1. Genomic Structures of the kW1 Loci on the Z and W Chromosomes in Ratite Birds: Structural Changes at an Early Stage of W Chromosome Differentiation.
- Author
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Ishijima, Junko, Uno, Yoshinobu, Nishida, Chizuko, and Matsuda, Yoichi
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CHROMOSOMES , *GENETICS , *BIRDS , *GENOMES , *GENE expression , *CROCODILIANS , *PHYSIOLOGY ,CROCODILIAN genetics - Abstract
The W chromosome of ratite birds shows minimal morphological differentiation and retains homology of genetic linkage and gene order with a substantial stretch of the Z chromosome; however, the molecular structure in the differentiated region is still not well known. The kW1 sequence was isolated from the kiwi as a W-specific DNA marker for PCR-based molecular sexing of ratite birds. In ratite W chromosomes, this sequence commonly contains a ∼200-bp deletion. To characterize the very early event of avian sex chromosome differentiation, we performed molecular cytogenetic analyses of kW1 and its flanking sequences in paleognathous and neognathous birds and reptiles. Female-specific repeats were found in the kW1-flanking sequence of the cassowary (Casuarius casuarius), and the repeats have been amplified in the pericentromeric region of the W chromosomes of ratites, which may have resulted from the cessation of meiotic recombination between the Z and W chromosomes at an early stage of sex chromosome differentiation. The presence of the kW1 sequence in neognathous birds and a crocodilian species suggests that the kW1 sequence was present in the ancestral genome of Archosauria; however, it disappeared in other reptilian taxa and several lineages of neognathous birds. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]
- Published
- 2014
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