Figure 4

Detection and tracking of a cell of interest. (A) Sketch of the “detect and track scenario”. Once a cell of interest is found in the field of view, the field of view is centered on that cell and the stage is periodically moved to maintain this cell in the center of the field of view. (B) We mixed two populations of yeast cells in a microfluidic chamber, one of which express a HTB2-mCherry fluorescent reporter (1:10 cell ratio). The algorithm scans through several positions and when it detects cells with a signal in the RFP channel, picks one such cell randomly and centers it on the field of view. This cell is then tracked using brightfield segmentation, and the stage position is corrected through a feedback loop to compensate for cell displacement. (C) The cell of interest moves because it is pushed by the growth of neighboring cells, traveling approximately 20 µm during the course of the experiment. The real-time stage compensation keeps the cell in the center of the field of view. The duration of the experiment (around 9 h) is long enough to observe the appearance of the progeny of the cell of interest. (D) Tracking a non-fluorescent yeast cell growing in a dead-end narrow microfluidic chamber, leading to global directed motion of all cells. The tracked cell remains in the field of view, even though it travels approximately 80 µm; in contrast, the field of view is only ~ 25 × 25 µm.