Showing papers by "University of Oviedo published in 1992"

Wheat and barley allergens associated with baker's asthma. Glycosylated subunits of the alpha-amylase-inhibitor family have enhanced IgE-binding capacity.

Abstract: A 16 kDa protein, designated CM16*, which strongly binds IgE from baker's-asthma patients has been identified as a glycosylated form of the previously reported WTAI-CM16, which is a subunit of the wheat tetrameric alpha-amylase inhibitor. A glycosylated form (CMb*) of BTAI-CMb, the equivalent inhibitor subunit from barley, has been also found to have significantly enhanced IgE-binding capacity. In all, 14 purified members of the alpha-amylase/trypsin-inhibitor family showed very different IgE-binding capacities when tested by a dot-blot assay. The glycosylated components CM16*, CMb* and the previously described non-glycosylated 14.5 kDa allergen from barley (renamed BMAI-1) were found to be the strongest allergens.

Experimentally produced oscillatory zoning in the (Ba, Sr)SO 4 solid solution

Abstract: WHEN crystals grow from a multicomponent fluid phase under conditions where ionic diffusion in the solid is negligible compared to that in the liquid, any compositional gradients in the crystal record the evolution of the solid/liquid interface composition during growth. For the particular case of oscillatory zoning1–3, a relatively common feature of natural crystal growth4, there has been considerable theoretical interest4–6, but the specific question of whether high or low supersaturations are required to explain the development of the zoning remains unanswered. Experimentally produced compositional oscillations have been observed7,8, but the role of supersaturation had to be inferred, rather than measured directly. Here we describe major-element oscillatory zoning in (Ba, Sr)SO4 solid solutions grown by the counter-diffusion of (Ba2+, Sr2+) and SO2−4 ions through a porous silica-gel transport medium. We demonstrate how the different solubilities of the two pure phases determine the threshold supersaturation for nucleation, and show how coupling between the compositional gradients in the solid and the liquid results in the observed oscilla-tory behaviour.

The ICL1 gene from Saccharomyces cerevisiae

Abstract: The glyoxylate cycle is essential for the utilization of C2 compounds by the yeast Saccharomyces cerevisiae. Within this cycle, isocitrate lyase catalyzes one of the key reactions. We obtained mutants lacking detectable isocitrate lyase activity, screening for their inability to grow on ethanol. Genetic and biochemical analysis suggested that they carried a defect in the structural gene, ICL1. The mutants were used for the isolation of this gene and it was located on a 3.1-kb Bg/II-SphI DNA fragment. We then constructed a deletion-substitution mutant in the haploid yeast genome. It did not have any isocitrate lyase activity and lacked the ability to grow on ethanol as the sole carbon source. Both strands of a DNA fragment carrying the gene and its flanking regions were sequenced. An open reading frame of 1671 bp was detected, encoding a protein of 557 amino acids with a calculated molecular mass of 62515 Da. The deduced amino acid sequence shows extensive similarities to genes encoding isocitrate lyases from various organisms. Two putative cAMP-dependent protein-kinase phosphorylation sites may explain the susceptibility of the enzyme to carbon catabolite inactivation.

The distribution of spontaneous mutations on quantitative traits and fitness in Drosophila melanogaster.

Abstract: Starting from a completely homozygous population of Drosophila melanogaster, two groups of 100 inbred lines each were established and maintained for 46 generations, by a single brother-sister mating and two double first cousin matings, respectively. Sternopleural bristle number, wing length and wing width were simultaneously scored in all lines every 4-5 generations. The means of four lines in each group departed significantly from the overall mean and, in each case, this was attributed to a single mutation of relatively large effect on at least one trait (0.3-1.4 environmental standard deviations in absolute value). Further analyses revealed widespread pleiotropy, similar gene action of a given mutation for all traits affected, and predominant additive action. No apparent association was found between the magnitudes of mutational effects on the traits and fitness. However, all recessive mutations were deleterious. The distribution of mutant effects was asymmetrical (positive for bristles and negative for wing measurements). Moreover, these distributions had a high variance and may be leptokurtic, due to the presence of major genes. Estimates of the ratio of new mutational variance to environmental variance ranged within (0.7-3.4) x 10(-3), those for wing measurements being generally larger. In agreement with theory, the rate of between-line differentiation was independent of population size.

