Animalisation de l'œuf de l'oursinParacentrotus lividus par des substances polysulfoniques

Summary The effects of two compounds with sulfonic acid groups, chlorazol sky blue and Germanin (Bayer 205), are being studied on the developing egg of the sea urchin,Paracentrotus lividus. The chlorazol sky blue (1/5000) is a very effective animalizing agent. In dilute solutions (1/25000 and 1/100000), it induces the development of radial larvae. The lithium chloride counteracts the animalizing effects of chlorazol sky blue. The Germanin has an animalizing effect only at high concentrations. The penetration of these agents appears essential for the animalization. The reaction of the sulfonic acid groups with the basic groups of the intracellular proteins appears to be concerned with the animalizing effect. The results of these experiments are discussed in relation to the animalizing effects of various sulfonated dyes and zinc ions.     

Végétativisation de l'œuf de l'oursin par la Phénazone

Summary Phenazone employed in various concentrations on the eggs of the sea urchin,Paracentrotus lividus, has a powerful vegetalizing effect on their development. The role of the interference between phenazone and synthetic process of specific proteins is considered.     

Étude cytochimique des groupes sulfhydriles au cours des modifications de la détermination embryonnaire chez l'œuf de l'oursinParacentrotus lividus

Summary A cytochemical study of the distribution of sulfhydryl groups in animalized and vegetalized embryos of the sea-urchinParacentrotus lividus has been made by use of the Bennett's reagent. The distribution of the sulfhydryl groups appears homogeneous in these embryos. No gradient has been observed in the experimental conditions used.     

Action de la triéthylènemélamie sur les mitoses de segmentation de l'œuf de Pleurodèle

Summary Triethylenemelamine (1/400 to 1/12000) induces pseudo-chiasmas and chromosome-breakage in the egg-segmentation mitoses ofPleurodeles waltlii Michah. The primitive effect is stickiness, breakages appear subsequently, but without an interval of time between: the primary physiological and the secondary genetical effect cannot be separated. There are points of breakability, which explains the symmetry of certain fragments. The action is inverted in the epidermal cells of the larvae, where spindle alterations are prominent. Cytodieresis is never inhibited.     

Effets de l'actinomycine D sur le développement normal et sur les modifications expérimentales de la morphogénèse de l'oeuf de l'oursinParacentrotus lividus

Summary In the presence of actinomycin D (20–40 µg/ml), the development of the eggs of the sea urchin,Paracentrotus lividus, is slowed from the late morula and stopped at the blastula stage. The development is immediately stopped in the blastula treated with actinomycin D (20–40 µg/ml). The inhibitory effects of actinomycin D are prevented by deoxyribonucleic acid. Actinomycin D does not exert animalizing or vegetalizing effects. However, the enhancing of vegetalizing action of lithium and the weakening of animalizing effects of zinc ions and Evans blue have been observed in the presence of actinomycin D. These observations may reflect some difference in the state of dependence of differentiation of entomesodermic and ectodermic structures towards the nucleus.     

Dégénérescence rétinienne expérimentale provoquée par le fluorure de sodium

Zusammenfassung Die Einspritzung von NaFl beim Kaninchen verursacht Netzhautveränderungen, welche derRetinitis pigmentosa ähnlich (Fundus, ERG, Histologie), aber auf einen Bezirk beschränkt sind.     

Sur le rôle de la sélection sexuellen dans l'évolution

Zusammenfassung Von Darwins Theorie der geschlechtlichen Zuchtwahl ausgehend werden einige Resultate experimenteller Forschung dargestellt, die auf neue Aspekte dieser Frage hinweisen. Es wird der qualitative Unterschied zwischen interspezifischer und intraspezifischer geschlechtlicher Zuchtwahl aufgezeigt. Die erstere hindert den Genaustausch zwischen den Arten, die letztere dagegen führt zu einem optimalen Genaustausch innerhalb einer Art. Es werden die Rolle der Weibchen und Männchen, der selektive Wert des Wildtypus verglichen mit Mutanten und die genetische Basis der Aktivität der Männchen diskutiert.     

La phosphatase des os et le mécanisme général de l'ossification

Summary A general survey of the actual knowledges on the bone phosphatase is given. The enzyme plays an important rôle in the calcification of bone and teeth, this process being unable to proceed at a physiological speed without the participation of a phosphatase. The biological function of the enzyme is thus to accelerate and not to promote the calcification.The knowledge of the mechanism of phosphatase activity in the skeletal organs and of the chemical composition of the bone salt cannot lead to a full understanding of the physiology of ossification. A prominent function in this field is devoted to the proteins of the ground substance of bone and to their evolution. The study of the protein matrix of bone is now the most important subject of work for the biochemistry of ossification.

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Conférence faite le 28 mai 1946 au Hallerianum de l'Université de Berne.     

Principes généraux de la magnétochimie,ses applications à l'étude des structures

Summary This article presents the general principles of magnetochemistry, its methods and the results to which it leads. Firstly, the definitions of magnetic units of isotropic substances are defined. Then the main apparatus for measuring magnetic susceptibilities is indicated.The notion of a magneto-chemical system is developed and its use in the study of molecular structure is shown. Finally, the author shows how magnetochemistry has been used to study the electronic delocalisation in aromatic molecules, and the concomitance existing between this delocalization and the biological properties of certain substances, such as their mitotic and carcinogenic activities.     

