Fig 1

(A) The mutant line lmod3^sa13018 harboured a premature stop codon within exon 3 of lmod3, the start codon of which locates at 13’814’978 bp on chromosome 23. Scissors mark single gRNA targets and scale is 1 kbp. (B) The codon GAA encoding for E338 was changed to the nonsense mutation TAA within lmod3^sa13018. (C) Western blot analysis with antibodies against human LMOD3 detected Lmod3 epitope (76 kDa predicted) in siblings (left lane), but not in lmod3^sa13018 homozygotes (right lane). ß-tubulin was used as loading control. (D) In contrast to siblings, the swimming bladder (arrowhead) of 4-dpf-old lmod3^sa13018 homozygotes was not inflated. The bar indicates larval length without the caudal fin. (E) Whereas 4-dpf-old siblings were 3.68 ± 0.03 mm long, the larval length of lmod3^sa13018 homozygotes was with 3.51 ± 0.04 mm significantly shorter (n = 10 larvae). (F) Under polarised light, the muscle of lmod3^sa13018 homozygotes appeared darker compared to their siblings due to a reduction in birefringence. (G) After rescaling to siblings, the birefringence of lmod3^sa13018 homozygotes was significantly reduced to 79 ± 2% compared to their 3-dpf-old siblings. Crosses represent averaged birefringence of clutches with a minimum of 5 larvae per genotype (n = 5 clutches). At 6 dpf, the birefringence of lmod3^sa13018 homozygotes remained significantly reduced to 54 ± 2% of their siblings (n = 8 individual larvae). (H) Signs of fibrosis were absent on cross sections of 6-dpf-old lmod3^sa13018 siblings and homozygotes stained with hematoxylin and eosin (H&E). (I) lmod3^ex3 harboured a deletion of 1385 bp and insertion of 5 bp in exon 3 of lmod3. (J) After rescaling to siblings, the birefringence reduction of lmod3^ex3 homozygotes was 83 ± 2% at 3 dpf and 55 ± 2% at 6 dpf. Similarly, lmod3^ex3/sa13018 compound heterozygotes had a highly significant reduction in birefringence to 83 ± 2% at 3 dpf and to 58 ± 2% at 6 dpf. At 3 dpf, crosses represent averaged birefringence of clutches with a minimum of 5 larvae per genotype (n = 5 clutches) and individual larvae at 6 dpf (n = 8 larvae). Data are presented as mean ± SEM; ** P < 0.01 and *** P < 0.001 were calculated by Student’s t-test. Scale bar sizes are indicated.