Showing papers by "Spanish National Research Council published in 1981"
TL;DR: Absence of mycorrhizal infection in some wheat varieties was associated with lack of sugar exudation from the roots rather than with the sugar content of the roots, and VA infection led to a decrease in the reducing and total Sugar content of root extracts, and this effect was correlated with the degree of myCorrhizAL infection.
Abstract: SUMMARY
Wheat cultivars inoculated with Glomus mosseae show different degrees of mycorrhizal infection and mycorrhizal dependency. Mycorrhizal dependency was affected by root and root/shoot (R/S) ratio dry wts, but neither mycorrhizal dependency nor mycorrhizal infection levels were directly affected by N, P, K, Ca or Mg concentrations in plant tissues.
Absence of mycorrhizal infection in some wheat varieties was associated with lack of sugar exudation from the roots rather than with the sugar content of the roots. VA infection led to a decrease in the reducing and total sugar content of root extracts, and this effect was correlated with the degree of mycorrhizal infection.
291 citations
TL;DR: In this article, a measurement of the splitting of the discrete lines in the 5-min oscillations of the solar surface produced experimental evidence for the rapid internal rotation of the Sun, and the number of components into which the lines are split also allows unambiguous identification of 11 examples of each of the l = 0, l = 1 and l = 2 modes in the frequency range 2.40-3.85 mHz.
Abstract: The observation of line-of-sight velocities of the solar surface by means of Doppler shift measurements of the Fraunhofer absorption lines, using optical resonance scattering, has proved a useful technique in solar physics enabling the discovery of long period solar oscillation1, the discrete, regular structure in the 5-min oscillation2 and, as we report here the splitting of this structure by rotational effects. A measurement of the splitting of the discrete lines in the 5-min oscillations of the solar surface produced experimental evidence for the rapid internal rotation of the Sun. These data demonstrate that the Sun does not rotate uniformly but that the ‘core’ of the Sun rotates 2–9 times as rapidly as the observed surface rotation. The number of components into which the lines are split also allows unambiguous identification of 11 examples of each of the l = 0, l = 1 and l = 2 modes in the frequency range 2.40–3.85 mHz.
116 citations
TL;DR: This chapter discusses the multimodulation of enzyme activity; Phosphorylase provided the first example for many aspects of metabolic regulation at the enzyme level, including both noncovalent and covalent types.
Abstract: Publisher Summary This chapter discusses the multimodulation of enzyme activity. Multimodulation of enzyme activity arises from the accumulation in a given enzyme of several regulatory mechanisms, whether of different types—cooperative, allosteric, interconversion, or of the same type—multiple allosteric effects, or of any combination of these. Modulation of enzyme activity was considered initially as synonymous with feedback inhibition, typically by the end product. With time, some enzymes appeared to have more than one mechanism for modulation of activity. Eventually, plurality increased for certain enzymes from more than one to many modulation mechanisms, including both noncovalent and covalent types. Phosphorylase provided the first example for many aspects of metabolic regulation at the enzyme level. It shows that marked co-operativity for the substrate P i , is inhibited by glucose 6-phosphate (Glc 6-P) and can be activated by either noncovalent (adenosine monophosphate —AMP) or covalent (phosphorylation) modulation. The two activation mechanisms make excellent physiological sense—AMP serves as energy-need signal and the phosphorylation ultimately reflects hormonal control.
104 citations
TL;DR: African swine fever virus synthesizes in vitro four classes of capped and polyadenylated RNAs with sedimentation coefficients of about 16,12, 10, and 7 S, free poly(A) with a sedimentation coefficient of about 4 S and a material, smaller than 4 S, labeled with S -adenosyl[ methyl - 3 H]methionine and partially polyadenyated.
85 citations
TL;DR: It is demonstrated that papulacandin B and aculeacin A are indeed inhibitors of the synthase and it is shown that the inhibition is specific and occurs not only ‘in vitro’ but also ‘ in vivo’ since the addition of the antibiotics to a culture leads to cell-free extracts with a partially inactive synthase.
