[Free amino acids of hemolymph during pubertal molting and senescence in Spaeroma serratum (Isopoda, Flabellifera].

In Sphaeroma serratum, the amino-acidemia is high (about 120 mg/100 ml) during the intermolt stages. The relative proportions of the different free amino acids show only slight differences in young males and senescent ones. At the time of the puberty molt, the total amino-acids concentration (including taurine) of the hemolymph increases sharply during premolt (up to 267 mg/100 ml), falls after ecdysis (down to 97 mg/100 ml and then rises up to the level of the intermolt stage. These variations are due not only to concentration or dilution of the whole hemolymph constituents, but also to specific modifications of the concentration of some of the free amino-acids with respect to the others. These variations of the amino-acidemia, mainly those of serine, proline, glycine, alanine and of the amine taurine, could play a definite role in increasing the osmotic pressure of the hemolymph during premolt, as a preparation to ecdysis.