Fluorescent Nanoparticle Uptake by Myzocytosis and Endocytosis in Colpodella sp. ATCC 50594

Abstract

Colpodella sp. (ATCC 50594) is a free-living biflagellate predator closely related to pathogenic Apicomplexa such as Plasmodium, Cryptosporidium and Toxoplasma gondii. Colpodella sp. (ATCC 50594) obtain nutrients by preying on Parabodo caudatus using myzocytosis. The organization of the myzocytic apparatus and the mechanism of nutrient uptake into the posterior food vacuole of Colpodella species is unknown. In this study, we investigated myzocytosis using light and transmission electron microscopy. We investigated the uptake of 40 nm and 100 nm fluorescent nanoparticles and E. coli BioParticles by Colpodella sp. (ATCC 50594) in a diprotist culture. Transmission electron microscopy was used to investigate the morphology of the tubular tether formed during myzocytosis. E. coli BioParticles were taken up by P. caudatus but not by Colpodella sp. (ATCC 50594). Both protists took up the 100 nm and 40 nm beads, which were observed distributed in the cytoplasm of free unattached Colpodella sp. (ATCC 50594) trophozoites, and also in feeding Colpodella sp. (ATCC 50594) trophozoites and in the pre-cysts. Fragments of the nucleus and kinetoplast of P. caudatus and the nanoparticles were identified in the tubular tether being aspirated into the posterior food vacuole of Colpodella sp. (ATCC 50594). Unattached Colpodella sp. (ATCC 50594) endocytose nutrients from the culture medium independently from myzocytosis. The mechanisms of myzocytosis and endocytosis among Colpodella species may provide important insights into nutrient uptake among the pathogenic apicomplexans.

Emerging Opportunistic Colpodella Species: Nutrient Uptake and Approaches to Diagnose Infections

“…In previous studies we showed that the process of myzocytosis in Colpodella sp. (ATCC 50594) occurs sequentially, beginning with attachment to the prey P. caudatus, engulfment of the plasma membrane of the prey, destruction of the prey's plasma membrane and aspiration of the prey's cytoplasmic contents into a posterior food vacuole [25]. In addition to myzocytosis for nutrient uptake, Colpodella sp.…”

“…In addition to myzocytosis for nutrient uptake, Colpodella sp. (ATCC 50594) trophozoites can also carry out endocytosis in culture [25]. Following myzocytosis, and nutrient acquisition, Colpodella sp.…”

“…We showed in previous studies that unattached Colpodella sp. (ATCC 50594) trophozoites can endocytose nanoparticles of 40 and 100 nm from culture suggesting that in addition to myzocytosis, the predator can acquire nutrients by endocytosis [25]. Whether endocytosis is sufficient to form the food vacuole and lead to encystation is unknown and requires further investigation.…”

From Myzocytosis to Cytostomal Nutrient Uptake and Transport by Intracellular Plasmodium Species

“…before the degradation of the membrane. This aperture may represent a structure similar to the cytostome [ 13 ]. Once inside the predator’s cytoplasm, the prey’s cytoplasmic contents are aspirated across a tubular tether into the posterior food vacuole of the predator [ 13 ].…”

“…This aperture may represent a structure similar to the cytostome [ 13 ]. Once inside the predator’s cytoplasm, the prey’s cytoplasmic contents are aspirated across a tubular tether into the posterior food vacuole of the predator [ 13 ]. The resemblance of the myzocytic aperture to the cytostome remains speculative and will require experimental studies for verification.…”