Tesis sobre el tema "Nucleolus"
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Jellbauer, Stephan. "The nucleolus". Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-101704.
Texto completoInder, Kerry y n/a. "The Functional Role of NRAP in the Nucleolus". Griffith University. School of Biomolecular and Biomedical Science, 2006. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20070201.133347.
Texto completoInder, Kerry. "The Functional Role of NRAP in the Nucleolus". Thesis, Griffith University, 2006. http://hdl.handle.net/10072/367738.
Texto completoThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Biomedical Sciences
Full Text
Moore, Duncan Alan. "FUS, RNA and the nucleolus". Thesis, University of Sussex, 2016. http://sro.sussex.ac.uk/id/eprint/65760/.
Texto completoMcKeown, Peter. "Chromatin components of the Arabidopsis nucleolus". Thesis, University of East Anglia, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441526.
Texto completoLeung, Anthony Kar Lun. "Proteomics and dynamics of the human nucleolus". Thesis, University of Dundee, 2003. https://discovery.dundee.ac.uk/en/studentTheses/46f8836d-a114-4320-b1a8-70622068c68e.
Texto completoPeruquetti, Rita Luiza [UNESP]. "Caracterização do ciclo nucleolar e da formação do corpo cromatóide na espermatogênese de alguns vertebrados". Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/102725.
Texto completoConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
O corpo cromatóide (CB) é uma organela citoplasmática que, aparentemente, possui um papel no estoque de RNA e proteínas para a diferenciação final dos espermatozóides. Existem algumas teorias que tentam explicar a origem do material que compõe essa organela. Uma dessas teorias, proposta por alguns autores, sugere que o CB se origine a partir de material nucleolar, que se fragmenta nas etapas iniciais da espermatogênese e, em seguida, migra para o citoplasma. O objetivo do presente estudo foi acompanhar o ciclo nucleolar por meio de análises citoquímicas – hematoxilina-eosina (HE); azul de toluidina (AT); variante da concentração crítica de eletrólitos (CEC); reação de Feulgen; impregnação por íons prata (AgNOR); citogenéticas – impregnação por íons prata (AgNOR), e análises ultra-estruturais – microscopia eletrônica de transmissão (MET), para verificar a relação da fragmentação do material nucleolar com a formação do corpo cromatóide (CB), em algumas espécies de vertebrados: Tilapia rendalli (Teleostei, Cichlidae); Dendropsophus minutus (Amphibia, Anura); Phrynops geoffroanus (Reptilia, Testudines) e coelho albino da raça Nova Zelândia – Oryctolagus cuniculus (Mammalia, Lagomorpha). Por meio das análises citoquímicas foi possível observar que ocorre uma fragmentação do material nucleolar no início da prófase I, em todas as espécies analisadas, e uma posterior reorganização do nucléolo no núcleo de espermátides iniciais, com uma área significantemente menor do que a área do nucléolo das espermatogônias. Três fenômenos podem contribuir para essa diferença significante entre as áreas nucleolar de espermatogônias e espermátides: a) Modificação no estado funcional da célula; b) Diminuição no número de RONs nas espermátides; c) Migração de material nucleolar fragmentado...
The chromatoid body (CB) is a cytoplasmic organelle that has a function related to RNA and protein accumulation and ⁄ or storage for later germ-cell differentiation. Many theories have been postulated in order to explain the origins of the CB material. One of the most accepted theory describes that it originates from a nucleolar material, where it was fragmented in the early spermatogenesis, and finally, this fragmented nucleolar material migrates to cytoplasm. The aims of the present study were: 1) monitoring the nucleolar material distribution by means of cytochemical techniques (hematoxylin–eosin (HE), toluidine blue (TB), modified Critical Electrolyte Concentration for detecting RNA (CEC), silver-ion impregnation (AgNOR) and Feulgen reaction), and by ultrastructural analysis (Transmission Electron Microscopy – TEM); and 2) comparing the nucleolar material distribution with the formation of CB in some vertebrate species: Tilapia rendalli (Teleostei, Cichlidae); Dendropsophus minutus (Amphibia, Anura); Phrynops geoffroanus (Reptilia, Testudines); and Oryctolagus cuniculus (Mammalia, Lagomorpha). For all analyzed species, the cytochemical techniques showed that the nucleolar fragmentation occurred during the beginning of prophase I, and the nucleolus reorganization occurred in the early spermatids nucleus. Statistical tests evidenced that area of the early spermatids nucleolus were smaller than the spermatogonia nucleolus area. Three phenomena can contribute for the statistical difference between the spermatogonia nucleolar area and the early spermatids nucleolar area: a) Modification of cell activity; b) Decrease of the number of NORs in the spermatids; c) Migration of the fragmented nucleolar material from the nucleus to the cytoplasm. This nucleolar material will participate in the CB formation process. The ultrastructural analysis showed an ...(Complete abstract click electronic access below)
Jacob, Mathieu. "Functional Remodelling of the Nucleolus by Long Noncoding RNA". Thesis, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/30288.
Texto completoMorral, Martínez Clara 1989. "The Nucleolus : a connection between cell fate and tumorigenesis in colorectal cancer". Doctoral thesis, Universitat Pompeu Fabra, 2017. http://hdl.handle.net/10803/663807.
Texto completoColorectal cancers (CRCs) are amalgams of phenotypically distinct tumor cell populations in which only a subset of cells retain the capacity to sustain tumor growth and propagate the disease. The research in this thesis has focus on the biological functions specifically enriched in this population compared with their differentiated and non-tumorigenic counterparts. Data mining of the expression profiles of normal and cancer stem cells suggested that nucleolar function was enhanced in both types of stem cells. We have validated these in silico observations using different in vitro and in vivo models that allow us to reproduce the intestinal biology and disease. We have discovered that nucleolar activity is heterogeneously regulated in colorectal cancer (CRC) and that high levels of this activity correlate with the undifferentiated state of tumor cells. By means of CRISPR-Cas9 technology we have generated colorectal cancer organoids expressing endogenous RNA Polymerase I (RNA POL I) fused to a EGFP reporter protein. Analysis of tumor cells purified from patient derived xenografts (PDX) expressing high levels of RNA Pol I demonstrated that these cells display elevated rDNA transcriptional activity as well as tumorigenic potential. On the contrary, tumor cells with low levels of RNA Pol I represent a differentiated population with dismal tumor capacity. Furthermore, we also put forward evidence that nucleolar activity is WNT regulated and that the WNT target MYC may be essential in this scenario. Taken together, our data provides new insights on the biology behind the differential tumorigenic behavior and fate of tumor cells in CRCs. Importantly, it also contributes to better understanding cell heterogeneity and may provide the basis for the development of new therapeutic strategies to tackle this disease.
Galliot, Sonia. "A la recherche de nouvelles AgNORs: une famille de protéines nucléolaires conservées et marqueurs potentiels du cancers". Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210190.
Texto completo1-identifier des protéines AgNORs chez la levure
2-caractériser les propriétés physico-fonctionnelles et physico-chimiques de ces protéines AgNORs.
3-utiliser ces caractéristiques physico-chimiques pour rechercher de nouvelles AgNORs humaines, spécifiques de processus de cancérisation et potentiellement utilisables comme marqueurs tumoraux./The nucleolus is a subnuclear compartment that organized around ribosomal gene (rDNA) repeats NORs, which encode for ribosomal RNA. A peculiar group of acidic proteins which are highly argyrophilic are also localized at the same sites as NORs, thus allowing NORs to be very clearly and rapidly visualized by silver nitrate staining procedures. However, if three human argyrophilic proteins, UBF, C23 (nucleolin) and B23 (nucleophosmin), have been associated for staining of NOR, the exact number of AgNOR proteins and their intrinsic biochemical feature are unclear. Here, we have performed an heterologous screen in a genetically tractable eukaryotic organism (budding yeast) for the identification of novel AgNOR proteins and in vitro characterized an intrinsic feature that underlies silver binding and offers a strong predictive value for the identification of novel human AgNOR proteins.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Utama, B. "Isolation and characterization of Nrap, a novel nucleolar protein /". [St. Lucia, Qld.], 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16281.pdf.
Texto completoBizhanova, Aizhan. "Characterization of Nucleolus-Associated Domains in Mouse Embryonic Stem Cells". eScholarship@UMMS, 2020. https://escholarship.umassmed.edu/gsbs_diss/1077.
Texto completoUkil, Leena. "Isolation of copy number suppressors of the nimA1kinase and mitotic regulation of nucleolar structure in Aspergillus nidulans". Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1196234699.
Texto completoBardella, Vanessa Bellini [UNESP]. "Análise citogenética molecular em túbulos seminíferos de triatomíneos (Triatominae, Heteroptera)". Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/92476.
