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  • Polymer and Materials Science  (31)
  • Physics  (5)
  • kiwifruit  (5)
  • Cardiac muscle  (3)
  • 1
    Electronic Resource
    Electronic Resource
    The effects of 2,3-butanedione monoxime on initial heat, tension, and aequorin light output of ferret papillary muscles (1990)
    Springer
    Pflügers Archiv 416 (1990), S. 219-221 
    Details
    ISSN: 1432-2013
    Keywords: Cardiac muscle ; butanedione monoxime ; heat production ; aequorin luminescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract At low concentrations (up to 5 mM) the compound 2,3-butanedione monoxime (BDM) was found to reduce twitch tension and initial heat production in isolated papillary muscles without significantly affecting the size of the intracellular Ca transient measured with aequorin luminescence. Higher concentrations of BDM caused further inhibition of twitch tension and heat production with a fall in the size of the Ca+ transient. The size of the aequorin transient was 50% of the control value at 15 mM BDM while twitch tension was negligible. These results suggest that BDM selectively inhibits Ca2+ activated force in cardiac muscle at low concentrations with additional effects on intracellular calcium at concentrations above 5 mM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00370248
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  • 2
    Electronic Resource
    Electronic Resource
    The effects of caffeine and Ca2+ on rigor tension in triton-treated rat ventricular trabeculae (1992)
    Springer
    Pflügers Archiv 421 (1992), S. 343-349 
    Details
    ISSN: 1432-2013
    Keywords: Cardiac muscle ; Rigor tension ; Ca2+ ; Caffeine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Ventricular trabeculae from rat heart were chemically skinned with Triton-X100, which disrupts all cellular membranes including the sarcoplasmic reticulum. Trabeculae developed a maintained rigor contracture when adenosine triphosphate was withdrawn from the bathing medium. In all preparations, the final level of rigor force developed in the presence of caffeine (10–40 mM) was greater than under control conditions. However, caffeine failed to increase rigor tension when applied after contracture had fully developed. The effect of caffeine on rigor was maximal at about 15 mM; concentrations greater or less than 15 mM were less effective. On average, caffeine decreased the time required to develop half-maximum rigor force. The caffeine-induced potentiation of rigor force occurred in the effective absence of Ca2+ (10−9 M), in solutions strongly Ca2+-buffered with [ethylenebis(oxonitrilo)]tetraaceticacid (10–50 mM). In all preparations, rigor force was found to be independent of [Ca2+] over the range 10−10 M to about 10−7 M. These results suggest that caffeine affects rigor force by a direct effect on the myofilaments via a mechanism that is independent of Ca2+.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00374222
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of anions on the potassium status and productivity of kiwifruit (Actinidia deliciosa) vines (1991)
    Springer
    Plant and soil 133 (1991), S. 209-218 
    Details
    ISSN: 1573-5036
    Keywords: Key words ; anions ; chloride ; flowers ; fruit yield ; kiwifruit ; potassium ; sulphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of K fertiliser (160 kg ha-1) applied with Cl- or SO4 2- as the accompanying anion on the K nutrition of kiwifruit (Actinidia deliciosa var. deliciosa) were assessed in a field experiment, using vines with varying degrees of K deficiency. Leaf K concentrations in spring were significantly higher for vines receiving KCl, compared to those receiving K2SO4. This effect did not interact significantly with the degree of K deficiency, and persisted for about 6 weeks. Subsequently there was no significant difference between the leaf K concentrations for the vines receiving KCl or K2SO4. Applying K as KCl increased the leaf Cl concentration, especially in spring, while applying K as K2SO4 had no significant effect on the leaf S concentration at that time. These results implied a greater requirement for organic acid anions for K+ uptake from K2SO4 than from KCl, and the importance of organic acid anions for K+ uptake from different sources of K fertiliser is discussed. This transient effect of the accompanying anion on leaf K status was associated with large effects on flowering, and fruit yields were about 28% higher for plants receiving KCl rather than K2SO4. The effects on growth and tissue nutrient composition of varying the concentrations of Cl-, NO3 -, SO4 2- and H2PO4 - around the roots of kiwifruit vines were examined in a solution culture experiment. For H2PO4 -, plant growth was very similar over a wide range of rates of addition. For the other anions, the range between deficiency and ‘toxicity’ was clearly delineated. For Cl- and NO3 -, toxicity was associated with high tissue concentrations of Cl and N, respectively, and was consistent with competition for uptake between Cl- and NO3 -. However, for SO4 2-, toxicity was associated with only a small increase in the tissue S concentration relative to that associated with maximum growth, and appeared to result more from effects on uptake of other anions and cations rather than from direct effects of high tissue S concentrations. It is concluded that the sensitivity of kiwifruit to the anion accompanying K+ in fertiliser may be related to the unusually high requirement for Cl previously reported for this species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00009193
