Le CEA-Genoscope vous invite à son prochain séminaire sur le thème :
"The universal markers and the conflicting signals"
Le séminaire est présenté par Morgan Gaia, Institut Pasteur
Invité par Olivier Jaillon
Rue Gaston Crémieux
Most tree of life studies rely on the analyses of genes conserved between the three domains. In order to get a vertical evolutionary signal among potential horizontal transfers, these conserved genes are often concatenated together ; the resulting phylogenetic tree hence reflects the global signal carried by the majority of the genes, supposed to correspond to a species tree. However, universal markers concatenations do not systematically carry one global signal with minor noise, but contradicting signals supported by sets of genes. As a consequence, phylogenetic trees obtained from concatenated proteins can reflect the strongest signal within the markers, which is dependent on the markers used or potential biases. This raises several questions : which markers evolved along the species tree ? What does the remaining signal(s) reveal ? Does the repartition of universal markers in different sets correspond to differences in protein size, function, or other factors ? To get more insights on these points, we are performing extensive phylogenetic analyses on each universal marker, individually and in different concatenations. This approach also allows the study of complex co-evolutionary patterns between cells and viruses sharing markers, an aspect rarely considered in the topology of the tree of life and the different associated scenarios.