Fig. 6: Photophobic response in Chlamydomonas reinhardtii cells to blue light pulses.

a Representative track of a single wild-type cell illuminated with 470-nm light (1.75 × 10²⁰ photons/m²s) three times for 1 s with 2 s dark periods at 100 µM Ca²⁺. Change of cell velocity upon illumination corresponding to a photophobic response (STOP) where τ_R is the reaction time and τ_RC is the recovery time. Velocity plots of 250 averaged tracks were obtained for the wild-type (b), C1 (c) and C2 (d) strains, point mutants C1-E162T (e), C2-E123T (f), C2-E90Q (g), C2-E90R (h) and the double knock-out ΔC1ΔC2 (i) at different Ca²⁺ concentrations. j Mean photophobic reaction velocity after the 1^st and the 3^rd light pulse at 100 µm Ca²⁺. k Mean photophobic reaction velocity after the 1^st and the 3^rd light pulse at 10 µm Ca²⁺. Lines and bars represent the mean value ± S.E. N = 3 experiments. Source data are available as a Source Data file.