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  • 4
    Electronic Resource
    Electronic Resource
    Fate of 15N-labelled nitrogen fertilizer applied to kiwifruit (Actinidia deliciosa) vines (1992)
    Springer
    Plant and soil 147 (1992), S. 49-57 
    Details
    ISSN: 1573-5036
    Keywords: ammonium ; field ; kiwifruit ; 15N ; nitrogen fertilizer ; recovery ; soil nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The fate of 15N-labelled ammonium fertilizer applied once to six-year-old field-grown kiwifruit (Actinidia deliciosa ‘Hayward’) vines was measured over three years. The three main treatments were nitrogen (N) applied singularly at 100 or 200 kg N ha−1 in early spring (two weeks before bud burst) or split with 100 kg N ha−1 (unlabelled) in early spring and 100 kg N ha−1 (15N-labelled) ten weeks later. All N treatments were applied to vines with a history of either 50 or 200 kg N ha−1 yr−1. For three years after 15n application, components of the vines and soil (0–600 mm depth) were sampled at harvest in late autumn and the N and 15N contents determined. By the first harvest, all plant uptake of 15N had occurred and this represented 48–53% of the 15N applied. There was no significant effect of current N fertilizer treatment or of N history on 15N recovery by vines. Removal of 15N in harvested fruit was small at 5–6% in the first year and 8% over 3 years. After 2–3 years, most plant 15N occurred in the roots and this component declined only slowly over time. In contrast, there was a large temporal decline in 15N in above-ground plant components due to the annual ‘removal’ in leaf fall and pruning. An associated experiment showed that when 15N-labelled prunings and leaves were mulched and returned to the soil, only about 9% was recovered by plants within 2 years. Almost all remaining mulched material had been immobilised into the soil organic N. In all treatments, about 20% of the added 15N remained in soil at the first harvest. This was almost entirely in organic fractions (〈0.4% in inorganic N) and mostly in the surface 150-mm layer. The 15N content in soil changed little over time (from 20 to 17% between the first and third harvests respectively) and indicated that most of the N had been immobilised into stable humus forms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00009370
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  • 5
    Electronic Resource
    Electronic Resource
    Fate of 15N-labelled nitrogen fertilizer applied to kiwifruit (Actinidia deliciosa) vines (1992)
    Springer
    Plant and soil 147 (1992), S. 59-68 
    Details
    ISSN: 1573-5036
    Keywords: kiwifruit ; 15N ; plant uptake ; remobilisation ; temporal changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Temporal changes in the nitrogen (N) and 15N content of various components of six-year-old kiwifruit (Actinidia deliciosa ‘Hayward’) vines which had received 15N-labelled ammonium fertilizer were measured. The fertilizer was applied singularly at 100 or 200 kg N ha−1 in early spring (two weeks before bud burst) or split with 100 kg N ha−1 (unlabelled) in early spring and 100 kg N ha−1 (15N-labelled) ten weeks later. All treatments were applied to vines with a history of either 50 or 200 kg N ha−1 yr−1. The N concentration of leaf and fruit tissue was generally lower in the 100 kg N ha−1 treatment than in the 200 kg N ha−1 treatments and this effect was greater than that of N fertilizer history. During the first 8 weeks after bud burst there was a rapid accumulation of N in leaves (ca. 80 kg N ha−1). Analysis of xylem sap at 4 weeks after bud burst revealed that about 60% of the N utilised for new growth was from remobilisation of N stored within the vines and about 40% from soil and fertilizer N. This was unaffected by rate of N application. Plant uptake of added 15N was rapid and almost complete within 10 weeks of application in either early spring or early summer. Initially, most 15N was present in the leaf and root components but these subsequently declined due to translocation into other components of the vine. The decline in leaf 15N coincided with an equivalent accumulation of 15N in the fruit. The 15N enrichment of the ‘annual’ components (leaves, fruit and current-season's shoots) was about twice that of the structural components (one-year-old shoots, cordon, stem and structural roots) during the first year after application. By the third year the 15N concentration of the annual components had declined to similar levels to that of the structural components. These changes were used to estimate the annual throughput of N from soil in vines which received no N fertilizer in years 2 and 3 at 50% of total above-ground N and only 7% in roots. This was equivalent to about 120 kg N ha−1 yr−1. Where fertilizer N (200 kg ha−1) was applied in year 2 the annual throughput of N from soil and fertilizer was about 170 kg N ha−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00009371