Texto completoConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Os heterópteros apresentam a meiose cística nos túbulos seminíferos. Esses possuem o cisto espermatogonial envolto pelas células císticas, as quais desenvolvem a função de nutrição das células em divisão celular. Quanto às características citogenéticas, esses insetos apresentam cromossomos holocinéticos, baixa variabilidade cariotípica e meiose invertida dos cromossomos sexuais. No presente trabalho foram caracterizadas as células císticas quanto a sua localização, ultraestrutura e citogenética e, também, foram analisados os aspectos citogenéticos de quatro espécies do gênero Triatoma. Foram utilizadas as técnicas de microscopia eletrônica de transmissão, citogenética convencional (orceína e AgNOR), bandamento C CMA3/DAPI e a técnica de hibridização in situ fluorescente (FISH), com sonda de DNAr 45S de Drosophila melanogaster. Os resultados indicaram que a célula cística envolve um cisto espermatogonial e apresenta um grande núcleo com invaginações citoplasmáticas. Em todas as espécies foram observados vários graus de ploidia da célula cística. Triatoma infestans e T. infestans melanosoma apresentaram vários blocos heterocromáticos com a periferia CMA3 + e o interior DAPI+. Associada às bordas dos blocos heterocromáticos foram observados os segmentos de DNAr 45S, além da presença de vários nucléolos em cada núcleo. Triatoma matogrossensis, T. rubrovaria e T. brasiliensis apresentaram apenas um bloco heterocromático com as mesmas características, com exceção de T. brasiliensis, que apresentou em algumas células vários blocos CMA3 + dispersos. Nessas espécies foi observado apenas um nucléolo com similaridade na localização dos sítios de DNAr. Quanto aos aspectos citogenéticos, todas as espécies apresentaram 2n = 20A + XY, com decréscimo do tamanho relativo dos cromossomos. Em T. infestans melanosoma os cromossomos foram...
Heteroptera, or true bugs, exhibit meiosis in their seminiferous tubules. They posses the spermatogonial cysts that are enclosed by cyst cells, which develop the nutritional function of the cells during cell division. In terms of cytogenetic characteristics, these insects possess holokinetic chromosomes, low karyotype variability, and inverted meiosis in the sex chromosomes. In this study, cyst cells from four species of the genus Triatoma were characterized by their location, superstructure, and cytogenetic makeup. Electronic transmission microscopy techniques were used, as well as conventional cytogenetic techniques (Orcein and AgNOR), C-banding with CMA3 and DAPI banding, and Fluorescence in situ Hybridization (FISH) with a 45S DNA probe of Drosophila melanogaster. The results indicated that the the spermatogonial cyst is enclosed by the cyst cell, and that the cyst cell possesses a large nucleus with cytopasmic invaginations. In all species studied, varying degrees of ploidy were observed in the cyst cells. Triatoma infestans and T. infestans melanosoma presented with various heterochromatic blocks, with CMA3 + at the periphery and DAPI+ at the interior. Segments of rDNA 45S were found along the edges of the heterochromatic blocks, along with the presence of various nucleoli in each nucleus. Triatoma matogrossensis, T. rubrovaria and T. brasiliensis presented with only one heterochromatic block with the same characteristics (with the exception of T. brasiliensis, which presented with various dispersed CMA3 + blocks). In these species, only one nucleolus that was similar to the localization of the rDNA sites was found. All species presented with 2n = 20A + XY, with a decrease in size relative to the chromosomes. In the case of T. infestans melanosoma, the chromosomes were split into groups based on their relative sizes. The heterochromatin of this species presented... (Complete abstract click electronic access below)
Hillyar, Christopher. "Auger electron radionuclide therapy utilising F3 peptide to target the nucleolus". Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:43bb1e8a-6f52-4eac-b742-0a988562e7fc.
Texto completoPeruquetti, Rita Luiza. "Caracterização do ciclo nucleolar e da formação do corpo cromatóide na espermatogênese de alguns vertebrados /". São José do Rio Preto : [s.n.], 2009. http://hdl.handle.net/11449/102725.
Texto completoBanca: Maria Luiza Silveira Mello
Banca: Reinaldo Azoubel
Banca: Carlos Alberto Vicentini
Banca: Eliana Morielle Versute
Resumo: O corpo cromatóide (CB) é uma organela citoplasmática que, aparentemente, possui um papel no estoque de RNA e proteínas para a diferenciação final dos espermatozóides. Existem algumas teorias que tentam explicar a origem do material que compõe essa organela. Uma dessas teorias, proposta por alguns autores, sugere que o CB se origine a partir de material nucleolar, que se fragmenta nas etapas iniciais da espermatogênese e, em seguida, migra para o citoplasma. O objetivo do presente estudo foi acompanhar o ciclo nucleolar por meio de análises citoquímicas - hematoxilina-eosina (HE); azul de toluidina (AT); variante da concentração crítica de eletrólitos (CEC); reação de Feulgen; impregnação por íons prata (AgNOR); citogenéticas - impregnação por íons prata (AgNOR), e análises ultra-estruturais - microscopia eletrônica de transmissão (MET), para verificar a relação da fragmentação do material nucleolar com a formação do corpo cromatóide (CB), em algumas espécies de vertebrados: Tilapia rendalli (Teleostei, Cichlidae); Dendropsophus minutus (Amphibia, Anura); Phrynops geoffroanus (Reptilia, Testudines) e coelho albino da raça Nova Zelândia - Oryctolagus cuniculus (Mammalia, Lagomorpha). Por meio das análises citoquímicas foi possível observar que ocorre uma fragmentação do material nucleolar no início da prófase I, em todas as espécies analisadas, e uma posterior reorganização do nucléolo no núcleo de espermátides iniciais, com uma área significantemente menor do que a área do nucléolo das espermatogônias. Três fenômenos podem contribuir para essa diferença significante entre as áreas nucleolar de espermatogônias e espermátides: a) Modificação no estado funcional da célula; b) Diminuição no número de RONs nas espermátides; c) Migração de material nucleolar fragmentado ...(Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The chromatoid body (CB) is a cytoplasmic organelle that has a function related to RNA and protein accumulation and ⁄ or storage for later germ-cell differentiation. Many theories have been postulated in order to explain the origins of the CB material. One of the most accepted theory describes that it originates from a nucleolar material, where it was fragmented in the early spermatogenesis, and finally, this fragmented nucleolar material migrates to cytoplasm. The aims of the present study were: 1) monitoring the nucleolar material distribution by means of cytochemical techniques (hematoxylin-eosin (HE), toluidine blue (TB), modified Critical Electrolyte Concentration for detecting RNA (CEC), silver-ion impregnation (AgNOR) and Feulgen reaction), and by ultrastructural analysis (Transmission Electron Microscopy - TEM); and 2) comparing the nucleolar material distribution with the formation of CB in some vertebrate species: Tilapia rendalli (Teleostei, Cichlidae); Dendropsophus minutus (Amphibia, Anura); Phrynops geoffroanus (Reptilia, Testudines); and Oryctolagus cuniculus (Mammalia, Lagomorpha). For all analyzed species, the cytochemical techniques showed that the nucleolar fragmentation occurred during the beginning of prophase I, and the nucleolus reorganization occurred in the early spermatids nucleus. Statistical tests evidenced that area of the early spermatids nucleolus were smaller than the spermatogonia nucleolus area. Three phenomena can contribute for the statistical difference between the spermatogonia nucleolar area and the early spermatids nucleolar area: a) Modification of cell activity; b) Decrease of the number of NORs in the spermatids; c) Migration of the fragmented nucleolar material from the nucleus to the cytoplasm. This nucleolar material will participate in the CB formation process. The ultrastructural analysis showed an ...(Complete abstract click electronic access below)
Doutor
Guillen, Ana Karina Zavala. "Structural and transcriptional polymorphisms of nucleolus organizer regions (NORs) in humans and chimpanzees". 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/145465.
Texto completoQuindere, Yeda Rumi Serra Douglas. "Citogenetica de populações e especies de Physalaemus do grupo "cuvieri" (Anura, Leiuperidae)". [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/317680.
