The transcription factor RFX3 directs nodal cilium development and left-right asymmetry specification - PubMed (original) (raw)

FIG. 4.

Rfx3 is expressed in the embryonic node and regulates ciliary growth. The localization of Rfx3 mRNA (A) and protein (B) was examined in the embryonic node at E7.5. (C) Changes in the lengths of node monocilia between 7 and 8 days of embryonic development in control and mutant embryos. Theiler stage 10c, late streak, early bud; Theiler stage 11a, early neural plate; Theiler stage 11b, late neural plate; Theiler stage 11c/11d, early to late head fold; Theiler stage 12a, one to three somites. (D to O) Scanning electron micrographs of the embryonic nodes of wild-type (D, E, H, I, L, and M) and _Rfx3_-deficient (F, G, J, K, N, and O) embryos at three different stages. For each embryo, two magnifications are presented to show the position of the node and the nodal monociliated cells. At late streak stages (D to G), the node monocilia were of similar sizes (average, 1.6 μm) in control (D and E [n = 6]) and _Rfx3_-deficient (F and G [n = 4]) embryos. By the late neural plate stage (H to K), the cilia were longer in control embryos (average, 2.7 μm; n = 3) (H and I) but had not grown in _Rfx3_-deficient embryos (average size, 1.6 μm; n = 3) (J and K). This difference was even greater at stage 11c/11d, when cilia in control embryos had an average size of 3.3 μm (L and M [n = 3]), whereas cilia in the _Rfx3_-deficient embryos still had an average length of only 1.5 μm (N and O [n = 2]). The apparent morphological alteration of the mutant node in panel N is not significant as it was not observed for all mutant embryos. At late somite stages, the nodal monocilia in the mutants started to grow slightly but remained half as long as in the controls (data not shown). Bars, 100 μm (D, F, H, J, L, and N) and 2 μm (E, G, I, K, M, and O). n, node; nc, notochord; ps, primitive streak; R, rostral; C, caudal.