Stressful Situations: Investigating Cell Death Pathways in Protozoal Parasite Crithidia fasciculata

Protozoa of the Class Kinetoplastida include clinically-relevant pathogens such as Leishmania and Trypanosoma. Although specific mechanisms or biological significance of programmed cell death (PCD) have yet to be established in these organisms, morphological and biochemical characteristics similar to mammalian PCD have been observed when triggered by various stressors. Crithidia fasciculata is a trypanosomatid that does not infect humans and is a model for studying cell death pathways. This study identifies orthologous proteins potentially involved in PCD in C. fasciculata and clinically-relevant species. Oxidative stress, thermal stress, rotenone, and starvation were used to induce PCD-like processes. Morphological and nuclear features were assessed by fluorescent microscopy with annexin-V, Hoechst, and propidium iodide. Oncosis-like and apoptosis-like features emerged following cellular stress. Additionally, monodansylcadaverine staining of vacuoles suggests autophagic processes occur. The results establish that cell death pathways in C. fasciculata share features with but are distinct from mammalian PCD