The repeated DNA in the genomes of three fish species (Dario rerio, Monopterus albus and Mastacembelus aculeatus), were compared with those in human Y chromosome-specific heterochromatin by genomic comparative in situ hybridization.The results showed that the repeated DNA in the genomes of three fish species could not hybridize with those in human Y chromosome-specific heterochromatin region and the human Y chromosome had its specific repeated DNA sequence.Some problems about the evolution of the repeated DNA in human Y chromosome-specific heterochromatin region were discussed.
