Biol Cell

Background informationThe current consensus on cilia development posits that the ciliary transition zone (TZ) is formed via extension of nine centrosomal microtubules. In this model, TZ structure remains unchanged in microtubule number throughout the cilium life cycle. This model does not however explain structural variations of TZ structure seen in nature, and could also lend itself to the misinterpretation that deviations from nine-doublet microtubule ultrastructure represent an abnormal phenotype. Thus, a better understanding of events that occur at the TZ in vivo during metazoan development is required.ResultsTo address this issue, we characterized ultrastructure of two types of sensory cilia in developing Caenorhabditis elegans. We discovered that, in cephalic male (CEM) and inner labial quadrant (IL2Q) sensory neurons, ciliary TZs are structurally plastic and remodel from one structure to another during animal development. The number of microtubules doublets forming the TZ can be increased or decreased over time, depending on cilia type. Both cases result in structural TZ intermediates different from TZ in cilia of adult animals. In CEM cilia, axonemal extension and maturation occurs concurrently with TZ structural maturation.Conclusions and SignificanceOur work extends the current model to include the structural plasticity of metazoan transition zone, which can be structurally delayed, maintained or remodeled in cell type-specific manner.20192019-12-19T00:00:00ZCSCR16FEL008/New Jersey Commission on Spinal Cord Research/P40 OD010440/CD/ODCDC CDC HHS/United StatesR24 OD010943/OD/NIH HHS/United StatesP40 OD010440/OD/NIH HHS/United StatesP41 GM103310/GM/NIGMS NIH HHS/United StatesR01 DK059418/DK/NIDDK NIH HHS/United StatesS10 RR029300/RR/NCRR NIH HHS/United StatesSF349247/Simons Foundation/R01 DK116606/DK/NIDDK NIH HHS/United StatesF00316/Agouron Institute/DK116606/DK/NIDDK NIH HHS/United StatesDK059418/DK/NIDDK NIH HHS/United StatesS10 OD019994/OD/NIH HHS/United StatesOD010943/NIH Office of the Director/30681171PMC69225836997vault:3427