Fig. 2

six1 morphants have a reduced fast muscle area. (A) Ventral and lateral views of head (left two columns) and lateral view and cross-section of the trunk (right two columns) of 3-dpf tg(mylz2:GFP)ⁱ¹³⁵ embryos uninjected and injected with six1a and six1b morpholinos alone or in combination. Cross-sections are stained with F310. (B) F310⁺ cross-section area of 24-hpf and 3-dpf embryos; the area of uninjected control embryos is set as 100%. Compared with control embryos at 24hpf (n = 5), six1a morphants have an area of 94.0% (n = 5), six1b morphants 88.4% (n = 5) and six1a and six1b double morphants 92.8% (n = 5). In 3-dpf embryos compared with control embryos, (n = 5) six1a morphants have an area of 84.9% (n = 5), six1b morphants 55.0% (n = 5) and six1a/six1b double morphants 37.2% (n = 6). Compared with uninjected control embryos (n = 4) set as 100%, six1a/p53 morphants have an F310⁺ cross-section area of 79.7% (n = 4), six1b/p53 morphant embryos 62.1% (n = 5) and six1a/six1b/p53 triple morphants have an area of 55.6% (n = 4). (C) Average number of DAPI-stained nuclei per F310⁺ (fast muscle specific) cross-section area of 3-dpf embryos. Uninjected control embryos have an average of 151.3 DAPI-stained nuclei per F310⁺ cross-section area (n = 5), six1a morphants have 156.0 (n = 5), six1b morphants 135.2 (n = 6) and six1a/six1b double morphants 119.5 (n = 7). 3-dpf six1a/p53 morphants have an average number of 156 DAPI-stained nuclei per F310⁺ cross-section area (n = 4), six1b/p53 morphants 152.2 (n = 5), six1a/six1b/p53 triple morphants 119.3 (n = 4) and control embryos have 159.5 (n = 4). (D) Number of slow fibres per somite in 24-hpf and 3-dpf embryos. fb, fin bud; hh, hyohyoideus; ih, interhyoideus; ima, intermandibular anterior; imp, intermandibular posterior; om, ocular muscles; sh, sternohyoideus; som, somites. Cross-sections were made at somite number 10 for 24-hpf embryos, and at somite number 8 for 3-dpf embryos. *P<0.05, **P<0.01, ***P<0.001. Scale bars: 50μm.