title: Genetic Diversity of Microbial Eukaryotes in Anoxic Sediment of the Saline Meromictic Lake Namako-ike (Japan): On the Detection of Anaerobic or Anoxic-tolerant Lineages of Eukaryotes.
abstract: Available sequence data on eukaryotic small-subunit ribosomal DNA (SSU rDNA) directly retrieved from various environments have increased recently, and the diversity of microbial eukaryotes (protists) has been shown to be much greater than previously expected. However, the molecular information accumulated to date does still not thoroughly reveal ecological distribution patterns of microbial eukaryotes. In the ongoing challenge to detect anaerobic or anoxic-tolerant lineages of eukaryotes, we directly extracted DNA from the anoxic sediment of a saline meromictic lake, constructed genetic libraries of PCR-amplified SSU rDNA, and performed phylogenetic analyses with the cloned SSU rDNA sequences. Although a few sequences could not be confidently assigned to any major eukaryotic groups in the analyses and are debatable regarding their taxonomic positions, most sequences obtained have affiliations with known major lineages of eukaryotes (Cercozoa, Alveolata, Stramenopiles, and Opisthokonta). Among these sequences, some branched with lineages predominantly composed of uncultured environmental clones retrieved from other anoxic environments, while others were closely related to those of eukaryotic parasites (e.g. Phytomyxea of Cercozoa, Gregarinea of Alveolata, and Ichthyosporea of Opisthokonta).
authors.affiliation: Extremobiosphere Research Center, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Kanagawa 237-0061, Japan. takishitak@jamstec.go.jp
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Takishita
authors.forename: Masashi
authors.initials: M
authors.lastname: Tsuchiya
authors.forename: Masaru
authors.initials: M
authors.lastname: Kawato
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Oguri
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitazato
authors.forename: Tadashi
authors.initials: T
authors.lastname: Maruyama
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D004275:DNA, Ribosomal / Q000032:analysis; D005057:Eukaryotic Cells / Q000145:classification*; D005618:Fresh Water / Q000382:microbiology*; D014644:Genetic Variation; D019015:Geologic Sediments / Q000382:microbiology*; D007564:Japan; D008969:Molecular Sequence Data; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D012965:Sodium Chloride
chemical_list: D004275:DNA, Ribosomal; D012965:Sodium Chloride