Isolation of l(+)-methionine sulfoxide related to diapause induction in the silkworm, Bombyx mori

l( + )-Methionine sulfoxide [l( + )-Met(O)] was isolated from pupal hemolymph of the silkworm, Bombyx mori, by means of thin layer chromatography and high performance liquid chromatography. Its stucture was determined by FD-and FAB-mass spectrometry and by comparison with authentic l( + )-Met(O). The concentration of natural l( + )-Met(O) was very low in the fifth larval instar, but increased rapidly during the progression of the wandering stage and throughout the pupal and adult stages. The concentration of l( + )-Met(O) was higher in the hemolymph of diapause egg producers than in non-diapause egg producers, suggesting a relationship with the regulation of diapause and/or development.