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. Author manuscript; available in PMC: 2023 Feb 19.
Published in final edited form as: Science. 2023 Jan 5;379(6627):71–78. doi: 10.1126/science.abq7317

Fig. 4. Ciliary mechanosensation is determinative for LR asymmetry.

Fig. 4.

(A) Schematic depicting the approach followed to assess dand5 expression and cardiac laterality in c21orf59 morphants (MO) after oscillatory optical bending of one LRO cilium. (B to C’) Representative images of LRO cilia (arrows) from c21orf59 embryos in the absence [(B) white arrow, OFF] or presence of optical tweezers [(C) orange arrow, ON]. [(B’) and (C’)] Cilium highlighted in white box in [(B) and (C)]. Scales: [(B) and (C)]: 5 μm; [(B’) and (C’)]: 2 μm. (D and E) Representative kymographs of LRO cilia from c21orf59 embryos in the absence [(D) OFF] or presence of oscillatory optical tweezers [(E) ON]. Scales: vertical: 1 μm; horizontal: 1 s. (F) Graph with illustrative pictures, representing percentage of uninjected and c21orf59 morphants displaying normal right-sided (dark blue) and abnormal left-sided (green) or bilateral (magenta) dand5 expression. n = total number of embryos analyzed. Statistical comparison was analyzed by a Pearson’s chi-square test (Bonferroni corrected); *P < 0.05 and ns: P ≥ 0.05. Scale: 50 μm. (G) Graph represents percentage of uninjected, control morpholino-injected (CMO) and c21orf59 morphants displaying normal left-sided (light blue) and abnormal right-sided (green) or middle (magenta) positioned hearts. n = total number of embryos analyzed. Data shown are pooled from three independent experiments. Statistical comparison was analyzed by one-way ANOVA with Tukey’s multiple comparison test; ***P < 0.001, ****P < 0.0001 and ns: P ≥ 0.05. (H to K) Model for calcium-mediated ciliary mechanosensation in the LRO during LR development. At early stages of LR patterning, counterclockwise left-biased flow (curved orange arrow) or ciliary optical bending triggers Pkd2-dependent intraciliary calcium signaling (in cilia, magenta ICOs; in cells, dark blue) on the side of the LRO subjected to ciliary mechanical stimulation (1). Cilia-to-cytosolic LRO calcium (2) is then transmitted to neighboring cells of the mesendoderm in a side-biased manner (3), which in turn ultimately direct asymmetric gene expression (4) leading to LR patterning A, anterior; P, posterior; L, left; R, right.