Revealing spatio-temporal dynamics with long-term trypanosomatid live-cell imaging

Abstract

Trypanosoma brucei, the causative agent of human African trypanosomiasis, employs a flagellum for dissemination within the parasite's mammalian and insect hosts. T. brucei cells are highly motile in culture and must be able to move in all three dimensions for reliable cell division. These characteristics have made long-term microscopic imaging of live T. brucei cells challenging, which has limited our understanding of a variety of important cell-cycle events. To address this issue, we have devised an imaging approach that confines cells to small volumes that can be imaged continuously for up to 24 h. This system employs cast agarose microwells generated using a PDMS stamp that can be made with different dimensions to maximize cell viability and imaging quality. Using this approach, we have imaged individual T. brucei through multiple rounds of cell division with high spatial and temporal resolution. We have employed this method to study the differential rate of T. brucei daughter cell division and show that the approach is compatible with loss-of-function experiments such as small molecule inhibition and RNAi. We have also developed a strategy that employs in-well "sentinel" cells to monitor potential toxicity due to imaging. This live-cell imaging method will provide a novel avenue for studying a wide variety of cellular events in trypanosomatids that have previously been inaccessible.