Showing papers by "Spanish National Research Council published in 1975"
TL;DR: The possibility of inducing, at any developmental age, cells with different cell-cycle lengths and clones that are larger or smaller than normal provides a powerful new technique with which to approach developmental problems.
889 citations
TL;DR: In systems containing untreated and toxin-treated ribosomes the ability to polymerize phenylalanine was proportional to the concentration of untreated Ribosomes, and there was a linear relationship between toxin A-chain concentration and the number of ribosome inactivated per minute.
Abstract: A sensitive test system for toxin-treated ribosomes was worked out by treating rabbit reticulocyte ribosomes with abrin A-chain, ricin A-chain or ricinus agglutinin A-chain, adding neutralizing amounts of specific antitoxins and testing for polyphenylalanine-synthesizing activity in a system where the concentration of elongation factors and ribosomes were varied. The strongest inhibition was obtained in the presence of low concentrations of elongation factor (EF-2). The activity of the ribosomes decreased with time of incubation with the toxin A-chains. Addition of anti-toxins stopped further inactivation. In systems containing untreated and toxin-treated ribosomes the ability to polymerize phenylalanine was proportional to the concentration of untreated ribosomes. There was a linear relationship between toxin A-chain concentration and the number of ribosomes inactivated per minute. The inactivation rate increased with temperature, and the estimated activation energy was 10.6 kcal (44.3 kJ). Linewaver-Burk plots of the data obtained by incubating various ribosome concentrations with toxins indicated a molecular activity of about 1500 ribosomes/minute for abrin and ricin A-chains and 100 ribosomes/minute for ricinus agglutinin A-chain. The apparent Michaelis constant was 0.1-0.2 muM for all three A-chains. The activity of the A-chains in the intact cell is discussed.
204 citations
TL;DR: The mea-urement by RIA of changes in GH content of the rat pituitary may provide the most adequate parameter available at present for a biological effect in vivo of single doses of the thyroid hormones, a measurement clearly related to an important physiological role.
Abstract: The effects of thyroid hormone deprivation and restitution on growth hormone (GH) economy have been studied in the rat by means of a specific radioimmunoassay. The pituitary GH content and the plasma GH levels before and during stimulation with pentobarbital (“PB-test”) were studied in male rats at different intervals after surgical thyroidectomy (Ť), and in Ť rats at different time intervals after the ip injection of 0.20,1.75, and 5.0 µgthyroxine (T4) or 0.05, 0.10, 0.20 and 1.0 µg triiodothyronine (T3),all doses being referred to 100 g body wt. Pituitary GH content decreased very rapidly after Ť, a difference being shown at the end of the shortest time interval studied (24 h); 24 days after Ť, pituitary GH content was 0.3% or less of the pre-Ť level, the basal plasma GH was lower than in intact controls and an increase in plasma GH during PB-stimulation wasno longer observed. When rats Ť for 30 days or longer were injected once with T4or T3, pituitary GH content increased; basal plasma GH levels increa...
191 citations
TL;DR: The results obtained suggest the existence of a biosynthetic precursor of higher molecular weight or procalcitonin, present in small amounts in chicken ultimobranchial glands and it is biologically active in rats.
Abstract: Calcitonin biosynthesis has been studied in chicken ultimobranchial glands incubated in vitro in the presence of radioactive amino acids. The results obtained suggest the existence of a biosynthetic precursor of higher molecular weight or procalcitonin. This precursor has been identified by pulsechase experiments, molecular weight determinations, biological activity measurements and analysis of tryptic peptides. Its molecular weight is about 13000 (calcitonin, about 3500) as determined by polyacrylamide gel electrophoresis. Procalcitonin is present in small amounts in chicken ultimobranchial glands and it is biologically active in rats.
89 citations
TL;DR: The effects of ricin on the different steps of the elongation cycle of protein synthesis in a rabbit reticulocyte cell-free system are studied and apparently conflicting results are discussed.
Abstract: The effects of ricin on the different steps of the elongation cycle of protein synthesis in a rabbit reticulocyte cell-free system are studied in this paper. The toxin most probably acts by catalytically inactivating the ribosomes, since a single molecule of the toxin can inactivate 300 ribosomes for poly(U)-directed phenylalanine incorporation. The effect of the toxin on the ribosome is irreversible.
