Morphological observation and statistical analysis for dmrt2a-MO and Cont-MO injected zebrafish embryos at 24 hpf. (A) The morphology of normal phenotype embryos (a), mild defect embryos (b) and severe defect embryos (c) after morpholino injection. (B) The percentage of normal phenotype, mild defect and severe defect in Cont-MO injected, dmrt2a-MO injected, dmrt2a MO and mRNA co-injected embryos (100 embryos in each experiment). Error bars indicate mean ± SD, n = 3. Student's t-test was used for statistical analysis (*P < 0.05).

Knockdown of dmrt2a affected the levels of dmrt2b, myhz-2 and myhz-5 mRNA in zebrafish embryos. (A) The fold changes of dmrt2b mRNA in Cont-MO and dmrt2a-MO injected embryos at 24 hpf by qRT-PCR. (B) qRT-PCR detection of the fold changes of myhz-2 mRNA and myhz-5 mRNA in Cont-MO and dmrt2a-MO injected embryos at 24 hpf. (C) Whole mount in situ hybridization of muscle maker genes myod (a,d), myhz-2 (b,e) and myhz-5 (c,f) in Cont-MO embryos (a–c) and dmrt2a-MO embryos (d-f) at 24 hpf. Transverse sections of trunk regions in the corresponding embryos were shown in the right bottom. The ratios of embryos with specific signals are indicated. (D) The fold changes of myhz-2 mRNA and myhz-5 mRNA in control and dmrt2a-mRNA injected embryos at 24 hpf by qRT-PCR. Error bars indicate mean ± SD, n = 3, 30 embryos for RT-PCR and 20 embryos for WISH in each experiment. Student's t-test was used for statistical analysis (*P < 0.05).

Morphological observation and statistical analysis for miR-203a mimic and its negative control mimic (NC) injected group at 24 hpf. (A) Levels of miR-203a in 24 hpf embryos injected with NC and miR-203a mimic. 30 embryos in each experiment. (B) The morphology of normal phenotype embryos (a), mild defect embryos (b) and severe defect embryos (c) after injection. (C) The percentage of normal phenotype, mild defect and severe defect in 20 μM NC, 10 μM and 20 μM miR-203a mimic, 10 μM miR-203a mimic and dmrt2a mRNA injected embryos. 100 embryos in each experiment. Error bars indicate mean ± SD, n = 3. Student's t-test was used for statistical analysis (*P < 0.05).

miR-203a regulates muscle development in zebrafish embryos. (A) qRT-PCR detection of dmrt2a expression after miR-203a overexpression. (B) qRT-PCR detection of myhz-2 and myhz-5 expression level after miR-203a overexpression. NC, negative control mimic. (C) Whole mount in situ hybridization to check zebrafish muscle maker genes myhz-2 (a,b) and myhz-5 (c,d) in NC injected embryos (a,c) and miR-203a mimic injected embryos (b,d) at 24 hpf. Transverse sections of trunk regions in the corresponding embryos were shown in the right bottom. Error bars indicate mean ± SD, n = 3. 30 embryos for RT-PCR and 20 embryos for WISH in each experiment. Student's t-test was used for statistical analysis (*P < 0.05).