Evidence for an unusual ZW/ZW’/ZZ sex-chromosome system in Scardinius erythrophthalmus (Pisces, Cyprinidae), as detected by cytogenetic and H-Y antigen analyses
作者:
M.R. Koehler,
D. Neuhaus,
W. Engel,
M. Schartl,
M. Schmid,
期刊:
Cytogenetic and Genome Research
(Karger Available online 1995)
卷期:
Volume 71,
issue 4
页码: 356-362
ISSN:1424-8581
年代: 1995
DOI:10.1159/000134139
出版商: S. Karger AG
数据来源: Karger
摘要:
Fifty-seven individuals of the European cyprinid fish species Scardinius erythrophthalmus were sexed by gonad histology, and their karyotypes were analyzed by Giemsa staining and C-banding. The chromosome number in somatic meta-phase plates was 2n = 50. Karyotypes of all gonadal male animals were identical, consisting of 48 small meta- or submetacentric chromosomes and a pair of large metacentric chromosomes (ZZ males). Of the 33 gonadal females, 16 had a karyotype similar to the males’ (ZW females) and 17 had a heteromorhic pair of chromosomes, including a large metacentric Z chromosome and a small acrocentric W chromosome (ZW females). H-Y antigen typing with cells obtained from a variety of tissues revealed that the homogametic ZZ males were H-Y negative and the heterogametic ZW females were H-Y positive in all tissues tested. In contrast, ZW’ females showed no expression of the H-Y antigen in somatic cells but were H-Y positive in ovarian cells. These results suggest that the ZW/ZW7ZZ sex chromosomes of S. erythrophthalmus represent an unusual system of sex determination and that H-Y antigen expression is coupled with the heterogametic sex. Whether the ZW individuals are indeed heterogametic females or actually sex-reversed ZZ males, in which chromosomal sex determination is overruled by external factors, is discus
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