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Doctoral Thesis
DOI
https://doi.org/10.11606/T.42.2013.tde-03062014-175441
Document
Author
Full name
Simone Guedes Calderano
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2013
Supervisor
Committee
Sabbaga, Maria Carolina Quartim Barbosa Elias (President)
Bartholomeu, Daniella Castanheira
Machado, Carlos Renato
Teixeira, Santuza Maria Ribeiro
Winter, Lucile Maria Floeter
Title in Portuguese
Alternativas da replicação do DNA: vias de controle e dinâmica das forquilhas em trypanosomas.
Keywords in Portuguese
Trypanosoma cruzi
Trypanosoma
Replicação do DNA
Abstract in Portuguese
A replicação do DNA tem início nas origens de replicação que são licenciadas na transição das fases M/G1, pelo complexo de pré-replicação (CPR), e ativadas apenas na fase S. Existem diversas origens de replicação no genoma, mas apenas parte destas origens é disparada em diferentes momentos de S, havendo assim origens early (disparadas no início de S) e late (disparadas mais tardiamente). Em trypanosomas as origens de replicação são reconhecidas por um CPR formado por Orc1/Cdc6 e pelo complexo MCM2-7. Em T. cruzi observamos que existem dois mecanismos diferentes para controlar a replicação do DNA. Durante o ciclo celular da forma epimastigota, as proteínas do CPR são sempre expressas e ligadas ao DNA, mas durante o ciclo de vida Orc1/Cdc6 se liga ao DNA apenas nas formas que replicam, e Mcm7 não é expressa nas que não replicam. Também foi analisado o perfil das forquilhas de replicação em T. brucei utilizando a técnica de SMARD onde vimos que a velocidade da forquilha é semelhante a dos demais eucariontes, além de encontrarmos a primeira origem de replicação late.
Title in English
DNA replication alternatives: control pathways and fork dynamic in trypanosomas.
Keywords in English
Trypanosoma cruzi
Trypanosoma
DNA replication
Abstract in English
The DNA replication starts at the origins of replication, which are licensed at M/G1 transition, by the pre replication complex (PRC), and are activated just at S phase. There are many origins of replication along genome, but some of them are fired at different moments of S phase. So there are early and late origins fired at the beginning or later in S phase, respectively. The PRC of trypanosomes is composed of Orc1/Cdc6 and Mcm2-7. We could observe that in T. cruzi there are two distinct ways to control DNA replication. Whereas in epimastigote cell cycle the PRC are expressed and bound to DNA in all phases, during T. cruzi life cycle Orc1/Cdc6 is bound to DNA only in replicative forms and Mcm7 is absent in the non-replicative forms. We also analyzed the fork profile in T. brucei through SMARD technique. We found that the speed of replication fork is similar from other eukaryotes and that different replication origins are fired every cell cycle. Finally, we found a new origin of replication that is the first late origin described in this organism.
 
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Publishing Date
2014-06-05
 
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