title: microRNAs and the evolution of complex multicellularity: identification of a large, diverse complement of microRNAs in the brown alga Ectocarpus.
abstract: There is currently convincing evidence that microRNAs have evolved independently in at least six different eukaryotic lineages: animals, land plants, chlorophyte green algae, demosponges, slime molds and brown algae. MicroRNAs from different lineages are not homologous but some structural features are strongly conserved across the eukaryotic tree allowing the application of stringent criteria to identify novel microRNA loci. A large set of 63 microRNA families was identified in the brown alga Ectocarpus based on mapping of RNA-seq data and nine microRNAs were confirmed by northern blotting. The Ectocarpus microRNAs are highly diverse at the sequence level with few multi-gene families, and do not tend to occur in clusters but exhibit some highly conserved structural features such as the presence of a uracil at the first residue. No homologues of Ectocarpus microRNAs were found in other stramenopile genomes indicating that they emerged late in stramenopile evolution and are perhaps specific to the brown algae. The large number of microRNA loci in Ectocarpus is consistent with the developmental complexity of many brown algal species and supports a proposed link between the emergence and expansion of microRNA regulatory systems and the evolution of complex multicellularity.
authors.affiliation: School of Earth Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK Genome Evolution Laboratory, Department of Biology, The National University of Ireland, Maynooth, Kildare, Ireland.
authors.forename: James E
authors.initials: JE
authors.lastname: Tarver
authors.affiliation: Sorbonne Université, UPMC Univ Paris 06, CNRS, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Cormier
authors.affiliation: Institute of Human Genetics, UPR 1142, CNRS, 34396 Montpellier Cedex 5, France.
authors.forename: Natalia
authors.initials: N
authors.lastname: Pinzón
authors.affiliation: School of Earth Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK.
authors.forename: Richard S
authors.initials: RS
authors.lastname: Taylor
authors.affiliation: Sorbonne Université, UPMC Univ Paris 06, CNRS, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff, France.
authors.forename: Wilfrid
authors.initials: W
authors.lastname: Carré
authors.affiliation: Sorbonne Université, UPMC Univ Paris 06, CNRS, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff, France.
authors.forename: Martina
authors.initials: M
authors.lastname: Strittmatter
authors.affiliation: Institute of Human Genetics, UPR 1142, CNRS, 34396 Montpellier Cedex 5, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Seitz
authors.affiliation: Sorbonne Université, UPMC Univ Paris 06, CNRS, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff, France.
authors.forename: Susana M
authors.initials: SM
authors.lastname: Coelho
authors.affiliation: Sorbonne Université, UPMC Univ Paris 06, CNRS, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff, France cock@sb-roscoff.fr.
authors.forename: J Mark
authors.initials: JM
authors.lastname: Cock
mesh_terms: D019143:Evolution, Molecular; D056426:Genetic Loci; D014644:Genetic Variation; D016678:Genome; D035683:MicroRNAs / Q000737:chemistry / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D000459:Phaeophyceae / Q000235:genetics* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D017423:Sequence Analysis, RNA
chemical_list: D035683:MicroRNAs