title: Highly conserved linkage homology between birds and turtles: bird and turtle chromosomes are precise counterparts of each other.
abstract: The karyotypes of birds, turtles and snakes are characterized by two distinct chromosomal components, macrochromosomes and microchromosomes. This close karyological relationship between birds and reptiles has long been a topic of speculation among cytogeneticists and evolutionary biologists; however, there is scarcely any evidence for orthology at the molecular level. To define the conserved chromosome synteny among humans, chickens and reptiles and the process of genome evolution in the amniotes, we constructed comparative cytogenetic maps of the Chinese soft-shelled turtle (Pelodiscus sinensis) and the Japanese four-striped rat snake (Elaphe quadrivirgata) using cDNA clones of reptile functional genes. Homology between the turtle and chicken chromosomes is highly conserved, with the six largest chromosomes being almost equivalent to each other. On the other hand, homology to chicken chromosomes is lower in the snake than in the turtle. Turtle chromosome 6q and snake chromosome 2p represent conserved synteny with the chicken Z chromosome. These results suggest that the avian and turtle genomes have been well conserved during the evolution of the Arcosauria. The avian and snake sex Z chromosomes were derived from different autosomes in a common ancestor, indicating that the causative genes of sex determination may be different between birds and snakes.
authors.affiliation: Laboratory of Animal Cytogenetics, Division of Genome Dynamics, Creative Research Initiative "Sousei", Hokkaido University, North 10 West 8, Kita-ku, Sapporo 060-0810, Japan. yoimatsu@ees.hokudai.ac.jp
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Matsuda
authors.forename: Chizuko
authors.initials: C
authors.lastname: Nishida-Umehara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tarui
authors.forename: Asato
authors.initials: A
authors.lastname: Kuroiwa
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Yamada
authors.forename: Taku
authors.initials: T
authors.lastname: Isobe
authors.forename: Junko
authors.initials: J
authors.lastname: Ando
authors.forename: Atushi
authors.initials: A
authors.lastname: Fujiwara
authors.forename: Yukako
authors.initials: Y
authors.lastname: Hirao
authors.forename: Osamu
authors.initials: O
authors.lastname: Nishimura
authors.forename: Junko
authors.initials: J
authors.lastname: Ishijima
authors.forename: Akiko
authors.initials: A
authors.lastname: Hayashi
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Saito
authors.forename: Takahiro
authors.initials: T
authors.lastname: Murakami
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Murakami
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kuratani
authors.forename: Kiyokazu
authors.initials: K
authors.lastname: Agata
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001717:Birds / Q000235:genetics*; D002875:Chromosomes; D003001:Cloning, Molecular; D017931:DNA Primers; D018076:DNA, Complementary; D008040:Genetic Linkage; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics; D014426:Turtles / Q000235:genetics*
chemical_list: C110547:DMRT1 protein; D017931:DNA Primers; D018076:DNA, Complementary; D014157:Transcription Factors