Publicação
Testing endosymbiont-mediated immune protection in a novel host species
| Resumo: | The complexity of life forms cannot be explained without the concept of symbiosis. Symbiotic relations exist abundantly in nature, particularly the ones between bacteria and eukaryotic hosts. One of the most widespread endosymbiotic bacteria described belongs to the genus Wolbachia, naturally infecting arthropods and nematodes. In arthropods, Wolbachia induces reproductive manipulations, to promote infected female’s fitness as they are vertically transmitted, maternally. Additionally, in Drosophila melanogaster, they have been shown to confer protection against viral infections. Being an obligatory vertically-transmitted endosymbiont, Wolbachia phylogeny should recapitulate that of its hosts. However, several studies show that host and symbiont phylogenies are not concordant, suggesting that horizontal transfers must have occurred throughout time. This has been confirmed, namely between parasitoid wasps and their hosts. Considering these observations, the present project aimed at uncovering if and at which rate horizontal transmission of Wolbachia could occur between Drosophila melanogaster and its natural parasitoid Leptopilina boulardi. Also, we tested if the viral protection phenotype induced in Drosophila would be passed on to the novel host, after this horizontal transfer event. Simultaneously we screened a wild-caught population of Leptopilina heterotoma for Wolbachia presence. We obtained infected individuals with which we established an isofemale line and derived Wolbachia-negative counterparts using antibiotic treatment. With this tool, we characterized the effects of Wolbachia presence upon viral systemic infection. Our results show that horizontal transmission of Wolbachia happens between Leptopilina boulardi and its host, but the infection is not stably maintained. We also see that these wasps do not appear to be susceptible to viruses that are pathogenic in Drosophila (specifically DCV and FHV) and appear to be mildly Detrimental to Wolbachia-infected Leptopilina heterotoma. Finally, we have verified that a natural endosymbiont infection appears to delay full development time in Leptopilina heterotoma, although no effect is detected for longevity. With this work we have established an experimental system for the controlled and systematic study of the complex interactions between Drosophila, parasitoid wasps, Wolbachia and viruses. |
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| Autores principais: | Paulo, Tânia Filipa Teixeira |
| Assunto: | Vespa parasitóide Drosophila melanogaster Wolbachia Transmissão horizontal Proteção viral Teses de mestrado - 2015 |
| Ano: | 2015 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | The complexity of life forms cannot be explained without the concept of symbiosis. Symbiotic relations exist abundantly in nature, particularly the ones between bacteria and eukaryotic hosts. One of the most widespread endosymbiotic bacteria described belongs to the genus Wolbachia, naturally infecting arthropods and nematodes. In arthropods, Wolbachia induces reproductive manipulations, to promote infected female’s fitness as they are vertically transmitted, maternally. Additionally, in Drosophila melanogaster, they have been shown to confer protection against viral infections. Being an obligatory vertically-transmitted endosymbiont, Wolbachia phylogeny should recapitulate that of its hosts. However, several studies show that host and symbiont phylogenies are not concordant, suggesting that horizontal transfers must have occurred throughout time. This has been confirmed, namely between parasitoid wasps and their hosts. Considering these observations, the present project aimed at uncovering if and at which rate horizontal transmission of Wolbachia could occur between Drosophila melanogaster and its natural parasitoid Leptopilina boulardi. Also, we tested if the viral protection phenotype induced in Drosophila would be passed on to the novel host, after this horizontal transfer event. Simultaneously we screened a wild-caught population of Leptopilina heterotoma for Wolbachia presence. We obtained infected individuals with which we established an isofemale line and derived Wolbachia-negative counterparts using antibiotic treatment. With this tool, we characterized the effects of Wolbachia presence upon viral systemic infection. Our results show that horizontal transmission of Wolbachia happens between Leptopilina boulardi and its host, but the infection is not stably maintained. We also see that these wasps do not appear to be susceptible to viruses that are pathogenic in Drosophila (specifically DCV and FHV) and appear to be mildly Detrimental to Wolbachia-infected Leptopilina heterotoma. Finally, we have verified that a natural endosymbiont infection appears to delay full development time in Leptopilina heterotoma, although no effect is detected for longevity. With this work we have established an experimental system for the controlled and systematic study of the complex interactions between Drosophila, parasitoid wasps, Wolbachia and viruses. |
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