Showing papers by "University of Oviedo published in 1989"

Movement errors and levels of processing in sentence production

Abstract: From a corpus of 3,530 slips of the tongue in Spanish, a sample of 753 cases of movement errors was analyzed, comprising those tokens that could be unambiguously assigned to the major categories of anticipations, perseverations, exchanges, and shifts. The analysis was performed according to two main criteria: (a) the degree of correspondence between the linguistic elements interacting in an error, and (b) the distance between such elements in terms of the type and number of the intervening linguistic boundaries. The results of this analysis converge with those obtained in English, supporting a model of sentence planning with different levels of representation and processing. Furthermore, Spanish provides a clear case to attest the role of syllabic structure in production processes, the constraints set by word boundaries in sublexical errors, and the contribution of inflectional suffixes to the assignment of grammatical category to the root morphemes.

Walnut (Juglans spp.)

Abstract: Under the common name Walnut are included species belonging to the genus Juglans, order Juglandales, family Juglandaceae. There are three main groups in the genus Juglans: (1) Common walnuts: J. regia L. (Fig. 1); (2) Black walnuts: J. nigra L.; J. hindsii Jeps; J. californica Watson; J. major Heller and J. rupestris Engelm; (3) Grey walnuts and White walnuts: J. cinerea L., J. sieboldiana Maxim, J. catayensis Dode and J. manchurica Maxim (Germain et al. 1975; Luna Llorente 1979). Trees of the Caraya group are also called American walnuts.

The Mechanism of Intracellular Acidification Induced by Glucose in Saccharomyces cerevisiae

Abstract: Addition of glucose or fructose to cells of Saccharomyces cerevisiae adapted to grow in the absence of glucose induced an acidification of the intracellular medium. This acidification appeared to be due to the phosphorylation of the sugar since: (i) glucose analogues which are not efficiently phosphorylated did not induce internal acidification; (ii) glucose addition did not cause internal acidification in a mutant deficient in all the three sugar-phosphorylating enzymes; (iii) fructose did not affect the intracellular pH in a double mutant having only glucokinase activity; (iv) glucose was as effective as fructose in inducing the internal pH drop in a mutant deficient in phosphoglucose isomerase activity; and (v) in strains deficient in two of the three sugar-phosphorylating activities, there was a good correlation between the specific glucose- or fructose-phosphorylating activity of cell extracts and the sugar-induced internal acidification. In addition, in whole cells any of the three yeast sugar kinases were capable of mediating the internal acidification described. Glucose-induced internal acidification was observed even when yeast cells were suspended in growth medium and in cells suspended in buffer containing K+, which supports the possible signalling function of the glucose-induced internal acidification. Evaluation of internal pH by following fluorescence changes of fluorescein-loaded cells indicated that the change in intracellular pH occurred immediately after addition of sugar. The apparent Km for glucose in this process was 2 mM. Changes in both the internal and external pH were determined and it was found that the internal acidification induced by glucose was followed by a partial alkalinization coincident with the initiation of H+ efflux. This reversal of acidification could be due to the activity of the H+-ATPase, since it was inhibited by diethylstilboestrol. Coincidence between internal alkalinization and the H+ efflux was also observed after addition of ethanol.

Lectura y escritura de palabras a través de la ruta fonologica

Abstract: ResumenEn este trabajo se investigo si los mecanismos encargados de transformar los grafemas en fonemas son los mismos que transforman los fonemas en grafemas, que funcionan en ambas direcciones o si por el contrario se trata de mecanismos independientes. Para ello se presento una lista de 40 pseudopalabras para su lectura y escritura a 104 ninos de los primeros niveles de escolaridad. Los datos obtenidos parecen indicar que se trata de procesos distintos, ya que no existe concordancia entre las respuestas obtenidas en una y otra tarea. Ninos que transformaban correctamente determinados grafemas en fonemas fallaban al convertir esos mismos fonenas en grafemas, y viceversa. Estos resultados podrian tener importantes implicaciones en el aprendizaje de la lectura y la escritura.

