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Previous issue date: 2008-03-31 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The phylogeny is one of the main activities of the modern taxonomists and a way to reconstruct the history of the life through comparative analysis of these sequences
stored in their genomes aimed find any justification for the origin or evolution of them. Among the sequences with a high level of conservation are the genes of repair because it is important for the conservation and maintenance of genetic stability. Hence, variations in repair genes, as the genes of the nucleotide excision repair (NER), may indicate a possible gene transfer between species. This study aimed to examine the evolutionary history of the components of the NER. For this, sequences of UVRA, UVRB, UVRC and XPB were obtained from GenBank by Blast-p, considering 10-15 as cutoff to create a database. Phylogenetic studies were done using algorithms in PAUP programs, BAYES and PHYLIP package. Phylogenetic trees were build with protein sequences and with sequences of 16S ribosomal RNA for comparative analysis by the methods of parsimony, likelihood and Bayesian. The XPB tree shows that archaeal?s XPB helicases are similar to eukaryotic helicases. According to this data, we infer that the eukaryote nucleotide excision repair system had appeared in Archaea. At UVRA, UVRB and UVRC trees was found a monophyletic group formed by three species of epsilonproteobacterias class, three species of mollicutes class and archaeabacterias of Methanobacteria and Methanococci classes. This information is supported by a tree obtained with the proteins, UVRA, UVRB and UVRC concatenated. Thus, although there are arguments in the literature defending the horizontal transfer of the system uvrABC of bacteria to archaeabacterias, the analysis made in this study suggests that occurred a vertical transfer, from archaeabacteria, of both the NER genes: uvrABC and XPs. According the parsimony, this is the best way because of the occurrence of monophyletic groups, the time of divergence of classes and number of archaeabacterias species with uvrABC system / A filogen?mica estuda os organismos atrav?s de an?lises comparativas das seq??ncias conservadas presentes em seus genomas visando encontrar alguma justificativa para a origem ou a evolu??o dos mesmos. Dentre as seq??ncias com
elevado n?vel de conserva??o encontram-se os genes de reparo, pois s?o importantes para a conserva??o e manuten??o da estabilidade gen?tica. Por isso, varia??es em genes de reparo, como os da via de excis?o de nucleot?deos (REN),
podem indicar uma poss?vel transfer?ncia g?nica entre esp?cies. O presente trabalho teve o objetivo de analisar a hist?ria evolutiva dos componentes do REN. Para isso, seq??ncias de UVRA, UVRB, UVRC e XPB foram obtidas a partir do GenBank por Blast-p, considerando-se 10-15 como limiar, com o fim de criar um banco de dados. Estudos filogen?ticos foram feitos utilizando algoritmos presentes nos programas PAUP, BAYES e no pacote PHYLIP. Foram constru?das ?rvores com seq??ncias prot?icas e com seq??ncias de RNA riboss?mico 16S para an?lises comparativas atrav?s dos m?todos de parcim?nia, verossimilhan?a e bayesiano. De acordo com a ?rvore de XPB, as helicases dos eucariotos s?o similares as das arqueobact?rias e apresentam comportamento semelhante ao longo da evolu??o, ou seja, compartilham um mesmo ancestral. Nas filogenias feitas para cada prote?na do sistema uvrABC, foram encontradas tr?s esp?cies da classe epsilonproteobacterias, tr?s esp?cies da classe mollicutes e arqueobacterias das classes Methanobacteria e Methanococci formando um grupo monofil?tico. Esse dado ? fortalecido atrav?s de uma ?rvore obtida com as prote?nas, UVRA, UVRB e UVRC concatenadas. Assim, embora existam argumentos, na literatura, defendendo a transfer?ncia horizontal do sistema uvrABC de bact?rias para arqueobact?rias, a an?lise feita neste estudo sugere que a transfer?ncia vertical, tendo arquebacterias como origem, tanto do sistema uvrABC quanto dos genes XP, seja o caminho mais parcimonioso, considerando a ocorr?ncia de grupos monofil?ticos, o tempo de diverg?ncia das classes e o n?mero de esp?cies e arqueobact?rias portadoras dos genes do sistema uvrABC
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/16761 |
| Date | 31 March 2008 |
| Creators | Silva, Uaska Bezerra e |
| Contributors | CPF:00297997750, http://lattes.cnpq.br/1083882171718362, Melo, V?nia Maria Maciel, CPF:11269545353, http://lattes.cnpq.br/1572504650930605, Medeiros, S?lvia Regina Batistuzzo de, CPF:32398336468, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4781004Y8, Lima, Lucymara Fassarela Agnez |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Gen?tica e Biologia Molecular, UFRN, BR, Gen?tica e Biologia Molecular |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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