Fig. 4

Fig. 4 uxs1 expression during zebrafish embryogenesis. (A) RT-PCR for uxs1 transcript in animals of indicated ages, along with β-actin positive controls. Maternal uxs1 mRNA was detected at the 1–2 cell stage and detection decreased at sphere-dome stage. Zygotic uxs1 expression appeared to increase gradually and was maintained at least through 5 dpf. (B) Whole-mount in situ hybridization of a one-cell embryo revealed transcript in the fertilized egg. (C, D) Whole-mount (C) and section (D) of 24 hpf embryos illustrated general expression of uxs1 in brain and craniofacial mesenchyme, as well as in the yolk syncytial layer. The dashed line in panel C indicates the plane of section in panel D. (E) Lateral view of whole-mount 2 dpf embryo showed widespread uxs1 expression in the craniofacial region. (F–H) Horizontal sections of 3 dpf (F) and 5 dpf (G,H) animals. Expression of uxs1 became localized to layers of the retina, brain, and cartilages of the pharyngeal arches. Levels of uxs1 transcript were severely reduced or absent in pharyngeal regions of uxs1^hi3357 embryos. High magnification of 5 dpf ceratohyals shows uxs1 expression in both chondrocytes (c) and perichondral cells (pc) of wild types (G′), but low transcript levels in uxs1^hi3357 embryos (H′). Abbreviations: bp, basal plate; c, chondrocyte; cb1-5, ceratobranchials 1-5; ch, ceratohyal; e, eye; f, fin bud; fb, forebrain; hb, hindbrain; hs, hyosymplectic; mb, midbrain; no, notochord; pc, perichondrium; pq, palatoquadrate; y, yolk; ysl, yolk syncytial layer.