Figure 4. CTFR labeling does not impair P. falciparum erythrocyte invasion and normal parasite growth. Erythrocytes labeled with either CFDA-SE (20 µM), DDAO-SE (10 µM), or CTFR (2 µM) were individually incubated with equal volumes of schizont-infected erythrocytes from 3D7 and Dd2 parasite cultures under normal P. falciparum culturing conditions. (a) Graphs showing the parasite growth patterns for two successive asexual replication cycles in labeled erythrocytes relative to the unlabeled control erythrocytes. (b) Giemsa-stained parasites showing the parasite morphology in unstained (black squares), CFDA-SE-stained (blue squares), DDAO-SE-stained (green squares), and CTFR-stained erythrocytes (red squares). Culture aliquots harvested at regular time intervals were fixed with 100% methanol and stained with 10% Giemsa on glass microscope slides. Images were taken with a Cole Palmer light microscope (Vernon Hills, Illinois 60061, USA) coupled with a MoticamBTW8 camera (Motic China Group Co., Ltd).