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Raboisson_49191900_2025.pdf
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- The human lifespan is increasing considerably, but despite this progress, there are still many grey areas in our understanding of aging. The biological factors involved in this process have currently been defined by 12 ‘hallmarks of aging’, which include mitochondrial dysfunction. This dysfunction can occur due various problems, which includes impaired nuclear-encoded protein import, which induces the Unfolded Protein Response (UPRmt) in response to mitochondrial stress. This Master’s thesis focused on the study of mitochondrial protein import in the brain of Nothobranchius furzeri, a species relevant to study aging. The objectives are twofold: to develop a protocol for measuring the import of proteins into N. furzeri brain mitochondria, and to study the consequences of inhibition of mitochondrial import by MitoBloCK-6 on the components of the import machinery and the main players in UPRmt at 8 and 20 weeks of age, representing young and old fish. The import protocol was adapted from an established method for Saccharomyces cerevisiae. Although the optimisation of this assay could not be completed within the scope of this Master’s thesis, it nevertheless remains promising for N. furzeri, with some negative control problems to be resolved. Verification of mitochondrial integrity by electron microscopy is envisaged prior to further optimisation. N. furzeri were exposed to different concentrations of MitoBloCK-6 during their first 7 days of life. At 8 and 20 weeks of age, no clear trend was found for gene expression and protein abundance of the import machinery and UPRmt, contrary to our expectations. This lack of trend could reflect a reversibility of MitoBloCK-6 effects once treatment is stopped. It would therefore be interesting to expose N. furzeri for a week before brain collection from young and old fish to observe an acute response.