Marcel Florkin

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.

Recherche des enzymes du cycle de l'ureogenese chez l'escargot Helix pomatia L

Abstract 1. 1. A small incorporation of 14CO2 into urea has been observed in vivo in Helix pomatia when the snail was injected with NaH14CO3. 2. 2. The same incorporation could not be shown in vitro. 3. 3. The reaction ornithine → citrulline catalysed by ornithine transcarbamylase has been observed in vitro, when carbamylphosphate was added to the incubation mixture.

Prism conchiolin of modern or fossil molluscan shells. An empire of protein paleization

Abstract 1. 1. While global nacre conchiolin shows in its composition the predominantly concentrations of four amino acids: glycine, alanine, serine and aspartic acid, global prism conchiolin shows a different pattern, characterized by two predominantly amino acids: glycine and aspartic acid. 2. 2. Prism conchiolin has been isolated from fossil shells of Pinna affinis (London, Clay, Lower Eocene) and Inoceramus sp. (Gault, Cretaceous). The comparison of modern and fossil prism conchiolins shows differences in the pattern of amino acid composition. The significance of these differences is discussed.

N-terminal amino acid sequence of dromedary trypsinogen.

Abstract The sequence of the activation peptide of dromedary trypsinogen has been determined and compared with that of other artiodactyls and of one perissodactyl and two primitive fishes.

Sur la spécificité des principes extraits de la région neuro-glandulaire de l'ascidieCiona intestinalis

Despite controversial evidence, the authors still believe in the presence of specific substances (ocytocic and dilator of frogs melanophores) in the neuroglandular region of the ascidianCiona intestinalis.

Purification, propriétés et séquence N-terminale du trypsinogène de chèvre

Goat trypsinogen has been extracted with acid from goat pancreas and purified by two chromatographies on CM-cellulose. Its purity has been checked by ultracentrifugation and polyacrylamide gel electrophoresis. Its amino acid composition is only slightly different from that of sheep trypsinogen, but its isoelectric point must be lower Two N-terminal residues, phenylalanine and valine, have been detected. Semiquantitative results indicate that phenylalanine and valine are in the ratio of 4 Phe to 1 Val. Two activation peptides are split during the activation: the hexapeptide Val-Asp-Asp-Asp-Asp-Lys and the octapeptide Phe-Pro-Val-Asp-Asp-Asp-Asp-Lys. The same activation peptides have been found in sheep, red deer and roe deer trysinogens. We conclude to the existence of two trypsinogens, one of them lacking the first two residues Phe-Pro-. However, the production of the latter by the splitting of a Pro-Val bond, occurring either in situ, or during acid extraction, cannot be excluded. The sequence -Asp-Asp-Asp-Asp-Lys is common to all known trypsinogen activation peptides, including ox, sheep, goat, red deer, roe deer, pig, wild boar, horse and dogfish.

N-terminal amino acid sequence of trypsinogen from the lesser rorqual, Balaenoptera acutorostrata (Cetacea). Simultaneous isolation of trypsinogen, chymotrypsinogen and ribonuclease from pancreas.

Abstract Ribonuclease, trypsinogen and two chymotrypsinogens have been extracted from a pancreas of a whale. The activation peptide of trypsinogen has been isolated and its sequence compared with other known sequences. The relative position of the Cetacea among the orders of Mammalia is discussed. A sequence is proposed for the common ancestor of the mammals considered.

N-terminal amino acid sequence of trypsinogen from the elephant seal Mirounga leonina L. (Carnivora)☆

Abstract Trypsinogen has been extracted and purified from the pancreas of an elephant seal. The activation peptide has been isolated and its sequence compared with 13 other known sequences, including those from two primitive fishes and an insect.