title: Secondary structure of some elements of 18S rRNA suggests that strongylid and a part of rhabditid nematodes are monophyletic.
abstract: Analysis of the secondary structure of 18S rRNA molecules in nematodes revealed some new traits in the secondary structure peculiar to their hairpin 17. Some of them are characteristic of all the nematodes, whereas others are characteristic exclusively of the order Rhabditida. The loss of a nucleotide pair in the highly conservative region of hairpin 17 distinguishes 18S rRNA of the Strongylida and some species of the Rhabditida from other nematodes and, moreover, from all other organisms. Hence, it is possible to regard the Strongylida and a part of the Rhabditida including Caenorhabditis elegans as a new monophyletic taxon.
authors.affiliation: Russian Institute of Physiology, Biochemistry and Feeding of Livestock, RAAS, Kaluga Region.
authors.forename: V V
authors.initials: VV
authors.lastname: Aleshin
authors.forename: O S
authors.initials: OS
authors.lastname: Kedrova
authors.forename: I A
authors.initials: IA
authors.lastname: Milyutina
authors.forename: N S
authors.initials: NS
authors.lastname: Vladychenskaya
authors.forename: N B
authors.initials: NB
authors.lastname: Petrov
mesh_terms: D000818:Animals; D001483:Base Sequence; D018509:DNA, Helminth / Q000235:genetics*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D018510:RNA, Helminth / Q000737:chemistry*; D012337:RNA, Ribosomal, 18S / Q000737:chemistry* / Q000235:genetics; D017168:Rhabditida / Q000737:chemistry / Q000235:genetics*; D016415:Sequence Alignment; D017183:Strongylida / Q000737:chemistry / Q000235:genetics*
chemical_list: D018509:DNA, Helminth; D018510:RNA, Helminth; D012337:RNA, Ribosomal, 18S