title: Is Giardia a living fossil?
abstract: Despite enormous efforts, the patterns of the rise of eukaryotic life on Earth are not clearly defined. The ability of eukaryotes to produce energy using oxygen and sugars was a key factor in advancing life on Earth towards complex multicellular organisms. However, this was not the only way to produce energy and survive. Mitochondria probably appeared soon after the oxygen increase in the Earth's atmosphere but many microaerophilic protists require little or no oxygen to survive. New ultrastructural, biochemical and molecular phylogeny data about structures and processes involved in the generation of energy by currently known protists have forced the revision of understanding of the "tree of life".
authors.affiliation: Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, 615 North Wolfe Street, Baltimore, MD 21205, USA.
authors.forename: Thaddeus K
authors.initials: TK
authors.lastname: Graczyk
mesh_terms: D000818:Animals; D005057:Eukaryotic Cells / Q000502:physiology; D019143:Evolution, Molecular; D005872:Giardia / Q000235:genetics*; D006790:Host-Parasite Interactions; D008928:Mitochondria / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010802:Phylogeny; D011387:Prokaryotic Cells / Q000502:physiology; D013559:Symbiosis / Q000502:physiology
chemical_list: D010100:Oxygen