title: Nucleomorph genomes.
abstract: Nucleomorphs are the remnant nuclei of algal endosymbionts in cryptophytes and chlorarachniophytes, two evolutionarily distinct unicellular eukaryotic lineages that acquired photosynthesis secondarily by the engulfment of red and green algae, respectively. At less than one million base pairs in size, nucleomorph genomes are the most highly reduced nuclear genomes known, with three small linear chromosomes and a gene density similar to that seen in prokaryotes. The independent origin of nucleomorphs in cryptophytes and chlorarachniophytes presents an interesting opportunity to study the reductive evolutionary forces that have led to their remarkable convergence upon similar genome architectures and coding capacities. In this article, we review the current state of knowledge with respect to the structure, function, origin, and evolution of nucleomorph genomes across the known diversity of cryptophyte and chlorarachniophyte algae.
authors.affiliation: The Canadian Institute for Advanced Research, Program in Integrated Microbial Biodiversity, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 1X5, Canada.
authors.forename: Christa E
authors.initials: CE
authors.lastname: Moore
authors.forename: John M
authors.initials: JM
authors.lastname: Archibald
mesh_terms: D000460:Chlorophyta / Q000235:genetics; D044785:Cryptophyta / Q000145:classification / Q000166:cytology / Q000235:genetics*; D056890:Eukaryota / Q000145:classification / Q000166:cytology / Q000235:genetics*; D016678:Genome; D000461:Rhodophyta / Q000235:genetics