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Figure 4 | BMC Developmental Biology

Figure 4

From: A role for Insulin-like growth factor 2 in specification of the fast skeletal muscle fibre

Figure 4

One day old pups (P1) carrying the MIG transgene exhibit, (A) GFP immunoreactivity in all of their skeletal muscle fibres and show up-regulation of fast-myosin in (B) intercostal, (D) Diaphramatic, (F) Trapezial and (H) Deltoidal muscles compared to (C, E, G, I) the same skeletal muscles in their non-transgenic litter mates. (J) Immunostaining demonstrates that fast-myosin heavy chain (fast MyHC) is barely detectable at P1 in non-transgenic pups. Both fast MyHC and fast myosin light chain (MyLC) are substantially up-regulated in P1 MIG transgenic mice. (K) Comparison of the number of muscle fibres positively and negatively staining for fast-myosin shows an increase in the proportions of fast-myosin positive fibres in MIG transgenic muscles and a substantial shift from weak to strong staining in intercostal (IC), diaphragm (Dia), Trapezius (TpZ) and Deltoid (Del) muscles compared to non-transgenic controls. Data shown is of one MIG+ P1 pup and a non-transgenic control. Three other pups analysed in the same way showed essentially the same phenotype. 2 MG P1 pups had a phenotype indistinguishable from the WT littermate. GFP (and Igf-2) immunostaining patterns in both MG and MIG were consistent with published expression patterns for mCK.

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