Ricin specifically inhibits elongation-factor-1-dependent aminoacyl-tRNA binding to ribosomes but has no effect on the non-enzymic binding of aminoacyl-tRNA. Ricin also inhibits formation of the complex elongation-factor-2 · ribosome · nucleotide with GTP, GDP or GMP-P(CH2)P. However, the toxin has no effect on translocation. These apparently conflicting results are discussed in this study.
78 citations
TL;DR: The Betancuria Massif as mentioned in this paper is the largest area of the basement complex rocks in the Canary Islands and has been shown to be representative of oceanic crust formed at certain constructive plate margins.
Abstract: THE exposed portions of the Canary Islands largely comprise Cainozoic volcanic rocks erupted sub-aerially in successions essentially specific to each island, though with somewhat complex interrelationships1. On three islands, Fuerteventura, La Palma, and Gomera these rocks rest unconformably on older formations which are similar enough to suggest that a common basement may exist. The largest area of the basement complex rocks is the Betancuria Massif2–4, Fuerteventura. Gastesi4 has suggested that similarities exist between the Betancuria Massif and other ophiolite complexes (such as the Troodos Massif of Cyprus5,6) generally held to be representative of oceanic crust formed at certain constructive plate margins.
73 citations
TL;DR: The different Minutes characteristically increase the frequency of recombination clones arising after X-irradiation, and possible causal interrelationships of the different traits of the Minute syndrome are discussed.
Abstract: A sample of 16 Minutes, representing 12 loci distributed over all the chromosome arms and including 3 pairs of alleles and 4 deficiencies, has been studied with respect to several developmental and recombinational parameters. Cell marker mutants located in most of the chromosome arms were used to assess (1) spontaneous and X-ray-induced mitotic recombination frequencies of each Minute, and (2) clone sizes of the different cell marker clones. These parameters were analyzed both in the wing disc and in the abdominal histoblasts.—Whereas spontaneous frequencies are not affected by the presence of the Minutes studied, the different Minutes characteristically increase the frequency of recombination clones arising after X-irradiation. The recombinant clones which are M+/M+ are significantly larger than clones in the same fly which retain the M+/M condition. This is particularly striking in clones in the wing disc, slightly so in clones in the tergites. The occurrence of mitotic recombination in the fourth chromosome is reported for the first time.—Chaeta length and developmental delay correlates with the recombinational parameters in different ways. Possible causal interrelationships of the different traits of the Minute syndrome are discussed.
63 citations
52 citations
TL;DR: The final expression of a cell depends not on its immediate ancestry but perhaps on the level of the products of the wild-type alleles of bithorax and postbithorAX.
Abstract: Contrabithorax , a mutant of the bithorax system in Drosophila melanogaster produces a partial homeotic transformation of mesothorax (wing) into metathorax (haltere). The wing of a fly homozygous or heterozygous for the mutant is a mosaic of wing and haltere structures. A genetic analysis of the mutant suggests that its phenotype is due to some form of derepression in the wing of two other genes of the bithorax system ( bithorax and postbithorax ) which are not normally active there. This repression is not complete. The activity of the two genes is below the normal level resulting in only a partial transformation of wing into haltere.
Clones of marked cells were generated by X-rays and were found to include both transformed (haltere) and untransformed (wing) territory; this was true even for those generated late in development. Thus the final expression of a cell depends not on its immediate ancestry but perhaps on the level of the products of the wild-type alleles of bithorax and postbithorax .
52 citations
TL;DR: In this paper, the effectiveness of the CNDO/2 method for predicting molecular conformations was evaluated in twenty-six molecular systems, involving B, C, N, O, F, Si, S and Cl atoms.
49 citations
TL;DR: The finding of a significant rise in the calculated intramitochondrial concentration of oxaloacetate points to pyruvate carboxylation as an important site of glucagon interaction with the gluconeogenic pathway.
Abstract: The metabolic effects of glucagon and glucagon plus insulin on the isolated rat livers perfused with 10 mM sodium L-lactate as substrate were studied. Glucagon stimulated gluconeogenesis, ketogenesis and ureogenesis at the concentration used of 2.1 nM. The addition of insulin to give a glucagon-to-insulin ratio of 0.2 reversed all the glucagon effects.