Texto completoDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-09T06:46:34Z (GMT). No. of bitstreams: 1 Quindere_YedaRumiSerraDouglas_M.pdf: 8609021 bytes, checksum: 5a91bb6ce1e8fff91e49eb0b18f73d2d (MD5) Previous issue date: 2007
Resumo: O gênero Physalaemus é composto por 40 espécies divididas em sete grupos: ¿albifrons¿, ¿cuvieri¿, ¿deimaticus¿, ¿gracilis¿, ¿henselii¿, ¿olfersii¿ e ¿signifer¿. Nove espécies compõem o grupo "cuvieri" e dessas apenas P. cuvieri já teve seu cariótipo descrito com detalhes, tendo apresentado expressiva variação intra e interpopulacional em relação à localização de regiões organizadoras de nucléolo (NOR). Dado que P. Cuvieri apresenta ampla distribuição geográfica e que a variação mencionada foi encontrada em populações do sul e do sudeste do Brasil, no presente trabalho ampliamos seu estudo, com a análise cromossômica de quatro populações da região nordeste, uma da região norte e uma da região sudeste do Brasil. Adicionalmente uma população da Argentina também foi estudada. Com o intuito de comparar cariotipicamente P. cuvieri com outras espécies de Physalaemus, também foram estudados os cariótipos de P. albonotatus, P. centralis, P. cuqui e P. ephippifer, pertencentes ao grupo "cuvieri", P. albifrons, espécie recentemente removida desse grupo, e P. santafecinus atualmente do grupo de P. albifrons. Todas as populações de P. cuvieri aqui estudadas apresentaram cariótipo com 2n=22 cromossomos e grande variação em relação às NORs pôde ser observada. Duas populações de P. cuvieri (Urbano Santos-MA e Crateús-CE) apresentaram as NORs nos pares 8 e 9. No par 8, a NOR, de localização intersticial, mostrou-se adjacente a uma região de heterocromatina, enquanto a NOR presente no par 9 foi coincidente com um bloco heterocromático. Na população de São Pedro da Água Branca (MA), além dos pares 8 e 9, o par 7 foi também portador de NOR. Na população de Palmeiras (BA) e Uberlândia (MG), apenas um par cromossômico (8) foi portador de NOR. Na população mineira, diferenças intra-individuais foram encontradas principalmente em relação ao tamanho da NOR. Já nas populações da Argentina, a NOR intersticialmente localizada no o par cromossômico 8 não foi encontrada. Em todos os exemplares dessas populações argentinas, o par 11 foi portador de NOR e NORs adicionais foram encontradas nos cromossomos 1, 7 ou 8 (em posição pericentromérica) em alguns indivíduos. É interessante notar que o morfo 11 dessa população argentina é muito semelhante ao cromossomo 11 encontrado na população de Santa Maria (RS) analisada anteriormente. Já na população do estado de Tocantins, NORs múltiplas foram visualizadas em pelo menos cinco cromossomos (pertencentes aos pares 1, 3, 4 e 10), padrão que difere bastante daqueles encontrados nas outras populações de P. cuvieri. Também em relação ao padrão de distribuição de bandas heterocromáticas no cariótipo, a população de Tocantins analisada difere das demais, fato que intriga e corrobora a necessidade de uma revisão taxonômica da espécie em questão. A morfologia cariotípica de P. albifrons, P. albonotatus, P. centralis, P. cuqui, P. ephippifer e P. santafecinus foi muito semelhante, principalmente em relação aos primeiros pares cromossômicos, embora em P. albonotatus e P. cuqui a ordenação de alguns pares tenha sido diferente. Todas essas espécies puderam ser diferenciadas pela localização da NOR e em P.ephippifer um interessante heteromorfismo foi observado no par 8 portador de NOR em todas as fêmeas analisadas. Não foi descartada a hipótese de tal heteromorfismo estar relacionado à determinação sexual nessa espécie, no entanto, futuros estudos são necessários para sua comprovação. Exceto no cariótipo dos indivíduos de P. cuvieri de Tocantins, nos cariótipos aqui descritos a principal (ou única) NOR foi encontrada nos últimos pares cromossômicos, alterando a morfologia desses, o que dificultou a inferência de homeologias interespecíficas e dos possíveis rearranjos que envolveram a NOR durante a diferenciação das espécies em análise. Já com o bandamento C, algumas homeologias interespecíficas foram claramente notadas. Uma banda intersticial no braço curto do par 5, outras na região pericentromérica do braço curto dos pares 3 e 7, por exemplo, foram encontradas em P. cuvieri, P. centralis e P. ephippifer, e parecem homeólogas às encontradas nos pares classificados como 3, 5 e 7 no cariótipo de P. albonotatus
Abstract: The genus Physalaemus is composed by 41 species distributed in seven groups: ¿albifrons¿, ¿cuvieri¿, ¿deimaticus¿, ¿gracilis¿, ¿henselii¿, ¿olfersii¿ and ¿signifer¿. Nine species compose the group ¿cuvieri¿ but just P. cuvieri had already been karyotyped in details. Expressive intra and interpopulational variation related to the localization of the nucleolus organizer regions (NOR) was described for this species. Physalaemus cuvieri is widely geographically distributed and NOR variation was described based on populations from Southern and Southeastern Brazil. In the present work we analyzed the cytogenetic of four populations from Northeastern, one from Northern and one from Southeastern Brazil. Additionally, three Argentinian populations were also included. To cytogenetically compare P. cuvieri with other species of Physalaemus, species belonging to P. cuvieri group (i.e. P. albonotatus, P. centralis, P. cuqui and P. ephippifer), P. albifrons, recently removed from this group, and P. santafecinus, currently alocated in P. albifrons group, were also analyzed. All populations of P. cuvieri studied here showed diploid number of 22 chromosomes and high intraspecific variation was observed related to the NORs. Two populations of P. cuvieri (Urbano Santos, state of Maranhão (MA) and Crateús, state of Ceará (CE)) had pairs 8 and 9 as NOR-bearing chromosomes. In pair 8 the interstitial NOR was adjacent to C-bands whereas the NOR at the nineth pair was coincident with a heterochromatic block. In the population from São Pedro da Água Branca, state of Maranhão (MA), besides pairs 8 and 9, the seventh pair was also a NOR-bearing one. The specimens from Palmeiras, state of Bahia (BA) and Uberlândia, state of Minas Gerais (MG) showed only one NOR, which was located at pair 8. In the population from Uberlândia (MG) intraindividual differences was found related to the NOR size. In the populations from Argentina, the interstitial NOR in chromosome pair 8 was not found. In all the specimens of these Argentinean populations, pair 11 was the NOR-bearing chromosome pair and additional NORs were also found in chromosomes 1, 7 or 8 (in a pericentromeric position) in some of the individuals. The morph 11 of specimens from Argentina was very similar to the NOR-bearing eleventh pair described for specimens from Santa Maria (RS) previously analyzed. In contrast, in the population from Porto Nacional, state of Tocantins (TO), multiple NORs were visualized at least at five chromosomes (belonging to pair 1, 3, 4 and 10), a pattern that greatly differed from those found in the others populations of P. cuvieri. Also concerning the C-band distribution, the karyotype found in the population of Tocantins differed from the others. These findings are very interesting and can be useful for future taxonomic studies of this taxon. Regarding to chromosome morphology, P. albifrons, P. albonotatus, P. centralis, P. cuqui, P. ephippifer and P. santafecinus were very similar, specially for the seven first chromosome pairs, although in P. albonotatus and P. cuqui the position of some chromosome pairs was different. All the species could be differentiated by NOR localization and in P. ephippifer an interesting heteromorphism was detected in NOR bearing pair 8 of all the females. We do not discard the hypothesis that such heteromorphism could be related to sex determination in this species, but future studies are necessary to test it. Except for the karyotype of P. cuvieri from Tocantins, the karyotypes described here the principal (or only) NOR was found among the last chromosome pairs, resulting in different chromosome morphologies, what impaired interespecific inferences of homeologies and the recognition of possible rearrengements involving the NOR during the differentiation of the species analyzed. On the other hand, C-banding tecnique permitted to notice some interspecific homeologies. A band at an interstitial region in the short arm of pair 5, and pericentromeric C-bands in the short arm of pairs 3 and 7 were detected in P. cuvieri, P. centralis and P. ephippifer which seemed to be homeologous to C-bands found in pair 3, 5 and 7 of P. albonotatus
Mestrado
Biologia Celular
Mestre em Biologia Celular e Estrutural
Lobb, Ian Thomas. "The role of nucleolar stress in the anti-tumour activity of non-steroidal anti-inflammatory drugs (NSAIDs)". Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/17878.
Texto completoBerdougo, Eli. "Human CDC14 phosphatases are not essential for viability : and do not regulate mitotic exit /". Access full-text from WCMC, 2009. http://proquest.umi.com/pqdweb?did=1692102661&sid=2&Fmt=2&clientId=8424&RQT=309&VName=PQD.
Texto completoDuRose, Jenny Bratlien. "The unfolded protein response integrating stress signals from the endoplasmic reticulum to the nucleolus /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3330123.
Texto completoTitle from first page of PDF file (viewed November 13, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
Lackmann, Fredrik. "Nucleolar Ribosome Assembly". Doctoral thesis, Stockholms universitet, Institutionen för molekylär biovetenskap, Wenner-Grens institut, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-145639.
Texto completoAt the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.
Schmidt, Tracy E. "HIV-1 and the Nucleolus: A Role for Nucleophosmin/NPM1 in Viral Replication: A Dissertation". eScholarship@UMMS, 2013. https://escholarship.umassmed.edu/gsbs_diss/690.
Texto completoSchmidt, Tracy E. "HIV-1 and the Nucleolus: A Role for Nucleophosmin/NPM1 in Viral Replication: A Dissertation". eScholarship@UMMS, 2008. http://escholarship.umassmed.edu/gsbs_diss/690.
Texto completoLopez, Camacho Cesar. "A new role for Filamin A as a regulator of Runx2 function". Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/a-new-role-for-filamin-a-as-a-regulator-of-runx2-function(88321064-5c82-4f2b-a755-911ed3b42b2e).html.
Texto completoBusin, Carmen Silvia. "Estudo citogenetico de especies dos generos Pseudis e Lysapsus (Anura, Hylidae, Hylinae)". [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/317977.
