Showing papers by "Spanish National Research Council published in 1976"
TL;DR: The hypothesis is advanced that homoeotic genes control compartment development since homoeosis mutants transform entire developmental compartments into one another, and the property of M + M + recombinant cells to overgrow the M M + background cells was used to demonstrate the establishment of clonal restrictions during development.
342 citations
TL;DR: Ten different compounds have been partially purified and characterized and show a different degree of specificity as growth inhibitors of a series of enterobacteria as well as other non-enteric microorganisms.
165 citations
TL;DR: It is concluded that protein synthesis in eukaryotic cells is halted by inhibiting the peptide bone formation step using six compounds obtained from bulbs of the Amaryllidaceae family.
126 citations
TL;DR: The influence of several parameters on the viability and precision of the determination of the Kovats retention index, under conventional experimental conditions, has been examined in this paper, where the activity of the support and the dead-time correction have been considered.
111 citations
TL;DR: The total real length in space of dendrites and axons was obtained and the results compared in two groups of mice raised under different conditions, and preliminary observations show short axonal lengths in mice raised in darkness.
Abstract: Using the Golgi method, cells with intra-cortical axons in the visual cortex of young mice were classified according to defined geometrical axonal shapes. This study principally describes a computer technique and its application to the study of neuronal morphology. Neurons were converted in a sequence of three-coordinate points which were stored in digital form on magnetic tape. From the stored data and total real length in space of dendrites and axons was obtained and the results compared in two groups of mice raised under different conditions. Preliminary observations show short axonal lengths in mice raised in darkness. Using Eulerian coordinate transformations, reconstructions of individual neurons and of groups of several neurons and fibres were obtained by generating displays of different views after rotation around the horizontal axis. Reconstructed pictures were compared with their corresponding original drawings in order to describe particular aspects of cortical organization.
64 citations
TL;DR: Chicks of house sparrows, spotless starlings, jackdaws and swallows were readily aceepted and reared by the magpies, and a ‘parasitic’ form of behaviour appeard which led them to eliminate competitors in the nests.
57 citations
TL;DR: In this article, a compact formulation for the computation of the Raman tensors of vibrating molecules as a function of bond polarizabilities is presented, which is conceptually clearer than those given previously and also very convenient for the numerical computation of Raman intensities.
Abstract: A compact formulation for the computation of the Raman tensors of vibrating molecules as a function of bond polarizabilities is presented. This formulation is conceptually clearer than those given previously and also very convenient for the numerical computation of Raman intensities. The Raman tensors of the vibrational modes are expressed here in terms of the B, G and L matrices of the well-known Wilson FG method, in combination with the electro-optical parameters of the bonds. The computational steps are illustrated for the AB2 bent molecule. A relationship between Raman intensities and elements of the L matrix is derived for this molecule.
54 citations
TL;DR: A simple technique to detect the Met-tRNAf-40-S-subunit-poly(A, G, U) initiation complexes by chromatography on Sepharose 6B columns is developed and its comparison with the sucrose gradient centrifugation method is described.
Abstract: In order to elucidate the mechanism of action of inhibitors that block the initiation of protein synthesis in mammalian systems, we have studied the following steps: (a) formation of the ternary complex Met-tRNAr-IF-E2-GTP, (b) binding of the initiator Met-tRNAf to the 40-S ribosomal subunit in the presence of initiation factors and dependent or not on the addition of mRNA, (c) formation of the initiation complex with 80-S ribosomes and (d) formation of the first peptide bond. Adrenochrome, aurintricarboxylic acid, polydextran sulphate, pyrochatechol violet and showdomycin block the formation of the ternary complex Met-tRNAf-IF-E2-GTP. Edeine A1, aurintricarboxylic acid and polydextran sulphate block the binding of the mRNA to the 40-S ribosomal subunit. Pactamycin induces the formation of stable smaller initiation complexes which are unable to go through the subsequent steps of initiation. Stimulation of the binding of the initiator Met-tRNAf to the 80-S ribosome in the presence of initiation factors is observed with sparsomycin and antibiotics of the sesquiterpene family (verrucarin A, trichodermin and trichothecin). However, these antibiotics block the reaction of the bound Met-tRNAf with puromycin. Narciclasine has no effect on the binding of the initiator to the ribosome but strongly blocks its reaction with puromycin. We have developed a simple technique to detect the Met-tRNAf-40-S-subunit-poly(A, G, U) initiation complexes by chromatography on Sepharose 6B columns. The requirements for the formation of such complexes measured by this technique and its comparison with the sucrose gradient centrifugation method are described.
