(A–C) There does not appear to be a difference in the maturation or localization of e-cadherin in either 5ng prp1 morpholino injected AB zebrafish or uninjected prp1ua5003/ua5003; prp2ua5001/ua5001 homozygous mutant fish compared to uninjected wild-type controls. (F–E) After 3dpf wild-type larvae injected with prp1 MO (f) show significant signs of necrosis and developmental abnormalities compared to uninjected and control injected larvae (d, e)

smpx knockdown disturbs the proper fiber arrangement during development. (A–D) side views, anterior left, dorsal top. Paraffin sections of Control-MO (A,C) and smpx-MO (B,D) injected embryos at 48 hpf (A,B) and 4 dpf (C,D). The red asterisks indicate alterations in the muscle array. (E–H) side views, anterior left, dorsal top. Confocal Z-stacks taken from whole-mount embryos (48 hpf) and larvae (72 hpf) labelled with (E,F) myosin heavy chain (MHC) antibody for slow fibers and (G,H) phalloidin (act) for actin filaments of the fast fibers. The red (F) and white (H) asterisks indicate alterations in the normal muscle array (controls in (E,G), respectively). (I,J) representative lateral view of an embryo injected with the construct encoding the Smpx:GFP chimera (see Figure S1A for construct details); muscle fibers (arrowhead) and epithelial cells (arrow) are both uniformly painted with no accumulation of Smpx:GFP in the nuclei. Inset: magnification of a slow fiber with the nucleus (asterisk) labelled with DAPI (blue). Anterior left, dorsal top. Scale bars = 25 μm in (A–D); 20 μm in (E,F); 20 μm in (G,H); 100 μm in (I,J).

Aberrant mvda function causes developmental defects in zebrafish. A Quantitative real-time PCR (qRT-PCR) for twelve embryo development stages (0.2 hpf, 1 hpf, 2 hpf, 3.7 hpf, 6 hpf, 24 hpf, 30 hpf, 48 hpf, 72 hpf, 96 hpf, 120 hpf, and 144 hpf) demonstrates different expression patterns of mvda during embryonic development. B Effectiveness of mvda knockdown was confirmed by RT-PCR and sanger sequencing. The zebrafish mvda gene was targeted by specific morpholino antisense to prevent the proper splicing of exon 3 (E3I3-MO). Primers spanning mvda exon 1 (forward) and exon 4 (reverse) interrogate the presence of wild type (non-mutant) transcripts or those in which intron 3 has been inserted. RT-PCR of mvda transcript from control-MO and E3I3-MO injected embryos at 2-dpf, demonstrating insertion of intron 3. Sanger sequencing of both the wild-type band and the intron 3-inserted band validating the wild-type sequence and the intron 3-inserted sequence. C–J Gross morphology at 2-dpf and 4-dpf. Compared with the control group, knockdown of mvda presented hydrocephaly (E, blue arrowhead), eye defects (E, I, blue arrow), pericardial oedema (E, I, red arrow), blood accumulation in the caudal vein (E, F, red circled area), and skin defects (J, black arrows). Heartbeat and circulation in the caudal vein were visible in the control fish but were abnormal in mvda morphants (Additional file 2: Video S1, Additional file 3: Video S2). hpf, hours post fertilization; dpf, days post fertilization. Scale bars = 100 µm