Influence of temperature and growth selection on turkey pectoralis major muscle satellite cell adipogenic gene expression and lipid accumulation
Immature poults have an inefficient thermoregulatory system, and therefore extreme ambient temperatures can impact their internal body temperature. Satellite cells, the only posthatch myonuclei source, are multipotential stem cells and sensitive to temperature. Selection for faster-growing, high-yielding birds has altered satellite-cell properties. The objective of the current study was to determine how temperature affects adipogenic properties of satellite cells isolated from the pectoralis major (p. major) muscle of Randombred Control line (RBC2) and F line turkeys selected only for increased 16-wk body weight from the RBC2 line. Satellite cells were cultured at 2°C incremental temperatures between 33 and 43°C and compared to cells cultured at the control temperature of 38°C to ascertain temperature effects on lipid accumulation and expression of adipogenic genes: CCAAT/enhancer-binding protein-β (C/EBPβ), peroxisome proliferator-activated receptor-γ (PPARγ), and stearoyl-CoA desaturase (SCD). During proliferation, the amount of quantifiable lipid in both F and RBC2 satellite cells increased at temperatures above 38°C (P < 0.01) and decreased at temperatures below 38°C (P < 0.01). Above 38°C, RBC2 satellite cells had more lipid (P = 0.02) compared to the F line, whereas there were few differences between lines below 38°C. At 72 h of proliferation, expression of C/EBPβ, PPARγ, and SCD decreased (P ≤ 0.02) as temperatures increased from 33 to 43°C in both cell lines. During differentiation expression of C/EBPβ increased (P < 0.01) as temperatures increased from 33 to 43°C in both cell lines. In F line satellite cells, PPARγ expression decreased (P < 0.01) with increasing temperatures during differentiation, whereas there was no linear trend in RBC2 cells. During differentiation expression of SCD increased as temperatures increased (P < 0.01) in RBC2 cells, and there was no linear trend within the F line. Results from the current study suggest that environmental temperature can affect p. major satellite cellular fate; however, selection for increased body weight had little impact on these cellular responses.