Colpodella sp. (ATCC 50594) Life Cycle: Myzocytosis and Possible Links to the Origin of Intracellular Parasitism

Colpodella species are free living bi-flagellated protists that prey on algae and bodonids in a process known as myzocytosis. Colpodella species are phylogenetically related to Apicomplexa. We investigated the life cycle of Colpodella sp. (ATCC 50594) to understand the timing, duration and the transition stages of Colpodella sp. (ATCC 50594). Sam-Yellowe’s trichrome stains for light microscopy, confocal and differential interference contrast (DIC) microscopy was performed to identify cell morphology and determine cross reactivity of Plasmodium species and Toxoplasma gondii specific antibodies against Colpodella sp. (ATCC 50594) proteins. The ultrastructure of Colpodella sp. (ATCC 50594) was investigated by transmission electron microscopy (TEM). The duration of Colpodella sp. (ATCC 50594) life cycle is thirty-six hours. Colpodella sp. (ATCC 50594) were most active between 20–28 h. Myzocytosis is initiated by attachment of the Colpodella sp. (ATCC 50594) pseudo-conoid to the cell surface of Parabodo caudatus, followed by an expansion of microtubules at the attachment site and aspiration of the prey’s cytoplasmic contents. A pre-cyst formed at the conclusion of feeding differentiates into a transient or resting cyst. Both DIC and TEM microscopy identified asynchronous and asymmetric mitosis in Colpodella sp. (ATCC 50594) cysts. Knowledge of the life cycle and stages of Colpodella sp. (ATCC 50594) will provide insights into the development of intracellular parasitism among the apicomplexa.