Diversidade genética intrapopulacional e variabilidade de genes ligados a determinação do sexo: investigando um caso de reversão sexual em Akodon montensis
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2014-02-26
Autores
Caldara, Sílvia Ramira Lopes
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Universidade Federal do Espírito Santo
Resumo
The first case of sex reversal in Akodonwas reported in 1967 and since then nine news cases were reported. Many authors believe that these XY females are the result of problems in the Sry gene. For sexual reversion in A. montenis itwas suggestedthat maybe some gene that participates on sexual determinant events in X chromosome wouldbe changed. In A. montensisSry gene was detected but its structure, number of copies and functionality was not tested. A curious fact is that only one population (Iguape) has XY females record. Thus it is necessary to investigate what happened in this population the cause the origin or the maintenance of XY females in Iguape. The present study aimed to investigate the role of genes linked to sex determination in sexual reversion for A. montensis, verifying their integrity, copies number and functionality. We also studied demographic structure and phylogenetics patterns to verify bottle necks signals and if there is a common origin for sexual reversion in Akodon.We extracted DNA from 94 individuals from A. montensis and also used DNA for at least 6 species from Akodon genera. It was tested growth neutrality deviation, mismatch distribution, nucleotide and haplotype diversity, gene flow, number of migrants per generation using the control region of mitochondrial DNA. We also investigated the presence and structural integrity of Dax-1 and Sry. In Sry case we investigated the primary and tertiary protein structure using specific 3D modelling programs. Cytochrome b was employed to reconstruct Akodon phylogeny that were used to trace if XY sexual reversed females has one common origin. The results indicates that Iguape population shows signs for a recent population expansion due the possible bottleneck event. Furthermore, these XY females seems to be originated in this population over 15 hundred years. The integrity of Sry was demonstrated and this gene seems to be a species specific marker. There were no differences between Sry gene and protein from males and XY females. Due lack of information available in literature it was not possible to draw specific primersfor Dax-1 amplification and only the exon2 could be analyzed. The analysis form exon 2 also indicated no differences between XY males and females in this species. Real-time PCR can be inferred that there is no difference between the number of copies of the Sry gene between males and females XY.A. The phylogeny tree obtained corroborates previous phylogenies proposed for the genus Akodon and mapping character sex reversal in this phylogeny indicates that this characteristic has multiple origins within the genera. So we concluded that it were not mutations on exon 2 of Dax-1 or changes in the Sry gene, or a protein that lead to sex reversal and other genesfrom sexual cascade should be decisive for the case of XY females A. montensis
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diversidade , variabilidade , reversão sexual
Citação
CALDARA, Sílvia Ramira Lopes. Diversidade genética intrapopulacional e variabilidade de genes ligados a determinação do sexo: investigando um caso de reversão sexual em Akodon montensis. 2014. 148 f. Tese (Doutorado em Biologia Animal) - Universidade Federal do Espírito Santo, Centro de Ciências Humanas e Naturais, Vitória, 2014.