The glucagon enhancement of gluconeogenesis was accompanied by a rise in the cytosolic and mitochondrial state of reduction of the NAD system and a fall in the [ATP]/[ADP] ratio. The analysis of the intermediary metabolite concentrations suggested, as possible sites of glucagon action, the steps between pyruvate and phosphoenolpyruvate as well as the reactions catalyzed by phosphofructokinase and/or fructose bisphosphatase. All the changes in metabolite contents were abolished when insulin was present.
Glucagon increased the intramitochondrial concentration of all the metabolites, whose intracellular distribution was calculated. The finding of a significant rise in the calculated intramitochondrial concentration of oxaloacetate points to pyruvate carboxylation as an important site of glucagon interaction with the gluconeogenic pathway. A primary event in the glucagon action redistributing intracellular metabolites seems to be the mitochondrial entry of malate. The possibility is discussed that the changes in metabolite cellular distribution were brought about by the increased cellular state of reduction caused by the hormone.
TL;DR: In this article, phase diagrams for the pyrochlore structure compounds hafnialanthana and hafnia-neodimia are suggested based on experimental evidence obtained by X-ray diffraction and using precision lattice parameters.
TL;DR: Quantitative binding studies of [G-3H]anisomycin and [acetyl-14C]trichodermin to sensitive and resistant 80-S ribosomes from yeasts are described, suggesting that the resistance of TR1 Ribosomes to the effects of trichothecin and fusarenon X is caused by a decrease in the affinity of the ribosome for these drugs, as was seen with trichodermine.
Abstract: Quantitative binding studies of [G-3H]anisomycin and [acetyl-14C]trichodermin to sensitive and resistant 80-S ribosomes from yeasts are described in this work. A single mutation, most probably affecting the ribosome peptidyl transferase centre, appears to have pleiotropic effects on the ribosome leading to resistance to trichodermin and anisomycin and to an increased sensitivity to sparsomycin. Resistance to trichodermin is due to a reduced affinity of ribosomes from the mutant for the antibiotic. Ribosomes from the sensitive strain (Y166) bind [acetyl-14C]trichodermin with a dissociation constant of 0.99 μM while those from the resistant one (TR1) bind [acetyl-14C]trichodermin with a dissociation constant of 15.4 μM. Similar results are obtained when the binding of [acetyl-14C]-trichodermin to Y166 and TR1 60-S subunits is studied.
The mutant TR1 is also resistant to anisomycin. Although trichodermin and anisomycin bind to the ribosome at mutually exclusive sites, the higher affinity binding of [G-3H]anisomycin that is responsible for the inhibition of the peptidyl transferase center is practically identical for Y166 and TR1 ribosomes. Therefore, the mutation in the ribosome leading to resistance to trichodermin and anisomycin decreases the affinity for trichodermin but not for anisomycin.
Trichodermin, trichothecin and fusarenon X inhibit the binding of [G-3H]anisomycin to TR1 ribosomes to a lower extent than to Y166 ribosomes, suggesting that the resistance of TR1 ribosomes to the effects of trichothecin and fusarenon X is caused by a decrease in the affinity of the ribosomes for these drugs, as was seen with trichodermin. On the other hand, verrucarin A inhibits [G-3H]anisomycin binding to Y166 and TR1 ribosomes to a similar extent and therefore its affinity for the ribosome does not appear to be affected by the mutation leading to resistance.
Trichothecin, trichodermin and fusarenon X appear to have a common binding site on the 60-S ribosomal subunits, which overlaps or is closely linked to the binding sites of anisomycin and verrucarin A.
TL;DR: The total Krebs cycle acids seems to be in an inverse relationship in leaf and fruit during its development, and the protein nitrogen content slowly drops in the fruit during development with a small increase at maturity.
TL;DR: Excess volumes of the nine binary mixtures formed from benzene with n -hexane, n -octane, d -decane and n -dodecane have been measured at 323.15 K, as function of composition as discussed by the authors.
01 Sep 1975
TL;DR: Morphogenetic mosaics in the wing margin suggest that the differentiation of the marginal cuticular elements requires the interaction of the cells of the ventral and dorsal surfaces of the wing.