82 citations
TL;DR: A simple hypothesis is offered which explains the biphasic pattern in which presumptive ganglion cells detach from the ventricular lining of the chick retina, and is discussed in relation to data in the literature.
Abstract: An examination of retinal structure in chick embryos, impregnated with the Golgi-Stensaas method between 2 and 6 days of incubation, discloses, on the one hand, a uniform typology of the proliferating ventricular cells, the pre- and postmitotic forms of which were tentatively identified; on the other hand, postmitotic neuroblasts are evidenced in the stages of differentiation previous to the growth of their neurites.
76 citations
TL;DR: In this paper, the results of the interpretation of the data, together with published surface wave and earthquake data, suggest a layered structure of the crust having the following features: the basement, in some areas covered by up to 4 km of sediments, has a P-velocity of 61 km s−1; a lowvelocity layer, between 7 and 11 km depth, seems to exist on the basis of both P and S interpretation of seismic data.
Abstract: Summary Quarry blasts recorded along three lines on the central Iberian Meseta are used in an attempt to interpret the crustal structure The results of the interpretation of the data, together with published surface wave and earthquake data, suggest a layered structure of the crust having the following features: the basement, in some areas covered by up to 4 km of sediments, has a P-velocity of 61 km s−1; a low-velocity layer, between 7 and 11 km depth, seems to exist on the basis of both P and S interpretation of seismic data; a thick middle crust of 12 km has a P-velocity of 64 km s−1 and overlies a lower crust with a mean P-velocity of 69 km s−1 and a possible slight negative gradient; the mean vp/vs ratio for the crust is about 175; the Moho is reached at about 31 km depth and consists of a transition zone at least 15 km thick The P-velocity of the upper mantle is close to 81 km s−1 and the S-velocity about 45 km s−1, which gives a vp/vs ratio of 18 for the uppermost mantle A tentative petrological interpretation of the velocities and composition of the layers is given
76 citations
TL;DR: In this article, the authors identified seven fine-grained sediment types from eight distinct depositional environments. And they proposed two depositional models for these sediments, the first emphasizes downslope transformations resulting in progressively reduced flow concentration during transport: from slump and debris flow, and the second model developed for conditions of well-developed water mass stratification, well laminated rather than uniform mud prevails as the end product of low concentration flows.
Abstract: Sediment in tectonically active, topographically restricted settings of the western Hellenic Arc, eastern Mediterranean, consists primarily of clayey silt and silty clay. Failure of metastable sediment temporarily stored on relatively steep slopes is triggered by earthquake tremors and eustatic oscillations. Redeposition of these materials by gravitative transport has resulted in markedly different lithofacies from site to site. Most piston cores include three Late Quaternary stratigraphic units that can be correlated with sections in other parts of the eastern Mediterranean; numerous radiocarbon-age determinations enhance the correlation.
Seven fine-grained sediment types are identified in cores from eight distinct depositional environments. Some muds are closely related to specific environments (slump and debris flow deposits on slope and high-relief environments), or to time (well laminated mud during the latest Pleistocene-mid-Holocene), or to both (uniform and faintly laminated muds restricted to trench basins). Turbiditic and hemipelagic muds are common throughout the study area. Mud distribution patterns correlate closely with calculated sedimentation rates.
We propose two depositional models for these sediments. The first emphasizes downslope transformations resulting in progressively reduced flow concentration during transport: from slump and debris flow–>turbidity current–>low density turbidity current or turbid layer mechanisms. The distal end-member deposits settling from low concentration flows are thick, rapidly emplaced, fine-grained uniform muds closely associated with faintly laminated muds. These were ponded in flat trench basin-plains. Planktonic and terrigenous fractions in the turbiditic, finely laminated and uniform muds record mixing of materials of gravitative and suspension origin during redeposition. This sequence prevails under conditions of minimal stratification of water masses, as characterized by the present Mediterranean.
