Myofibrillar proteolysis in chick muscle cell cultures during heat stress
2004
Nakashima, K. (National Inst. of Livestock and Grassland Science, Tsukuba, Ibaraki (Japan)) | Nonaka, I. | Masaki, S. | Yamazaki, M. | Abe, H.
The effect of heat stress on protein oxidation and myofibrillar proteolysis in chick myotubes was investigated. Myotubes were incubated at 37 or 41 deg C for 6 and 24 h. Protein carbonyl content, as an index of protein oxidation, increased more at 41 deg C than at 37 deg C for 6 and 24 h incubations. Nt-methylhistidine release as an index of myofibrillar proteolysis also increased more at 41 deg C than at 37 deg C for 6 and 24 h incubations. Proteasome activity also increased more under those same conditions. Calpain and cathepsin D but not B + L activities showed a greater increase at 41 deg C than at 37 deg C for 24 but not the 6 h incubation. These results indicate that heat stress increases protein oxidation and proteasome activity, resulting in an increase in myofibrillar proteolysis for short-term incubation and, for long-term incubation, it increases calpain, proteasome and cathepsin D activities, finally accelerating myofibrillar proteolysis in chick myotubes.
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