Differentiation of Z and W chromosomes revealed by replication banding and FISH mapping of sex-chromosome-linked DNA markers in the cassowary (Aves, Ratitae).
We identified sex chromosomes of the double-wattled cassowary (Casuarius casuarius) by a replication banding method. The acrocentric Z chromosome, the fifth largest pair in males and slightly smaller W chromosome show no sign of heterochromatinization and share a nearly identical banding pattern in the distal half of the long arm. These chromosomes were further characterized by FISH with three probes linked either to Z or W chromosome in most avian species examined thus far. Contrary to the situation in the chicken, we obtained positive signals with Z-specific ZOV3 and W-specific EEO.6 in the distal region of both Z and W chromosomes. However, IREBP signals localized to the proximal half of the Z chromosome were not detected on the W chromosome. Thus, structural rearrangements such as deletions and inversions might have been the initial step of W chromosome differentiation from an ancestral homomorphic pair in this species.
Nishida-Umehara
C
C
Chromosome Research Unit, Faculty of Science, Hokkaido University, Sapporo, Japan.
Fujiwara
A
A
Ogawa
A
A
Mizuno
S
S
Abe
S
S
Yoshida
M C
MC
D000818:Animals; D002871:Chromosome Banding; D005819:Genetic Markers; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D046108:Palaeognathae / Q000235:genetics*; D012730:Sex Chromosomes
D005819:Genetic Markers