In the second model developed for conditions of well-developed water mass stratification, well laminated rather than uniform mud prevails as the end product of low concentration flows. These very finely laminated and graded muds record particle-by-particle settling from detached turbid layers concentrated along density interfaces; they include material from turbid layers complemented by the normal ‘rain’ of pelagic material. Stratification barriers resulted in region-wide distribution of such deposits, in both slope and trench environments.
72 citations
TL;DR: More direct evidence for the proton-transport activity of the enzyme is presented by demonstrating an ATPinduced quenching of acridine dye fluorescence in proteoliposomes reconstituted with the purified enzyme.
68 citations
TL;DR: Tissue levels from severely hypothyroid thyroidectomized rats may contain higher concentrations of T4 and T3 than previously thought, and the idea that thyroid hormone is not essential for life, based on the assumption that thyroidECTomized animals survive without thyroid hormones, might have to be reevaluated.
Abstract: Female rats were killed 15 days, 2 months, and 4 months after surgical thyroidectomy that was followed by injection of 100 μCi 131I. The concentrations of T3 and T4 were measured in tissues (liver, kidney, brain, heart, and hindleg muscle) by specific RIAs. Results were compared to those found in intact rats. Thyroidectomy resulted in severe hypothyroidism by 2 and 4 months after the operation, as assessed by undetectable levels of T44 and T3 in unextracted plasma, high circulating TSH, hypothermia, stasis of body weight increase, and depletion of pituitary GH content. Concentrations of T44 and T3 in plasma, as determined after extraction and concentration, were very low, being less than 5% of the normal value by the earliest observation period (15 days). In contrast, although tissue concentrations and total organ contents also decreased after thyroidectomy, they were still clearly detectable 4 months after thyroidectomy. The rates of decrease of T4 and T3 concentrations in most tissues were markedly slow...
65 citations
TL;DR: Howlers discriminated very much in their performance of various activities in the vertical strata of trees, their use being apparently controlled mainly by the howlers' quadrupedal locomotion and by the necessity for protection against predators.
Abstract: The behaviour of the red howler monkey (Alouatta seniculus) in the Llanos of Venezuela was studied from May 1975 to May 1976. The average size of the social groups was 6.3±2.1 individuals. The groups were heterosexual, comprising individuals of all ages, with an average of 40% adult females, 26% adult males, 16% juveniles and 18% infants. The daily rhythm of activity for the performance of locomotion, feeding, snoozing and sleeping was ascertained for dry and rainy seasons. The density of the population in the whole area of study was 0.25 individuals per hectare of woodland, although a density of as high as 0.54 individuals per hectare was reached in some places. The use of space was established by means of locations, howls, fecal piles and scent-marking. Howlers discriminated very much in their performance of various activities in the vertical strata of trees, their use being apparently controlled mainly by the howlers' quadrupedal locomotion and by the necessity for protection against predators.
TL;DR: In this article, a series of melt-crystallized polyethylene (PE) samples with a varying number of chain defects have been investigated and it was shown that the elastic modulus and surface hardness of PE markedly decrease with increasing number of defects.
Abstract: The stress-strain diagrams of a series of melt-crystallized polyethylene samples with a varying number of chain defects have been investigated. The elastic modulus,E, and the surface hardness,MH, markedly decrease with increasing number of defects. The mechanical behaviour of the lamellar structure of PE modulated by a major exclusion of chain defects from the crystals is discussed in the light of Takayanagi's two-phase model. The data suggest thatE is very sensitive to the fraction of tight crystalline bridges between lamellae. The correlation found betweenE andMH emphasizes, in addition, the different and complementary role played by the amorphous layer in each mechanical test. In the former case one measures the elastic deformation of the layer reinforced by tie molecules. In the latter test the plastic deformation under compression of the lamellae sandwiched between noncrystalline layers is contemplated. In both cases the influence of the number of defects drastically affects the nature of the crystalline lamellae and surface layer and consequently substantially modifies both types of properties.
TL;DR: The dual inoculation of Rhizobium + Glomus more than doubled yield compared to an uninoculated control and RhizOBium meliloti was also effective when inoculated alone.
