Length of DpHF18–Cy5 fibres as a function of time following a drop in pH from 8.0 to 3.4 or 3.1, followed by fluorescence microscopy. Data are presented as mean ± s.d. From left to right, the plot represents 510, 511, 414, 695, 563, 500 and 496 independent fibre objects at pH 3.4, and 698, 1,090, 466, 427, 113, 31 and 13 at pH 3.1. Fibres remain assembled at pH 3.4 but disassemble at pH 3.1, highlighting the sharp pH dependence of assembly.
