sulf1 knockdown leads to improper migration of the lateral line primordium and a change in cxcl12a (sdf1a) expression along the lateral midline, which can be rescued by inhibition of BMP. (A–C) In situ hybridization for cxcl12a (sdf1a) in control fish (A), sulf1 morphant fish (B), or sulf1 morphant fish treated at 12 hpf with 2 μM LDN19189 (C). In the control fish, the cxcl12a expression is in a stripe along the lateral midline. In sulf1 morphants, the cxcl12a expression is greatly reduced with gaps in the expression along the lateral midline. Treatment with 2 μM LDN beginning 12 hpf can rescue the intensity and positioning of cxcl12a expression. (D) Individual frames from two separate time lapse series of sulf1 morphant Tg(cldnb:lynGFP) zebrafish starting at <32 hpf with subsequent frames stacked vertically being 30 min apart. In both examples, the small primordium has recently deposited a neuromast and is moving toward the tail (right arrow). By the third frame the primordium begins to turn and completely turns itself around to reverse direction (curved arrow), and it then proceeds back toward the head. Scale bars: A–C: 100 μm; D: 50 μm.
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