Cristallisation de l'α-amylase de pancréas

Summary In a series of 32 urinary calculi, examined with X-rays and microscope, 2 were found to consist of hydroxylapatite, 4 of whewellite, 4 of struvite and 15 of uric acid. 4 stones contained two minerals: apatite + brushite, apatite + whewellite and both hydrates of Ca-oxalate.     

Réaction immunoallergique provoquée chez le rat par l'injection d'extraits chauffés de la tumeur de Walker

Summary When repeatly injected to Fisher Inbred rats, boiled Walker tumour extracts induced non specific and specific reactions; non specific reactions being catabolism, thymus involution, adrenal hypertrophy and perturbation of serum proteins relative distribution. The specific reactions attributable to the presence of the specific tumoral antigen in the tumour extracts are immunoallergic arthritis, liver and spleen hypertrophy, acceleration of serum albumin electrophoretic migratory rate and the apparition of the specific antigen in the liver.

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Travail subventionné par l'Institut du Cancer du Canada.     

Hydrolyse enzymatique de la propionylcholine,de l'acétylthiocholine et de la butyrylthiocholine par le rectus de grenouille

Summary The enzymatic hydrolysis of propionylcholine (PrCh), acetylthiocholine (AcThCh), and butyrylthiocholine (BuThCh), by extracts of the muscle rectus abdominis, was determined. Inhibition of this hydrolysis by D.F.P. and 3318 CT [bis(pipéridinométhylcoumaranyl- 5)cétone diméthiodide] — utilized over a range of concentrations covering both specific and non-specific concentrations—showed that PrCh is hydrolyzed by an acetylcholinesterase (70%) and an Xcholinesterase (30%), AcThCh by the AcChE (70%), the XChE (15%) and a thioesterase (15%) and BuThCh by the XChE (70%) and a thioesterase (30%).     

Déviation expérimentale de l'uretère primaire par la greffe de matériel cloacal chez le Triton

Summary A transplant consisting of the rudiment of a cloaca with some somatic material implanted at a certain distance ventral from the normal route taken by the pronephric duct can be the cause of a deviation of the duct from its normal course. The pronephric duct grows towards the secondary protodæum, whereas the duct is lacking in the part of the body behind the secondary proctodæum. It seems that the proctodæum exercises an attractive effect on the growing pronephric duct.The results of the experiments, at any rate, are in favour of the conception ofO'Connor (1938) andVan Geertruyden (1942), who found that the pronephric duct develops by its own independent growth. I cannot agree withVan Deth's opinion (1946), according to which the pronephric duct developsin situ out of the dorsal parts of the lateral plate.

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Expériences faites à Bruxelles, en avril 1947, grâce à une subvention de la « Nederlandse Commissie ter uitvoering van het Nederlands-Belgisch culturele verdrag ».     

Quelques problèmes physiologiques posés par leSalmo Salar. Intérêt de l'étude de lasmoltification type de préparation au comportement migratoire

Summary The author considers some physiological problems raised by particularities of the physiological cycle ofSalmo salar L. about which he and his fellow-workers have produced new data (especially those brought out by the physiological, normal fasting so particular to the adultS: The synchonic fasting of Mislin).He insists on the importance, for studies on the physiological mechanism of migrations and from the methodological point of view, of the following feature of the young Salmon in fresh water: a transformation which, in the population studied (S. s. of Adour waters), is so characteristic of and tightly bound to the preparation to catadromic migration that it marks the subjects ready for migration and makes it possible to particularise the new physiological conditions accompanying the phenomenon of migratory instinct (activation of thyroid and interrenal function, of some pituitary neurosecretions and secretions, metabolic changes ). By studying simultaneously: smoltified but not yet migrant fishes, smolts during migration, and a salmonid fish subjected to a current in conditions simulating those of migrating smolts, it is now possible to begin to distinguish the physiological features bound to the preparation for migration, from those resulting from migratory activity.     

Localisation par immunofluorescence de peptides analogues à l'α-endorphine dans les ganglions infra-œsophagiens du lombricideDendrobaena subrubicunda Eisen

Summary Using an -endorphin antiserum in brain and infra-sophageal ganglions ofDendrobaena (Lumbricidae), positive immunoreaction was found in 4 cells of the infra-oesophageal ganglions: a pair of conic perikarya in the anterior region and a pair of pear-shaped elements close to the origin of the last nerve of the ganglion. No reaction was observed with -endorphin, or neurophysin or vasopressin antisera.     

L'action de l'hypoglycémie sur l'électrorétinogramme du lapin

Summary Hypoglycaemia in the rabbit due to an intravenous injection of insulin results in an important diminution of the value of theb wave in the ERG (up till 80%). Nevertheless, this phenomenon does not follow directly upon the lowering of the blood glucose level but takes place, on the average, about 2 h later. This fact is explained by the enormous energy reserves of the retina, the lowering of the ERG taking place only when these reserves are exhausted.

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Travail subventionné par la FondationEmil Barell (Bâle).