Abstract: The mutantscut
6 (ct6) andBeadex of Jollos (Bx
J) show nicks in the wing margins as well as other malformations in different regions of the body. Clonal analysis of the wing disk's development in these mutants indicates that massive cell loss occurs during the third larval instar. Morphogenetic mosaics, originating from mitotic recombination, reveal a non-autonomous behaviour of both mutant and wild-type cells. X-rays applied during the third larval instar produce phenocopies of these mutants. A clonal and a genetic analysis of these phenocopies has been carried out. The hypothesis that scalloping mutants such asct
6, BxJ and others, as well as X-rays, affect properties of cellular interaction, such as cell adhesivity or cohesion, is discussed. Morphogenetic mosaics in the wing margin suggest that the differentiation of the marginal cuticular elements requires the interaction of the cells of the ventral and dorsal surfaces of the wing.
TL;DR: Cytogenetic studies of the child and his parents, completed with Q- and G-banding techniques led to the conclusion that it is a case of 22 trisomy inherited from his mother.
Abstract: The case of a 21/2-month-old male child with intrauterine distrophy features and multiple congenital malformations is presented. Cytogenetic studies of the child and his parents, completed with Q- and G-banding techniques led us to conclude that it is a case of 22 trisomy inherited from his mother.
TL;DR: Fructose-1,6-diphosphatase active fractions I and II earlier purified from spinach leaves show similar molecular weights, in the range 92 000–115 000, when calculated by Sephadex filtration and acrylamide gel electrophoresis.
TL;DR: The results are compatible with the postulated role of thecomplex in polypeptide synthesis inhibition and indicate that formation of the complex takes place by overriding the control that prevents interaction of EF-G when the donor site is occupied by peptidyl-tRNA.
Abstract: The inhibitory action of fusidic acid on peptide-chain elongation was studied with systems in vitro directed by either polyuridylic acid or endogenous messenger (Escherichia coli polysomes washed with 1 M NH4Cl) or R 17 RNA, and supplemented with either crude or purified elongation factors. In all cases strong inhibition of synthesis required high concentrations of the antibiotic (approx. 1 mM), while a similar inhibition of the EF-G-plus-ribosome-dependent GTP hydrolysis required between 10 and 100 times less antibiotic. Since most of the GTP hydrolysis observed was presumably due to free ribosomes (without aminoacyl-tRNA or peptidyl-tRNA), fusidic acid seemed to interact far more easily with these ribosomes than with ribosomes engaged in peptide-chain elongation.
The role of the GDP · EF-G · ribosome · fusidic acid complex in the inhibition of polypeptide synthesis was assessed by measuring formation of this complex on polysomes engaged in peptide-chain elongation. Using purified elongation factors the complex formed on only 25–35% of ribosomes, as measured either by retention of [3H]GDP or by hydrolysis of [3H, γ-32P]GTP. In contrast, with crude factors (S100 extract) it formed on more than 70% of ribosomes. The results are compatible with the postulated role of the complex in polypeptide synthesis inhibition (blockade of the ribosomal acceptor site and subsequent inhibition of aminoacyl-tRNA binding) and indicate that formation of the complex takes place by overriding the control that prevents interaction of EF-G when the donor site is occupied by peptidyl-tRNA.
In the polyuridylic-acid-directed system for synthesis of oligophenylalanine the antibiotic inhibits every round of peptide elongation, including dipeptide formation, to roughly the same extent.
TL;DR: The antibiotic tenuazionic acid appears to require for its inhibitory effect the ribosome sulphydryl residues, since its inhibitories action on the fragment reaction is greatly decreased in ribosomes treated with N-ethylmaleimide.
Abstract: Treatment of mammalian ribosomes with N-ethylmaleimide enhances up to 100% the ribosome efficiency in the "fragment reaction assay" for peptide bond formation by increasing the affinity of the substrate C-A-C-C-A-Leu-Ac for the donor site. This stimulation in peptidyl transferase activity was not observed when yeast ribosomes were treated in a similar manner. Stimulation of the peptidyl transferase activity of mammalian ribosomes was also observed by treatment with either p-chloromercuribenzoic acid or 5,5'-dithiobis-(2-nitrobenzoic acid) or 5,5'-dithiobis-(2-nitropyridine) or the maleimide-derived antibiotic showdomycin. N-Ethylmaleimide treatment also enhances C-A-C-C-A-Leu binding to the acceptor site of the peptidyl transferase centre. However, neither binding of N-Ac-Phe-tRNA in the presence of ethanol, nor binding of Phe-tRNA to the ribosomes is stimulated by N-ethylmaleimide. The antibiotic tenuazionic acid (a selective inhibitor of peptide bond formation by mammalian ribosomes) appears to require for its inhibitory effect the ribosome sulphydryl residues, since its inhibitory action on the fragment reaction is greatly decreased in ribosomes treated with N-ethylmaleimide.
