Demonstration of W chromosome-specific repetitive DNA sequences in the domestic fowl, Gallus g. domesticus.

Evidence is presented to demonstrate the presence of W chromosome-specific repetitive DNA sequences in the female White Leghorn chicken, Gallus g. domesticus, based on two different experimental approaches. First, 3H-labelled, female chicken DNA was hybridized with excess, unlabelled, mercurated, male DNA, and unhybridized single-stranded 3H-DNA (3H-SHU-DNA) was recovered by SH-Sepharose and hydroxyapatite column chromatography. Approximately 24% of the hybridizable 3H-SHU-DNA was female-specific and localized on the W chromosome. The second approach was to examine female-specific DNA fragments among the digests of chicken DNA with various restriction endonucleases. Among them, we found that digestion with XhoI produced two prominent female-specific brands of 0.60 kb (= kilobase pairs) and 1.1 kb. The 0.60 kb fragment was isolated and 3H-labelled by nick-translation. Female-specificity of the 3H-XhoI--0.60 kb DNA was judged to be at least 95% under the conditions of hybridization with membrane filter-bound DNA. Presence of amplified XhoI--0.60 kb DNA on the W chromosome seems to be limited to different lines of G.g. domesticus and no such repeat was detected in three species belonging to other genera in the order Galliformes and in three species belonging to other avian orders.