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Fig. 3
Knockdown of pgam2 specifically affects developing fast muscle fibers in zebrafish embryos. (A–C2) Morpholino mediated pgam2 knockdown (pgam2 MO) leads to a decrease in muscle birefringence. (A–C) Bright-field images; A2–C2 are the same embryos as in A–C under polarized light. Intensity of birefringence is color-coded. misMO, mismatch control morpholino injected embryos. (D–I) A muscle phenotype characterized by disturbance of fiber arrangement and reduced fiber diameters is only observed in fast muscle (G–I) of zebrafish pgam2 morphants. (D–F) Slow muscle fibers stained with the F59 antibody (green). (G–I) Fast muscle stained with phalloidin (red). (Scale bars: 11.9 μm.) (J and K) Fast fibers stained with Unc45-b-GFP (green) to reveal position of nuclei (arrowheads). (L) The number of nuclei per fast muscle fiber is significantly reduced in pgam2 morphants (***P = 0.0001). (M and N) The diameter (micrometers) of fast fibers (N), but not of slow fibers (M), is significantly reduced in pgam2 morphants (**P = 0.0027). A–I, M, and N: 48 hours postfertilization (hpf) embryos; J–L: 72 hpf embryos.