myf5hu2022 mutants appear normal as embryos but fail to mature into adults. (A) Myf5 truncation predicted from the myf5hu2022 allele. The location of the introduced stop codon is shown; B, basic domain; HLH, helix-loop-helix domain. (B) Genotyped zebrafish embryos from a myf5+/hu2022 carrier incross show no phenotype at 5 days post-fertilisation (5d) as compared with the wild type (+/+). (C) Survival at various ages of fish of each genoptype obtained from myf5+/hu2022 incrosses. The numbers of embryos are shown. (D) In situ mRNA hybridisation for myf5 revealed mildly reduced signal in putative myf5+/hu2022 (13/28) and lower levels in putative myf5hu2022/hu2022 (9/28) embryos. No such effect was observed in myf5 morphants (0/27). (E) Embryos from an myf5+/hu2022 incross lack adaxial myog mRNA early (15/49), and later have a mild delay in myog mRNA accumulation in fast muscle precursors correlated with reduced myf5 mRNA (20/74). Scale bars: 100 μm in D; 150 μm in E.
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