Showing papers by "Collège de France published in 1970"
TL;DR: The characteristics of a temperature conditional mutant of Escherichia coli K12 indicate that at high temperature, it can complete a DNA cycle already started, but not initiate a new one.
246 citations
TL;DR: Evidence is provided that, in the light period and by contrast to the night, the low rate of food intake results from the concomitant lipolysis and, that the control system of food Intake is responsive at a high threshold to a critical deficit of the availability of glucose for cell oxidation.
197 citations
TL;DR: Complementation tests performed in a strain lysogenic for λ indicate that the C17 mutation can suppress a r mutation in a cis position, even in the absence of the N-gene product, and results suggest that the expression of genes O and P, in addition to gene Q, is under the positive regulation of theN-Gene product.
Abstract: A selection technique, using the thermoinducible prophage λCI857Nsus7 Nsus53, has lead to the characterization of a new class of prophage mutations (called r), which prevent host killing upon thermal induction
80 citations
TL;DR: Biosynthesis of 3H-CA in discrete areas of the rat brain was examined after stereotaxic microinjection of3H-tyrosine and the effects of amphetamine and thioproperazine (TZ) on the accumulation of newly synthesized 2H-DA and 3H -NA were studied.
77 citations
01 Jan 1970
TL;DR: Extension de resultats de Eells-Sampson dans le cas riemannien as mentioned in this paper for varietes kAhleriennesM etM sous l'hypotese que la premiere classe de ChernC1(M) soit positive.
Abstract: Extension de resultats de Eells-Sampson dans le cas riemannien. Applications au cas de varietes kAhleriennesM etM’ sous l’hypotese que la premiere classe de ChernC1(M) soit positive.
75 citations
TL;DR: DnaA mutants exhibit associated membrane protein alterations; whether these are direct or secondary effects is still unclear.
75 citations
TL;DR: Octopine dehydrogenase is widely distributed among various orders of marine molluscs, besides the Cephalopoda previously studied, and the presence of this enzyme and of lactate dehydrogen enzyme seems to be mutually exclusive.
71 citations
TL;DR: Thioproperazine pretreatment potentiated amphetamine induced release of 3 H-DA but it blocked the other pharmacological effects of amphetamine occurring in animals.
70 citations
TL;DR: It is suggested that a protein kinase could be involved in the two cyclic AMP-mediated effects of neurohypophysial hormones on this epithelium, namely, increased osmotic water permeability and stimulation of active sodium transport.
65 citations
TL;DR: In this paper, a rigorous definition of conformal covariance of field equations in first and second quantized field theories is given, and the general implications of these definitions as well as the necessary and sufficient conditions for Poincare plus dilatation covariance to imply covariance are discussed.
62 citations
TL;DR: The phosphateodiesterase activity extracted from frog bladder epithelial cells and rat kidney may be described as the sum of the activities of two phosphodiesterases (I and II), which are stable on storage and heat denaturation and has a low affinity for cyclic AMP.
TL;DR: Genetic evidence is presented to demonstrate that all four phenotypes of A5-5–9A (increased sensitivity to ultraviolet and γ-radiation, deficiency in recombination, and loss of the ATP-dependent deoxyribonuclease activity) transfer as a single marker in transformation, a fact which shows that the defect inThe enzyme is apparently not essential for the process whereby different genetic pneumococcal markers are known to transform with markedly different efficiencies.
TL;DR: The in vitro release of FSH from rat pituitary glands, when stimulated by a specific releasing factor, viz., follicle-stimulating hormone releasing factor (FRF), or nonspecific factors such as cyclic 3′,5′-AMP, or high [K+] medium, required the presence of Ca++ in the external medium.
Abstract: The in vitro release of FSH from rat pituitary glands, when stimulated by a specific releasing factor, viz., follicle-stimulating hormone releasing factor (FRF), or nonspecific factors such as cyclic 3′,5′-AMP (cAMP), or high [K+] medium, required the presence of Ca++ in the external medium. Ca++ together with cAMP probably plays an active intracellular role in the processes leading to the release of FSH. No definite conclusion can be made as to the requirement for Mg++ in these processes. The synthesis (or activation) of FSH, observed during incubation in the presence of FRF, was also Ca++ dependent. However, further experiments are necessary in order to find out whether the presence of Ca++ is required directly for the synthesis of FSH, or whether the synthesis is only a secondary phenomenon arising from the release of FSH. In the latter case, the lack of Ca++, which inhibited the release of FSH, would consequently inhibit its synthesis. (Endocrinology 86: 761, 1970)
TL;DR: In this paper, a sample of 6665 annihilations of the type p (at rest)p → π + π − π+ π− π plus π-π − ε + ε−π−ε−γ ε+γγγδ ε ε − δγγ δ δ − γ ε is analyzed and a maximum-likelihood analysis is made using interferring Bose-symmetrized amplitudes to parametrize the reaction in terms of final
TL;DR: The enzyme was found to be active under alkaline conditions and to require a metal ion and a nucleoside triphosphate for its activity on nativeDNA, and to be much more active on native DNA than on heat-denatured DNA.
