Ultrastructural organization and RNA labelling of hepatic ribosomes in rats fed on diets deficient in essential amino acids.

Abstract

Rats were starved for 2 days and then refed on either a 25 % casein diet, a non protein diet with no amino acids, or a non protein diet with 25% amino acids. The latter diets contained either all or none of the essential amino acids or were devoid of one of them. The rats were given cytidine-3H, in one experiment 3 h and in another 24 h before death. 29 and 18 S RNA labelling of the livers were determined and liver ultrastructure examined. The specific RNA activity was highest in the rats given the diet with neither protein nor amino acids. Among the rats fed the amino acid diets, there was a tendency towards heavier specific activity in several of the groups on diets deficient in single essential amino acids as compared to the groups on the complete amino acid diet. The groups given all essential amino acids had a low labelling. The ultrastructural examination revealed heavily decreased amount of rough-surfaced endoplasmic reticulum in the groups deprived of protein and amino acids, and all essential amino acids, and also decreased amount in the groups deficient in single essential amino acids as compared to the groups given the complete amino acid diet. Free polysomes were present in large amounts in the groups fed on the deficient diets.