Deoxyribonucleic Acid Synthesis and Distribution During Growth and Amitosis of the Macronucleus of Euplotes

SYNOPSIS. Short sections of deoxyribonucleic acid (DNA) in the elongated macronucleus of Euplotes eurystomus were labeled by means of a short exposure to tritiated (H³-) thymidine to follow by autoradiography the fate of the labeled DNA during amitotic reorganization of the macronucleus. During amitosis the radioactive DNA that was restricted during interphase to short sections of the nucleus is dispersed and becomes evenly distributed throughout each daughter macronucleus.
Although the reorganization bands normally originate only at the ends of the macronucleus, additional bands can start at other places on the macronuclear surface. Bands of the same macronucleus originate with a high degree of synchrony. DNA synthesis is a constant feature of the rear zone of every reorganization band.