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When skeletal muscle is stretched or injured, myogenic satellite cells are activated to enter the cell cycle. This process depends on nitric oxide (NO) production by NO synthase (NOS), matrix metalloproteinase activation, release of hepatocyte growth factor (HGF) from the extraeellular matrix, and presentation of HGF to the c-met receptor as demonstrated by a primary culture and in vivo assays. We now add evidence that calcium-calmodulin is involved in the satellite cell activation cascade in vitro. Conditioned medium from cultures that were treated with a calcium ionophore (A23187, ionomycin) for 2 h activated cultured satellite cells and contained active HGF, similar to the effect of mechanical stretch or NO donor treatments. The response was abolished by addition of calmodulin inhibitors (calmidazolium, W-13, W-12) or a NOS inhibitor [N.sup.G]-nitro-L-arginine methyl ester hydrochloride but not by its less inactive enantiomer [N.sup.G]-nitro-Darginine methyl ester hydrochloride. Satellite cells were also shown to express functional calmodulin protein having a calcium-binding activity at 12 h postplating, which is the time at which the calcium ionophore was added in this study and the stretch treatment was applied in our previous experiments. Therefore, results from these experiments provide an additional insight that calcium-calmodulin mediates HGF release from the matrix and that this step in the activation pathway is upstream from NO synthesis. muscle regeneration; stretch-activation

The sense of taste plays an important role in the detection of nutrients or toxic substances in foods, and it is deeply related to the feeding behaviours of animals. Thus, elucidation of the taste-sensing system in chickens can improve our understanding of poultry nutrition and will be useful to make new alternative feedstuffs. In this review, we summarise the recent advances in the study of taste buds, taste receptors and taste perception in chickens. Recent studies have revealed the distribution of taste buds in the oral cavity of chickens and the expression of multiple taste receptors in the oral and gastrointestinal tissues of chickens. Functional analyses have shown that chicken taste receptors can recognise amino acids, fatty acids, and a wide variety of bitter compounds, and the activities of chicken bitter taste receptors can be inhibited by 6-methoxyflavanone. Behavioural analyses have demonstrated that chickens can respond to amino acids, bitter stimuli, salty stimuli, sour stimuli and fatty acids, but chickens have a low taste sensitivity for sugars. The recent histological, molecular biological, and behavioural evidence indicates that chickens have well-developed nutrient-sensing systems. [ABSTRACT FROM AUTHOR]