Submitted by Vasti Diniz (vastijpa@hotmail.com) on 2017-09-08T11:33:23Z No. of bitstreams: 1 arquivototal.pdf: 1921817 bytes, checksum: 7ba035d7ef40f1aafd9f93476aabedd6 (MD5) / Made available in DSpace on 2017-09-08T11:33:23Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1921817 bytes, checksum: 7ba035d7ef40f1aafd9f93476aabedd6 (MD5) Previous issue date: 2016-03-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Epigenetics is the study heritable changes of in gene expression without modifications in the primary sequence of DNA. In our study we investigated the influence of sun exposure on global DNA methylation and hydroxymethylation status and at specific sites of the miR-9-1, miR9-3 and MTHFR genes in skin samples of subjects with no history of skin diseases. Skin biopsies were obtained by punch on sun-exposed and sun-protected arm areas from 24 corpses aged 16-89 years old from the Brazilian Service of Death Investigation. Genomic DNA was extracted from skin samples that were ranked according to Fitzpatrick’s criteria as light, moderate and dark brown. Global DNA methylation and hydroxymethylation and DNA methylation at specific sites analyses were performed using an ELISA and MSP, respectively. No significant differences in global DNA methylation and hydroxymethylation levels were found between the skin areas, skin type or age. However, gender-related differences were detected, where women showed higher methylation levels in comparison to those in men. Global DNA methylation levels were higher than hydroxymethylation levels, and the levels of these DNA modifications correlated in skin tissue. For specific sites, it was detected no differences among areas. Additional analyses showed no differences in the methylation status when age, gender and skin type were considered. We conclude that sun exposure does not induce changes in the global DNA methylation and hydroxymethylation status or at specific sites in the miR-9-1, miR-9-3 and MTHFR genes for skin types studied. / A epigenética é o estudo das alterações hereditárias na expressão gênica sem mudanças na sequência primária do DNA. No nosso estudo investigamos a influência da exposição solar sobre o perfil de metilação e hidroximetilação global de DNA e em sítios específicos nos genes miR-9-1, miR-9-3 e MTHFR em amostras de pele humana. Para isso, biópsias foram obtidas por punch circular de área exposta e não exposta ao sol do braço de 24 cadáveres de ambos os sexos, com idade entre 16-89 anos sem histórico de doenças de pele oriundos do Serviço de Verificação de Óbitos da Paraíba (SVO). O DNA foi extraído e a análise de metilação e hidroximetilação global do DNA foi realizada através de Elisa indireto. A análise de metilação nos sítios específicos dos genes miR-9-1, miR-9-3 e MTHFR foi realizada por meio de PCR específica para metilação (MSP) seguida de eletroforese. As análises estatísticas foram realizadas pelo software BioEstat 5.0 ao nível de significância de 5%. Não encontramos diferenças significativas nos níveis de metilação e hidroximetilação global de DNA entre as áreas exposta e não exposta da pele, tipo de pele ou idade. No entanto, foram detectadas diferenças em relação ao gênero, onde as mulheres apresentaram nível de metilação global mais alto em comparação aos homens. O nível de metilação global de DNA foi maior do que o nível de hidroximetilação, sendo estes, correlacionados no tecido da pele. Para sítios específicos, não foi detectada nenhuma diferença entre as áreas. Análises adicionais mostraram não haver diferenças significativas no perfil de metilação quando consideradas a idade, gênero e o tipo de pele. Conclui-se que a exposição ao sol não induz mudanças no perfil de metilação e hidroximetilação global do DNA ou em sítios específicos dos genes miR-9-1, miR-9-3 e MTHFR para os tipos de pele estudado.

Hematopoiesis is a highly orchestrated process, in which a single hematopoietic stem cell (HSC) gives a rise to all blood cellular components. For myeloid and lymphoid development precise controlled expression of the PU.1 transcription factor is needed. Deletion of PU.1 gene in mouse is lethal and its dysregulation during hematopoietic differentiation is associated with blood malignancies including acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). MDS and AML are serious blood disorders characterized by expansion of immature blood cells and lack of differentiated functional cells. Not only genetic but also epigenetic aberrations represent a very important field for studying pathophysiology of leukemia genesis and dysregulation of the PU.1 gene represents intensively studied candidate mechanism. Modern therapy of selected MDS and subset of AML patients is based on treatment with DNA hypomethylating agent Azacytidine (AZA) interfering in PU.1 gene regulatory mechanism. However, poor response or resistance to this therapy often occurs. In this thesis we present data obtained from AZA-resistant clones of MDS/AML cell line OCI-M2. We analysed DNA methylation and DNA hydroxymethylation at the key regulatory element of the PU.1 gene (URE). We found that these epigenetic modifications at URE...

Ces travaux de thèse portent sur la conversion par catalyse hétérogène du furfural (produit biosourcé produit, par déshydratation du xylose issu de l'hydrolyse acide de l'hémicellulose) en acide 2,5-furane dicarboxylique (FDCA, substituant potentiel de l'acide téréphtalique, monomère de polyesters et polyamides, issu du pétrole). Cette transformation a été envisagée en deux étapes catalytiques: 1) l'hydroxyméthylation du furfural en 5-hydroxyméthylfurfural (HMF) par le formaldéhyde aqueux ou le trioxane en présence d'un catalyseur acide. Les rendements maxima de 40% ont été obtenus en utilisant le formaldéhyde aqueux en présence de nanoparticules de ZSM-5. L'instabilité du furfural et du HMF dans ces conditions réactionnelles est la principale difficulté. 2) l'oxydation aérobie du HMF en FDCA. En milieu alcalin faible (Na2CO3), en présence d'un catalyseur Pt/C promu par le Bi (rapport molaire Bi/Pt = 0,2) à 100 °C et sous 40 bar d'air, le FDCA est obtenu avec un rendement quantitatif. La modification du Pt par le bismuth permet de limiter la lixiviation du Pt dans le milieu réactionnel et de recycler le catalyseur sans prétraitement préalable et sans perte significative de l'activité, comme démontré ensuite en réacteur continu / This thesis reports a study of heterogeneously catalyzed conversion of furfural (biobased product formed from the acid-catalyzed dehydration of xylose) into 2,5-furane dicarboxylique acid (FDCA, possible replacement monomer for terephtalic acid for the production of polyethylene terephtalate). This transformation has been considered in two catalytic steps: 1) hydroxymethylation of furfural with aqueous formaldehyde or trioxane into 5-hydroxymethylfurfural (HMF) in the presence of solid acids. The maximum yields of 40% have been obtained using aqueous formaldehyde in the presence of nanoparticles of ZSM-5. The main problem was the lack of stability of furfural and HMF in reaction conditions. 2) aerobic oxidation of HMF into FDCA. HMF was oxidized in alkaline aqueous solutions over Pt-based catalysts using dioxygen from air. Promotion of the catalyst with bismuth and the presence of a weak base (Na2CO3) yielded a catalytic system with a remarkable activity and selectivity. HMF was completely and exclusively converted to FDCA within 2,5 h. The catalyst could be recovered by simple filtration and reused several times without significant loss of activity and with no platinum or bismuth leaching