53 citations
TL;DR: In this paper, various mixtures of imaginal disc cells from wild-type and from homoeotic bithorax mutants have been studied in an in vivo Drosophila cell culture system.
49 citations
TL;DR: A revertant from this mutant, susB610, was isolated, being suppressed by both the su+3 and su+44 suppressor strains, suggesting that strain su+ 44 contains an amber and strain su-3 an ochre suppressor.
Abstract: By treatment of Bacillus subtilis MO-101-P spoA− met thr− su− with ethyl methanesulfonate, a strong suppressor strain of nonsense mutations, B. subtilis MO-101-P spoA− [met−]+ thr− su+44 was isolated. This strain does not suppress phage φ 29 mutant susB47, selected on a B. subtilis strain containing the su+3 suppressor isolated by Georgopoulos. A revertant from this mutant, susB610, was isolated, being suppressed by both the su+3 and su+44 suppressor strains. The efficiency of suppression by strain su+44 is about 50%. The experiments shown in this paper suggest that strain su+44 contains an amber and strain su+3 an ochre suppressor.
43 citations
TL;DR: In this paper, the 1H NMR spectra of the six acetylated glycals as well as that of tetra-O-acetyl-2-hydroxy-Dglucal have been carried out.
Abstract: The complete analysis of the 1H NMR spectra of the six acetylated glycals as well as that of tetra-O-acetyl-2-hydroxy-D-glucal has been carried out. The conformation of these compounds, as determined from the proton couplings (±0.05Hz) obtained, has been interpreted in terms of a rapid interconversion equilibrium between the two possible dihydropyran half-chair conformations. A computer treatment of all observed couplings has been carried out to obtain optimized values for the populations and couplings characteristic of the two alternative half-chair conformations. The rotamer populations of the acetoxy–methyl group are discussed on the basis of the measured 5J16 and 5J36 couplings.
TL;DR: This work has shown that in Drosophila in genetic mosaics, where the heterozygous, phenotypically wild-type individual is a carrier of clones of homozygous mutant cells, the morphogenetic mutants, even if they are lethal to the individual, can be detected, studied and interpreted directly at the cellular level.
Abstract: GENETIC analysis has been used successfully for identifying the elements responsible for biological processes1,2, and understanding the logic of their interactions. This approach has, however, been little used in the study of morphogenesis in multicellular organisms, chiefly because of a dearth of viable mutants and the difficulties of interpreting the altered primary gene function from the mutant phenotype. The existence of pleiotropy in particular makes this analysis difficult3,4. An alternative approach would be to study the effect of mutations on individual cell behaviour5. This approach depends on the well founded assumption that normal morphogenesis results from the ordered integration of discrete cell autonomous functions. This can be done in Drosophila in genetic mosaics, where the heterozygous, phenotypically wild-type individual is a carrier of clones of homozygous mutant cells. This approach has the advantage that morphogenetic mutants, even if they are lethal to the individual, can be detected, studied and interpreted directly at the cellular level.
TL;DR: It was found that in T rats on 1.8 μg T4 or 0.4 μg T3⁄IOO g BW⁄day, response to TRH decreased after the injection of the hormone, maximum suppressive effect being found about 7–8 h after T4, or 4H after T3, in agreement with present views on TRH, T4 and T3 interactions at the pituitary level.
Abstract: Rats were thyroidectomized (T) and injected once daily with thyroxine (T4) or triiodothyronine (T3) ip; circulating thyrotropin (TSH) levels and TSH response to 100 ng of thyrotropin releasing hormone (TRH) iv, were measured in different groups of rats at several intervals after the last dose of T4 or T3. It was found that in T rats on 1.8 μg T4 or 0.4 μg T3⁄IOO g BW⁄day, response to TRH decreased after the injection of the hormone, maximum suppressive effect being found about 7–8 h after T4, or 4 h after T3. The response increased as T4 or T3 levels reached a nadir, in agreement with present views on TRH, T4, and T3 interactions at the pituitary level. The degree of TSH response to TRH appears as a sensitive parameter of T4 or T3 activity in this experimental model. However, in T rats on 0.2μg T3⁄lOOg BW⁄day, TSH response to TRH did not decrease, but actually increased, after the daily injection of T3. These animals appeared to be in a state of continuous thyroid hormone deficiency. The same 0.2 μg T3 do...
TL;DR: In this article, the absolute Raman intensities and the depolarization ratios of the vibrational bands of gaseous CH4, CH3D, CH2D2, CHD3 and CD4 were computed using a compact formulation of the bond polarizability theory, in its zero and first-order approximations.