The hexokinase isoenzyme PII of Saccharomyces cerevisiae is a protein kinase

Abstract: The HXK2 gene product has an important role in controlling carbon catabolite repression in Saccharomyces cerevisiae. We have raised specific antibodies against the hexokinase PII protein and have demonstrated that it is a 58 kDa phosphoprotein with protein kinase activity. The predict amino acid sequence of the HXK2 gene product has significant homology to the catalytic domain of mammalian and yeast protein kinases. Protein kinase activity was located in a different domain of the protein from the hexose-phosphorylating activity. The hexokinase PII protein level remained unchanged in P2T22D mutant cells (hxk1 HXK2 glk1) growing in a complex medium with glucose. The protein kinase activity of hexokinase PII is regulated by the glucose concentration of the culture medium. Exit from the carbon catabolite repression phase and entry into the derepression phase may be controlled, in part, by modulation of the 58 kDa protein kinase activity by changes in cyclic AMP concentration.

Simulation of ionic transition-metal crystals: The cluster model and the cluster-lattice interaction in the light of the theory of electronic separability

Abstract: The cluster model often applied to the study of transition-metal ions in ionic crystals is rigorously formulated in the framework of the theory of electronic separability (TES). This theory shows that the cluster-lattice coupling appearing in the effective cluster Hamiltonian should include two separate operators: (1) the lattice effective potential containing nuclear attraction, Coulomb, and exchange terms, and (2) a lattice projection operator enforcing the cluster-lattice orthogonality required by the Pauli principle. The analysis of the TES equations also suggests a hierarchy of lattice models for dealing with the cluster-lattice interaction in an approximate way. Using a Hartree-Fock-Roothaan description for the intracluster interactions, three of these models are investigated and illustrated by means of several examples. First, the familiar point-charge model is deduced from the TES equations. The main conceptual and practical deficiencies of this model are discussed. Then, a TES-consistent lattice model in which the cluster-lattice exchange interactions are approximated by Slater X\ensuremath{\alpha} formula is presented. It is shown that this scheme, named the PX\ensuremath{\alpha} model, does not suffer from most limitations of the point-charge approximation and gives a coherent and reasonable description of the equilibrium geometry of the (${\mathrm{CrF}}_{6}$${)}^{4\mathrm{\ensuremath{-}}}$ unit in ${\mathrm{KCrF}}_{3}$. Finally, the model potential (MP) lattice model is presented and discussed. In this model the lattice ions are described by accurate local model potentials without resorting to the X\ensuremath{\alpha} approximation. The MP scheme gives satisfactory equilibrium geometries and relative stabilization energies for V, Cr, and Mn impurities in ${\mathrm{KMgF}}_{3}$.

Regulation of nitrogen catabolic enzymes in Streptomyces clavuligerus.

Abstract: SUMMARY: The levels of several enzymes involved in assimilation of different nitrogen compounds were investigated in Streptomyces clavuligems in relation to the nitrogen source supplied to the cultures. Threonine dehydratase, serine dehydratase, proline dehydrogenase, histidase and urocanase were not decreased in the presence of ammonium. The latter two enzymes were induced by histidine in the culture medium, while proline dehydrogenase was induced by proline. Glutamine synthetase, urease and ornithine aminotransferase levels were higher with poor nitrogen sources and were repressed by ammonium. Arginase was induced by arginine and repressed by ammonium. Glutamine synthetase was rapidly inactivated upon addition of ammonium to the culture, and could be reactivated in vitro by treatment with snake venom phosphodiesterase, which suggested that adenylylation is involved in the inactivation. Three previously isolated mutants with abnormal glutamine synthetase activities showed pleiotropic effects on urease formation. All these data point to a mechanism controlling preferential utilization of some nitrogen sources in this species.

Reading Errors in Spanish

Abstract: During the last ten to fifteen years, reading and writing have received considerable attention from cognitive psychologists and neuropsychologists. The aim of these studies has been to discover and specify the mechanisms and processes that mediate reading. But since the great majority of research data come from the English language, it is quite possible that at least part of the findings reflects the particular nature of the language used and not the architecture of the processing system. A relatively uniform pattern of responses may be accounted for either by assuming certain structural constraints in the system, or by the characteristics of the language. It is, therefore, necessary to carry out cross-cultural studies using different languages with varied orthographies and phonologies and see to what extent the reading and spelling models that have been based on data from the English language are tenable when applied to these languages.

Observations on feeding relationships between fish predators and fish assemblages in a Mediterranean stream

Abstract: The diet of native and introduced fish predators has been examined in two contrasting localities of a very fluctuating, Mediterranean stream, in relation to fish (prey) assemblage structure. The general patterns of all the species studied (Lutra lutra, Natrix maura, Salmo trutta, S. gairdneri, Esox lucius, and Leuciscus cephalus) seem to be the result of a generalist-opportunist behaviour as their diets reflect the relative abundance of prey (fish) in the environment. The trophic levels are not well defined because of the opportunistic feeding of the predators and are also subjected to environmental changes. Non-competitive dynamics is suggested to operate throughout the trophic web.