TL;DR: The effect of a fifteen minutes stress, induced by mild electric shocks applied to the feet, on the utilization of 3H-NE synthesized from3H-tyrosine in the brain stem of rats has been investigated and the newly synthesized 3H,NE was preferentially utilized as compared with the 3H -amine stored for longer time periods.
TL;DR: The results obtained in the study of the binding of several nucleotide analogs to arginine kinase indicate that the formation of active nucleotide-enzyme complexes requires the presence of the γ- and β-phosphoryl groups as well as the 6-amino and N-1 groups in the purine ring.
TL;DR: Catalytic substitution of the peptide bound iodine by tritium results in labelling the hormone and in restoration of the biological activity of oxytocin.
Abstract: The tritium labelling of oxytocin has been attained by a two step procedure. First, di-iodo oxytocin is prepared. After a survey of various iodination reagents, ICI has been selected as it reacts much more rapidly with the tyrosyl ring than with the disulfide bridge, which under mild conditions remains unaffected. The di-iodo derivative, nevertheless, has lost most or all of its biological activity. Catalytic substitution of the peptide bound iodine by tritium results in labelling the hormone and in restoration of the biological activity. The 3H oxytocin obtained retains 90 % of its hydrosmotic activity and about 65 % of its avian depressor activity. Its specific radioactivity reaches 36 Ci/mMole, a value allowing further studies of the hormone at a molecular level.
TL;DR: In this paper, the authors show how to find a collision in high-energy, high energy, high luminosity, and high-altitude (HIGH ENERGY, HIGH-HEIGHT) environments.
Abstract: T h e i m p o r t a n c e of a ce r t a in t y p e of reac t ions , whe re two spacel ike p h o t o n s a re e x c h a n g e d in e lec t ron-e lec t ron or e l ec t ron-pos i t ron collisions, has been s t ressed severa l t imes in t h e pa s t (l-e). I t is t he pu rpose of th i s p a p e r to show t h a t u n d e r ce r t a in cond i t ions p h o t o n p h o t o n collisions can be p roduced , a t h i g h ene rgy a n d w i t h r e a s o n a b l y h i g h c o u n t i n g ra tes , b y us ing t h e new (high-energy, h igh luminos i ty ) e l ec t ron-pos i t ron s to rage r ings w h i c h are n o w u n d e r cons t ruc t ion . One will t h u s be able to s t u d y t he ma te r i a l i z a t i on of 2 p h o t o n s in to va r ious par t ic les , w i t h o u t need ing any special device ( such as sugg ( s t ed b y CSONKA (7)) for t h a t purpose . W h a t we sugges t is t h a t , in a n e lec t ron-pos i t ron collision, b o t h t h e ou tgo ing elect r o n a n d t h e ou tgo ing pos i t ron shou ld be de t ec t ed a t ve ry smal l angles (a few miUir ad ians ) w i t h respec t to t he i r i n c i d e n t d i rec t ions , in coinc idence w i t h o t h e r par t ic les (for i n s t ance , a pa i r of cha rged p a r t i c l e s ) e m i t t e d a t large angle w i t h respec t to t h e co l l id ing-beam axis. The m a i n c o n t r i b u t i o n will t h e n come f rom d i ag ram I ) o f Fig. 1, where two v i r t u a l spacel ike p h o t o n s are exchanged . T h e squa red f o u r m o m e n t a of b o t h these p h o t o n s (q2, q,2) h a v e va lues v a r y i n g f rom a few (keV) 2 to a few (MeV) 2, a n d in fac t (because of t h e q-a, q,-4 fac tors in t h e p ropaga to r s ) t he smal les t va lues will cont r i b u t e t h e mos t . Therefore , we m a y consider t he se p h o t o n s as (~ a l m o s t rea l ~ (in par t icular , we m a y neglec t t he i r l o n g i t u d i n a l com ponen t s ) a n d we m a y t r ea t , u n d e r t h e cond i t ions defined, a n y r eac t ion of t he t y p e e -e + -> e c + A A + as e q u i v a l e n t to yy--> A A + (here A • is a n y cha r ged par t ic le) . W e shal l now show t h a t :
TL;DR: In this paper, the bromation acido-catalysee des methyl-cetones R.CO.CH3 (R = cyclohexyle, cyclopentyle, benzyle) dans le methanol est une excellente methode de preparation des bromomethyl cetones, jusqu'alors difficilement accessible par halogenation directe.
