The amino acid pool of Bombyx mori eggs during diapause

Abstract

The levels of alanine and glutamine in the amino acid pool of Bombyx mori eggs changed significantly after oviposition. In diapause eggs the alanine content increased by about 8-fold between 24 and 48 hr after oviposition to reach 42.7 μmol/g. In non-diapause eggs, however, alanine levels remained constant over a similar period. In contrast the glutamine content remained constant at less than 0.5 μmol/g in diapause eggs but increased progressively in non-diapause eggs. At the end of diapause, the alanine content decreased and the glutamine content approached the same level as in non-diapause eggs. The glutamate level did not change at the initiation or termination of diapause, but the proline content increased markedly at the latter time. These results suggest that alanine accumulation at the initiation of diapause might serve a protective function similar to that of polyols. De novo alanine synthesis may require protein breakdown to provide the needed amino groups; at the termination of diapause, however, alanine might be converted to proline.