Abstract: The absolute Raman intensities and the depolarization ratios of the vibrational bands of gaseous CH4, CH3D, CH2D2, CHD3 and CD4 have been computed here using a compact formulation of the bond polarizability theory, in its zero and first-order approximations. The agreement with experimental values taken from the literature is very good for the first-order approximation, although the difference between both approximations is not very large for these molecules. The derivatives of the polarizability with respect to the symmetry coordinates of methane are given with signs that are physically meaningful.
TL;DR: Experiments in the laboratory have shown that glycosylation of the mannoproteins of yeast wall glycoprotein occurs at the level of nascent polypeptide, and some of the enzymes involv- ed in the synthesis of specific bonds have also been characterized.
TL;DR: In this article, a 3Bi2O3:5B 2O3 was obtained from the melt and subsequent devitrification of the glassy compound, at 450°C during 90 hours.
TL;DR: It has been found that previous aeration in water or heating in air of ilmenite greatly improved the flotation recovery of this mineral with oleic acid as discussed by the authors, due to the lower solubility of the ferric compounds.
TL;DR: An index to assess trophic diversity from presence-absence food data is proposed and contains two kinds of information, one referred to ‘species richness’ and another relative to the degree of between-samples heterogeneity.
Abstract: An index to assess trophic diversity from presence-absence food data is proposed. The index is computed according to the expression \(D = - \sum\limits_{i = 1}^s {1g} {\text{ }}\hat p_i \), where the \(\hat p_i \)'s are the frequencies of occurrence of the various prey categories. The upper and lower limits of D are derived. A test of the reliability of D was carried out by comparing D and H (Shannon's information function) values obtained from a set of twenty-three food analyses from vertebrate animals. Results show that, although a significant correlation exists between D and H, only a small fraction of H-variation is explained by D-variation. D contains two kinds of information, one referred to ‘species richness’ and another relative to the degree of between-samples heterogeneity. The former is shared in common with H and this presumably explains the fairly weak correlation found between both measures.
TL;DR: In this paper, a multi-step reaction sequence form 3,5-diamino-4H-1,2,6-thiadiazine 1,1-dioxide was used to obtain lead tetraacetate.
TL;DR: In this article, the half-projected Hartree-Fock function for singlet states (HPHF) was analyzed in terms of natural electronic configurations, and the HPHF spinless density matrix and its natural orbitals were first deduced.
Abstract: The half-projected Hartree–Fock function for singlet states (HPHF) is analysed in terms of natural electronic configurations. For this purpose the HPHF spinless density matrix and its natural orbitals are first deduced.
It is found that the HPHF function does not contain any contribution from odd-times excited configurations. It is seen in addition, in the case of the singlet ground states, this function is approximately equivalent to two closed-shell configurations, although the nature of the excited one depends on the nuclear geometry. An example is given in the case of the LiH ground state. Finally, the application of this model for studying systems of more that two atoms is criticized.
TL;DR: Allium cepa L. root meristems, after a brief fixing in cold methanol, retain endogenous RNA polymerase activity, supplying a new evidence in favour that prenucleolar bodies are not synthesized in telophase since they appear before any transcription reinitiates.
TL;DR: It is hypothesized that when defecation turned to function as a communicative signal of danger, a new selective force came into play, increasing the amplitude of the movements and originating the visual pattern of the rump patch that makes them more evident.
Abstract: The rump patch of the Fallow Deer shows different visual patterns according to the activities performed by the animals. While in calm conditions the black tail sways over the white anal field; if in alarm, the tail hangs still, dividing the white field into two parts ; in higher stress the tail tends to be raised to a horizontal position, leaving the white anal field unbroken and outlined by the two lateral black stripes; if danger is impeding the tail gets erect, showing the white underside, now seen as an extension of the white anal field, or may even go up and down, the white brush of the tail appearing and disappearing On the basis of our results on the use of the rump patch and on the frequency of defecation (high in conditions of stress) and considering that the posture of the tail during defecation is one of the most frequently observed in alarm, we hypothesize that when defecation turned to function as a communicative signal of danger, a new selective force came into play, increasing the amplitude of the movements and originating the visual pattern of the rump patch that makes them more evident.
TL;DR: The results show that protein L11 is not an absolute requirement either for peptidyl transferase activity or for the binding of thiostrepton, although in the last case the protein strongly enhances the ribosome affinity for the antibiotic.