Texto completoTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: A posição taxonômica, as relações filogenéticas, a sinonimização de espécies consideradas distintas, a existência de subespécies e as propostas de agrupamentos intragenéricos dos gêneros Pseudis e Lysapsus sempre foram bastante discutidas entre os herpetólogos. Os gêneros Pseudis e Lysapsus já foram considerados membros da família Pseudidae e também da subfamília de Hylidae. Recentemente, foram alocados na subfamília Hylinae como gêneros distintos. Pseudis paradoxa, P. minuta e Lysapsus limellus, já analisados citogeneticamente por outros autores, apresentam 2n=24 cromossomos e Pseudis sp. (aff. minuta), hoje confirmada citogeneticamente como a recentemente descrita P. cardosoi, apresenta 2n=28 cromossomos, com quatro pares adicionais de cromossomos telocêntricos. No presente trabalho foram analisadas, através de coloração convencional dos cromossomos, padrão de distribuição de heterocromatina, número e localização das regiões organizadoras de nucléolo (NOR), espécies do gênero Pseudis e do gênero Lysapsus, exceto L. laevis, com o objetivo de contribuir com caracteres citogenéticos para a sistemática e para os estudos de filogenia dos dois gêneros, além de buscar evidências para a compreensão dos processos envolvidos na evolução cromossômica nesses grupos. As análises citogenéticas revelaram que o complemento 2n=24 cromossomos é a condição plesiomórfica tanto no gênero Pseudis quanto no gênero Lysapsus e corroboraram a hipótese de que o cariótipo 2n=28 cromossomos tenha uma origem comum ao cariótipo 2n=24 de P. minuta, pois as bandas heterocromáticas marcadoras dos dois cariótipos não foram detectadas em nenhuma das espécies analisadas no presente trabalho. As análises da morfologia cromossômica e do padrão de distribuição de heterocromatina permitiram a separação inter- e intragenérica nos dois gêneros, exceção feita entre as subespécies Pseudis paradoxa paradoxa e P. p. platensis que apresentaram os dados citogenéticos comuns. As diferenças detectadas no padrão de distribuição de heterocromatina além de permitir a separação das espécies de Lysapsus e de Pseudis permitiu, também, sugerir uma reavaliação do status taxonômico das subespécies L. limellus limellus e L. ,. bolivianus, especialmente da população de L. I. bolivianus de Guajará-Mirim, que apresentaram diferenças na morfologia e padrão de bandamento dos cromossomos 7 e 8, também em relação às outras populações da mesma subespécie. A presença da região organizadora de nucléolo (NOR) nos braços longos dos cromossomos do par 7 é o caráter plesiomórfico tanto no gênero Pseudis como no gênero Lysapsus e a posição que a mesma ocupa ao longo do braço é um dado citogenético importante na separação das espécies de Pseudis. A morfometria cromossômica, padrão de bandamento e posição da NOR nos cromossomos 7 permitiram também verificar a presença de cromossomos sexuais heteromórficos no sistema ZZIZW em P. tocantins, com evidências de que mecanismos de inversão e de ganho de heterocromatina tenham ocasionado a diferenciação dos cromossomos Z e W
Abstract: The taxonomic position, phylogenetic relationships, synonymization of species considered to be distinct, existence of subspecies, and the proposals of intrageneric groups of the genera Pseudis and Lysapsus have always been a matter of discussion among herpetologists. The genera Pseudis and Lysapsus have already been included in the family Pseudidae and also in the subfamily Hylidae. Recently, these two genera have been allocated to the subfamily Hylinae as distinct genera. Pseudis paradoxa, P. minuta and Lysapsus limellus, cytogenetically analyzed by other investigators, show a chromosome number of 2n=24, and Pseudis sp. (aff. minuta), now cytogenetically confirmed as the recently described P. cardosoi, has 2n=28 chromosomes, including four additional pairs of telocentric chromosomes. In the present study, we analyzed the pattem of heterochromatin distribution and the number and location of the nucleolar organizer region (NOR) by conventional chromosome staining in species of the genera Pseudis and Lysapsus, except for L. laevis, in order to add cytogenetic traits to the systematics and to the study of the phylogeny of the two genera, in addition to providing evidence for the understanding of the processes involved in the chromosome evolution of these groups. Cytogenetic analysis revealed that the complement of 2n=24 chromosomes is a plesiomorphic condition both in the genus Pseudis and in the genus Lysapsus, and confirmed the hypothesis that the origin of the 2n=28 karyotype is the same as that of the 2n=24 karyotype of P. minuta since the heterochromatic marker bands in the two karyotypes were not detected in any of the species analyzed in the present study. Analysis of the chromosome morphology and the pattem of heterochromatin distribution permitted the inter- and intrageneric separation of the two genera, except for the subspecies Pseudis paradoxa paradoxa and P. p. platensis which presented common cytogenetic data. In addition to permitting the separation of Lysapsus and Pseudis species, the differences detected in the pattem of heterochromatin distribution also suggested the reassessment of the taxonomic status of the subspecies L. limellus limellus and L. I. bolivianus, especially of the L. I. bolivianus population from Guajará-Mirim, which differed in the morphology and banding pattem of chromosomes 7 and 8 in relation to the other populations of the same subspecies. The presence of the NOR on the long arms of the chromosomes of pair 7 was a plesiomorphic trait both in the genus Pseudis and in the genus Lysapsus, and the position the NOR occupies on the long arm is an important cytogenetic characteristic for the separation of Pseudis species. Chromosome morphometry, banding pattern and NOR position on chromosomes 7 also permitted the detection of heteromorphic sex chromosomes in the ZZlZW system of P. tocantins, with evidence that mechanisms of inversion and heterochromatinization caused the differentiation of the Z and W chromosomes
Doutorado
Biologia Celular
Doutor em Biologia Celular e Estrutural
Bardella, Vanessa Bellini. "Análise citogenética molecular em túbulos seminíferos de triatomíneos (Triatominae, Heteroptera) /". São José do Rio Preto : [s.n.], 2010. http://hdl.handle.net/11449/92476.
Texto completoBanca: Hermione Elly Melara de Campos Bicudo
Banca: Patricia Pasquali Parise Maltempi
Resumo: Os heterópteros apresentam a meiose cística nos túbulos seminíferos. Esses possuem o cisto espermatogonial envolto pelas células císticas, as quais desenvolvem a função de nutrição das células em divisão celular. Quanto às características citogenéticas, esses insetos apresentam cromossomos holocinéticos, baixa variabilidade cariotípica e meiose invertida dos cromossomos sexuais. No presente trabalho foram caracterizadas as células císticas quanto a sua localização, ultraestrutura e citogenética e, também, foram analisados os aspectos citogenéticos de quatro espécies do gênero Triatoma. Foram utilizadas as técnicas de microscopia eletrônica de transmissão, citogenética convencional (orceína e AgNOR), bandamento C CMA3/DAPI e a técnica de hibridização in situ fluorescente (FISH), com sonda de DNAr 45S de Drosophila melanogaster. Os resultados indicaram que a célula cística envolve um cisto espermatogonial e apresenta um grande núcleo com invaginações citoplasmáticas. Em todas as espécies foram observados vários graus de ploidia da célula cística. Triatoma infestans e T. infestans melanosoma apresentaram vários blocos heterocromáticos com a periferia CMA3 + e o interior DAPI+. Associada às bordas dos blocos heterocromáticos foram observados os segmentos de DNAr 45S, além da presença de vários nucléolos em cada núcleo. Triatoma matogrossensis, T. rubrovaria e T. brasiliensis apresentaram apenas um bloco heterocromático com as mesmas características, com exceção de T. brasiliensis, que apresentou em algumas células vários blocos CMA3 + dispersos. Nessas espécies foi observado apenas um nucléolo com similaridade na localização dos sítios de DNAr. Quanto aos aspectos citogenéticos, todas as espécies apresentaram 2n = 20A + XY, com decréscimo do tamanho relativo dos cromossomos. Em T. infestans melanosoma os cromossomos foram... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Heteroptera, or "true bugs", exhibit meiosis in their seminiferous tubules. They posses the spermatogonial cysts that are enclosed by cyst cells, which develop the nutritional function of the cells during cell division. In terms of cytogenetic characteristics, these insects possess holokinetic chromosomes, low karyotype variability, and inverted meiosis in the sex chromosomes. In this study, cyst cells from four species of the genus Triatoma were characterized by their location, superstructure, and cytogenetic makeup. Electronic transmission microscopy techniques were used, as well as conventional cytogenetic techniques (Orcein and AgNOR), C-banding with CMA3 and DAPI banding, and Fluorescence in situ Hybridization (FISH) with a 45S DNA probe of Drosophila melanogaster. The results indicated that the the spermatogonial cyst is enclosed by the cyst cell, and that the cyst cell possesses a large nucleus with cytopasmic invaginations. In all species studied, varying degrees of ploidy were observed in the cyst cells. Triatoma infestans and T. infestans melanosoma presented with various heterochromatic blocks, with CMA3 + at the periphery and DAPI+ at the interior. Segments of rDNA 45S were found along the edges of the heterochromatic blocks, along with the presence of various nucleoli in each nucleus. Triatoma matogrossensis, T. rubrovaria and T. brasiliensis presented with only one heterochromatic block with the same characteristics (with the exception of T. brasiliensis, which presented with various dispersed CMA3 + blocks). In these species, only one nucleolus that was similar to the localization of the rDNA sites was found. All species presented with 2n = 20A + XY, with a decrease in size relative to the chromosomes. In the case of T. infestans melanosoma, the chromosomes were split into groups based on their relative sizes. The heterochromatin of this species presented... (Complete abstract click electronic access below)
Mestre
Todd, Matthew Andrew Melville. "Characterizing the Cellular Role of PHF6". Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32337.
Texto completoBerger, Axel Bernhard. "Quantitative and functional analysis of chromosome dynamics : influence of the nucleolus on the regulation of gene expression". Paris 11, 2008. http://www.theses.fr/2008PA112226.
Texto completoChromatin is distributed non-randomly within the cell nucleus. Its spatial organization has been demonstrated to be important for nuclear metabolism such as, DNA replication, reparation or transcription. I studied the budding yeast HMG-box protein Hmo1. A screen demonstrated that this chromatin-associated protein is genetically linked to the RNA polymerase (Pol) I, to genes coding for ribosomal proteins (RPGs) as well as to genes implicated in stress response. I could show that Hmo1 physically interacts with the rRNA coding gene transcribed by Pol I and with a subset of RPG promoters. Global expression analyses showed a clear dependence on Hmo1 for the expression of a sub-set of RPGs. An hmo1 deletion strain is also largely alleviated in repressing RPG transcription after TOR complex 1 inhibition. These results suggested that Hmo1 is implicated in Pol I transcription as well as RPG regulation. Since Hmo1 is a bona fide nucleolar factor, we wanted to test if Pol II transcribed RPGs associated with Hmo1 are localized in the proximity of the nucleolus. We first developed a new method allowing determination of gene localization probabilities with very high accuracy and with respect to the nucleolus. We could demonstrate by analyzing thousands of cells, that genes are confined into sub-nuclear volumes. These ‘gene territories’ show a locus specific size and can be remodeled upon transcriptional activation. Applying this new method to Pol II transcribed genes required for ribosome biogenesis, such as the RPGs, indicates that the localization of the gene on the chromatin fiber has important implications for its three dimensional positioning
Rai, Urvashi. "Spindle Assembly Checkpoint Stability Depends on Integrity of the Nucleolus and Septins in Saccharomyces cerevisiae". Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1491568383512984.
