Deciphering the molecular and phenotypic effects of a Drosophila melanogaster transposable element located in a unique insertional cluster
[eng] Understanding how organisms adapt to their environment remains an open question in Biology. So far, most projects focus on the study of single nucleotide polymorphism variants, while other types of mutations, likely to play a role in adaptation, are largely ignored. Far instance, the effects o...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2020 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/180959 |
| Acceso en línea: | https://hdl.handle.net/2445/180959 http://hdl.handle.net/10803/672705 |
| Access Level: | acceso abierto |
| Palabra clave: | Genètica Drosòfila melanogaster Adaptació (Biologia) Estrès Genetics Drosophila melanogaster Adaptation (Biology) Stress |
| Sumario: | [eng] Understanding how organisms adapt to their environment remains an open question in Biology. So far, most projects focus on the study of single nucleotide polymorphism variants, while other types of mutations, likely to play a role in adaptation, are largely ignored. Far instance, the effects of transposable elements (TE), which are potent mutagens that introduce genomic variability in natural populations sometimes driving phenotypic adaptations to environmental conditions, are not so well studied. The aim of this work was to characterize the ecological adaptive effects of the Drosophila melanogaster roo insertion FBti0019985, which is located in the 5'UTR of the transcription factor CG18446. To that end, we studied its possible phenotypic effects and investigated the molecular mechanisms behind those functional changes. First, we discovered that besides FBti0019985, the CG18446 prometer region harbours 19 independent roo insertions. The presence of these recurrent roo insertions in the CG18446 promoter region is likely to be the result of several bursts of transposition. We suggest that chromatin accessibility could be one of the factors explaining the multiple insertions. We also investigated whether the identified insertions were functionally equivalent by performing S'RACE, gene expression, and cold-stress survival experiments. We found that only FBti00 19985 was associated with CG18446 up-regulation in embryos and with increased viability in nonstress and under cold-stress conditions. Second, we further studied the molecular and phenotypic effects of FBti00 19985 in different developmental stages and under different stress conditions. Performíng gene expression analysis and in vivo enhancer reporter assays we found that FBti0019985 drives the expression of its nearby gene CG18446 depending on both the developmental stage and the environmental conditions. We associated the presence of FBti0019985 with CG18446 down regulation. However, in embryos under nonstress conditions and in guts under immune-stress, FBti0019985 caused a CG18446 up-regulation. lndeed, we associated this up-regulation with an enhancer activity of the element under these specific contexts. Finally, with the generation of mutant strains with FBti0019985 deletions in O. melanogaster natural populations using the CRISPR/Cas9-mediated homology-directed repair technique, we could also associate the presence of FBti0019985 with tolerance to P. entomophila infection. Overall, this work gives more evidences of the role of TEs in relevant adaptive traits . Moreover, it also reflects the importance of considering the effect of a candidate adaptive insertion under different contexts to fully characterize its adaptive consequences. |
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