Protein metabolism: IV. Altered protein synthesis in hosts infected with Eimeria tenella or bacteria compared to synthesis in hosts infected with intestinal nematodes

Abstract

The cecal infection of the chicken by the protozoan coccidia Eimeria tenella, the generalized bacterial infection of the guinea pig by Yersinia pseudotuberculosis, and a bacterial infection of the feet of the sheep (foot-rot) were used to test the hypotheses, first, that a slower rate of muscle protein synthesis is not specific to nematode infections but also occurs in unrelated diseases characterized by anorexia, and second, that liver protein synthesis would not increase without loss of serum proteins. The first hypothesis was supported when the rate of incorporation of radioactively labeled l-leucine, in vivo by muscle and in vitro by isolated ribosomes, was reduced in coccidiosis and yersinosis, but the effect of foot-rot was uncertain. The possible reasons for the difference between foot-rot and the other two infections are discussed. The growth of wool was reduced in foot-rot as in nematode infections. The results of two infections did not support the second hypothesis because the rate of liver protein synthesis was unchanged in chickens with cecal hemorrhage, whereas incorporation of amino acid by membrane-bound ribosomes, which synthesize certain serum proteins was increased in foot-rot in which there is no intestinal loss. The hypothesis was supported in yersinosis, a disease without intestinal loss and in which the rate of liver protein synthesis was unchanged. Evidence that loss of protein may increase the apparent concentration of DNA and RNA of muscle and liver is presented.