Developmental changes in _D-serine level in the silkworm, Bombyx mori

抄録

To elucidate the physiological role of _D-serine, an optical isomer of the common _L-serine, in invertebrates, we investigated in detail changes in the _D-serine level (concentration) occurring with growth and development in the silkworm, Bombyx mori, since the silkworm is known for containing high concentrations of _D-serine. The body d-serine level increased with age until the late pupal stage. The total amount of _D-serine in the body also increased with age and formed two peaks at the pre-spinning to early spinning stage and the late pupal stage, suggesting that the larvae may require _D-serine to become pupae and imagoes, respectively. Contrary to the _D-serine level, the _L-serine level decreased with age after the second instar, with increase-decrease repeats until the pupal stage. High concentrations of _D-serine were excreted in feces, gut purge, meconium, and exuvium, suggesting that the body d-serine is maintained at a proper level for growth and development by excluding the amino acid from the body.