Abstract: Protein-deficient ribosomal particles obtained by treatment of 50-S subunits from Escherichia coli ribosomes with I M NH4Cl and 50% ethanol contain less than 3 % of proteins L7 and L12 and about 7 % of proteins L10 and L11. Proteins L1, L5, L8/9 and L25 are also released during the treatment but in amounts accounting for less than 40%.
The particles are able to form peptide bonds in different systems, such as ‘fragment reaction’, puromycin reaction and formation of dipeptides. They also bind N-acetylphenylalanyl-tRNA and phenylalanyl-tRNA non-enzymically but are unable to support any of the elongation-factordependent reactions tested. However, when methanol is present, they display up to 20% of the control EF-G-dependent GTP activities, such as GTP hydrolysis and formation of the ternary complex EF-G. GuoPP(CH2)P · ribosome. The first activity is totally sensitive to the antibiotic thiostrepton while the formation of the ternary complex is unaffected by the drug. When measured by equilibrium dialysis the core particles are shown to be able to bind radioactive thiostrepton.
The results show that protein L11 is not an absolute requirement either for peptidyl transferase activity or for the binding of thiostrepton, although in the last case the protein strongly enhances the ribosome affinity for the antibiotic.
TL;DR: The K m for rat liver 6-phosphogluconolactonase was found to be 80 μM, which is approximately 100 fold lower than the previously determined value, and is compatible with the kinetic paramaters of both glucose 6- phosphate dehydrogenase and 6- phosphogluconate dehydration, and hence with the flux through the oxidative segment of the pentose phosphate pathway.
TL;DR: Cell accumulation in a particular zone of interphase appears to be the cause of mitotic synchronization in onion root meristems, which seems to be located at the end of S period.
TL;DR: In this paper, the adsorption of O 2, CO, and CO 2 on Sc 2 O 3 was studied in the temperature range −195 to 550 °C. Isobars and isosteric heats were calculated, and ir spectra were measured for the identification of surface species.
TL;DR: It is suggested that both activities are catalysed by the same enzyme molecule, whose physiological role is not the formation of peptide crosslinks during peptidoglycan biosynthesis.
Abstract: 1. The membranes from Bacillus megaterium KM contained a DD-carboxypeptidase with optimum activity under the following conditions: pH 7; ionic strength, 1.3 M; temperature, 40 degrees C and below 20 degrees C. It did not require any divalent cation, but was inactivated by Cu2+ and Hg2+. It was stimulated by 2-mercaptoethanol and low concentrations of p-chloromercuribenzoate. 2. The membrane preparation also catalyzed a simple transpeptidation reaction using as carboxyl acceptors D-alanine or glycine. 3. The conditions for optimum activity, temperature-inactivation, temperature-dependence of the activity, carboxyl donor specificity, sensitivity to beta-lactam antibiotics, and insensitivity to potential peptide inhibitors of both enzyme activities, was identical. The DD-carboxypeptidase showed inhibition by D-alanine and Ac2-L-Lys-D-Ala. 4. The inhibition by beta-lactam antibiotic was reversible for both enzymic activities and the time-dependence for their recovery was identical. 5. The DD-carboxypeptidase was very sensitive to changes in the configuration and size of the side-chains of the C-terminal dipeptide of the substrate. Amino acid residues at the C-terminus that precluded the peptide from being a DD-carboxypeptidase substrate were not acceptors in the transpeptidation reaction. Dipeptides were not acceptors for the 'model transpeptidase'. 6. It is suggested that both activities are catalysed by the same enzyme molecule, whose physiological role is not the formation of peptide crosslinks during peptidoglycan biosynthesis.
TL;DR: The efficiency of incorporation of labelled acetate, propionate and p-aminobenzoic acid into candicidin by phosphate-limited resting cells of Streptomyces griseus was similar to that achieved previously in long-term experiments using growing cells.
Abstract: Labeled acetate, propionate and p-aminobenzoic acid were efficiently incorporated into candicidin by phosphate-limited resting cells of Streptomyces griseus. The efficiency of incorporation in short-term experiments using phosphate-limited resting cells was similar to that achieved previously in long-term experiments using growing cells. (2-14C)Propionate was more efficiently incorporated than (1-14C)propionate, (U-14C)propionate, or (U-14C)-acetate. p-Aminobenzoic acid incorporation is linear over a 10-hour period while those of acetate or propionate reach a constant level after approximately 4 hours of incubation. Double-labeled candicidin of high specific activity was prepared by supplementing the resting cell system with (3H)acetate and (14C)p-aminobenzoic acid.