Texto completoBruschi, Daniel Pacheco 1987. "Relações inter- e intraespecíficas no grupo de Phyllomedusa hypochondrialis (Anura, Hylidae) = estudo citogenético e de DNA mitocondrial". [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/317992.
Texto completoDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: A taxonomia e as relações de parentesco em Phyllomedusa são temas de constantes discussões. Hipóteses sobre os relacionamentos intra- e interespecíficos desse gênero decorrem basicamente de análises morfológicas e comportamentais, o que não têm sido suficiente para responder alguns dos questionamentos. O grupo de P. hypochondrialis, o maior dentro do gênero, apresenta dificuldades na sua delimitação e, até o momento, não foi observada nenhuma sinapomorfia que possa reunir as espécies atualmente alocadas no grupo, de maneira que outras ferramentas podem ser elucidativas para resolução dessa problemática. O presente trabalho teve como objetivo utilizar dados citogenéticos e de sequências de DNA mitocondrial para o estudo de algumas das espécies do grupo de P. hypochondrialis. Todos os espécimes apresentaram o número diplóide 2n=26 e morfologia dos cromossomos bastante conservada, o que permitiu a inferência de homeologias cromossômicas. Exceto nas populações de Phyllomedusa sp. (aff. azurea) que apresentam o par 7 submetacêntrico, os cariótipos das demais populações analisadas foram constituídos por seis pares metacêntricos (1, 4, 8, 11-13), seis submetacêntricos (2, 3, 5, 6, 9, 10) e um subtelocêntrico (par 7). A diferença detectada no par 7 pode ser atribuída à presença de uma NOR nos braços curtos dos cromossomos 7 submetacêntricos. Pequenas variações na morfologia de alguns pares cromossômicos, incluindo a localização da NOR, foram observadas em P. rohdei de Ilhéus/BA em relação à descrita por outros autores, corroborando a hipótese da provável existência de espécies crípticas sob esse nome. O cariótipo de P. nordestina se diferenciou dos demais principalmente pela grande quantidade de heterocromatina e pela posição da NOR em 9p. A análise de morfologia externa relativa aos dois caracteres indicados para diagnose e separação de P. hypochondrialis e P. azurea, aplicados a todos os espécimes de diferentes localidades brasileiras, mostrou variações intrapopulacionais não acompanhadas de variações citogenéticas e moleculares. Esses dados apontam a necessidade de uma re-avaliação desses caracteres de diagnose e separação para essas espécies. A análise conjunta de dados citogenéticos e moleculares das populações permitiu identificar a população de Belterra/PA como P. hypochondrialis, portadora de NOR intersticial em 8p. Dados moleculares sugerem que as populações de Uberlândia (Minas Gerais), de São Luís, Bacabeira e Urbano Santos (Maranhão) e de Porto Nacional (Tocantins) possivelmente correspondam a um mesmo táxon, P. azurea. Nesse caso, a NOR em 7p nas populações ao Norte (Maranhão e Tocantins) e em 4p ao sudeste (Minas Gerais) corresponderia a variação interpopulacional. Na análise filogenética molecular, os haplótipos de Chapada dos Guimarães + Santa Terezinha (Mato Grosso) formaram um clado e as populações de Laranjal do Jari (Amapá) e de Prainha (Pará) formaram cada uma um ramo independente. Os dados dessas quatro populações (portadoras de NOR pericentromérica em 8q) sugerem que uma revisão minuciosa deva ser realizada para auxiliar no esclarecimento de seus status taxonômicos.
Abstract: Taxonomy and phylogenetic relationships of Phyllomedusa have been subject of continuous discussions. Hypotheses about the intra- and interspecific relationships within this genus have basically arised from morphological and behavioral characteristics, which have not been enough to elucidate the problems as the assigning of species to the P. hypochondrialis group. So, other tools may help to solve this problem. This work aimed to contribute with cytogenetic analysis and mitochondrial DNA sequencing data to the understanding of intra- and interspecific relationships involving the species P. rohdei, P. nordestina, P. hypochondrialis and P. azurea of the P. hypochondrialis group. These species showed the same chromosome number, 2n=26, with a very similar morphology. All populations had karyotypes with six metacentric (1, 4, 8, 11-13), six submetacentric (2, 3, 5, 6, 9, 10) pairs and one subtelocentric pair (7). The populations of Phyllomedusa sp. (aff. azurea) from São Luis, Bacabeira, Urbano Santos (Maranhão state) and Porto Nacional (Tocantins state) had the pair 7 submetacentric. This morphological difference in pair 7 can be attributed to the Nucleolus Organizer Region (NOR) that is located only in the submetacentric pair 7. The karyotype of P. nordestina was distinguished from P. rohdei by the large amount of heterochromatin and by the position of the NOR in chromosome 9p, whereas in P. rohdei it is located in 9q. The karyotype of P. rohdei also differed from that described by other author, suggesting the existence of cryptic species. Brazilian populations of P. azurea, P. hypochondrialis and other populations related to those species were analyzed. Intrapopulational variations in characters of external morphology were not associated with cytogenetic and molecular variations, showing that it is necessary a reevaluation of the diagnosis and separation characters for those species. The combined analysis of molecular and cytogenetic data allowed classifying the population of Belterra/PA as P. hypochondrialis, with NOR in pair 8p. Molecular data suggested that populations from Uberlândia (Minas Gerais), São Luiz, Bacabeira e Urbano Santos (Maranhão) and Porto Nacional (Tocantins) probably correspond to the taxon P. azurea. By comparing the karyotype of specimens from North populations (Maranhão and Tocantins) and from Southeast populations (Minas Gerais) different NOR positions were observed and interpreted as an interpopulational variation. The genetic diversity observed among populations with pericentromeric NOR in 8q (Laranjal do Jari, Prainha and Chapada dos Guimarães + Santa Terezinha; three clades in the molecular phylogenetic analysis) suggests that these populations could be in incipient process of speciation.
Mestrado
Biologia Celular
Mestre em Biologia Celular e Estrutural
Méndez, Vidal Cristina. "Molecular studies of WIG-1, A P53-induced zinc finger protein /". Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-732-0.
Texto completoLiu, Gin-Yun. "Analysis of the effects of Leptomycin B on Cells Exiting Mitosis". The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1153488860.
Texto completoMehta, Ishita Shailesh. "Chromosome territory position and active relocation in normal and Hutchinson-Gilford progeria fibroblasts". Thesis, Brunel University, 2009. http://bura.brunel.ac.uk/handle/2438/4261.
Texto completoChen, Jingyu. "Nucleolar stress stimulates the NF-kappaB pathway : mechanism underlying the proapoptotic effects of aspirin". Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28901.
Texto completoColau, Geoffroy. "La triméthylguanosine synthase (TGS1): implication dans la morphogenèse nucléolaire et caractérisation de son environnement physique et fonctionnel". Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210721.
Texto completoDans un premier temps, l’analyse du processing des ARN ribosomiques dans la souche délétée pour TGS1 nous a permis de mettre en évidence l’implication de Tgs1 dans la formation de l’ARNr de la petite sous-unité, l’ARNr 18S. Des mutants catalytiques de Tgs1, incapables de reconnaître et de modifier les coiffes m7G, ont été crées. L’analyse de la voie de biogenèse des ribosomes dans ces souches ne présente pas les défauts constatés dans la souche délétée, révélant que c’est la protéine et non sa fonction catalytique qui est requise. De plus, ces mutants sont autant défectueux dans l’épissage des ARN messagers, excluant toute implication du défaut d’épissage dans le ralentissement de la voie de biogenèse des ribosomes observé dans la souche délétée. L’ultrastructure des souches délétées pour TGS1 observée en microscopie électronique nous a permis de mettre en évidence un effet de l’absence de Tgs1 sur la morphologie nucléolaire. En effet, le nucléole dans ces souches ne présente plus de nucléole structuré, bi-compartimenté. Les analyses en microscopie à fluorescence ont confirmé la disparition de la ségrégation des deux compartiments nucléolaires, suggérant que le défaut dans la biogenèse des ribosomes puisse être une conséquence de la perte de cohérence du nucléole.
La caractérisation de l’environnement physique et fonctionnel de Tgs1 a été entreprise afin de mettre à jour des fonctions additionnelles de la protéine. Diverses approches ont été envisagées: la recherche de partenaires physiques par l’emploi d’un allèle de TGS1 étiquetté TAP permettant la purification puis l’analyse de partenaires physiques ainsi que la recherche de partenaires fonctionnels par la méthode du crible synthétique létal. La recherche de partenaires physiques a permis de révéler l’existence d’un grand nombre d’ARN non codants coprécipités avec Tgs1. Certains sont des substrats connus de la protéine mais un grand nombre d’ARN ne possédant pas de coiffes monométhylées. La recherche de partenaires fonctionnels a permis la découverte de candidats synthétiques létaux appartenant à deux groupes, un groupe lié à l’épissage des ARN messagers et un autre groupe constitué de membres du complexe SWR1, complexe impliqué dans la régulation transcriptionnelle par modification de la chromatine. Lors de ce crible de candidats synthétiques létaux, il est apparu que la délétion de TGS1 restaure partiellement le défaut de croissance à chaud induit par la délétion du gène RRP47, dont le produit est impliqué dans la maturation de l’extrémité 3’ de plusieurs types d’ARN non codants. Les travaux préliminaires effectués ne permettent pas encore d’expliquer un tel phénotype.
