Metabolic changes in free amino acids and peptides during urodele development

Abstract

1. 1. Metabolic changes in free amino acids and peptides during the development of three urodeles, Triton alpestris, Triton palmatus and Triton cristatus, were studied by the method of paper partition chromatography. 2. 2. In the early blastulae of Triton alpestris the following free ninhydrinpositive substances have been identified: aspartic acid, glutamic acid, cystine, serine, threonine, α-alanine, glutamine, and one peptide. In the newly hatched larvae the free amino acids and peptides are present in a much higher concentration. In addition to the substances detected in the early blastulae, they contain free glycine, tyrosine, lysine, arginine, histidine, tryptophan, γ-aminobutyric acid, valine, methionine, leucine, proline and at least three more peptides. 3. 3. Quantitative determinations of total free amino acids and peptides performed on embryos of all three urodele species showed that the increase of these substances starts at the onset of gastrulation, becomes more obvious during neurulation and rises rapidly in later embryonic development. 4. 4. Aspartic acid and glutamic acid fall to a minimum at the late blastula stage, increase steadily afterwards and again show a slight drop prior to hatching. Glutamine behaves in the opposite manner. It rises to a high concentration at the late blastula stage, then decreases to a low level and reaches a maximum in the newly hatched larvae. With the exception of a minor drop at the early gastrula stage, the peptide shows a steady increase in concentration as development proceeds. Finally, a general increase of tyrosine, leucine, valine, α-alanine, serine and glycine was detected during later development. The concentration of tyrosine rises more rapidly as the pigmentation of the embryo becomes obvious. 5. 5. The significance of the experimental results in relation to morphogenetic processes and their bearing on problems of protein metabolism are discussed.