Insights on diplochromosome structure and behaviour.
Diplochromosomes from colchicine-induced endoreduplicated HeLa cells were analyzed by light and electron microscopy. The patterns of C-, G-, NOR-, and late replicating DNA-rich bands obtained clearly indicate that the four chromatids constituting a diplochromosome are structurally identical and behave the same, at least in terms of replication kinetics and r-DNA transcription. Under the electron microscope, whole-mounted diplochromosomes appeared formed by two completely divided chromosomes showing no physical connection at their centromeric regions. The two chromosomes forming a diplochromosome seem to be held together by chromatin fiber loops connecting the two neighbouring chromatids of the sister chromosomes. These connecting loops clearly decrease in number as chromosome condensation progresses.
D001973:Bromodeoxyuridine; D002877:Chromosomes, Human / Q000648:ultrastructure*; D004261:DNA Replication; D006367:HeLa Cells / Q000648:ultrastructure*; D006801:Humans; D008854:Microscopy, Electron; D013194:Staining and Labeling
D001973:Bromodeoxyuridine