Effets de l'irradiation sur le métabolisme des acides nucléiques et de leurs dérivés acidosolubles chez le rat

Summary In the rat, X-irradiation leads to a decrease of the net RNA and DNA content of the spleen, without, however, increasing the low molecular weight nucleic acid derivatives in the acid-soluble fractions of the same tissue. It is suggested that an alteration of the cell membranes could account for the apparent elimination of these nucleic acid degradation products which should normally appear in the acid-soluble fraction.     

Propriétés chitinolytiques du liquide exuvial du ver à soie (Bombyx mori L.)

Summary The authors add further confirmation to the hypothesis of the role played by a chitinase during the process of moulting. By ligaturingBombyx mori-larvae between head and thorax, accumulation of moulting fluid takes place between the larval and nymphal cuticles, swallowing of this fluid being prevented. The chitinolytic properties of this moulting fluid are demonstratedin vitro. The activity of chitinase at different pH is investigated: the optimum pH lying at about 5.4.     

Sur la caractérisation de dérivés guanidiques d'origine biologique par électrophorèse et chromatographie sur papier (chromatoélectrophorèse)

Summary Paper chromatography has been used in conjonction with electrophoresis in a perpendicular direction (chromatoelectrophoresis), in order to characterize various guanidoderivatives of biological interest and also citrulline. The isolation of definite spots can be obtained with a satisfactory selectivity by this procedure, at a higher speed than by bidimensional chromatography; and the use of a few coloured reactions (ninhydrine,Sakaguchi, diacetyle--naphtol andp-dimethylaminobenzaldehyde) on the same electrochromatogram has been successfully practised in this field.     

Etude de l'hydrolyse et des propriétés toxiques vis-à-vis des mitochondries de maïs Texas,d'un insecticide,le méthomyl ou S-méthyl-N [(méthylcarbamoy)oxyl] thioacétimidate

Summary Methomyl, or S-methyl-N [(methylcarbamoyl)oxy] thioacetimidate, a common insecticide, has been found to be a specific poison of mitochondria of corn with Texas cytoplasm. Its hydrolysis under very mild acidic conditions affords thiomethyl methylthiosulphonate, which strongly inhibits the activity of CmST and N mitochondria of corn.     

Inhibition sélective des «vraies» et «pseudo»-cholinestérases du rectus de grenouille

Summary The hydrolysis of acetylcholine chloride (0.01M) by frog's rectus extracts, is inhibited by low concentrations of 3318 CT (CI-50 3.2×10^–7) and high concentrations of D.F.P. (CI-50 1.3×10^–5). Inversely, the hydrolysis of butyrylcholine perchlorate is inhibited by low concentrations of D.F.P. (CI-50 3×10^–9) and high concentrations of 3318 CT (CI-50 3×10^–4). Both are inhibited by similar concentrations of neostigmine (CI-50 1.1×10^–7 and 1.5×10^–7). Frog's rectus thus contains true and pseudo-cholinesterases. The inhibitions produced by D.F.P. added to the muscle itself (and not the extract) correlates well with the potentiation of the corresponding ester. Sensitization to AcCh and to BuCh appears to be specifically related to the inhibition of Ac ChE for the former ester, of XChE for the second one.     

Activation concomitante par l'hétéroauxine de la résorption du corps paranucléaire ribonucléique et de la germination des zygotes chezAllomyces

Summary Heteroauxin (optimal concentration 10^–5) activates the germination of the zygotes and the dissolution of their RNA nuclear cap inAllomyces javanicus.Alkaline phosphatase has been located cytochemically in the cytoplasm surrounding the RNA nuclear cap.These new observations lead the author to postulate a relationship between the stimulating action of heteroauxin, activation of the phosphatases and awakening of the RNA-protein synthesis dynamic system during the germination of the zygotes inAllomyces.     

Technique d'inclusion et d'ultramicrotomie,destinée à l'étude du développement des organelles dans une cellule isolée

Summary (1) Control of cell orientation and knowledge of the plane of sectioning are indispensable (but generally ignored) requirements for studies of the development of cellular constituents. (2) A simple technique that meets these requirements for the electron microscope is given. (3) As applied toParamecium, it is shown that the ciliary complexes of the new gullet develop outside of the old one, and that invagination begins at the anterior end of the gullet anlage.

---

---

Travail effectué dans le cadre d'une recherche faite en collaboration avec les Instituts d'Histologie et de Biophysique, grâce à une subvention de «Fritz Hoffmann-La Roche-Stiftung zur Förderung wissenschaftlicher Arbeitsgemeinschaften in der Schweiz».     

