Figure 7

Rate of protein synthesis in cardiac and skeletal muscles of ground squirrels. SA summer activity, IBA interbout arousal. (A) Total protein synthesis. Full-length representative immunoblot for puromycin on PVDF membrane (brightness, + 30; contrast, – 50). The levels of proteins synthesised in vivo were identified relative to the total protein level. The total protein level in the samples was measured by the Bradford method. Bovine serum albumin was used as a standard. M, molecular weight marker. The original images are at: https://drive.google.com/open?id=1XljyCN3sfWktjuHRPACab3eQfOc6i2AC. (B) Syntheses of nebulin and titin. Ponceau S staining and representative immunoblots for puromycin on nitrocellulose membranes (puromycin for heart: brightness, – 88; contrast, + 200; puromycin for m. longissimus dorsi: brightness, – 90; contrast, + 200; Ponceau S for heart and m. longissimus dorsi, without changes). The levels of proteins synthesised in vivo were identified relative to the total protein level (stained with Ponceau S). SDS-PAGE analysis was performed using agarose-strengthened 2.2% polyacrylamide gel. MyHC, myosin heavy chains. Full-length Ponceau S and puromycin stained membranes are shown in Supplementary Figs. S16–S23. The first and second tracks (heart, Supplementary Figs. S16, S18), the second and third tracks (m. longissimus dorsi, Supplementary Figs. S20, S22) from the full-length membranes are shown in (B). (C) Bar graphs of total protein synthesis in the heart and m. longissimus dorsi (Supplementary Tables S25, S26). There was a significant decrease in the rate of total protein synthesis in the heart (by 3.67, p < 0.01) and m. longissimus dorsi (by 2.96, p < 0.01) during interbout arousal in comparison with those in summer active animals (n = 5/group). (D) Bar graphs of titin and nebulin syntheses in striated muscles (Supplementary Tables S27–S29). No significant differences were found between the synthesis rates of titin and nebulin in muscles of ground squirrels from the two groups (n = 3/group). The data were analysed using the nonparametric Mann–Whitney U criterion. Values are means ± SD. **p < 0.01.