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  • 6
    Electronic Resource
    Electronic Resource
    Magnesium deficiency of kiwifruit (Actinidia deliciosa) (1987)
    Springer
    Plant and soil 104 (1987), S. 281-289 
    Details
    ISSN: 1573-5036
    Keywords: Actinidia deliciosa ; foliar analysis ; kiwifruit ; magnesium deficiency ; mineral nutrition ; postharvest fruit storage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Magnesium deficiency was associated with large yield reductions in a five-year-old commercial kiwifruit (Actinidia deliciosa) orchard. The effect on yield resulted primarily from a reduction in fruit numbers, there being no difference in mean fruit weight between fruit harvested from affected and unaffected vines. Magnesium deficiency had no deleterious effect on postharvest storage characteristics of fruit stored at 0.5–1°C for 18 weeks; fruit from deficient vines were firmer but had slightly lower soluble solids than fruit from control vines. Although deficiency symptoms were first observed on the basal leaves of the non-fruiting shoots mid season, indications of the impending deficiency could be established very early in the season using foliar analysis. Magnesium concentrations in youngest fully expanded leaves (YFEL) on the affected vines were less than 2.0 g kg−1 DM four weeks after budbreak and remained below this value for the rest of the season; concentrations in YFEL on unaffected vines did not decrease below this value and gradually increased after fruitset to 4.5 g kg−1 DM at harvest. To avert potential production losses, it is suggested that soluble magnesium fertilizers (containing at least 200 kg ha−1 Mg) should be broadcast early in the season if foliar magnesium concentrations less than 2.0 gkg−1 DM are measured four–six weeks after budbreak.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02372543
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  • 7
    Electronic Resource
    Electronic Resource
    The effects of lactic acid production on contraction and intracellular pH during hypoxia in cardiac muscle (1993)
    Springer
    Basic research in cardiology 88 (1993), S. 421-429 
    Details
    ISSN: 1435-1803
    Keywords: Cardiac muscle ; hypoxia ; pH ; lactate ; ischaemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary During hypoxia cardiac contraction declines and there is an intracellular acidosis. We find that, if this acidosis is abolished by decreasing pCO2 there is little restoration of force. Therefore the acidosis is not the major cause of the decline of force. The acidosis may partly result from the generation of lactic acid. No acidosis, is however, seen in isolated cardiac cells. Furthermore a theoretical model shows that lactic acid production would be expected to produce a transient acidosis. We suggest that the observed maintained acidosis may be a consequence of extracellular lactic acid accumulation affecting intracellular pH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00795409
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  • 8
    Electronic Resource
    Electronic Resource
    The development and effects of nitrogen deficiency in field-grown kiwifruit (Actinidia deliciosa) vines (1990)
    Springer
    Plant and soil 129 (1990), S. 173-182 
    Details
    ISSN: 1573-5036
    Keywords: chloride ; kiwifruit ; leaf nitrogen concentration ; nitrate ; plant density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The development and effects of nitrogen (N) deficiency in kiwifruit (Actinidia deliciosa ‘Hayward’) vines planted at three densities (25.0, 12.5 and 8.33 m2 vine−1) were examined in a long term (1982 to 1989) field experiment in which N was applied at rates from 0 to 200 kg N ha−1 year−1. The rate of applied N significantly affected leaf N concentrations every year from 1985 onwards, and the average leaf N concentrations declined throughout the experiment. Fruit N concentrations varied significantly with the level of applied N as early as 1986. The average fruit N concentrations varied strongly between years, and were inversely proportional to the fruit number (per m2), indicating that, after fruit set, growth of individual fruit was relatively insensitive to the vine N status. Effects of N supply on fruit yields resulted mostly from changes in fruit number (per m2). For vines planted at the high density, fruit yields responded significantly to the level of applied N each season from 1986 onwards. In any year, maximum fruit yields for vines planted at the high density were associated with leaf N concentrations (20 weeks after bud burst) of at least 1.8 mmol g−1. For vines planted at low density, significant yield responses to the level of applied N were not recorded until 1988, and maximum yields in that year were associated with leaf N concentrations of at least 1.4 mmol