[Studies on late replication bands of giant panda (Ailuropoda melanoleuca) chromosomes]

Using the cultured giant panda (Ailuropoda melanoleuca) lymphocytes as experimental material, we carried out the terminal marking on the chromosomes which were in replication by adding BrdU (a final concentration: 10 micrograms/ml) about four hours before harvesting the cells. The chromosomes marked by BrdU were proceeded by staining with acridine orange solution (0.05%), irradiated by ultraviolet and counter-stained by Giemsa, we obtained clear chromosomes replication patterns. According to the different replication bands, every chromosome's characteristics in late replication behavior could be identified. In the two X chromosomes of female individual, one X chromosome is obviously much later than the other one. Especially in the large area near centromere on the long arm of late replicating X chromosome. In the male individual, there is also a large area on the long arm of chromosome Y which replicates very late, but the end of long arm of chromosome Y replicates much earlier.