Algal Development and Evolution

Susana Coelho

Susana Coelho 143 cropped
  • PhD, Marine Biological Association of the UK (2003)
  • EMBO and Marie Curie Postdoctoral fellow, CNRS-Sorbonne University, France (2004-2006)
  • Group Leader, then Research Director at the CNRS Station Biologique de Roscoff, France (2006-2020)
  • Director at the MPI for Developmental Biology (since 2020)

 

 

Research Interest

Our research focuses on understanding the origin, evolution and regulation of sexual development and sex determining systems. We use the brown algae as model organisms. The brown algae are a eukaryotic supergroup that has been evolving independently of animals and land plants for more than a billion years. During that time, they acquired multicellularity independently of the former groups and have become the third most complex multicellular lineage on the planet. In addition, extant brown algae exhibit a remarkable diversity of types of sexual life cycles and sex determination systems. Surprisingly, whilst an enormous effort has been expended to understand the developmental and reproductive biology of animals and land plants, the brown algae have been almost completely ignored and very little is known about how these organisms function at the molecular level. Exploration of this group of eukaryotes is expected to provide important, fundamental insights into the processes underlying the evolution of complex multicellular life. In our department, we use a combination of genetic, genomic and molecular evolution approaches to understand how sexual development and sex determining systems are regulated in the brown algae and how these processes interact at the functional and evolutionary level.

Our previous work has allowed the identification of several major developmental regulators and we have dissected the chromosomal basis of sex determination in this group of eukaryotes, providing a solid foundation for the future advances of brown algal developmental biology and comparative molecular biology. Ongoing work on large scale evolution of sex chromosomes is making use of a large number of brown algal full genome sequences, in the context of SEXSEA and TETHYS (ERC Starting and Consolidator grants) in collaboration with Phaeoexplorer (France Genomique genome project). We are addressing two fundamental questions: i) the origin, evolution and regulation of sexual systems diversity across eukaryotes and ii) the molecular and evolutionary mechanisms that underlie the emergence of complex multicellularity and associated reproductive features in the brown algae. We tackle these problems using the outstanding diversity of reproductive and life cycle features of the brown algae, and their amenability for genetic, genomic and molecular evolutionary approaches.

Available PhD Projects

Evolutionary developmental transcriptomics in the brown algae

The goal of the project is to reveal the evolution of genetic programs controlling sexual development in the brown algae, in a phylogenetic framework, using evolutionary transcriptomics approaches. We aim to generate a time-resolved transcriptional map for key stages of sexual development in 18 brown algal species representing a range of sexual traits, taking into account both patterns of expression during sexual development and changes in these patterns over evolutionary time across the brown algal group, with a particular focus on changes associated with sexual system transitions. We will delineate orthologous protein families and compute the multi-dimensional patterns of expression throughout the ontogeny of sexual development and across the phylogeny. In order to assess the evolutionary history and age of the transcriptome at a given stage of the life cycle we will use genomic phylostratigraphy and examine if there is a phylotypic stage (i.e., the stage where transcriptomes are most conserved) and whether switches between sexual systems impact this phylotypic stage. Results from this project are expected to shed light into the evolution of gene regulatory pathways during multicellular development, and specifically during sex determination and differentiation in a underexplored eukaryotic lineage.

Selected Reading

1) Ahmed S, Cock JM, Pessia E, Luthringer R, Cormier A, Robuchon M, Sterck L, Peters AF, Dittami SM, Corre E, Valero M, Aury J-M, Roze D, Van de Peer Y, Bothwell J, Marais GAB, Coelho SM. 2014. A haploid system of sex determination in the brown alga Ectocarpus sp. Curr Biol 24:1945–1957. doi:10.1016/j.cub.2014.07.042

2) Coelho SM, Gueno J, Lipinska AP, Cock JM, Umen JG. 2018. UV Chromosomes and Haploid Sexual Systems. Trends Plant Sci 23:794–807. doi:10.1016/j.tplants.2018.06.005

3) Godfroy O, Uji T, Nagasato C, Lipinska AP, Scornet D, Peters AF, Avia K, Colin S, Laure M, Motomura T, Cock JM, Coelho SM. 2017. DISTAG/TBCCd1 Is Required for Basal Cell Fate Determination in Ectocarpus. Plant Cell. doi:10.1105/tpc.17.00440

4) Lipinska AP, Toda NRT, Heesch S, Peters AF, Cock JM, Coelho SM. 2017. Multiple gene movements into and out of haploid sex chromosomes. Genome Biol 18:104. doi:10.1186/s13059-017-1201-7