g−1. The delayed expression of effects of N deficiency on fruit yields for vines planted at low density appeared to follow a shift in partitioning of resources in favour of fruit growth. This shift in partitioning did not appear to be sustainable, and by 1989 the fruit yield response to applied N continued to the highest N level tested. In that year, the leaf N concentration associated with maximum yield was 1.8 mmol g−1, the same as that recorded throughout the experiment for the vines planted at high density. In the last two seasons of the experiment, leaf necrosis developed extensively on vines receiving less than the highest rate of N. This necrosis appeared to be premature senescence resulting from N deficiency. Leaf chloride (Cl) concentrations increased significantly with increasing severity of N deficiency, but were never more than those associated with Cl toxicity. While N supply significantly affected fruit firmness immediately post-harvest, there were no significant effects on fruit firmness after 12–20 weeks storage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00032410
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  • 9
    Electronic Resource
    Electronic Resource
    Crystal and molecular structure of isoleucinomycin, cyclo[-(D-Ile-Lac-Ile-D-Hyi)3-](C60H102N6O18) (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1517-1534 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of a synthetic analog of valinomycin, cyclo[-(D-Ile-Lac-Ile-D-Hyi)3-] (C60H102N6O18), has been determined by x-ray diffraction procedures. The crystals are orthorhombic, space group P212121, with cell parameters a = 11.516, b = 15.705, c = 39.310 Å, and Z = 4. The atomic coordinates for the C, N, O atoms were refined in the anisotropic thermal motion approximation and for the H atoms in the isotropic approximation. Values of standard (R) and weighted (Rw) reliability factors after refinement are 0.073 and 0.056, respectively. The structure is completely asymmetric. The cyclic molecular backbone is stabilized by six intramolecular hydrogen bonds N—H…O=C, five bonds being of the 4→1 type and one being of the 5→1 type. The side chains are located on the molecular periphery. The conformational state of isoleucinomycin in the crystal is intermediate between the corresponding crystalline states of valinomycin and meso-valinomycin. The observed conformation suggests that complexation could proceed via entry of the ion at the face possessing the L-Lac residues, the less crowded face.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190808
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  • 10
    Electronic Resource
    Electronic Resource
    Molecular structure of cyclo[-(D-Val-L-Hyi-L-Val-D-Hyi)2-] revealed by X-ray analysis (1992)
    New York : Wiley-Blackwell
    Biopolymers 32 (1992), S. 757-764 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of a synthetic analogue of valinomycin, cyclo [-(D-Val-L-Hyi-L-Val-D-Hyi)2-] (octa-meso-valinomycin) (I) (C40H68N4O12 · 1.5 · C4H8O2, Mr = 937.01 + 88.10), has been determined. Crystals grown from dioxane are monoclinic, space group P21/a, with cell parameters a = 21.487(8), b = 16.836(5), c = 16.089(4) Å, β = 111.70(4), and Z = 4. The atomic coordinates for nonhydrogen atoms were refined in the anisotropic thermal motion approximation. H atom positions were included in the structure factor calculations at their geometrically expected positions. Values of the standard and weighted R factors after refinement are 0.11 and 0.13, respectively. The conformation of the depsipeptide crystallized from dioxane is different from that crystallized from chloroform (II). The molecule adopts a rectangular shape with two type IV β-turns containing a hydrogen bond and possesses pseudorotational symmetry. The side chains are located on the molecular periphery. The orientation of the carbonyl groups of the molecule is not conducive for efficient metal-ion coordination and in the observed conformation cannot behave as an ionophore.In the crystal the molecules form infinite chains parallel to the c axis, and are stabilized by two intermolecular hydrogen bonds that are shorter and have better geometry than the intramolecular hydrogen bonds.A φ/Ψ plot for dodecadepsipeptides with a (DLLD)3 sequence has well-defined areas for Val and Hyi residues only in cases when the crystals have been grown from nonpolar or medium-polar solvents. The Φ/Ψ plot for octadepsipeptides crystallized from chloroform (II) shows this behavior also. There also is a correlation between the polarity of the solvent from which crystals of octa-meso-valinomycin or valinomycin analogues with a (DLLD) sequence of configuration have been grown and the number of the intramolecular hydrogen bonds that are formed. The more polar the solvent the fewer the number of intramolecular hydrogen bonds.Empirical energy calculations on octa-meso-valinomycin indicate that for isolated molecules, the energy of the bracelet form (II) is 4.7 kcal/mole lower than that of the rectangular form (I).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360320705
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