Émélie Leroux
Project
Mitochondrial DNA methylation in common mussel (Mytilus edulis)DNA methylation is an essential epigenetic mechanism found in most living organisms, and is crucial in the regulation of gene expression. Several environmental stimuli can influence the management of this mechanism during the development and throughout the life of organisms. Methylation of the nuclear genome in mammals is generally restricted to cytosines preceding a guanine, while it operates in several other context in bacteria. Several studies suggest that methylation of the genome found in the mitochondria not only exists, but is also found in a much more varied context than in the nuclear genome, just like in their evolutionary relative, the bacteria. In particular, it is mainly found on cytosines which does not precede a guanine, and on adenines. Studies on mitochondrial DNA (mtDNA) methylation is mostly limited to mammals and a few unicellular organisms, and remain almost non-existent in invertebrates. However, certain characteristics found in some invertebrates species, such as bivalves, make the study of this mechanism particularly interesting. Indeed, rather than transmitting their mitochondria exclusively through the mother, like most animal species, the majority of bivalves species own a system called doubly uniparental inheritance (or DUI). In this system, each individual inherits two parental mtDNAs: the one from their father (M mtDNA) and the one from their mother (F mtDNA). After development, females have only F mtDNA in all of their tissues, while males have exclusively M mtDNA in their gametes and a varying proportion of both mtDNAs in their somatic and gonadal tissues. Since methylation is influenced by the environment, my project will study the variability of methylation patterns, both on cytosines and adenines, between M and F mtDNAs found in different cellular environments of a bivalve DUI species, the common mussel (Mytilus edulis).
