The metabolism of the aestivating African lungfish

Abstract

1. 1. Changes in the concentration of glycogen and urea and activities of key enzymes in protein and amino acid metabolism were measured in fed control, starved and aestivating African lungfish. 2. 2. The concentration of glycogen in the livers of starved and aestivating 3. fish was lower by 40 per cent than in controls. In muscle, the concentration of glycogen fell by 75 per cent after starvation, but increased by 50 per cent during aestivation. 4. 3. During aestivation, urea accumulated in the tissues to a level five times higher than in control or starved fish. This urea was excreted on return to water. 5. 4. No change in protease activity could be detected during aestivation or starvation. 6. 5. The concentration of glutamic pyruvic transaminase in both liver and muscle fell by a factor of 10 during aestivation. 7. 6. The concentration of glutamic oxaloacetic transaminase did not change during starvation or aestivation. 8. 7. The importance of carbohydrate reserves to animals which enter phases of torpidity is discussed and it is suggested that the change from production of ammonia to production of urea following dehydration may be brought about by alteration in transaminase activity. 9. 8. An apparatus is described by which Protopterus may be induced to enter into aestivation in the laboratory.