title: Sequence features of Oxytricha trifallax (class Spirotrichea) macronuclear telomeric and subtelomeric sequences.
abstract: We sequenced and analyzed the subtelomeric regions of 1356 macronuclear "nanochromosomes" of the spirotrichous ciliate Oxytricha trifallax. We show that the telomeres in this species have a length of 20 nt, with minor deviations; there is no correlation between telomere lengths at the two ends of the molecule. A search for open reading frames revealed that the 3' and 5' untranslated regions are short, with a median length of approximately 130 nt, and that surprisingly there are no detectable differences between sequences upstream and downstream of genes. Our results confirm a previously reported purine bias in the first approximately 80 nucleotides of the subtelomeric regions, but with this larger data set we curiously detected a 10 bp periodicity in the bias; we relate this finding to the possible regulatory and structural functions these regions must serve. Palindromic sequences in opposing subtelomeric regions, although present in most sequences, are not statistically significant.
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, NJ 08544, USA.
authors.forename: Andre R O
authors.initials: AR
authors.lastname: Cavalcanti
authors.forename: Diane M
authors.initials: DM
authors.lastname: Dunn
authors.forename: Robert
authors.initials: R
authors.lastname: Weiss
authors.forename: Glenn
authors.initials: G
authors.lastname: Herrick
authors.forename: Laura F
authors.initials: LF
authors.lastname: Landweber
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Doak
mesh_terms: D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D016373:DNA, Antisense / Q000737:chemistry / Q000235:genetics; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D019277:Entropy; D016366:Open Reading Frames; D016813:Oxytricha / Q000235:genetics*; D016615:Telomere / Q000235:genetics*
chemical_list: D016373:DNA, Antisense; D016054:DNA, Protozoan