Identification of the Major Protein Components in Breast Secretions from Women with Benign and Malignant Breast Diseases

Abstract: The protein composition of breast secretions from 99 premenopausal women with benign or malignant breast diseases and from 70 control women without breast pathologies has been studied by using polyacrylamide gel electrophoresis. These fluids have been classified into two types according to their major polypeptide components. Type I fluids are defined by three major distinctive bands at Mr 44,000, 24,000, and 17,000, while those designated Type II present distinctive bands at Mr 80,000, 15,000, and 14,000. Amino acid sequencing and immunoblotting analysis demonstrated that proteins in Type I secretions correspond to Zn-α2-glycoprotein, apolipoprotein D, and gross cystic disease fluid protein-15, while those from Type II fluids have been identified as lactoferrin, lysozyme, and α-lactalbumin. Most women (93%) without breast pathology and most patients (88%) with benign diseases had secretions with a Type I polypeptide pattern. By contrast, a large percentage (57%) of secretions from women with breast carcinoma presented a Type II protein pattern. Further studies with a large number of women will be useful for corroborating the potential clinical interest of breast fluid protein analysis.

Role of glycosylation and deglycosylation in biosynthesis of and resistance to oleandomycin in the producer organism, Streptomyces antibioticus.

Abstract: Cell extracts of Streptomyces antibioticus, an oleandomycin producer, can inactivate oleandomycin in the presence of UDP-glucose. The inactivation can be detected through the loss of biological activity or by alteration in the chromatographic mobility of the antibiotic. This enzyme activity also inactivates other macrolides (rosaramicin, methymycin, and lankamycin) which contain a free 2'-OH group in a monosaccharide linked to the lactone ring (with the exception of erythromycin), but not those which contain a disaccharide (tylosin, spiramycin, carbomycin, josamycin, niddamycin, and relomycin). Interestingly, the culture supernatant contains another enzyme activity capable of reactivating the glycosylated oleandomycin and regenerating the biological activity through the release of a glucose molecule. It is proposed that these two enzyme activities could be an integral part of the oleandomycin biosynthetic pathway.

Cloning and expression of the thyrotropin-releasing hormone receptor from GH3 rat anterior pituitary cells.

Abstract: Functional thyrotropin-releasing hormone (TRH) receptors have been expressed in Xenopus laevis oocytes following the microinjection of total and poly(A)+ RNA from GH3 rat anterior pituitary tumour cells. Under voltage-clamp conditions, application of the peptide induced a biphasic Ca(2+)-dependent chloride current. The amplitude of the initial, fast, component of the response was dependent on the concentration of the hormone and on the amount of mRNA injected. Size fractionation of poly(A)+ RNA on a continuous sucrose gradient and Northern blot analysis indicated that the receptor was encoded by an mRNA of approx. 3.5 kb. A 3.28 kbp cDNA encoding the TRH receptor has been cloned and sequenced. Full functionality of the predicted 412-amino-acid receptor protein was demonstrated by functional expression of cell surface receptors in Xenopus oocytes after both cytoplasmic injection of sense RNA transcribed in vitro from this cDNA and nuclear injection of the cDNA under the control of the Herpes simplex virus thymidine kinase promoter. The predicted protein contains seven putative membrane-spanning domains and shows significant sequence identify with some G-protein-coupled receptors. RNA blot analysis indicates that the mRNA for the TRH receptor is exclusively expressed in the pituitary gland. Expression studies performed with clones in which the 3' region of the mRNA has been successively shortened indicate that the 3' terminal region is not an important determinant for efficient functional expression in oocytes.

Lower Paleozoic extensional tectonics in the limit between the West Asturian-Leonese and Central Iberian Zones of the Variscan Fold-Belt in NW Spain

Abstract: The limit between the West Asturian-Leonese and Central-Iberian Zones in the NW of the Iberian Peninsula is described in the area of Caurel-Truchas (Provinces of Orense and Leon). From the distribution of the sedimentary formations and the Variscan structures it is inferred that the transition between the two zones was a fault system, which was active during, at least, the Ordovician and Lower Silurian. The faults were supposedly normal, though they had probably some strike-slip component, and gave rise to a half-graben in which a syn-rift sequence was deposited. The latter underwent inversion at the onset of the Variscan tectonism, producing a ramp anticline-syncline pair that forms the more important folds in the area. The varying geometry of these folds is interpreted partly as being due to the existence of previous en echelon folds related to the strike-slip component of the faults and, partly, as a result of the variable intensity of the shear strain undergone during the first variscan phase.

Ambulatory blood pressure monitoring in elderly patients with isolated systolic hypertension.

