Showing papers by "Spanish National Research Council published in 1968"
TL;DR: The results indicated that enucleation produces a series of transneuronal changes, significant diminution of the number of spines in the apical dendritic segments located in layer IV, which is more pronounced in younger animals.
Abstract: The optic pathways of the mouse have been studied by tracing of degenerating fibers after enucleation and coagulation of the lateral geniculate nucleus. The effects of unilateral enucleation at birth in the contralateral area striata of the mouse have been studied with the Golgi method. The number of spines on three different portions of the apical dendrites of layer V pyramidal cells have been counted in the affected area striata of mice 24 and 48 days old enucleated at birth. The results were compared with the countings obtained in the area striata homolateral to the enucleated side and with controls of the same ages. The results indicated that enucleation produces, through a series of transneuronal changes, significant diminution of the number of spines in the apical dendritic segments located in layer IV. The diminution of dendritic spines is more pronounced in younger animals. Specific variations in the orientation of dendrites of stellate cells with ascending axons have been observed in enucleated animals. The significance of these findings has been discussed suggesting the existence of compensatory mechanisms which affect significantly the intrinsic organization of the area striata.
269 citations
TL;DR: Evidence is shown of the existence of a NADH dependent enzymatic activity reducing triose phosphate to α-glycerophosphate which can roughly account for the glycerol production.
Abstract: The utilization of glycerol by Candida utilis has been studied It has been found that this yeast has a permeability for glycerol and other three carbon compounds much greater than that of baker's yeast This permeability allows the entrance of glycerol in Candida cells rapidly enough to permit its efficient utilization even at low concentrations The inducibility of glycerol kinase has been established An increase in the concentration of the mitochondrial L-α-glycerophosphate oxidase when the yeast is grown on glycerol has also been observed
A model is presented for the substrate specificity pattern of glycerol kinase of C mycoderma It postulates the involvement of three hydroxyl groups in the spatial distribution corresponding to the formation of L-α-glycerophosphate from glycerol This requirement can be met by aldo-and ketotrioses in their respective hydrated forms
The pathway of glycerol formation in S cerevisiae has also been studied Evidence is shown of the existence of a NADH dependent enzymatic activity reducing triose phosphate to α-glycerophosphate which can roughly account for the glycerol production A low ionic strength seems to be required for the activity of this enzyme The α-glycerophosphatase is specific for the L from, the efficiency of α-glycerophosphatase on D-α-glycerophosphate being 1/30 of that on L-α-glycerophosphate The concentration of the α-glycerophosphatase in yeasts is higher when grown on hexoses than when grown on non-sugar carbon sources
252 citations
TL;DR: A method has been developed based on the osmotic sensitivity of protoplasts, that permits turbidimetrical estimation of the penetration of non-metabolizable compounds into yeast protoplast, which leads to the establishment of the structural requirements that a compound has to meet in order to be transported.
Abstract: A method has been developed based on the osmotic sensitivity of protoplasts, that permits turbidimetrical estimation of the penetration of non-metabolizable compounds into yeast protoplasts. Using this method a wide variety of sugars and related compounds have been tested as presumptive substrates for the constitutive hexose transport system in baker's yeast. An integration of the results obtained by this method with those obtained by other approaches has led to the establishment of the structural requirements that a compound has to meet in order to be transported. The basic structural requirement seems to be met by a pyranose ring for glucose and a furanose ring for fructose. With compounds that can be regarded as structurally related to d-glucopyranose, there is a broad tolerance for modifications at carbons 1 and 2, and somewhat less so for modifications at carbon 3. Similar requirements, except for carbon 2, apply to compounds that can be regarded as structurally related to D-fructofuranose.
Physical diffusion of sugars, and related compounds, through the cell membrane of baker's yeast is very low, so that they only can enter into the cell at measurable rates by means of specific transport devices. The factor by which the entrance of glucose is increased over its physical diffusion, at concentrations in the millimolar range, is of the order of 106.
108 citations
TL;DR: The binding of phenylalanyl-tRNA to purified yeast ribosomes at low magnesium concentrations is dependent upon one of the yeast supernatant transfer factors (factor A) and requires GTP, which cannot be substituted for GTP but it acts as a good inhibitor.
Abstract: The binding of phenylalanyl-tRNA to purified yeast ribosomes at low magnesium concentrations is dependent upon one of the yeast supernatant transfer factors (factor A). This reaction requires GTP. The GTP analogue guanylyl methylene diphosphonate cannot be substituted for GTP but it acts as a good inhibitor. After incubation of the ribosomes with phenylalanyl-tRNA, factor A and GTP practically no compound other than phenylalanyl-tRNA itself is found linked to the ribosomes.
In addition to this enzymic type of binding, phenylalanyl-tRNA is also bound to yeast ribosomes in the absence of factor A and GTP provided that the magnesium concentration is increased to about 20 mM. This non-enzymic binding is effectively inhibited by deacylated tRNA and this inhibition is prevented if factor A and GTP are included in the incubation mixtures.
The binding of N-acetylphenylalanyl-tRNA to yeast ribosomes also requires GTP, and is dependent upon factor(s) other than the amino acid transfer factors, which are bound to the ribosomes.
37 citations
TL;DR: Knowledge of the components of new cell walls which appear during the reversion of yeast protoplasts constitutes the first stage in the study of cell wall biosynthesis.
Abstract: ALTHOUGH many results have been published in the past decade on the formation and physiology of yeast protoplasts, little information has been presented so far concerning the de novo synthesis of cell walls by these protoplasts1,2 in defined conditions. Knowledge of the components of new cell walls which appear during the reversion of yeast protoplasts constitutes the first stage in the study of cell wall biosynthesis.
