Subject index pathway

Volume 28. Morphogenesis, differentiation and development I. Fertilization by A. Monroy. II. Behaviour of nucleic acids during early development by J. Brachet. 111. Biochemical pathways in embryos by E. Scarano and G. Augusti-Tocco. IV. Factors of embryonic induction by T. Yamada. V. Biochemistry of amphibian metamorphosis by R. Weber. VI. Biochemical correlations in insect metamorphosis by L. I. Gilbert. Subject index. 

The smdy of tissue protein breakdown in vivo is difficult, because amino acids released during intracellular breakdown of proteins can be extensively reutilized for protein synthesis within the cell, or the amino acids may be transported to other organs where they enter anabohc pathways. However, actin and myosin are methylated by a posttranslational reaction, forming d-methylliistidine. During intracellular breakdown of actin and myosin, 3-methylhistidine is released and excreted into the urine. The urinary output of the methylated amino acid provides a rehable index of the rate of myofibrillar protein breakdown in the musculature of human subjects. 

Finally, it was found (B7) that the excretion of 5-hydroxyindoleacetic acid, which is taken as an index of tryptophan metabolism by the serotonin pathway, is affected by the administration of tryptophan neither in normal nor in schizophrenic subjects. 

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