ABSTRACT
Ethidium bromide (EB) induces characteristic and constant nuclear changes on Pleurodeles waltlii embryonic cells cultured in vitro:
Nucleolar segregation - that is, a modification of ribonucleic constituents which are present in the nucleolus in two forms, granular and fibrillar particles; this phenomenon is reversible after short treatments (until 12h) and not reversible after 24 h and longer treatments.
Appearance of ribonucleoprotein intranuclear inclusions which is not reversible, whatever the treatment duration may be.
Important changes are also observed at the chromatin level.
At the cytoplasmic level an important alteration of the chondrioma morphology occurs and an inhibition of the utilization of yolk platelets.
On the other hand EB generally inhibits neuroblast and myoblast differentiation. This inhibition appears to be reversible in myoblasts after short treatments.
The chromosomal DNA synthesis (incorporation of [3H]thymidine) does not seem to be affected by EB treatments while [3H]uridine incorporation in RNAs is completely inhibited after 24 h and longer treatments.