33 citations
26 citations
TL;DR: From the characteristics of the enzyme, as well as from the results of the activation and inactivation reactions, it is concluded that kidney phosphorylase is a form of the enzymes which is different from both liver and muscle phosphoryLase.
26 citations
TL;DR: It is found that arsenate, but not phosphate, either induces or greatly enhances enzyme activity on non-phosphorylated substrates in all cases examined, viz, an aldolase, two dehydrogenases, an isomerase, and a kinase.
21 citations
TL;DR: Hypothyroidism was intense enough to produce effects similar to those following thyroid-ectomy on the plasma PBI, body growth and pituitary content of a protein associated with GH, and exogenous insulin was induced in the rats on low iodine diet + KClO4.
Abstract: Placing rats soon after weaning on a low idoine diet and KClO4 resulted in hypothyroidism which was intense enough to produce effects similar to those following thyroid-ectomy on the plasma PBI, body growth and pituitary content of a protein associated with GH. Plasma insulin levels were also very low. Once growth stasis had occurred, l-T4 in very low doses (0.13−0.28 μg/100 g/day) or KI (1−11.5 μg I/day) was administered, while KClO4 treatment was continued until the animals were killed. These treatments were accompanied by an increase in the weight of the body and organs, the pituitary protein associated with GH, the plasma insulin levels, the plasma PBI, and sometimes the thyroidal 127I content. The weight of the thyroid gland increased significantly. The last of these effects was induced by exogenous insulin in the rats on low iodine diet + KClO4, although plasma TSH activity did not increase further. The results are discussed in relation to the hypothesis that a) the “goitrogenic” effects of small do...
21 citations
TL;DR: The relevant growth-promoting activity in the acidic biohistogram seems not to be completely due to the presence of the acids mentioned, but no IAA has been found.
16 citations
TL;DR: Spectral changes in the presence of a complexing reagent are reported for thirteen cinnamic acids, naturally occurring in the plant kingdom as mentioned in this paper, and the advantage of the method is emphasized for some methoxy derivatives, which are difficult to distinguish in plant tissues.
TL;DR: In this article, the interconnection between the sextet and the quartet system in Ni IV was established, and 35 observed lines were explained as intercombinations, a complete list of which is given.
TL;DR: In the cat, whose capacity for the formation of glucuronides seems to be low, a progressive decline of β-glucuronidase activity was observed from the very young animals to adults; the decline is extraordinarily manifested in the liver and also observed in the adrenal gland and the spleen.
TL;DR: This enzyme, that is likely to be the major componen t o f the total pa tential glutaminase activity o f rat liver, presents a marked sigmoidicity within the range o f phy~iologieal values o f glutamine in liver.
TL;DR: In this paper, the surface reaction of Sn with aqueous solutions of thiourea has been studied and the kinetics of the growing film are determined by temperature, concentration and atmospheric conditions.
TL;DR: In this paper, a study of the polarographic behavior of oxalate oxalates has been conducted and the results confirm the fast exchange of electrons at the electrode interface and the important role played by adsorption in the mechanism of this electrode reaction.
TL;DR: In this article, the decay of K20 → 2γ is studied in the framework of a pole model with vectors and axial particles as poles, and the usual treatment which considers only intermediate pseudoscalar particles is considered.
Abstract: The decay K20 → 2γ is studied in the framework of a pole model. In addition to the usual treatment which considers only intermediate pseudoscalar particles, we also discuss models with vectors and axial particles as poles.
TL;DR: In this article, the authors generalize slightly the expression given by VENEZ~A~O for the scattering amplitude, in such a way that it can be applied to processes of different types.
Abstract: A very interesting model for relativistic scattering ampli tude has been recently proposed by VE~EZlA~O (1), in which crossing symmetry and Regge asymptotic behavfour are ensured by the requirement of l inearly rising trajectories. The scattering amplitude exhibits Regge poles in families of parallel trajectories with residues in definite ratios, and satisfies generalized supereonvergence relations. In this note, we discuss the implication of the model when applied to different processes, and show how the constraints imposed on the Regge trajectories give rise to mass relations. Wi th this aim, we generalize slightly the expression given by VENEZ~A~O for the scattering amplitude, in such a way that it can be applied to processes of different types. We shall restrict here to those processes in which each channel is dominated by a single trajectory. The inclusion of more trajectories in the same channel, owing to the rather stringent conditions imposed by the model, makes a solution possible only in the case of degenerate trajectories. We keep the hypothesis of linearly rising trajectories, and follow the approximation of real trajectory functions, which is equivalent to narrow-width resonance approximation. We shall consider the following types of processes:
09 Dec 1968
TL;DR: In this paper, the authors deal with the question of determining the true strength of concrete in its final functional state, and also provide recommendations on safety, and on the dispersal of results.
Abstract: This paper deals, in a highly practical manner, with the question of determining the true strength of concrete in its final functional state, and it also contains recommendations on safety, and on the dispersal of results. Some testing methods are mentioned and discussed, which are applicable to working site use, and detailed information is given on the precautions that should be taken so that a non destructive auscultation should give reliable data on the actual strength of the concrete.
TL;DR: A simple proof of the quantum mechanical extended adiabatic invariance is presented, avoiding the study of the character of the series that appear when the authors solve the problem by perturbations.
TL;DR: In this paper, the soft-meson results obtained from current algebra and meson pole dominance in the matrix elements of the vector current and the axial and tensor current divergences are equivalent to those obtained from an effective Yang-Mills Lagrangian.
Abstract: It is shown that the soft-meson results, obtained from current algebra and meson pole dominance in the matrix elements of the vector current and the axial and tensor current divergences, are equivalent to those obtained from an effective Yang-Mills Lagrangian.