The amino acid metabolism of the developing sea urchin egg

The amino acid composition of the sea urchin egg in different developmental stages has been studied. In early development the changes in amino acid composition are relatively small. Clear changes in the content of most amino acids begin to occur in mesenchyme blastula stage or during gastrulation. Glutamine and the peptide containing fraction of tungstic acid extracts show greater quantitative changes than any of the other amino acids or fractions studied. Li treatment, which checks ectoderm-formation and favours entoderm-development also interferes on the amino acid level. The present results have been discussed in relation to other results from experimental, cytological and enzymic studies. An attempt to synthesize all these findings has been made.