TL;DR: The results suggest the existence of three distinct poly(A) polymerases, designated I, IIA and IIB, in dense cultures of NIL and NIL-HS virus cells.
TL;DR: The ranking of the subjects was much the same for Restraining and genital display as discussed by the authors and the hierarchies for Approaching and Following fitted well with each other, showing few similarities with the above two.
Abstract: Under different criteria the individual members of groups of squirrel monkeys show different social capacities. The ranking of the subjects was much the same for Restraining and Genital display. The hierarchies for Approaching and Following fitted well with each other, showing few similarities with the above two. Location of individual ranks for Withdrawing tended to be the opposite to that of Approaching and Following.
TL;DR: In this paper, the thermodynamic properties of a sufficiently general Dicke model were derived by means of the use of the gap equations, which correspond to the condition of second-order phase transition from the normal to the super-radiant state.
TL;DR: Kinetic velocity curves are sigmoidal, which suggests a strong regulatory role of fructose-1,6-diphosphate in the range of physiological substrate concns, and pH activity profiles of fractions I and II are similar, with optima at 8·65–8·70, both showing a high specificity for fructose- 1,6
TL;DR: The significant decrease of corticosteroids observed after repeated administration of morphine and the rise in adrenal cortiosteroids found after the injection of nalorphine to the morphinized animals suggest that some kind of morphine dependence had been developed in the cats after repeated Administration of the drug.
TL;DR: Four new diterpenes have been isolated from Sideritis serata by isolating lagascol, tobarrol, benuol and serradiol and sideritol from the same source.
TL;DR: It is concluded that physical dependence on morphine is reached by cats chronically treated with morphine and that this effect of the drug influences adrenomedulllary function in a different fashion depending on the stage of morphine treatment.
TL;DR: The rate of nucleologenesis per ribosomal cistron seems to be constant in the different species growing in similar conditions, but this mean rate was modified in metabolically different subpopulations in the same root.
Abstract: THE nucleolus is not a permanent organelle in the life of a cell; at the initiation of a new cycle, the nucleolar formation seems to depend on RNA synthesis directed by nucleolar RNA polymerase1. We have compared the rate of nucleologenesis in meristem cells of Allium cepa L. and in those of four Vicia species with different numbers of ribosomal cistrons and different DNA contents3,4 as well as the rate of nucleologenesis in four different cell populations lying side by side in the root of Zea mays. The rate of nucleologenesis per ribosomal cistron seems to be constant in the different species growing in similar conditions, but this mean rate was modified in metabolically different subpopulations in the same root.
TL;DR: This article showed that sulfhydryl groups and disulfide bridges play a role in the structural organization of these prokaryotic membranes and that they are readily accessible to titration with 5,5′-dithiobis(2-dinitrobenzoic acid).
Abstract: Plasma membranes from Streptomyces albus had 5.2 mol of sulfhydryl groups and 6 mol of disulfide bridges/50 kg protein whereas Escherichia coli membranes had 3.4 mol sulfhydryl groups and 4 mol disulfide bridges/50 kg protein. About 66% of the sulfhydryl groups of S. albus membranes and 22% of those of E. coli membranes were readily accessible to titration with 5,5′-dithiobis(2-dinitrobenzoic acid). o-[(3 Hydroxymercuri-2-methoxypropyl)-carbamyl]-phenoxyacetic acid (mersalyc acid). and p-chloromercuribenzoate were effective in solubilizing membrane proteins from the two bacteria. Other sulfhydryl group reagents, such as N-ethylmaleimide, iodoacetamide and iodoacetic acid, were less effective. Dithiothreitol affected the dodecylsulphate gel electrophoresis patterns of S. albus membranes and soluble fractions. This effect resulted from the reduction of pre-existing disulfide intramolecular bridges and some interchain disulfide formed during solubilization and/or storage. Dithiothreitol also affected the dodecylsulphate gel electrophoresis patterns of E. coli membranes and their soluble fractions. These results suggest that sulfhydryl groups and disulfide bridges play a role in the structural organization of these prokaryotic membranes.
TL;DR: Binucleate cells obtained of a 2 h treatment with caffeine from cells labelled with [3H]thymidine showed the sister chromatids to be distributed in a totally random fashion.