Abstract: Objectives: This study compared clinic and ambulatory blood pressure measurement and the reproducibility of these measurements in older patients with isolated systolic hypertension (Isti). Patients: Eighty-seven patients aged 260 years with ISH on clinic measurement were followed in the placebo run-in phase of the Syst-Eur trial. Methods: Clinic blood pressure was defined as the mean of two blood pressure readings on each of three clinic visits (six readings in total). Ambulatory blood pressure was measured over 24 h using non-invasive ambulatory blood pressure monitors. Results: Daytime ambulatory systolic pressure was, on average, 21 mmHg lower than the clinic blood pressure, whereas diastolic pressure was, on average, similar with both techniques of measurement. In the 42 patients who had repeat measurements, clinic blood pressure levels and the amplitude of the diurnal blood pressure profile (fitted by Fourier analysis) were equally reproducible. However, both were less reproducible than ambulatory blood pressure levels. The repeatability coefficients, expressed as per cent of near gaximum variation (four times the standard deviation of a given measurement), were 52% and 45% for the clinic systolic and diastolic pressures, 56010 and 42% for the amplitude of the diurnal profile, and 29% and 26% for mean 24-h pressures. Conclusions: In older patients with ISH, clinic and ambulatory systolic blood pressure measurements may differ largely: the prognostic significance of this difference remains to be elucidated. Furthermore, in these patients the level of pressure is more reproducible by daytime ambulatory blood pressure measurement than by clinic measurement.

Localization of 5-hydroxytryptamine-like immunoreactive cells and nerve fibers in the rat female reproductive system.

Abstract: The presence of 5-hydroxytryptamine (5-HT)-like immunoreactivity (IR) was studied in the rat female reproductive system using polyclonal antibodies directed against 5-HT. Moreover, 5-HT levels in the ovary, oviduct, uterus, and cervix were measured by high-pressure liquid chromatography with electrochemical detection. The highest 5-HT concentrations were found in the oviduct, followed in descending order by the cervix, the ovary, and the uterus. Most 5-HT-like IR was observed in the cytoplasm of mast cells. These cells were found in the connective tissue around the fimbria, in the oviduct, in the uterus, and in the ovary. Mast cells are clustered in the proximity of the parenchymal blood vessels. Moreover, a few 5-HT-like nerve fibers were found distributed mainly perivascularily in the uterine cervix and in the uterine horns as well as in the oviduct. IR nerve fibers were rarely seen within the ovary. The present data provide direct evidence that 5-HT in the female reproductive system not only is associated with mast cells but is located in nerve fibre-like structures as well. The functional significance of this probable 5-HT-ergic innervation of the female reproductive tract discovered in the present study should be clarified in future investigations.

Characteristics and modulation by thyrotropin-releasing hormone of an inwardly rectifying K+ current in patch-perforated GH3 anterior pituitary cells.

Abstract: Hyperpolarization of patch-perforated GH3 rat anterior pituitary cells in high-K+ Ca2+-free medium reveals an inwardly rectifying K+ current. This current showed potential-dependent activation and inactivation kinetics, complete inactivation during strong hyperpolarization and rectification at depolarized potentials. The current was blocked by millimolar concentrations of external Cs+, Ba2+, Cd2+ and Co2+, but it was almost insensitive to tetraethylammonium, 4-aminopyridine and two dihydropyridines, nisoldipine and nitrendipine. Verapamil and methoxyverapamil produced a strong and reversible inhibition of the current. In the presence of 100 nM thyrotropin-releasing hormone (TRH), the current was reduced. This reduction was increased by holding the cell at more negative potentials and was accompanied by a shift in steady-state voltage dependence of inactivation towards more positive voltages. Furthermore, the current slowly returned to the initial levels upon washout. Treatment of the cell with the protein phosphatase inhibitor okadaic acid increased the magnitude of the inhibition caused by TRH. Moreover, the current did not return towards the control level during a 30-min washout period. It is concluded that protein phosphatases participate in modulation of the GH3 cell inwardly rectifying K+ channels by TRH. Furthermore, these data indicate that either a protein phosphatase or a factor necessary for its activation is lost under whole-cell mode, which could account for the permanent reduction of the current in response to TRH.

Water motion and morphology in chondrus crispus (rhodophyta)1

Abstract: Morphological variability of intertidal Chondrus crispus Stackh. fronds along a small open rocky coast was related to wave exposure and emersion. Cluster analysis revealed two well-defined morphologies: filiform and planiform, named the N morphotype and B morphotype, respectively. We propose a rapid method of classifying fronds based on the morphology of the cross section at half the height on the thallus. The N morphotype is characterized by fewer dichotomies per unit length, a circular cross section with a large inner cortex, and narrow fronds. It is abundant at low intertidal and exposed sites. The B morphotype is characterized by more dichotomies, smaller sizes, a subelliptical or flattened cross section, and broad fronds. It is abundant at high intertidal sites in sheltered areas. Regression analysis revealed a major effect of water movements on frond morphology with respect to tidal level, which was more evident at high intertidal levels. No relationships were observed between morphology and life history phases.

