Overexpression of GFP-MpH promotes M fragmentation and elongation. The CU428 WT strain was modified by replacing the native promoter of MPH with the cadmium-inducible promoter MTT1 to drive expression of GFP-MpH. (A–B″) Two sets of SR-SIM images of cells overproducing GFP-MpH after exposure to cadmium chloride 2.5 μg/ml for 6 h. The cells were labeled with 20H5 anti-centrin (red) and DAPI (blue); GFP-MpH (green) was detected directly. Note the fragmented OP in the dividing cell in panel A–A″. (C) Quantifications of the percentage of cells with OAs having fragmented M rows. Mean ± SD. N = 3 independent experiments indicated by symbol colors (100 cells scored per experiment). P = 0.0032 in an unpaired t test with Welch’s correction. (D) Quantification of the length of M1 in cells carrying the MTT1-GFP-MpH transgene that were grown without (−cd) or with (+cd) 2.5 μg/ml cadmium chloride for 6 h to induce overexpression. Mean ± SD. N = 3 experiments. The individual measurements made in each experiment are marked by different symbol colors (9 cells measured per experiment, a total of 27 per condition). P < 0.0001 in a two-way ANOVA test with Geisser–Greenhouse correction for variability. oa, parental oral apparatus; noa, new oral apparatus or OP; rw, ribbed wall.