Abstract: Field inoculation of Medicago sativa with its symbiotic partners Rhizobium meliloti and the endomycorrhizal fungus Glomus mosseae was assayed under standard agricultural conditions in untreated arable phosphate-fixing soil. Glomus mosseae was successfully introduced and efficiently stimulated plant growth, N incorporation and P uptake. In contrast with a previous filed experiment, Rhizobium meliloti was also effective when inoculated alone. The dual inoculation of Rhizobium + Glomus more than doubled yield compared to an uninoculated control.
TL;DR: The results support the existence of an in vivo thioredoxin/fructose-1,6-bisphosphatase interaction, in accordance with the light-activation mechanism by the ferredoxin-thiOREDoxin system, which could be of physiological significance in the dark-light transition.
TL;DR: In this article, the fruit food of robins wintering in southern Spanish Mediterranean scrubland was investigated and the authors found that robins prefer the fruit in the scrubland environment.
Abstract: (1981). Fruit food of Robins wintering in southern Spanish Mediterranean scrubland. Bird Study: Vol. 28, No. 2, pp. 115-122.
TL;DR: In this paper, the symmetry basis vectors which represent in box form the Hamiltonian operator were used to simplify the resolution of the two-rotor equation of the acetone molecule.
Abstract: The group theory for nonrigid molecules is used for studying the internal dynamics of the two equivalent C3v rotor “bent” molecules. Special emphasis is given to the deduction of the symmetry basis vectors which represent in box form the Hamiltonian operator. It is shown that these basis vectors may be advantageously employed in order to simplify the resolution of the two-rotor equation. The procedure is applied to the acetone molecule. It is found that the lowest solutions are clustered into groups of four. The four lowest levels are related to vibrational states, the upper 64 to vibro–rotational states, in which the rotors are rotating in a restricted manner. Only few states show some cogwheel effect. Internal rotation contributions to the principal thermodynamic parameters of acetone are also computed.
TL;DR: Saccharomyces cerevisiae has important features that make it a less than ‘ideal’ facultative anaerobe and whether the present criteria by which facultatives anaerobes are defined are adequate.
TL;DR: A new orthonaphthoquinone diterpene has been isolated from Salvia aethiopis and given the trivial name aETHiopinone and the structure of this natural is described.
TL;DR: The IAA-oxidase system of olive tree ( Olea europea ) in the presence of its substrate, IAA, and cofactors, DCP and Mn 2, forms ethylene from 1-aminocyclopropane-l-carboxylic acid (ACC) bound as a Schiffs base to pyridoxal phosphate.
TL;DR: In this paper, Fischer and Kollmar have been extended to the MNDO SCF-MO method and used in an effort to ascertain the main factors which determine the greater basicity of imidazole and oxazole relative to pyrazole and isoxazole, respectively.
TL;DR: The axenic germination of Glomus mosseae spores was found to be sensitive to ethrel suggesting that at least part of the effect of ethrel on mycorrhization could come from its effect on fungal development.
Abstract: Ethrel, a compound which readily releases ethylene, depressed VA mycorrhiza formation inMedicago sativa andTriticum vulgare when it was either applied to the rooting medium or sprayed to the foliage. The axenic germination ofGlomus mosseae spores was found to be sensitive to ethrel suggesting that at least part of the effect of ethrel on mycorrhization could come from its effect on fungal development. The possible ecological significance of these findings is discussed.
TL;DR: In females only early prophase stages were observed, that are similar to those of the males, and the characteristics of this abnormal meiosis and its evolutionary and cytotaxonomic significance are discussed.
Abstract: The meiotic process was studied in fifty-three species belonging to the caraboid families Bembidiidae (48). Trechidae (3), Pogonidae (1), and Harpalidae (1). Males show achiasmatic meiosis patterns of the Callimantis type. In females only early prophase stages were observed, that are similar to those of the males. The characteristics of this abnormal meiosis and its evolutionary and cytotaxonomic significance are discussed.
TL;DR: In this article, the preparation and properties of complexes of the general formulae [Rh(TFB)(diolefin)]ClO4, [Rh (TFB)L2] ClO4 and [Rh[TFB]L2 ClO 4 are described.
