Genome-Enabled Explorations of Evolutionary Ecophysiology in Marine Diatoms
Environmental and Evolutionary Genomics Section
Institut de Biologie de l’Ecole Normale Supérieure, Paris, France
Chris Bowler is currently the Director of the Environmental and Evolutionary Genomics programme in the Institute of Biology at the Ecole Normale Supérieure in Paris. He has published more than 100 peer-reviewed scientific articles in international journals (such as Nature, Science, PNAS, Plant Cell, etc.). His major interest is in understanding the response of plants and marine diatoms to environmental signals. He is member of the European Molecular Biology Organization (EMBO), associate editor of several major scientific journals (Plant Cell, J Phycology, and Marine Biotechnology), and is member of the scientific advisory boards of several internationally renowned research institutes.
Diatoms are thought to be the most successful group of eukaryotic phytoplankton in the modern ocean.Recently completed whole genome sequences from two species,Thalassiosira pseudonanaandPhaeodactylum tricornutum, have revealed a wealth of information about the evolutionary origins and metabolic adaptations that may have led to their ecological success. A major finding is that they have acquired genes both from their endosymbiotic ancestors and by horizontal gene transfer from marine bacteria. This unique melting pot of genes encodes novel capacities for metabolic management, for example allowing the integration of a urea cycle into a photosynthetic cell.Our studies focus onP. tricornutumand exploit the availability of techniques for reverse genetics, digital gene expression profiling, genome and epigenome maps, ecotypes with differential capacities to adapt to different conditions, and distinct morphotypes that can be induced to change shape in response to ecologically relevant stimuli.Using these resources we explore both the physiological functions of diatom gene products and the evolutionary mechanisms that have led to diatom success in contemporary oceans. Specific research topics that we are currently addressing are: 1. How has diatom evolution enabled interactions between chloroplasts and mitochondria that have provided diatoms with physiological and metabolic innovations, and 2.What are the relative contributions of DNA sequence variation and epigenetic processes in diatom adaptive dynamics? Our recent studies have revealed a heretofore unsuspected link between photosynthesis and respiration that centres on the mitochondrial alternative oxidase (AOX), and our exploration of nitrate metabolism has implicated the urea cycle as a hub for the repackaging and distribution of inorganic carbon and nitrogen. Comparative whole genome studies of chromatin landscapes have further revealed fundamental differences with respect to animals, plants, and fungi. A summary of recent findings will be presented.