TL;DR: An unexpected result is discussed with respect to the mechanisms of finickiness and to the role of oro-sensory afferents in the control of a constant daily intake.
TL;DR: In this article, the CD within the 1 L b band of tetrahydroberberine alkaloids is rationalized with the aid of a rule taking into account the chirality of the second sphere, a sector rule for third (fourth, …) sphere contributions.
TL;DR: The lack of interaction of arginine with apoenzyme is a possible direct evidence of an obligatory, ordered reaction sequence in enzymic reactions.
TL;DR: The results confirm the validity of recording chewing and swallowing movements as a new method for describing the true dimensions of oral sensory stimulations by food textures.
Abstract: Chewing and swallowing patterns were recorded in three subjects eating freely pieces of foods of various initial textures in an attempt to assess objectively these food textures as sensory stimuli in the mouth. In each phase of masticatory and swallowing movements corresponding to each piece of food, variations were noted differentiating the 16 textures tested. The number of masticatory movements, the time of mastication up to complete swallowing, the time course of the force of mastication and the number and distribution of swallowing movements were found to be the most discriminating parameters. In considering them, foods might be placed on a scale from hard and dry to soft and fluid textures. The results confirm the validity of recording chewing and swallowing movements as a new method for describing the true dimensions of oral sensory stimulations by food textures.
TL;DR: The nitration of arginine kinase from lobster muscle (Homarus vulgaris) with tetranitromethane has been studied after reversible blocking of its thiol groups and an important conformational change occurring onNitration of one reactive tyrosine residue is demonstrated.
Abstract: The nitration of arginine kinase from lobster muscle (Homarus vulgaris) with tetranitromethane has been studied after reversible blocking of its thiol groups.
Experimental procedure for nitration of one essential tyrosyl residue is described. The introduction of one mononitrotyrosine per mole of arginine kinase results in a total loss of activity. Reduction to the aminotyrosine derivative does not restore enzymic activity.
The mononitrotyrosyl arginine kinase is unable to bind its nucleotides or guanidine substrates as judged by differential spectrophotometry. An important conformational change occurring on nitration of one reactive tyrosine residue is demonstrated by means of optical rotatory dispersion measurements and immunodiffusion.
TL;DR: In this paper, the authors compare the performance of deux methode, employee quand le racemique n'est pas accessible, utilise un procede connu de dosage des impuretes dans des corps presque purs.
TL;DR: The evidence suggests that a lamellar inclusion arises from the cooperation of several granular inclusions and a lipidic vacuole, and are often found in close association with lipidic Vacuoles.
Abstract: Les pneumocytes granuleux, qui constituent l'un des principaux types cellulaires de l'epithelium pulmonaire, sont caracterises par la presence de volumineuses inclusions osmiophiles lamellaires.
TL;DR: A study of the modification of the water and non-electrolyte permeability of phospholipid membrane under the influence of calcium suggests the possible role of this ion in the control of cell membrane permeability to non-ionic species.
Abstract: THE study of the effect of Ca2+ ions on phospholipid membranes by Tobias et al.1–3 has chiefly been devoted to electrical properties and ion fluxes in relation to the hypotheses concerning the axon shifts from the resting to the excited state4. Although Leitch and Tobias2 have shown that Ca2+ also induces great changes in the osmotic water flow across these membranes, little attention has been paid to this particular aspect of their behaviour. This report is a study of the modification of the water and non-electrolyte permeability of phospholipid membrane under the influence of calcium. The results obtained suggest the possible role of this ion in the control of cell membrane permeability to non-ionic species.
TL;DR: The sedimentation constants of lobster and crab arginine and lombricine kinases and taurocyamine kinases from earthworm and arenicola were determined and were shown to be dimers with two subunits of about 40 000 each.