FIG. 3.

Recovery following cell cycle arrest in Giardia cultures. (A and B) Giardia cultures propagated under normal growth conditions (A) and exposed to 100 nM nocodazole (noc) for 2 h arrest in G₂ (B). (C) Following the removal of nocodazole-containing medium and the addition of medium containing 6 μM aphidicolin (aph), cells arrest in G₁. (D to F) After the removal of aphidicolin medium and replacement with fresh medium, the cells are allowed to recover under normal growth conditions for 3.0, 3.5, and 4.0 h. (G) By 4.5 h, the cells begin to go through mitosis and accumulate in G₁. (H to J) After 5.0, 5.5, and 6.0 h of recovery, the cells continue to accumulate in G₁. (L) After 12 h of recovery, the cells have returned to the normal 5:1 ratio of G₂ to G₁ cells as seen in the control sample.