title: Identification of a second rRNA gene unit in the Perkinsus andrewsi genome.
abstract: Perkinsus species are parasitic protozoa of mollusks, currently classified within the Perkinsozoa, a recently established phylum that is basal to the Apicomplexa and Dinozoa. Ribosomal RNA (rRNA) genes and their intergenic spacers have been used to support the taxonomy of Perkinsus species, the description of new species, and to develop molecular probes for their detection and identification. We previously described ultrastructure, behavior in culture, and partial sequence of the rRNA locus of a Perkinsus species isolated from the baltic clam Macoma balthica. The rRNA genes and intergenic spacers of this Perkinsus isolate differed from those described in the currently accepted species to a degree that led to its designation as a new species, Perkinsus andrewsi. In this study, we identify an additional rRNA gene unit (rRNA-B) in the P. andrewsi holotype, and report the complete sequences of both rRNA gene units. Except for the 5.8S, all regions of the rRNA-B gene unit exhibited sequence differences from that initially described (rRNA-A). Each rRNA gene unit is arranged in a "head-to-tail" tandem repeat. This is the first report demonstrating two distinct rRNA units in a Perkinsus species.
authors.affiliation: Center of Marine Biotechnology, University of Maryland Biotechnology Institute, University of Maryland, Baltimore, Maryland 21202, USA.
authors.forename: Wolf T
authors.initials: WT
authors.lastname: Pecher
authors.forename: José A F
authors.initials: JA
authors.lastname: Robledo
authors.forename: Gerardo R
authors.initials: GR
authors.lastname: Vasta
mesh_terms: D000818:Animals; D001483:Base Sequence; D021901:DNA, Intergenic / Q000235:genetics; D016054:DNA, Protozoan / Q000737:chemistry / Q000302:isolation & purification; D004275:DNA, Ribosomal / Q000235:genetics*; D021903:DNA, Ribosomal Spacer / Q000235:genetics*; D056890:Eukaryota / Q000235:genetics*; D023061:Gene Order; D020459:Genes, rRNA; D016678:Genome; D018503:Genome, Protozoan; D008969:Molecular Sequence Data; D008974:Mollusca / Q000469:parasitology; D012340:RNA, Ribosomal, 5.8S / Q000235:genetics; D012341:RNA, Ribosomal, 5S / Q000235:genetics; D015183:Restriction Mapping; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D012407:rRNA Operon
chemical_list: D021901:DNA, Intergenic; D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer; D012340:RNA, Ribosomal, 5.8S; D012341:RNA, Ribosomal, 5S