Heterogeneous Response to a Quorum-Sensing Signal in the Luminescence of Individual Vibrio fischeri
Figure 6
Variation and mean of luminescence levels versus autoinducer concentration.
(A) Coefficient of variation (cv = standard deviation/mean) in the luminescence of different cells. Variation is calculated from emission levels recorded t >100 minutes after introduction of exogenous AI; (B) Luminescence emission detected from 188 individual cells (blue circles) after 150–250 minutes exposure to AI. Data for each AI concentration represents a different group of cells. Solid curve (blue) is a fit to a cooperative binding model, giving Keq≈120±20 nM and Hill coefficient n≈2.7±0.8. For comparison with the expected average behavior, the dashed curve (red) shows the AI response that is obtained from a bulk population after 150–250 minutes in autoinducer (Figure 1).