Au cours de ce travail de thèse, nous avons pu répondre à un certain nombre de questions sur la fonction et le rôle de Tgs1 dans la cellule. La fonction catalytique de Tgs1 dans la méthylation des coiffes m7G est clairement nécessaire à l’efficacité de l’épissage des ARN messagers mais le rôle de la triméthylation de la coiffe des snoARN n’est pas élucidé à ce jour. Le fait que la fonction catalytique de Tgs1 n’est pas impliquée dans le défaut dans la biogenèse des ribosomes et la découverte du rôle de la protéine dans la morphologie nucléolaire, laisse entrevoir l’existence de fonctions additionnelles de Tgs1 dans la cellule. La caractérisation de son environnement physique et fonctionnel abonde justement dans ce sens, mettant à jour plusieurs interactions probablement liées à sa fonction catalytique, notamment dans l’épissage des ARN messagers mais également un grand nombre d’interactions impliquant la participation de Tgs1 dans d’autres voies métaboliques.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Pinheiro, Stefania Morisco Tasca. "Corpúsculos de Cajal e nucléolos em células normais e tumorais em cultura e sua associação com proliferação celular e alterações destas estruturas nucleares após o uso de inibidores de síntese de RNA". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/42/42134/tde-15062009-163448/.
Texto completoThe nucleus is a structure that has sub-compartments which can be called nuclear organelles. Among them, may be cited the nucleoli and the Cajal bodies (CBs). These nuclear compartments are dynamic structures, maintained by association and stock of macromolecules involved in gene expression. The main protein found in the CB is a p-80-coilin and therefore the main epitope able to label these structures. Their functions are still to be clarified. There is a protein in common to the nucleolus and Cajal bodies, the fibrillarin that takes part in the processing of rRNA. The CBs can be found at the periphery of the nucleoli or even physically connected to them. It is believed that the CBs may have role in the synthesis of rRNA and maturation, transport and association of ribosome subunits. In view of this relationship between Cajal bodies and nucleoli, this work aims to study the interrelationship between these structures in normal cells and their respective tumor cell line in culture before and after treatments with actinomycin D, which in low concentrations, blocks the transcription of genes that were decoded by the RNA polymerase I and II and -amanitin, which is responsible for blocking the transcription of genes decoded by the RNA polymerase II and find out a relationship between cell proliferation and Cajal bodies frequencies in control and treated cells. The confocal microscope of laser scanning enabled the study of these structures in preparations immunofluorescent providing a three-dimensional analysis of these structures when used specific antibodies before and after treatment. Cell lines that shown low cell grow, appears to have lass CB/ nucleus in the other hand, cell lines that have fastest grow shown nuclei with more Cajal bodies frequencies and more variation in the number of Cajal/nucleus After treatment with inhibitors, both Cajal bodies as nucleoli, made quite clear morphological changes, sometimes giving large accumulation of proteins in organelles and sometimes appeared disorganized in the nucleoplasm. Changes in the size and shape were also highlighted. The tumor cell lines also showed changes compared to their normal cell type.
Cong, Rong. "Functional analysis of nucleolin-chromatin interaction in vivo". Thesis, Lyon, École normale supérieure, 2011. http://www.theses.fr/2011ENSL0636.
Texto completoBesides the well-known role of the nucleolus in ribosome biogenesis, nucleoli play important roles in the regulation of many fundamental cellular processes, including cell cycle regulation, apoptosis, telomerase production, RNA processing and therefore it is not surprising that many nucleolar proteins appear to be multifunctional proteins. Nucleolin, one of the most abundant non-ribosomal proteins of the nucleolus, has been the focus of many studies since it was first described 35 years ago. It seems to be involved in many aspects of DNA metabolism, chromatin regulation and appeared to be a good pharmacological target for drug development in addition to its role in RNA polymerase I transcription and pre-ribosomal processing and assembly in pre-ribosomes. In eukaryotic cells, DNA is packed into nucleosomes to form chromatin in the nucleus. The cells develop a variety of strategies to overcome the nucleosomal barriers. These strategies include DNA methylation, histone post-translational modifications, incorporation of histone variants and ATP dependent chromatin remodeling. The aim of this thesis is to study the interaction of nucleolin with chromatin, and to decipher the mechanism of nucleolin in gene regulation. It was reported that nucleolin possesses a histone chaperone activity, helps the transcription through nucleosomes, and it is required for ribosomal DNA gene (rDNA) transcription in vivo, but the mechanism by which nucleolin modulates RNA polymerase I (Pol I) transcription is unknown. In the thesis it is shown that nucleolin knockdown results in an increase of the heterochromatin mark H3K9me2 and a decrease of H4K12Ac and H3K4me3 euchromatin histone marks in rDNA genes. Nucleolin is associated with unmethylated rDNA genes and ChIP-seq experiments identified a strong enrichment of nucleolin in the promoter and coding regions of rDNA. Nucleolin is able to interfere with the binding of TTF-1 on the promoter-proximal terminator T0 thus inhibiting the recruitment of the nucleolar remodeling complex (NoRC) subunit TIP5 and HDAC1 and the establishment of a repressive heterochromatin state. In addition, in absence of nucleolin or after inhibition of Pol I by actinomycin D, a strong relocalization of the histone variant macroH2A1 to the nucleolus and on the rDNA genes was observed. This invasion of macroH2A1 in the nucleolus plays a major role in the inhibition of Pol I transcription in absence of nucleolin, as knockdown of macroH2A1 eliminates the repressive effect of nucleolin depletion. These results reveal the importance of nucleolin for the maintenance of the euchromatin state of rDNA required for an efficient production of ribosomal RNAs and the role of macroH2A1 in rDNA transcription
Dillinger, Stefan [Verfasser] y Attila [Akademischer Betreuer] Németh. "Characterization of nucleolus-associated chromatin domains during cellular aging and upon genetic inactivation of the Upstream Binding Factor protein / Stefan Dillinger. Betreuer: Attila Németh". Regensburg : Universitätsbibliothek Regensburg, 2016. http://d-nb.info/109675164X/34.
Texto completoSilva, Natalia de Sousa Teixeira e. "Dinâmica nucleolar e a herança epigenética dos genes ribossomais". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/11/11137/tde-11082014-174129/.
Texto completoThe nucleolus is a subnuclear organelle formed as a result of transcriptional activity of ribosomal RNA genes 18S-5.8S-26S (45S rDNA) and subsequent ribosome biogenesis. This activity forms the nucleolar organizing region (NOR) as a secondary constriction in metaphase chromosomes. The secondary constrictions progressively condense during mitosis and decondense at the end of telophase, when nucleoli start to reassemble. Genomes presenting more than one 45S rDNA locus must have at least one pair of NOR bearing chromosomes, while other loci may be expressed or not. Ribosomal gene expression and nucleolar chromatin assembly are modulated by specific epigenetic events. Although some topics related to rDNA gene activity and nucleolus formation are well understood, questions such as the behavior of nucleolar chromatin condensation during mitosis, standard functions associated with rDNA additional sites, role of epigenetic modifications in nucleolar chromatin and 45S rDNA expression processes, and inheritance mechanism of active genes, remain to be solved. Crotalaria juncea (Leguminosae - Papilionoideae) has 2n=2x=16 chromosomes and carries a 45S rDNA locus at the short arm of chromosome 1, always presenting a secondary constriction, and an additional site with facultative activity at the short arm of chromosome 4, being an excellent model to resolve these questions. Thus, this study aimed to study NOR condensation dynamics during the cell cycle and its correlation with ribosomal gene activity, including the additional locus, while analyzing the role of rDNA cytosine methylation during this process. The results show that NOR chromatin segregate in a decondensed way throughout mitosis, as a secondary constriction. In other words, this structure does not condense during metaphase and the NOR is not reassembled at the beginning of telophase. Misinterpretations relating nucleolar activity with morphological observations of secondary constrictions, appear to be induced by the artificial contraction of NOR chromatin caused by antimitotic drugs. This segregation model in an open state may be supported by strong diversity of proteins that are maintained attached to NORs during mitosis, serving as a physic barrier for condensation. Both principal and additional 45S rDNA sites of C. juncea are transcriptionally active, although the additional locus in chromosome 4 presented facultative activity depending upon ribosomal request. Unlike what was previously proposed, once the additional site is activated, it remains in an open configuration throughout the cell cycle, similarly to principal site behavior. Secondary constrictions and nucleolar chromatin are hypermethylated at cytological level, regardless of their activity. The seeming hipomethylated state of 45S rDNA in interphase nucleus and mitotic chromosomes is due to a lower compaction level of nucleolar organizing regions and subsequent low chromatin density.
Gueiderikh, Anna. "Liens entre dommages de l’ADN et stress nucléolaire dans les insuffisances médullaires héréditaires : le cas de l’anémie de Fanconi". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS413.
