Consequences of increased ciliary length on signaling and motility functions of cilia. (A) The expression pattern of ptc1 in a 24 hpf wild-type embryo and an embryo that overexpressed Arl13b. (B) The quantitative comparison of gli1 and ptc1 mRNA levels between wild-type and Arl13b overexpression using qRT-PCR. The rplpo gene was used as an internal loading control, and the levels of the transcripts in wild-type embryos were arbitrarily set at 1. 6 samples from 2 independent batches of embryos were analyzed. (C) Quantitation of heart looping positions in 24 hpf wild-type and embryos that overexpressed Arl13b. 100 embryos were analyzed from each group. Left position (L), middle position (M), right position (R). (D) Motile cilia in KV of a 12 hpf wild-type embryo and an embryo that overexpressed Arl13b. (E) Quantitation of motile cilia length increase in response to Arl13b overexpression in KV. 10 embryos were analyzed from each group, 20 cilia from each embryo. (F) TEM of motile cilia in pronephric (kidney) duct of a 24 hpf wild type embryo and an embryo overexpressing Arl13b. Yellow arrows indicate the central pair, red arrow the outer microtubule doublets and green arrow the outer dynein arms. Scale bar=0.1 nM. 3 embryos were sectioned and analyzed in each category. Ciliary axonemes in panel C were stained with anti-acetylated tubulin antibodies (red), and Arl13b was visualized with GFP fluorescence (green).