Le rôle du scientifique dans la conservation de la nature

Summary The concept of nature conservation has greatly varied in recent years. Instead of forbidding any human interference with nature the modern conservationnists think that man must control the natural balance in the protected areas through appropriate measures.This action must be under the permanent control of ecologists, who have the task of determining, among many other data, the carrying capacity of the area, the evolution of habitats under physical and biological influences, the structure of animal populations and the rate of reproduction.In the case of large animals, this new concept leads to substituting game management for static protection. Thus conservation of natural resources will need more and more cooperation from scientists, especially in the field of ecology and population studies.     

Conséquences de la thymectomie sur la formule leucocytaire chez le cobaye

Summary In infantile guinea pigs, thymectomy determined a decrease of the leucocyte count in the circulating blood, resulting essentially from the decreased number of lymphocytes.Eosinophiles increased noticeably in the same animals.Thus the consequences of thymectomy were proved to be exactly opposite to those of administration of thymus extract as described in a previous publication.     

Appareil pour la mesure de la consommation d'oxygène des petits animaux de laboratoire

Summary An apparatus has been described for measuring oxygen consumption in small animals. In this apparatus, the temperature changes are very small, the determinations of oxygen consumption are rapid and frequent, the oxygen tension is normal and the animals are in a good state of quietness.     

Etude photophysique de la ptérobiline

Summary The first results of a photophysical study on pterobilin (biliverdin IX , a Lepidopter blue bile pigment) are presented. From the absorption and fluorescence spectra, it is deduced that the low yield of fluorescence indicates a desactivation of the excited singlet state occurring mainly by a non-radiative process. Analyses of the chemical compounds formed after irradiation of pterobilin in methanol show that it is rearranged into a series of new blue pigments among which phorcabilin and sarpedobilin (the two neobiliverdins IX isolated from Lepidopters) have been identified.

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Remerciements. Nous remercions le ProfesseurJ. Bergerard pour son intérêt. Ces recherches ont été réalisées dans le cadre de l'ATP CNRS No. 4699-10.     

Activité de la monoamine-oxydase au cours de la période perí-natale chez le Lapin

Summary The activity of enzyme monoamine oxidase was studied from 3 days before birth up to 2 days after birth in the heart, liver and kidney of albino rabbits. At the end of ftal life, the MAO activity of heart and liver expressed per unit of organ weight was nearly the same as the adult one. At birth and 1 day, the activity showed decrease in the 3 organs. The possible causes of these decreases are discussed.

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Remerciements. Nous remercions MM. les ProfesseursChevallier et Jost de nous avoir permis d'utiliser certains appareils de leur laboratoire.     

Importance des modifications de la glycémie dans la régulation de la vitesse d'absorption de solutions de glucose de différentes concentrations chez l'animal intact

Summary In intact guinea-pigs fed with glucose solutions of different concentrations, the main limiting factor of absorption is not the gastric emptying but the hyperglycaemia.     

Répression par l'oxygène de la biosynthèse de la thiosulfate-réductase deProteus vulgaris

Summary The extracts obtained from aerobic cultures ofProteus vulgaris are completely without thiosulfate reductase activity. This phenomenon can be explained by the repression of biosynthesis of the enzyme by oxygen.     

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%).     

Purification de la pénicillinase deBacillus cereus

Summary A method for purification of Penicillinase fromBacillus cereus is described whereby we obtain the enzyme in a very pure form and in excellent yields. Starting from a crude acetone precipitate, the purification is obtained by using successive separations with ammonium sulphate, in controlled conditions, and final ion exchange.     

Effet inhibiteur de la tétrabénazine sur l'influence corticosurrénalienne de la réserpine

Summary Reserpine provokes an intense and long-lasting (more than 20 h) stimulation of the adrenocortical activity of the rat. Tetrabenazin (50 mg/kg) also produces an adrenocortical stimulation which is, however, of a much shorter duration. The injection of tetrabenazin 1 h before the injection of reserpine (5 mg/kg) prevents the prolonged stimulating effect of reserpine on the adrenal cortex. This effect can be compared with the blocking effect of tetrabenazin, a short-acting central depressant with monoamine-liberator properties, against the prolonged central sedative influence of reserpine.     

Action répressive de l'oxygène sur la biosynthèse de la fumarique-réductase d'Aerobacter aerogenes

Summary The cells obtained from anaerobic cultures ofA. aerogenes contain both a hydrogenase and a fumaric reductase, but lack one or several electron transporters necessary for the coupling of the two enzymes. It is possible to measure the fumaric reductase activity of the extracts in the presence of hydrogen, hydrogenase and benzyl viologen, using the Warburg manometric technique. In anaerobic cultures the reductase is an inducible enzyme. In aerobic cultures its formation is strongly repressed by atmospheric oxygen.     

De la réaction mitotique de l'épiderme de la tétine de cobaye à la suite d'applications répétées de diverses substances

Summary (1) The majority of substances tested produced a weaker mitotic reaction of the epidermis of the guinea pig nipple after 3 applications (24 h intervals) of the same substance than after a single application.(2) This decrease in the ability of the epidermic cells to be divided has to be attributed, it seems, to a habit-forming processus and not to an exhaustion of the cells; indeed after two applications of geraniol, the application of a substance of different nature, Hormoestrol, produced in the nipple epidermis a mitotic flare up as intense as that obtained in the epidermis of a nipple not previously treated.(3) Aldehyde C₉ alone, among the substances tested, does not produce a decrease of epidermic mitoses after three applications but induces cellular alterations.     

Effet du fluoroacétate et des rayons X sur la teneur en acide citrique du foie de la souris

Summary In contrast to rats, male mice injected with sodium fluoroacetate accumulate citrate in their livers, whereas females do not. Whole-body irradiation reduces the level of accumulated citrate in the liver as well as in other tissues of the mouse.     

Pharmacodynamie de la circulation cérébrale

Sans résuméRelation présentée au XXI^e Congrès International des Sciences Physiologiques, Buenos Aires, 9–15 août 1959.     

Activation de la phosphatase acide par l'acide β-indolylacétique et ses répercussions sur la phosphorolyse de l'amidon

Summary IAA-induced activation of purified acid phosphatase is reported and shown to determine an acceleration of phosphorolysis of starch.     

Sur la teneur en composés polyphosphoriques de l'oxychlorure de phosphore hydraté et des esters amides polyphosphoriques de la thiamine

Zusammenfassung Hydratisiertes Phosphoroxychlorid besteht aus zyklischen und langkettigen Polyphosphorsäure-Chloriden, die nicht beständig sind und leicht hydrolysiert werden. Hydratisiertes Phosphoroxychlorid erlaubt die Synthese von langkettigen Thiaminpolyphosphorsäureestern, die mehr als drei Phosphorsäure-Reste je Molekül enthalten.     

De l'action radio-protectrice exercée sur la muqueuse rectale par la cystéamine administrée par voie générale et par la cystamine administrée par voie intra-rectale

Summary The authors studied the lesions observed in the rectal and vaginal smears of the rat after a local irradiation of the rectum. They observed that an injection of cysteamine before the irradiation strongly diminishes the ratio of damaged rectal and vaginal cells. A local treatment with cysteamine in the rectum before and during the irradiation diminishes only the ratio of damaged rectal cells.