Effects of the regulation of follistatin mRNA expression by IGF-1 in duck (Anas platyrhynchos) skeletal muscle

Characterization of muscle development and gene expression in early embryos of chicken, quail, and their hybrids

Myogenesis is a complex, regulated process that involves myoblast proliferation, migration, adhesion, and fusion into myotubes. To investigate early development of embryonic muscles and the expression of regulatory genes during myogenesis in chicken, quail and their hybrids, meat-breeding cocks and egg-breeding cocks were selected as male parents, quails were used as female parents. Their offspring were meat and egg hybrids via Artificial insemination. We measured expression of MUSTN1, IGF-1, and PDK4 using qRT-PCR. We examined muscle fiber diameter using scanning electron microscopy. The results showed that muscle development was two days slower in chicken, egg hybrid, and meat hybrid than in quail. Muscle fiber spacing was the largest in chicken, followed by meat hybrid, egg hybrid, and quail. A similar trend was obtained for muscle fiber diameter. Additionally, muscle fiber diameter increased with embryogenesis. The sarcomere was present on day 17 of incubation in quail, but not in the other species. MUSTN1 could up-regulated IGF-1 by activating PI3K/Akt. IGF-1 expression was consistent with myoblast proliferation and myotube fusion. PDK4 was expressed from E7 to E17. The first peak was reached on E10, egg hybrid and meat hybrid reached their peak at E15. PDK4 is involved in the early proliferation and differentiation of muscle, thereby affecting muscle growth and development. Our findings demonstrated that MUSTN1, IGF-1 and PDK4 genes are expressed to varying levels in breast muscle of chicken, quail, egg hybrid and meat hybrid during the embryonic period. Interestingly, with increasing embryonic age, muscle development was approximately 48 h faster in quail than in other species. We speculated that MUSTN1, IGF-1 and PDK4 genes may be the main candidate genes that cause differences in poultry muscle traits, but the molecular regulation mechanisms need to be further studied. Our findings shed some light on the avian embryo muscle formation and molecular breeding of poultry muscle traits, which provide theoretical basis for poultry breeding.

Change in Ubiquitin Proteasome System of Grass Carp Ctenopharyngodon idellus Reared in the Different Stocking Densities

The ubiquitin proteasome system (UPS) is a highly regulated mechanism of intracellular protein degradation and turnover. To evaluate the effect of crowding stress on the UPS in fish, grass carp (Ctenopharyngodon idellus) were randomly reared at low stocking density (LSD, 0.9 kg m⁻²) or high stocking density (HSD, 5.9 kg m⁻²) for 70 days. The expression of the genes regulating UPS, stress-related parameters, and profiles of amino acid in white muscle as well as growth rate of fish reared at two stocking densities were investigated. Fish exhibited significantly higher growth rate in the LSD group compared to the HSD group. Serum concentrations of cortisol, total protein, and glucose did not vary significantly in fish between two groups. There was no significant difference in the mRNA levels of nrf2, keap1, and hsp90 in white muscle of fish stocked at two densities at the endpoint of the experiment. In the UPS pathway, the expressions of ub, chip, psmc1 in the LSD group were significantly higher than those in the HSD group (P < 0.05). Ubiquitinated protein level and the content of 3-Methylhistidine elevated significantly in the LSD group (P < 0.05). The mRNA levels of mafbx, murf1, and s6k1 in the LSD group were significantly higher than those in HSD group (P < 0.05). These results illustrate that the fish cultured in lower stocking density would exhibit a greater growth rate and a fast protein turnover in muscle.

Positive effect of IGF-1 injection on gastrocnemius of rat during distraction osteogenesis

Distraction osteogenesis (DO) is used to form new bone between bone segments to lengthen the callus. Skeletal muscles frequently fail to adapt to distraction, which causes complications. Insulin-like growth factor-1 (IGF-1) has been implicated as a central regulator of muscle repair. We hypothesized that IGF-1 injection could reduce muscle complications in DO. A total of 102 Sprague-Dawley rats received DO or did not were randomly assigned into saline, IGF-1 and normal groups. On the day before the distraction, the rats in the IGF-1 group were injected with IGF-1. The gastrocnemius muscles of the rats were harvested at the 0, 1st, 4th, 7th, and 10th days of distraction. The weight of the muscles, cross-sectional area (CSA) of the muscle fibers, collagen volume fraction (CVF), maximum limit load (MLL), maximum contraction forces, and gene expression of Akt, MyoD, myogenin, myostatin, and collagen I were analyzed. The results indicated that IGF-1 injection had increased the weights, CSA of the muscle fibers, MLL and force generation of the gastrocnemius. Also, Akt, MyoD, and myogenin were upregulated, and myostatin was downregulated in the IGF-1 group. Injection of IGF-1 could attenuate the gastrocnemius atrophy, prevent fibrosis, increase MLL, and regulate the related mRNA.