TL;DR: The results obtained suggest that GA( 1) metabolites are preferentially compartmentalized in the vacuoles relative to GA(1), indicating that neither the leaf structure nor the cell wall is necessary for this metabolism.
Abstract: The metabolism and efflux of gibberellin A 1 (GA 1 ) taken up by leaves of cowpea ( Vigna sinensis cv. Blackeye pea No. 5), as well as the distribution of GA 1 metabolites in the protoplasts and vacuoles of cowpea and barley ( Hordeum vulgare L. cv. Numar), were studied. GA 1 is metabolized rapidly in cowpea leaf discs to products tentatively identified as gibberellin A 8 (GA 8 ) and gibberellin A 8 glucoside (GA 8 -glu). After labeling leaf discs with [ 3 H]GA 1 for 1 hour, the release of radioactivity from the leaf was followed. Over a 12-hour period, the level of radioisotope in the tissue declined to about 35% of the original, after which no further release was observed. At this time, almost all of the radioactivity remaining in the leaf was GA 8 -glu, while most of the radioactivity which had been released was unmetabolized GA 1 . Mesophyll protoplasts and vacuoles were isolated from cowpea and barley leaves previously fed [ 3 H]GA 1 . These protoplasts retain the ability to metabolize GA 1 , indicating that neither the leaf structure nor the cell wall is necessary for this metabolism. A higher proportion of GA 8 -glu was found in the vacuoles relative to the entire protoplasts. The results obtained suggest that GA 1 metabolites are preferentially compartmentalized in the vacuoles relative to GA 1 .
TL;DR: In this paper, the cracking of n -heptane has been studied at 400, 450, and 470 °C over a CrHNaY zeolite catalyst using a tubular packed-bed reactor.
TL;DR: On HNaY zeolites the fractions of acid sites which are active for cracking, isomerization and dehydrogenation of methylcyclohexane do not increase linearly with increasing degree of exchange as mentioned in this paper.
Abstract: On HNaY zeolites the fractions of acid sites which are active for cracking, isomerization and dehydrogenation of methylcyclohexane do not increase linearly with increasing degree of exchange. Isomerization and dehydrogenation seem to involve a similar activated complex, while cracking proceeds through a different one and requires stronger acid sites. Activation energies are independent of exchange degree.
TL;DR: The phase diagram for the system ZrO2-Er2O3 was redetermined as discussed by the authors, and three ordered phases were found: the first compound was present at 40 mol % Er2O 3 and corresponds to the ideal formula Er4Zr3O12 with rhombohedral symmetry (space group R¯3), is isostructural with UY6O12, and decomposes at about 1500° C into fluorite solid solution by an order-disorder process.
Abstract: The phase diagram for the system ZrO2-Er2O3 was redetermined. At high temperatures, the system is dominated by wide regions of solid solution based on ZrO2 and Er2O3 separated by a two-phase field which appears to extend to the solidus. The range of existence of these solid solution fields was determined using the precision lattice parameter method. A low-temperature (<1800° C) long-range ordering occurred between 20 and 90 mol % Er2O3, and three ordered phases were found: the first compound was present at 40 mol % Er2O3 and corresponds to the ideal formula Er4Zr3O12 with rhombohedral symmetry (space group R¯3), is isostructural with UY6O12, and decomposes at about 1500° C into fluorite solid solution by an order-disorder process; the second ordered phase is formed at about 55 mol % Er2O3, its formula is close to Er5Zr2O11.5, and it decomposes at about 1650° C into cubic solid solutions of the fluorite and C-type; the third compound is formed at 75 mol % Er2O3, its formula is Er6ZrO11, it has a wide homogeneity range, and it decomposes above 1700° C into a cubic solid solution of the C-type. Liquidus determination indicated the existence of a peritectic at 62 mol % Er2O3.
TL;DR: In this article, a linear relationship between molybdena loading, up to about 15 wt % MoO3, and equivalent moly bdena area was found, which suggests a high moly-bdenum dispersion on the alumina surface.