Regionen im Genom koordiniert zeit- und ortsabhängig reprimiert werden können. In Saccharomyces cerevisiae entsteht Hetero-chromatin an den silent-mating-type Loci HMRa und HMLalpha durch die zielgerichtete Rekrutierung des Sir-Komplexes über eine Gruppe von Proteinen, die an sogenannte silencer-DNA Sequenzen binden. In diese Arbeit wird gezeigt, daß das Protein Sum1, bisher bekannt als Repressor meiotischer Gene im vegetativen Zellzyklus, als Heterochromatin-Rekrutierungsfaktor für HMLalpha fungiert. Sum1 konnte in vitro und in vivo an HMLalpha über ein funktionelles Element innerhalb des HML-E silencers binden und die Deletion von SUM1 verursachte einen Verlust von Repression an HMLalpha. SUM1 beeinflußte außerdem die Fähigkeit von HML-E als Replikationsstartpunkt (origin) zu agieren, was eine Rolle von Sum1 in der Replikation nahelegt. Die Beobachtung, daß orc2-1 und orc5-1 mit sum1Delta synthetisch lethal waren und daß cdc6-1, cdc7-1 oder cdc45-1 mit sum1Delta einen synthetischen Wachstumsdefekt aufwiesen unterstützt die Vermutung, daß SUM1 eine globale Rolle in der Replikationsinitiation besitzt. In einer genomweiten Suche wurden ARS Elemente gefunden, die sowohl Sum1 als auch ORC rekrutieren. Dabei konnte gezeigt werden, daß die Replikationsaktivität dieser ARS Elemente von Sum1 bzw. Sum1 Bindungsstellen abhängig war. Als Repressor von meiosespezifischen Genen interagiert Sum1 oft mit der Histondeacetylase Hst1. In diesem Zusammenhang konnte gezeigt werden, daß SUM1-regulierte origins ebenfalls HST1 zur vollen Aktivität benötigten. Zusammenfassend schlagen wir Sum1 als neuartigen Modulator für die Replikationsinitiation an einer Untergruppe chromosomaler Replikationsstartpunkte vor. / The division of eukaryotic chromatin into functionally distinct domains is critical to implement gene expression programs that drive the development of multicellular organisms. Regions termed euchromatin exist in the genome that are generally conducive to transcription, whereas heterochromatin contains specialized chromatin binding proteins that repress transcription in these regions. A central question in heterochromatin biology is how the heterochromatin factors are targeted to specific genomic regions, a process that is crucial to ensure that the designated domains, and only they, are repressed in the appropriate spatial and temporal fashion. In Saccharomyces cerevisiae heterochromatinization at the silent mating-type loci HMRa and HMLalpha is achieved by targeting the Sir complex to these regions via a set of anchor proteins that bind to the silencers. Here, we have identified a novel heterochromatin targeting factor for HMLalpha, the protein Sum1, a repressor of meiotic genes during vegetative growth. Sum1 bound both in vitro and in vivo to HMLalpha via a functional element within the HML-E silencer, and deletion of SUM1 caused HMLalpha derepression. Significantly SUM1 was also required for origin activity of HML-E, suggesting a role of Sum1 in replication initiation. Our observations of a synthetic lethality between orc2-1 or orc5-1 and sum1Delta as well as a synthetic growth defect of cdc6-1, cdc7-1 and cdc45-1 with sum1Delta support the notion that SUM1 has a global role in replication initiation. In a genome-wide search for Sum1-regulated origins, we identified a set of autonomous replicative sequences (ARS elements) that bound both the origin recognition complex and Sum1. Full initiation activity of these origins required Sum1, and their origin activity was decreased upon removal of the Sum1 binding site. In its role as a repressor of meiosis specific genes, Sum1 often works in concert with the histone deacetylase Hst1. We found that SUM1-regulated origins also required HST1 for full activity. Taken together we propose that Sum1 is a novel replication initiation modulator for a subset of chromosomal origins.

No description available.