Chapter 1. A brief introduction is given reviewing the physiology and biochemistry of fish myotomal muscle. Aspects of protein turnover and metabolism in muscle are discussed and related with previous studies on starvation and refeeding in both mammals and fish. Chapter 2. The marine teleost Pollachius virens L. undergoes a natural starvation during the winter months, and provides a reversible, non-pathological model for studying muscle wasting. In this study fish were kept without food under laboratory conditions for up to 12 weeks. The effects of starvation on muscle fibre cross-sectional area, volume fractions of mitochondria and myofibrils, and capillary supply were determined. Mechanisms of myofibrillar degradation during muscle wasting are discussed. Chapter 3. Starvation in the winter months is followed by a period of refeeding in the late spring, and the musculature degraded during the winter is regenerated. In the present study muscle fine structure has been investigated for fish kept without food, under laboratory conditions, for 74 days, and following 10, 20, and 54 days' refeeding. Muscle fibre cross-sectional area, capillary supply, and volume fractions of myofibrils, nuclei and mitochondria were determined from electron micrographs, using digital planimetry and stereological techniques. In contrast to the starvation atrophy observed in chapter 2 the 74 day starvation reported in this chapter resulted in a decrease in the mean fibre cross-sectional area in both fast and slow muscle. Chapter 4. Experiments were performed using SDS/polyacrylamide gel electrophoresis, to consider the effects of starvation on the relative abundance of actin and myosin heavy chains. Both slow and fast muscle proteins were analysed from control and 66 day starved fish, using densitometric scans of comassie blue stained polyacrylamide gels. The results were expressed as the ratio of each protein relative to actin. Chapter 5. A wide range of biochemical parameters were determined to consider the metabolic effects of starvation and refeeding in saithe. Chapter 6. This chapter investigates the involvement of acid hydrolases and the lysosomal system in muscle atrophy and regeneration, during starvation and refeeding. The results suggest a role for lysosomal enzymes in the breakdown of myofibrillar proteins during starvation. Chapter 7. The results are discussed with reference to the overall strategy of fish to survive starvation immediately followed by a period of rapid muscle repair and growth, during refeeding. The mechanisms Involved in the disassembly and degradation of the myofibrillar proteins are discussed with specific reference to the involvment of the sarcoplasmic reticulum, t-tubules and proteinases. Suggestions are made for further work that may give an insight into some of the questions generated by this research.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:355537 |
| Date | January 1985 |
| Creators | Beardall, Charles Henry |
| Contributors | Johnston, Ian A. |
| Publisher | University of St Andrews |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/10023/14990 |
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