title: Molecular cytogenetic characterization of chromosome site-specific repetitive sequences in the Arctic lamprey (Lethenteron camtschaticum, Petromyzontidae).
abstract: All extant lamprey karyotypes are characterized by almost all dot-shaped microchromosomes. To understand the molecular basis of chromosome structure in lampreys, we performed chromosome C-banding and silver staining and chromosome mapping of the 18S-28S and 5S ribosomal RNA (rRNA) genes and telomeric TTAGGG repeats in the Arctic lamprey (Lethenteron camtschaticum). In addition, we cloned chromosome site-specific repetitive DNA sequences and characterized them by nucleotide sequencing, chromosome in situ hybridization, and filter hybridization. Three types of repetitive sequences were detected; a 200-bp AT-rich repetitive sequence, LCA-EcoRIa that co-localized with the 18S-28S rRNA gene clusters of 3 chromosomal pairs; a 364-bp AT-rich LCA-EcoRIb sequence that showed homology to the EcoRI sequence family from the sea lamprey (Petromyzon marinus), which contains short repeats as centromeric motifs; and a GC-rich 702-bp LCA-ApaI sequence that was distributed on nearly all chromosomes and showed significant homology with the integrase-coding region of a Ty3/Gypsy family long terminal repeat (LTR) retrotransposon. All three repetitive sequences are highly conserved within the Petromyzontidae or within Petromyzontidae and Mordaciidae. Molecular cytogenetic characterization of these site-specific repeats showed that they may be correlated with programed genome rearrangement (LCA-EcoRIa), centromere structure and function (LCA-EcoRIb), and site-specific amplification of LTR retroelements through homogenization between non-homologous chromosomes (LCA-ApaI).
authors.affiliation: Laboratory of Animal Cytogenetics, Department of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Ishijima
authors.affiliation: Laboratory of Animal Genetics, Department of Applied Molecular Biosciences, Nagoya University, Nagoya, Aichi 464-8601, Japan.
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Uno
authors.affiliation: Avian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan.
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Nunome
authors.affiliation: Department of Natural History Sciences, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan.
authors.forename: Chizuko
authors.initials: C
authors.lastname: Nishida
authors.affiliation: Phyloinformatics Unit, RIKEN Center for Life Science Technologies, Kobe 650-0047, Japan.
authors.forename: Shigehiro
authors.initials: S
authors.lastname: Kuraku
authors.affiliation: Laboratory of Animal Genetics, Department of Applied Molecular Biosciences, Nagoya University, Nagoya, Aichi 464-8601, Japan.|Avian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Matsuda
mesh_terms: D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D016678:Genome; D007621:Karyotyping; D007798:Lampreys / Q000145:classification / Q000235:genetics*; D010802:Phylogeny; D012335:RNA, Ribosomal / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D016615:Telomere
chemical_list: D012335:RNA, Ribosomal
keywords: chromosome evolution; lamprey; repetitive sequence; retrotransposon; satellite DNA