title: The Ectocarpus IMMEDIATE UPRIGHT gene encodes a member of a novel family of cysteine-rich proteins with an unusual distribution across the eukaryotes.
abstract: The sporophyte generation of the brown alga Ectocarpus sp. exhibits an unusual pattern of development compared with the majority of brown algae. The first cell division is symmetrical and the apical-basal axis is established late in development. In the immediate upright (imm) mutant, the initial cell undergoes an asymmetric division to immediately establish the apical-basal axis. We provide evidence which suggests that this phenotype corresponds to the ancestral state of the sporophyte. The IMM gene encodes a protein of unknown function that contains a repeated motif also found in the EsV-1-7 gene of the Ectocarpus virus EsV-1. Brown algae possess large families of EsV-1-7 domain genes but these genes are rare in other stramenopiles, suggesting that the expansion of this family might have been linked with the emergence of multicellular complexity. EsV-1-7 domain genes have a patchy distribution across eukaryotic supergroups and occur in several viral genomes, suggesting possible horizontal transfer during eukaryote evolution.
authors.affiliation: CNRS, Sorbonne Université, UPMC University Paris 06, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, Roscoff F-29688, France.
authors.forename: Nicolas
authors.identifier: 0000-0002-0109-9845
authors.initials: N
authors.lastname: Macaisne
authors.affiliation: CNRS, Sorbonne Université, UPMC University Paris 06, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, Roscoff F-29688, France.
authors.forename: Fuli
authors.initials: F
authors.lastname: Liu
authors.affiliation: CNRS, Sorbonne Université, UPMC University Paris 06, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, Roscoff F-29688, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Scornet
authors.affiliation: Bezhin Rosko, Santec 29250, France.
authors.forename: Akira F
authors.identifier: 0000-0001-5332-199X
authors.initials: AF
authors.lastname: Peters
authors.affiliation: CNRS, Sorbonne Université, UPMC University Paris 06, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, Roscoff F-29688, France.
authors.forename: Agnieszka
authors.identifier: 0000-0002-1829-8293
authors.initials: A
authors.lastname: Lipinska
authors.affiliation: CNRS, Sorbonne Université, UPMC University Paris 06, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, Roscoff F-29688, France.
authors.forename: Marie-Mathilde
authors.initials: MM
authors.lastname: Perrineau
authors.affiliation: CNRS, Sorbonne Université, UPMC University Paris 06, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, Roscoff F-29688, France.
authors.forename: Antoine
authors.identifier: 0000-0003-4952-5812
authors.initials: A
authors.lastname: Henry
authors.affiliation: CNRS, Sorbonne Université, UPMC University Paris 06, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, Roscoff F-29688, France.
authors.forename: Martina
authors.initials: M
authors.lastname: Strittmatter
authors.affiliation: CNRS, Sorbonne Université, UPMC University Paris 06, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, Roscoff F-29688, France.
authors.forename: Susana M
authors.initials: SM
authors.lastname: Coelho
authors.affiliation: CNRS, Sorbonne Université, UPMC University Paris 06, Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, Roscoff F-29688, France cock@sb-roscoff.fr.
authors.forename: J Mark
authors.identifier: 0000-0002-2650-0383
authors.initials: JM
authors.lastname: Cock
mesh_terms: D020418:Algal Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D003545:Cysteine / Q000737:chemistry; D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D022761:Gene Transfer, Horizontal; D008957:Models, Genetic; D005810:Multigene Family; D009154:Mutation; D000459:Phaeophyceae / Q000235:genetics* / Q000254:growth & development / Q000821:virology; D010802:Phylogeny; D034622:RNA Interference; D017386:Sequence Homology, Amino Acid; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics
chemical_list: D020418:Algal Proteins; D014764:Viral Proteins; D003545:Cysteine
keywords: Brown algae; Ectocarpus; Horizontal gene transfer; Initial cell division; Life cycle; Virus