The role of mitochondria and their genome in plasticity and adaptation

The importance of mitochondria in promoting adaptation to both short- and long-term environmental changes is still largely unexplored. Our research group aims at better understand how organisms exploit mitochondrial epigenetics and genetics to fuel phenotypic variation and evolutionary innovation. By unravelling the links between environment and mt(epi)genotype-phenotype, our research shed new light on our understanding of the living world.

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The mitochondrial alternative proteome

Mitochondria possess a genome (mitochondrial DNA or mtDNA), a vestige of their bacterial ancestor. Over the course of evolution, most of the genes of the ancestor have been lost or transferred to the nucleus. In humans, the mtDNA is limited to 37 genes, with little room for evolutionary novelties. This is radically different from bacterial genomes, which are much larger, and in which we can find genes inside other genes. These sequences are called alternatives open reading frames or altORFs, and they have key functions. By ignoring altORFs, we clearly have underestimated the coding potential of the mtDNA. One interest of our lab is the functional study of the mitochondrial alternative proteome, i.e. characterize the functions of these alternative proteins at the cellular and organism levels.

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Mitogenomics, mitochondrial inheritance

and the DUI system

The mtDNA is described, in the majority of animal species, as coding for 13 proteins involved in energy production. However, we discovered additional protein-coding genes in bivalves (mtORFans with unknown ontology) involved in function other than ATP production (possibly sex determination or sex differentiation), challenging textbooks and indicating that animal mtDNAs have a larger functional repertoire than previously believed. Another interest of our lab is to better understand the function(s) of these mitochondrial ORFan genes.

The mtDNA in animals is strictly maternally inherited (SMI). SMI has apparently evolved to maintain optimal mitonuclear interactions. However, its underlying mechanisms remain largely unknown. To investigate the potential causes of the near-universal stability of SMI, our research aims to unravel the mechanisms underlying the only exception to SMI in animals: the “Doubly Uniparental Inheritance of mtDNA” or DUI in bivalves.

Image de Philipp Deus