Gh. Duchâteau-Bosson

Change in intracellular concentration of free amino acids as a factor of euryhalinity in the crayfish Astacus astacus

Abstract 1. 1. Astacus astacus survives in twice-diluted seawater in spite of the fact that the osmoregulatory mechanism which is active in freshwater maintains the concentration of the blood at an even higher level than that of the diluted seawater. 2. 2. In these conditions, the degree of hydration and the potassium content of the abdominal muscle show only a very slight modification. 3. 3. The adaptation results from an increase of intracellular concentration which is partly due to an increase of free amino acids. 4. 4. While the increase of blood concentration, in a crayfish transferred from fresh water to twice-diluted seawater, amounts to a change in Δ of 0·24°C, the increase in concentration of intracellular amino acids corresponds to 0·15°C, which shows that the free amino acids play an important role in the mechanism of adjustment.

Contributions à la biochimie du ver à soie. XXVII. Tréhalose, tréhalase et mue

AbstractDuring the development of the Silkworm, the amount of blood trehalose sharply decreases at each moult, and also during the fasting period corresponding to spinning. the fall of blood trehalose concentration during the moults is related to the release of the inhibition of the trehalase present in the hemolymph.The presence of a trehalase in the muscles and in the digestive tract is confirmed. This enzyme has not been detected in the fat body, in the epidermis or in the silkglands.In the fat body, there exists an inverse relationship between glycogen and trehalose, the former disappearing almost completely at each moult, whereas the amount of trehalose tends to remain at a nearly constant level. On the other hand, the bulk of the fat body is consumed to a large extent during the periods of chitin synthesis.The gluconeogenesis during the silkworm development and the metabolism of chitin synthesis at each moult, are discussed in the light of these experimental data.

Les constituants osmotiquement actifs des muscles et leur contribution a la regulation isosmotique intracellulaire chez Limulus polyphemus

Resume 1. 1. The chemical composition of the blood and of the intracellular medium of the muscles has been studied in the king crab ( Limulus polyphemus ) and compared with that of marine decapods (Crustaceans) and of a scorpion, Androctonus australis . 2. 2. The blood of Limulus contains only very small amounts of free amino acids. The amino-acid composition of the muscles of Limulus differs from that of decapods, but is similar to that of the scorpion, with respect to its lower concentration and to the relative proportions of free arginine and free glycine. 3. 3. The intracellular osmolar effectors in Limulus are principally dialysable nitrogenous compounds, other than amino acids and taurine. These unidentified substances play an important role in the isosmotic intracellular regulation which takes place when Limulus is adapted to brackish water (40% sea water). This is another difference between Limulus and marine decapods; the latter show a regulation in which free amino acids are among the most important effectors.