LATE DNA REPLICATION PATTERN IN SEX CHROMOSOMES OF MELANDRIUM

Abstract

DNA replication patterns in somatic cells of female and male Meladrium album were studied with autoradiographic methods. The S-period and the average generation time have been estimated to be 5.7 and 15.5 hours respectively. The heterochromatin observed in interphase nuclei may represent the late replicating and presumably inactivated sex chromosome.One arm of one X chromosome is late replicating in females. In the Y chromosome a region near the centromere replicates late in the S-period. The DNA replication sequence in sex chromosomes of female and male cells of Melandrium album suggests that their pattern is similar to that of mammalian sex chromosomes.