Paramecium, a model to study basal body anchoring defects. (A) A1-A4: Control Paramecium (A1, A3) and FOPNL-depleted Paramecium (A2, A4) decorated for basal bodies (ID5 antibodies) observed by confocal at the cell cortex (A1, A3) or at intracytoplasmic level (A2, A4). Note that FOPNL depletion leads to a disorganized pattern of basal bodies at the cell cortex. Unanchored basal bodies are found in the cytoplasm (A4) (reproduced/adapted with permission "Aubusson et al, 2012. Journal of cell science, 125, 4395-440"). (B) Transmission electron microscopic images of a basal body doublet anchored at the cell surface. Note that the TZ vary in height between the ciliated basal body and the unciliated one (B1). B2-B4: Depletion of Centrin2 (B2), OFD1 (B3) (reprint from Bengueddach et al, 2017, Cilia 6, 6. doi:10.1186/s13630-017-0050-z), and FOPNL (B4) lead to unanchored basal bodies with defective organization of its distal end (reproduced/adapted with permission Aubusson et al, 2012. Journal of cell science, 125, 4395-4404). B5-B6: immunofluorescence of a control Paramecium (B5), or cell depleted for SF-assemblin depleted group-I proteins (B6) from Nabi et al., 2019 with permission, stained for the kinetodesmal fiber (red) and microtubule rootlets (green). Note the disorganization of the basal bodies and mis-orientation of their rootlets at the cell surface (Nabi et al., 2019). Depletion of Vfl3 protein (B7) induces the formation of more than one kinetodesmal fiber indicating rotational polarity defect (reprint from Bengueddach et al, 2017, Cilia 6, 6. doi:10.1186/s13630-017-0050-z). By contrast, the distal end of the basal body is well organized as after depletion of Centrin3 (B9) (reproduced/adapted with permission Aubusson et al, 2012. Journal of cell science, 125, 4395-4404). Scale bars: 250 nm.