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| Author(s): |
Cíntia Pelegrineti Targueta
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia |
| Defense date: | 2013-05-03 |
| Examining board members: |
Luciana Bolsoni Lourenço;
Santiago Ron;
Diego Baldo;
Patricia Pasquali Parise Maltempi;
Marcelo de Bello Cioffi
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| Advisor: | Luciana Bolsoni Lourenço |
| Abstract | |
Of the species in the genus Engystomops, only three species of the Edentulus clade (E. freibergi, E. petersi and E. pustulosus) and two species of the Duovox clade (E. pustulatus and E. puyango) have had their diploid number described, while the NOR (nucleolus organizer region) and the heterochromatic sites were known only for E. freibergi, E. petersi and E. puyango karyotypes. The species of Duovox clade had 2n=20, while the diploid chromosome number of all species of Edentulus clade was 2n=22, which is the same diploid number of species of Physalaemus and Edalohina, genera closely related to Engystomops. Thus, the diploid number reduction from 2n=22 to 2n=20 was supposed, but it was not possible to infer if this was a synapomorphy of E. puyango and E. pustulatus or a synapomorphy of the entire Duovox clade. With regards to the Edentulus clade, some doubts also persisted. Recent studies proposed a complex of Amazonian species misidentified as E. petersi and it was possible to cytogenetically recognize three groups in this complex that corresponded to populations from Puyo (Ecuador), Yasuní (Ecuador) and La Selva (Ecuador). All of these karyotypes also differed from the E. freibergi (Brazil) karyotype. Chromosome homologies are not easily recognized between these groups, a fact that makes difficult the identification of chromosome rearrangements involved in karyotypic divergence in this genus. Additionally, the differentiation of the heteromorphic sex chromosomes found in the E. petersi and E. freibergi karyotypes remained unexplored. The goals of the present work are (1) to cytogenetically study the species of Duovox clade, (2) to better characterize the sex chromosomes of E. freibergi by means of chromosome painting and (3) to find new cytogenetic markers to identify potential chromosome homologies in this genus. The karyotypic analysis showed that the species E. randi, E. guayaco, E. montubio, E. pustulatus and E. coloradorum had 2n=20, as previously described in E. pustulatus and E. puyango. This corroborates the hypothesis that the diploid number 2n=20 is likely a synapomorphy of the Duovox clade. Among the specimens of E. coloradorum, a triploid female was found, which is the first report of polyploidy for the genus Engystomops. In all the females of this species, there was a NOR heteromorphism in the homologous chromosomes 10, suggesting that these may be ZZ/ZW sex chromosomes. Regarding the sex chromosomes of E. freibergi, it was possible to isolate the X and Y chromosomes by microdissection and to produce probes by amplifying segments of the microdissected chromosomes. The hybridization of these probes in E. freibergi metaphases showed that the proximal regions of the X and Y chromosomes of this species had molecular similarity, thus suggesting that they may be pseudoautosomal regions. The sex chromosome probes from E. freibergi detected neither the X nor the Y chromosome of E. petersi from Puyo nor the chromosomes of homomorphic pair 11 of E. petersi from Yasuní. This implies no significant similarity between them and the E. freibergi sex chromosomes. The isolation, characterization and karyotypic localization of the rDNA 5S from the species of the Duovox clade made it possible to infer the homeology of chromosome pair 6 of those species, as well as their homeology with chromosome pair 6 of the species of the Edentulus clade. Further, the probes PcP190EcoRI, which are related to a family of satellite DNA derived from rDNA 5S, made it possible to identify chromosome 5 of E. randi, E. guayaco and E. coloradorum and to differentiate them from chromosome 6, which carry type II rDNA 5S. In conclusion, both classical and molecular cytogenetic techniques provided important contributions for the study of the evolution of the genus Engystomops (AU) | |
| FAPESP's process: | 08/11326-6 - Comparactive cytogenetics of the genera Engystomops with the isolation and characterization of repetitive DNA sequences |
| Grantee: | Cíntia Pelegrineti Targueta de Azevedo Brito |
| Support Opportunities: | Scholarships in Brazil - Doctorate |