Fig. 1
From: Spatial self-organization resolves conflicts between individuality and collective migration
Collective migration of a phenotypically-diverse clonal population. a When concentrated at the bottom of a nutrient channel, motile E. coli cells emerge from the high cell density region and travel in bands along the channel by following gradients of attractant produced by their consumption. b Microfluidic device used to quantify the band migration and the phenotypic diversity within the band. Control gates along the channel (black vertical lines) are initially open (top) and later closed to capture different bands of cells in the observation chamber (bottom), where single cells are tracked to quantify the distribution of phenotypes within the band (Supplementary Fig. 1). c Time-lapse imaging of E. coli cells expressing the fluorescent protein mRFP1 showing the collective migration of bands in M9 glycerol medium (M9 salts, glycerol, and casamino acids; Methods). In this undefined medium, several bands emerge that travel at different speeds (red: 0.68 mm min−1, yellow: 0.23 mm min−1)8. We verified that labeling cells did not affect band speeds nor tumble bias distributions (Supplementary Fig. 2). Scale bar, 0.6 mm. d The tumble bias (color)—average probability to tumble—of individual cells was quantified by tracking a cell for 2 min in a uniform environment (no gradient) and detecting tumbles (black dots) as previously described21, 22. Scale bar, 200 μm. e Collective migration selects against high TB cells. Tumble bias distributions from the first (red) and second (yellow) bands (n = 3), and from the population that was introduced in the device (black; n = 3). f The tumble bias distribution of the cells in the first wave (red in e) gradually shifted back toward the original distribution (black) during growth in the perfused chamber. Fresh M9 glycerol medium was supplied every 30 min. The TB distribution was measured every 20 min