Texto completoInherited bone marrow failure syndromes (iBMFs) group four main syndromes: Shwachman-Diamond syndrome, Dyskeratosis Congenita, Diamond Blackfan anemia and Fanconi anemia (FA), which is the most frequent one. Whereas the pathogenesis of the other iBMFs is linked to ribosomal biogenesis and nucleolar abnormalities, the pathogenesis of FA is considered to be mainly due to misrepaired DNA damage.The FA syndrome is a rare autosomic recessive disorder, which includes developmental defects, cancer predisposition and evolutive haematological alterations. The patients present an early pancytopenia associated with a progressive myelodysplasia that eventually predisposes them to acute myeloid leukemia. Cellular hypersensitivity to crosslinking agents is the main difference between this syndrome and other iBMFs. The pathology is due to homozygous mutations in the FANC-BRCA pathway, that groups more than twenty proteins necessary for interstrand crosslinks (ICls) repair, replication stress response and managing of conflicts between replication and transcription. Among them, the FANCA protein is mutated in 60% of the FA patients.In this work, we asked whether the FANC pathway or the FANCA protein might be involved in the nucleolar homeostasy or in ribosomal biogenesis.We observed that FANCA defective cells have an altered nucleolar homeostasy and a slowed ribosomal rRNA synthesis and processing, independently from DNA damage signalling but related to conflicts between replication and transcription in the nucleolus. We show that the destructuration of the nucleolus can lead to p21 stabilisation by the nucleolar protein NPM1. Also, we show that ribosomes in FANCA deficient cells present a misbalance of Eukaryotic translation Initiation Factors (EIFs), and of some ribosomal proteins isoforms, such as the increase of RPL22L1, leading to a translation slowdown.In conclusion, this study shows that nucleolar stress is involved in FA pathogenesis, which links FA to other iBMFs. This paves the way for the investigation of interplays between DNA damage and nucleolar stress in bone marrow failure onset
Akudugu, John Mbabuni. "Examination of irradiated neuroblastoma and neuroepithelial cell lines for the interrelationship between cell survival, micronucleation, apoptosis and DNA repair". Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51755.
Texto completoENGLISH ABSTRACT: Predictive assays are of key importance in clinical radiotherapy, chemotherapy and toxicology. Prior to exposing malignant tissues to irradiation or drugs in the clinic, a good understanding of the damage response to the cytotoxic agent is required. Such information is necessary for effective planning and treatment. Regrettably however the methods which detect DNA damage, namely micronucleus, apoptosis and DNA repair assays do not rank cells according to their intrinsic survival response to cytotoxic agents. The application of predictive assays based on micronuclei and apoptosis in the clinic therefore remains unreliable. Using a panel of 7 neuroblastoma and 6 neuroepithelial cell lines, it is shown that damage assays also do not rank cell lines according to cell survival. However, radiosensitivity can be reconstructed from micronuclei formation and apoptosis, and a new parameter, cell death due to small deletions, chromosome aberrations and misrepair. The interrelationships between radiation-induced micronuclei, apoptosis and repair is complex and varies between cell lines. Micronuclei formation and apoptosis are exponentially interrelated. This suggests that these cell inactivation pathways are strongly correlated. Evidence exists to show that the expression of apoptosis and micronuclei is influenced by the extent of DNA double-strand break repair within the first 2 hours after irradiation. Cell lines which repair more damage in the first 2 hours express more micronuclei and less apoptosis. Micronuclei formation and apoptosis and are not significantly correlated with the 20 hours slow repair component. There is however a strong correlation between 20 hours of repair and radiosensitivity, with the more radioresistant cell lines being more repair proficient. This suggests that the 2 hours (fast) DNA repair component is more error prone, and that cells lines repairing more damage late after irradiation tend to show better survival. In conclusion, micronuclei formation, apoptosis and DNA repair are strictly cell type specific and are not suitable for predicting radiosensitivity in terms of cell survival. However, these assays are very useful for studies on the influences of dose modifying agents i.e. oxygen tension, radiation modality, pH, cytotoxic sensitisers and radiation protectors which alter cellular responses and provide insight into damage mechanisms.
AFRIKAANSE OPSOMMING: Toetse wat kliniese gevolge kan voorspel is van uiterse beking in stralingsterapie, chemoterapie en toksikologie. Voordat kwaadaardige weefsels aan bestraling of chemise middels blootgestel can word in die kliniek, moet daar 'n goeie begrip van die skade weerstand wees van die selgiftige middel. Hierdie inligting is noodsaaklik vir effektiewe beplanning en behandeling. Ongelukkig stem die metodes wat ONS skade, apoptose en ONS hersteltoetse, nie ooreen met die selle se inherente straling sensitiwiteit nie. Die aanwending van voorspelbare toetse gebaseer op mikrokerne en apoptose in die kliniek bly dus onbetroubaar. Deur gebruik te maak van 'n paneel van 13 neurologiese sellyne, is daar bewys dat ONS skade toetse nie sellyne rangskik volgens seloorlewing nie. Radiosensitiwiteit kan herbou word deur 'n neiging om mikrokerne te vorm, apoptose, en sel sterftes weens klein vermiste ONS volgordes, chromosoom aberrasies en verkeerd herstelde ONS. Die verhouding tussen straling-geïnduseerde mikrokerne, apoptose en selgenees is kompleks en varieer tussen sellyne. Die ontstaan van mikrokerne en apoptose is eksponensiel verbind. Dit dui aan dat hierdie seltraagheidsbane streng gekorreleer word. Daar is bewys dat die uitdrukking van apoptose en mikrokerne deur die mate van herstel van die ONS dubbelstring-breuke binne die eerste 2 ure na bestraling beïnvloed is. Daar is gevind dat sellyne wat meer skade herstel binne die eerste 2 ure meer mikrokerne en minder apoptose toon. Die ontstaan van mikrokerne en apoptose is nie betekenisvol gekorreleer met die 20-uur stadige herstel komponent nie. Daar is inderdaad 'n sterk korrelasie tussen die 20-uur herstel komponent en radiosensitiwiteit, en die meer radioweerstandbiedende sellyne net In hoër herstel bekwaamheid. Dit laat mens dink dat die 2 uur (vinnige) DNS herstel komponent meer geneig is om foutief te wees, en dat sellyne wat meer skade, laat na bestraling herstel, beter oorlewing toon. Ten slotte, die ontstaan van mikrokerne, apoptose en DNS herstel is strenggesproke seltipe spesifiek en is nie toepaslik om radiosensitiviteit, in terme van seloorlewing, te voorspel nie. Hierdie toetse is nuttig vir studies waar die invloed van dosismodifiseringsagente, soos suurstof-spanning, straling-tipe, pH, sitotoksieke sensiteerders en stralingsbeskermers, wat sellulêre gevoeligheid verander en insig gee tot skade meganismes.
Albert, Benjamin. "Étude de l'organisation spatiale de la transcription des gènes d'ADN ribosomiques". Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1630/.
Texto completoPol I is the most active and abundant RNA polymerase in eukaryotes. Its enormous transcriptional output can best be visualized using the DNA spread method previously developed by Miller et al. (1969), where the 35S rRNA genes (rDNA) adopt a "Christmas tree" conformation. Pol I activity is associated with the largest nuclear body, the nucleolus, where all earlier steps of ribosome biogenesis take place. In this work, we studied transcription by pol I at different level. At level of the organization of rDNA genes in the nuclear volume, and at molecular level, we studied both function of specific subunits of pol I and role of HMGB proteins on transcription of rDNA. In part, we studied spatial organization of chromosome XII which contains all rDNA genes. Focusing on chromosome XII, we could sample positions of loci distributed on chromosome arms, and extrapolate gene territories determination of the entire chromosome. We could show that the nucleolus is a major determinant of the organization of genome of S. Cerevisiae. Moreover, we have also speculated about spatial organization of rDNA gene in the nucleolus. We have also shown that the Rpa49 and Rpa34 Pol I subunits, which do not have counterparts in Pol II and Pol III complexes, are functionally conserved. Statistical analysis of Miller spreads in the absence of Rpa49 demonstrates a fourfold decrease in Pol I loading rate per gene and decreased contact between adjacent Pol I complexes. We have suggested that Rpa34 and Rpa49 Pol I-specific subunits are essential for nucleolar assembly and for the High polymerase loading rate associated with frequent contact between adjacent enzymes. Moreover, we shown that Pol I activation is achieved by a conserved Pol I transcription factor containing an HMG-B box motif, called HMG-P protein. We could identify three interchangeable HMG-P by heterospecific complementation assay in Saccharomyces cerevisiae, Hmo1 in budding yeast, UBF1, the major regulator of rRNAs transcription in human and a newly characterize fission yeast Sp-Hmo1. We have proposed that stimulation is achieved by maintaining active genes competent for productive elongation
Gouzil, Julie. "Etude du facteur de virulence NSs du virus Schmallenberg". Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC0079.
