Studies on the embryonic diapause of thepnd mutant of the silkworm,Bombyx mori : III. Accumulation of alanine in the diapause eggs.

The changing pattern in free amino acids following the embryonic development in the non-diapause and diapause eggs of thepnd mutant of theBombyx silkworm was studied. In the diapause eggs, heterozygous for thepnd gene, the levels of most of the amino acids increased concomitantly with the substantial decrease in oxygen consumption. Among the amino acids, alanine was the only amino acid that showed a large accumulation. The accumulation could be induced experimentally in the non-diapause eggs, homozygous for thepnd gene, by reducing the oxygen supply. In contrast, it was prevented in the diapause eggs by increasing the oxygen supply. From these results, it is suggested that the alanine accumulation is the consequence of anaerobic metabolism in the eggs during diapause. The possible significance of the alanine accumulation is discussed in relation to the anaerobic carbohydrate metabolism associated with the embryonic diapause in thepnd mutant.