title: The origin and differentiation process of X and Y chromosomes of the black marsh turtle (Siebenrockiella crassicollis, Geoemydidae, Testudines).
abstract: The black marsh turtle (Siebenrockiella crassicollis) has morphologically differentiated X and Y sex chromosomes. To elucidate the origin and evolutionary process of S. crassicollis X and Y chromosomes, we performed cross-species chromosome painting with chromosome-specific DNA from Chinese soft-shelled turtle (Pelodiscus sinensis) and chromosome mapping of the sex-linked genes of S. crassicollis using FISH. The X and Y chromosomes of S. crassicollis were hybridized with DNA probe of P. sinensis chromosome 5, which is homologous to chicken chromosome 5. S. crassicollis homologues of 14 chicken chromosome 5-linked genes were all localized to the X long arm, whereas two genes were mapped to the Y short arm and the other 12 genes were localized to the Y long arm in the same order as the X chromosome. This result suggests that extensive linkage homology has been retained between chicken chromosome 5 and S. crassicollis X and Y chromosomes and that S. crassicollis X and Y chromosomes are at an early stage of sex chromosome differentiation. Comparison of the locations of two site-specific repetitive DNA sequences on the X and Y chromosomes demonstrated that the centromere shift was the result of centromere repositioning, not of pericentric inversion.
authors.affiliation: Laboratory of Animal Genetics, Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Japan.
authors.forename: Taiki
authors.initials: T
authors.lastname: Kawagoshi
authors.forename: Chizuko
authors.initials: C
authors.lastname: Nishida
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Matsuda
mesh_terms: D000818:Animals; D002503:Centromere / Q000235:genetics; D002645:Chickens / Q000235:genetics; D002874:Chromosome Mapping / Q000379:methods; D020223:Chromosome Painting / Q000379:methods; D003001:Cloning, Molecular; D055028:Comparative Genomic Hybridization / Q000379:methods; D019143:Evolution, Molecular; D023061:Gene Order; D008040:Genetic Linkage; D008969:Molecular Sequence Data; D012091:Repetitive Sequences, Nucleic Acid; D012689:Sequence Homology, Nucleic Acid; D012733:Sex Differentiation; D014426:Turtles / Q000235:genetics*; D014960:X Chromosome / Q000235:genetics*; D014998:Y Chromosome / Q000235:genetics*