Texto completoIntroduction: In 2011, an emerging arbovirus named Schmallenberg virus (SBV), and belonging to the Bunyaviridae family, was discovered in Germany. Then, SBV has rapidly spread to Europe infecting wild and domestic ruminants. Adult infection is basically mild and associated with a short viremia (2-5 days). However, in case of pregnant females’ infection, SBV has the ability to cross the placental barrier to infect the foetuses, which can lead to stillbirth and central nervous system developmental abnormalities (arthrogyposis, hydranencephaly). Among bunyavirus-encoded proteins, the non-structural protein NSs has been shown to be an important virulence factor. Indeed, it is able to degrade the Rpb1 subunit of RNA polymerase II, leading to the inhibition of cellular transcription. The work of my thesis aimed to study biochemical and functional properties of NSs and to identify the molecular patterns ruling its main activities.Methods and results: An in silico amino acids sequence analysis was used to predict some common features of NSs and to help the design of several NSs mutants. As predicted by several algorithms, NSs and its mutants are mainly localised to cell nucleus in different cell types (from human and ovine origin). Interestingly, we highlighted an internal sequence (residues 33 to 51) containing a nucleolar localisation signal (NoLS), and have shown that NSs co-localises with several nucleolar proteins. Moreover, infections of human and ovine cell lines with SBV lead to re-localisation of nucleolar proteins to nucleoplasm (B23 and fibrillarin), demonstrating a viral-induced nucleolar stress. To assess the role of the NSs nucleolar localisation in this phenomenon, a recombinant virus, with a mutated version of NSs devoid of its NolS motif (SBVΔNoLS), was constructed by reverse genetic. Infection with SBVΔNoLS does not induce nucleolar stress, suggesting that the nucleolar stress induced by SBV occurs only if NSs is addressed to the nucleolus. Moreover, these results have been confirmed in human neural stem cells, which coud be a more relevant cellular model to mimic SBV infection in foetuses.Another way to study NSs functions was to identify its cellular partners by means of a yeast-two hybrid screen and using NSs as bait. Eight putative interactors of NSs have been discovered, including the dynein light chain type 1 (Tctex-1) and the Major Vault protein (MVP). These proteins are involved in cellular protein transport, notably by their associations with the microtubules network. Thus, NSs might interact with Tctex-1 and MVP to favour its shuttling from cell cytoplasm to the nucleus.Conclusions and perspectives: Altogether, these data indicate that SBV-NSs protein is mainly localised into cell nucleus and nucleolus, by means of its internal NoLS contained in the 33-51 NSs domain. SBV infection induces a nucleolar stress, particularly in human neural stem cells. NSs-induced nucleolar disruption could promote NSs inhibitory function on cellular transcription, and subsequently modulate cellular antiviral state and/or induce cell death. Regarding the pathogenesis in SBV-infected foetuses, nucleolar stress could be responsible for neurons degeneration and subsequent developmental abnormalities. At molecular level, our aim is to define the role of nucleolar protein B23 on viral replication, which is strongly relocalised to the nucleoplasm during SBV infection. Finally, hypothesis of NSs retrograde transport from cell cytoplasm to nucleus and the possible contributions of MVP and/or Tctex-1 needs to be further investigate
Fremerey, Julia [Verfasser], Arndt [Gutachter] Borkhardt y Holger [Gutachter] Schwender. "Nucleolin: a nucleolar rna-binding protein involved in ribosome biogenesis / Julia Fremerey ; Gutachter: Arndt Borkhardt, Holger Schwender". Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2017. http://d-nb.info/1123197792/34.
Texto completoOsička, Ondřej. "Využití teorie her v odpadovém hospodářství". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254425.
Texto completoMontacié, Charlotte. "Le protéasome et le fer : rôles et/ou régulations dans le nucléole d’Arabidopsis thaliana". Thesis, Perpignan, 2019. http://www.theses.fr/2019PERP0002/document.
Texto completoThe aim of this thesis work is to highlight the impact of both nucleolus content and structure on nucleolar functions in A. thaliana. For this I followed two approaches: 1- I performed nucleolus proteome and characterized one of its non-ribosomal activity / 2- I studied nucleolar iron impact on ribosomes biogenesis.Firstly, the A. thaliana nucleolar proteome allowed me to identify nucleolar proteins with non-ribosomal functions. Among these, I showed that 26S proteasome activity can be regulated by nucleolus. More precisely, proteasome activity decreases with nucleolus disorganization. Moreover, I also showed that 26S proteasome, together with Nucleolin, might play a role in ribosomal RNA transcription and/or maturation.Secondly, I proved that loss of nucleolar iron (in nas1,2,4 mutant plants) induces an increase of nucleolar transcriptional structures (fibrillar centers). This observation is correlated with the transcription of normally silenced rDNA from NOR2 and, interestingly, with hypermethylation of rDNA promoters in CHH context. And so, iron might regulate factors implicated in epigenetic pathways responsible of either rDNA transcription or repression
Arabi, Azadeh. "Regulation of the ribosomal RNA transcription by c-MYC oncoprotein /". Stockholm, 2006. http://diss.kib.ki.se/2006/91-7140-947-5/.
Texto completoPerrin, Aurélien. "Caenorhabditis elegans un modèle d’étude des différents compartiments du noyau : de l’étude d’un stress du nucléole par inhibition de la voie de neddylation à la mesure de la compaction de la chromatine in vivo". Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTT049/document.
Texto completoThe ubiquitin-like molecule NEDD8 is conserved and essential for viability, growth and development; its activation pathway is a promising target for therapeutic intervention. We found that the small molecule inhibitor of NEDDylation, MLN4924, alters the morphology and increases the surface size of the nucleolus in human cells and Caenorhabditis elegans germ cells in the absence of nucleolar fragmentation. Through SILAC proteomic analysis and rRNA production, processing and ribosome profiling, we show that MLN4924 changes the composition of the nucleolar proteome but does not inhibit RNA Pol I transcription. Further analysis demonstrates that MLN4924 activates the p53 tumour suppressor through the RPL11/RPL5-Mdm2 pathway, with characteristics of nucleolar stress. The study identifies the nucleolus as a target of the NEDDylation pathway and provides a mechanism for p53 activation upon NEDD8 inhibition.Then we adapted a quantitative FRET (Förster resonance energy transfer)-based fluorescence lifetime imaging microscopy (FLIM) approach to assay the nano-scale chromatin compaction in a living organism, the nematode Caenorhabditis elegans. By measuring FRET between histone-tagged fluorescent proteins, we visualized distinct chromosomal regions and quantified the different levels of nanoscale compaction in meiotic cells. Using RNAi and repetitive extrachromosomal array approaches, we defined the heterochromatin state and showed that its architecture presents a nanoscale-compacted organization controlled by Heterochromatin Protein-1 (HP1) and SETDB1 H3-lysine-9 methyl-transferase homologs in vivo. Next, we functionally explored condensin complexes. We found that condensin I and condensin II are essential for heterochromatin compaction and that condensin I additionally controls lowly compacted regions. Our data show that, in living animals, nanoscale chromatin compaction is controlled not only by histone modifiers and readers but also by condensin complexes.We confirm that C. elegans is an interesting model to study nuclear signalling and perfectly adapt to be a platform for pre-clinical studies
Andrade, Larissa Mara de. "Arquitetura da cromatina na região organizadora do nucléolo e o seu papel no controle da expressão dos genes ribossomais". Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/11/11137/tde-19102011-085333/.
Texto completoThe nucleolus is a nuclear organelle responsible for the ribosomes production, by Nucleolus Organizer Regions (NORs). Species presenting more than one chromosome pair with NORs should present, one pair expressing the genes, at least; while the other pairs expressing their genes accordingly to cellular demand. Dosage compensation mechanism is visualized and well established of interspecific hybrids as a well-described phenomena named nucleolar dominance, where a NOR from one parental could lead to inactivation of a NOR from the other parental which is dominated. The chromatin architecture and expression of the NORs were studied to address the mechanism involved in the nucleolar dominance of diploid species containing multiple sites of 45S rDNA. The model species used in the present study was the crop Crotalaria juncea (Leguminosae-Papilionoideae) characterized by 2n=2x=16 chromosomes, being the main NOR mapped into chromosome 1 short arm and presenting an additional site (minor site) in the chromosome 4 long arm adjacent to a centromeric heterochromatin and facultatively expressed. Synchronized meristematic root tip cells determined to nucleologenesis starts during the late-telophase, often expressing every ribosomal gene sites, when up to four nucleoli could be observed and these become merged during interphases. FISH allowed nucleolar chromatin architecture be accessed revealing distinct chromosomal domains (territories), suggesting a non-random distribution of the 45S rDNA, even between homologous chromosomes, into the nucleolus. The 45S rDNA sites from both chromosome pairs 1 and 4 of C. juncea showed differences in their array sizes. The differences in the 45S rDNA array sizes and the order of loci expression suggest a hierarchy of dominance, a feature of nucleolar dominance; being the small RONs activated only on demand. Immunodetection of histone modifications showed different patterns to methylation distribution across the chromatin as a whole; where H3K9Met1 was found mainly distributed along the nuclear chromatin without an evident signal into nucleolus, while H3K9Met2 was detected as conspicuous dots in the nuclear chromatin and highly accumulated into the nucleolus. The results indicate different control on heterochromatin establishment and maintenance, being the modifications specific to certain chromosomal regions. Indeed, H3K9Met is a key component in the nucleolus chromatin architecture and expression. The chromatin inside the nucleolus showed a high accumulation of H3K14ac, with a weak fluorescent signal along the nucleus; on the other hand H4K8ac showed a strong signal homogenously distributed across the nuclear chromatin, but without evident signals inside the nucleolus. DNA methylation was directly associated with different levels of chromatin organization of the NORs. The heterochromatic regions associated to RON are highly methylated, while the chromatin inside the nucleolus showed weaker signals, with some bright spots probably in condensed regions and related to chromatin inactivity. Extended DNA fiber allowed a higher resolution mapping that revealed long methylated regions intermingled by nomethylated ones, being the last probably associated to transcriptional loops of rRNA genes into the nucleolus. The results presented herein contributes to a better understand about the nucleolar chromatin architecture and the genetic and epigenetic control of the ribosomal genes expression on plant genomes.