High-resolution analysis of Allium cepa chromosome replication by an FPG technique

In Allium cepa meristematic cells, BrdU incorporation into late-replicating DNA and its detection by FPG technique has shown to allow the visualization of characteristic late replicated segments (LRS) in metaphase chromosomes not detected till now. Since these LRS have very similar characteristics with the 'dot-like' exchanges reported previously in this system, they seem to represent a new support for the idea of a regular organization of chromatin in metaphase.