抄録
We have previously cloned 4 bovine male-specific and 3 gender-neutral repetitive DNA fragments [1] and successfully utilized them to sex bovine embryos [2]. Further characterization and mapping of these repetitive fragments were made here. All 4 male-specific repeats were mapped to the proximal region of the short arm of the Y-chromosome. Although a Southern blot analysis showed no specific hybridization to sheep, goat, and pig DNAs, the fluorescence in situ hybridization (FISH) identified weak signals in the proximal region of the short arm of the ovine and caprine Y-chromosomes. The copy number of the male-specific repeats was roughly estimated to be around 100 in the bovine genome. One of gender-neutral repeats was a part of mitochondrial DNA (NADH dehydrogenase5 gene), which showed crucial deviations from the known sequence [3] and thought to be a pseudo-gene in the nucleus. Another one was a combination of an autosomal sequence and satellite DNA, which was mapped to centromeric region of most bovine chromosomes excepting sex-chromosomes. This hybrid DNA was bovine-specific as revealed by the Southern blot analysis against the other domestic animals.
