Fig. 7

Overexpression of NRG1 Type III does not rescue myelination in peripheral nerves of gpr126 mutants. (A-H) Lateral views (anterior to the left, dorsal to the top) of mbp expression in control (A,C,E,G) or hNRG1 type III transgenic (B,D,F,H) embryos at 3 dpf. The white arrows in A and B mark mbp-expressing Schwann cells of the PLLn, and the white arrowheads in F mark Schwann cells along motor nerves. Control heterozygous embryos at 3 dpf express mbp in the PLLn (A) but not motor nerves (E) (n=35 fish), but transgenic embryos overexpressing hNRG1 type III show precocious mbp expression in motor nerves (F), in addition to expression in the PLLn (B) (n=89 fish). No expression in the PLLn or motor nerves was observed in gpr126^st49/st49 mutant embryos in either control (C,G; n=6 fish) or hNRG1 type III transgenic fish (D,H; n=29 fish), although mbp staining in the spinal cord was evident. White asterisks mark CNS expression in all panels. Scale bars: 50 μm.