Sporulation of Streptomyces antibioticus ETHZ 7451 in submerged culture.

Abstract: Streptomyces antibioticus ETHZ 7451 formed spores in cultures grown in a liquid medium from either a spore or a mycelium inoculum. The spores formed were similar to those formed on surface-grown cu...

Geographic distribution and community structure of bumblebees in the northern Iberian peninsula

Abstract: Relationships between species distribution and abundance, the influence of proboscis length on species-packing, and species associations within the local assemblages were studied in local communities of bumblebees in northern Spain along an altitudinal gradient Local species abundance and altitudinal range occupied accounted for much of the variation in species distribution Altitudinal range occupied by species was related to species distribution, but the most important variable accounting for species distribution was the local percentage abundance Despite this, there was no evidence for age abundance Despite this, there was no evidence for bimodality in the distributions of species incidence A general trends for mean proboscis length in each locality to be greater in lowland localities exists, but this variable was not related to species distribution or abundance Proboscis length spacings were studied among species in local assemblages and in most of the cases observed spacing did not differ from random expectations The same patterns were demonstrated calculating spacings for ‘core’ species in each local assemblage Furthermore, species showed little tendency towards associations, so it may be concluded that bumblebee assemblages were irregularly structured and no clear patterns emerged from the present study

Incentive learning and the motivational control of instrumental performance by thirst

Abstract: The role of incentive learning in instrumental performance following a shift in the degree of water deprivation was analyzed in three experiments. In Experiments 1A and IB, rats trained to perform an instrumental action reinforced with either sucrose or maltodextrin solutions when in a high-deprivation state were subsequently shifted to a low-deprivation state and tested in extinction. This within-state shift in water deprivation reduced instrumental performance only when the animals had been exposed to the reinforcer in the low-deprivation state prior to instrumental training. In Experiment 2, a concurrent training procedure was used to assess whether the change in the value of the reinforcer brought about by preexposurewas mediated by the contingency between the instrumental action and the reinforcer. Preexposure to the reinforcer under the low-deprivation state produced a selective reduction of the performance of the action upon which it was contingent during training when testing was conducted in extinction following a shift from the high- to the low-deprivation state. These experiments provide evidence that animals have to learn about the incentive value of a reinforcer in a particular motivational state through exposure to the reinforcer in that state.

Effects of angling on population structure of brown trout, Salmo trutta L., in mountain streams of Northern Spain

Abstract: Effects of angling exploitation on brown trout populations were assessed by comparing fished sections with close ones unfished for at least 20 years, in mountain streams of Asturias (Northern Spain). Both the fish size and age structure significantly differed among sections in the expected direction according to their exploitation status. The main effects were a significant decrease in age structure complexity (diversity), life span, and percent individuals above the legal limit size in the exploited stocks versus the unexploited ones. Trout above the minimum length limit for fishing (18 cm) averaged 19.47% of the fish caught in the unfished sections (sd = 4.01; n = 5), and 4.72% (sd = 3.46; n = 4) in those subjected to angling. Furthermore, fish older than 4 years represented 39.84% (sd = 8.53) and 1.19% (sd = 1.60) of the catch, respectively. Effects on recruitment (density of young fishes) and growth rates (length at age 1 + to 3 +) were not absolutely consistent, though maximum values were associated with fished sections.

Forelimb deformation in some natural examples of fault-propagation folds

Abstract: An analysis of two natural examples of fault-propagation folds from the Pyrenees and the Cantabrian zone (N Spain) is presented. These folds possess common features despite their different geological settings, i.e. related to thrust tectonics in the Pyrenean example and to strike-slip faulting in the Cantabrian zone. Transition from fault-bend to fault-propagation folding along individual thrusts is related to changes in lithology. The fault-propagation folds studied are tight and markedly asymmetric with respect to limb thickness and shape. The forelimbs are curvilinear and display progressive thinning of beds towards the fault surface, which can be interpreted in terms of a characteristic heterogeneous strain superimposed onto flexural shear, and restricted to them. This strain has been factorized by means of grid construction, and is found to be a combination of thrust-parallel heterogeneous simple shear and pure shear, attributed here to a shear zone with diverging walls and extrusion. In contrast with previous models, it is shown that thrust-parallel simple shear is not necessarily distributed above the entire fault surface but may instead be restricted to regions where motion was inhibited such as tip zones or ramps.