Fig 2. Nuclei cycle asynchronously in multinucleated parasites.

After nuclear division, hemispindle structures remain briefly within the separated nuclei. In parasites with two nuclei, one may enter S–phase earlier than the other; S–phase entry is marked by the rapid accumulation of the replication marker PCNA1 within a nucleus. Asynchrony is visible in both S–phase and nuclear division, as nuclei may show nuclear accumulation of PCNA1 as well as different microtubule structures at different times.