Fig. 8

Blockade of ingression of Pax7a⁺ cells by BIO. The pax7a:GFP BAC transgene was bred onto a pfe/pfe background to diminish xanthophores (left panels). Such fish bred onto myod^fh261/+ were in-crossed (right panels) and genotyped by sequencing. Larvae treated for 24 h with BIO or vehicle were stained in wholemount for GFP, Myog and DNA (left panels) or GFP, Pax7 (right panels). Confocal images are maximum intensity projections of short stacks in the deep myotome in lateral view with dorsal up and anterior to left, showing the decline of GFP⁺ cells (arrows) between fibres in the deep central myotome. VM vertical borders, CP central portion. Bars 50 µm. B. Number of pax7a:GFP⁺ cells in epaxial region of somites 16–18 of 12 BIO-treated 4 dpf embryos compared with 12 controls. Significantly fewer Pax7a⁺ cells were present deep within the somite, which was accounted for by highly significant loss from the deep CP. Sup = superficial. C. Larvae from an incross of pax7a:GFP;myod^fh261/+ were sorted for GFP, treated at 2.25 dpf with BIO or vehicle, stained at 3.25 dpf for GFP, Pax7 and myosin and genotyped by head muscle. Total (left) and deep CP (right) Pax7⁺ cells were counted from confocal stacks of five larvae in each condition and differences tested by ANOVA with Bonferroni multiple comparison test.