Relations entre oxydation phosphorylante et structure des mitochondries hépatiques de rats carencés en vitamines B1 et B2

Summary In the experimental B₁-avitaminosis a decrease of oxidative ATP-resynthesis in liver homogenates, and a significant diminution of the optical density of mitochondrial suspension were simultaneously observed: in other words a probable parallelism in the alteration of function and structure. In ariboflavinosis neither oxidative phosphorylation nor optical density seems to be notably impaired, but the nitrogen content of mitochondrial suspensions decreases significantly. Therefore this second type of avitaminosis would appear to affect the mitochondrial population rather than energetic metabolism or structural integrity of the protoplasmic granules.

---

---

Communication présentée au 3^e Congrès International de Biochimie, Bruxelles 1955.     

L'acide thymonucléique polymérisé, principe paraissant susceptible de déterminer la spécificité sérologique et l'équipement enzymatique des bactéries. Signification pour la biochimie de l'hérédité

Summary Interactions between two types of bacteria can produce either inhibition of the growth of one of these bacteria or transformation of their biochemical or antigenic properties. Authors have shown and studied one case of induction of a new serological specificity and a new enzymic equipment in aBacterium coli. This induction was produced through a substance liberated, during autolysis, by an otherBacterium coli. Active principle is a thymonucleic acid which, maybe, results from a solubilisation of chromosomes of the inductor bacteria. Hypothesis appears likely.     

Un nouveau type de détermination chromosomique du sexe chez les mammifèresEllobius lutescens Th. etMicrotus (Chilotus) oregoni Bachm. (Muridés-Microtinés)

Summary (1)Ellobius lutescens andMicrotus oregoni show the same type of sex-chromosomes. The diploid number is odd in both sexes, seventeen.(2) The odd element ofEllobius is morphologically alike in the male and in the female. InM. oregoni, the odd element of the male is acrocentric, that of the female metacentric.(3) Following a hypothesis ofWhite, it seems very probable that the heterochromosome of the male is built of the primitiveY (short arm) and the primitiveX (long arm) linked together. In the female of the same species (M. oregoni), the sex-chromosome represents both theX fused together.(4) Only the half of the Zygotes may develope, the other half being lethal.(5) The close kinship betweenEllobius andM. oregoni is certain, a parallel evolution appearing as highly improbable.     

Isolement et identification du 5β-prégnane 11β, 17α, 21-triol 3, 20-dione (Dihydrocortisol) dans l'urine humaine

Summary 5-pregnane 11, 17, 21-triol 3, 20-dione (dihydrocortisol) has been isolated and identified in the urine of patients with feminizing adrenal cortical cancer. This steroid showed the same Rf as synthetic dihydrocortisol in six different chromatographic systems. After acetylation, its Rf was the same as that of 21 monoacetate of dihydrocortisol. After bismuthic or chromic oxydation, it had the same chromatographic Rf as 5-androstane 11-ol 3, 17-dione and 5-androstane 3, 11, 17-trione respectively. After chromic oxydation of its acetate, the Rf was the same as that of 21 monoacetate of cortisone.     

Effets de la réserpine sur le développement d'Oedipoda coerulescens L. (Acridien,Orthoptère)

Summary Inhibitory effects of reserpine on ecdysis and chromatic adaptation inOedipoda appear to be linked with changes observed in both neural and neuro-endocrine regulating systems.     

Variations au cours de la journée de l'incorporation in vivo de la leucine tritiée dans les protéines du cervelet et du cerveau du jeune rat normal et hypothyro?dien. Daily variations of the in vivo [3H] leucine incorporation into the cerebellar and cerebral proteins of the normal and hypothyroid young rat [(author's transl)

In the normal and hypothyroid 6-day-old rat, the specific radioactivity (RSA) and the relative RSA (ratio of the RSA to the [3H] lecine concentration of the acido soluble phase) of the cerebral and cerebellar proteins, changes during the day synchronally. They show a maximum at 15.00 h and a minimum at 0.300 h. At all stages studied, these values are significantly lower in the hyothyroid animals than in normal ones.     

Über die tuberkulostatische Aktivität von 2,5-Bis-(aminooxymethyl)-3,6-diketopiperazin,eines Umwandlungsproduktes des Cycloserins

Summary It has been ascertained that racemic 2,5-bis-(aminooxymethyl)-3,6-diketopiperazine, being a transformation product ofD,L-cycloserine, possesses the same effect againstMycobacterium tuberculosis asD,L-cycloserine itself.