Hazelnut (Corylus avellana L.)

Abstract: Under the common names of hazel or filbert are included the species belonging to the genus Corylus, tribe Coryleae, family Betulacea. They are classified in the order Fagales, subclass Hamamelidae, class Magnoliopsida (Cronquist 1981). The genus currently includes some 15 species. The most interesting among them from the point of view of genetic improvement are: Corylus avellana, because of the characteristics of its fruits; Corylus maxima, because of its resistance to bud mites; C. americana and C. colurna, as they can resist low temperatures and diseases and C. colurna and C. chinensis, which may produce non-suckering rootstock (Romisondo 1976).

Isolation and characterization of nitrogen-deregulated mutants of Streptomyces clavuligerus.

Abstract: SUMMARY: Two screening methods for isolation of mutants of Streptomyces clavuligerus with altered control of nitrogen metabolism enzymes are described. Thirty-eight profotrophic mutants with simultaneous deregulation of urease and glutamine synthetase were isolated. Nine mutants were examined in more detail and they also showed deregulated formation of arginase and ornithine aminotransferase. Different patterns of altered control of all four enzymes were observed Inactivation of glutamine synthetase after ammonium shock took place to different extents in these nine strains, and seven of them had a thermosensitive glutamine synthetase activity. It is concluded that a system of nitrogen control, in which glutamine synthetase has a key role, is present in S. clavuligerus. Cephalosporin production was depressed by ammonium in all the mutants, irrespective of the alterations in nitrogen control of primary metabolism.

Intrapopulational variation of olfactory responses in Drosophila melanogaster.

Abstract: The existence of genetic variability for olfactory response within natural populations ofDrosophila melanogaster was studied in two newly collected natural populations from two very different habitats, the Sandiche population, from a very heterogeneous environment, and the Los Areneros population, from a very homogeneous one. Intrapopulational variability was estimated over approximately 50 isofemale lines derived from each population. Results confirm significant differences in olfactory response to ethyl alcohol and acetaldehyde in both populations and to ethyl acetate in the Sandiche population. The differences were due partially to common components of the olfactory responses to different chemical (nonspecifics) in the Sandiche population, but they were specific for the stimulus in the Los Areneros population.

Sequence of the coding regions from the 3.0 kb and 3.9 kb mRNA. Subgenomic species from a virulent isolate of transmissible gastroenteritis virus.

Abstract: Subgenomic mRNA from a virulent isolate of porcine transmissible gastroenteritis virus (TGEV) was used to produce cDNA clones covering the genome region from the 3′ end of the pelomer gene to the start of the integral membrane protein gene. The nucleotide sequence of this area was determined using clone pTG11 and a previously reported cDNA clone pTG22. Three open reading frames (ORFs) were identified encoding putative polypeptides of relative molecular masses (Mr) 6,600, 27,600, and 9,200. The sequence encoding the Mr 9,200 polypeptide was found to be present on the “unique” 5′ region of the 3.0 kb mRNA species whereas the other two ORFs mapped on the 3.9 kb mRNA species. Differences between the ORFs from this strain of TGEV and those from a previously reported avirulent strain of TGEV were compared.

Isolation and characterization of actinophages infecting streptomyces species and their interaction with host restriction-modification systems

Abstract: SUMMARY: Nine different phages, φA1 to φA9, were isolated from soil samples on Streptomyces antibioticus ATCC 11891, a strain which produces the macrolide antibiotic oleandomycin. Each phage displayed a different host-range which did not extend beyond Streptomyces species. Host-range was mainly limited by adsorption specificity and host-controlled restriction-modification systems. All the phages except φA3 and φA9 formed turbid plaques on S. antibioticus, but did not lysogenize this host. However, three of the phages (φA5, φA7 and φA8) were identified as temperate, since they were able to lysogenize other Streptomyces strains. All of the phages were morphologically similar and belonged to group B of Bradley's classification. They had polyhedral heads and long, non-contractile tails. φA5, φA6 and φA7 had a base plate at the terminal end of the tail. Analysis with restriction endonucleases indicated that the nine phages contained double-strandpd DNA. Hybridization studies between the phage genomes, together with results on genome structure, allowed classification of the phages into five groups: (I) φA2, φA4 and φA9, (II) φA3 and φA8, (III) φA7, (IV) φA5 and φA6, and (V) φA1.