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  • 11
    Electronic Resource
    Electronic Resource
    Two components of extracellularly-recorded photoreceptor potentials in the cephalopod retina: Differential effects of Na+, K+ and Ca2+ (1978)
    Springer
    European biophysics journal 4 (1978), S. 263-300 
    Details
    ISSN: 1432-1017
    Keywords: Cephalopod ; Retina ; Photoreceptor ; Potentials ; Cations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The ERG of the isolated, superfused half-eye of the cephalopod Sepiola atlantica, evoked by a brief (10 Μs) light flash, has been studied by recording intraretinal potentials with glass microelectrodes. The intensity-response characteristics of the potentials recorded at an electrode fixed at the surface (V s ) can be fitted by a simple equation derived from an equivalent circuit model based on a sodium conductance increase mechanism. Raising the external potassium level reduces the maximal response (δV m ), but does not alter the half-saturation intensity value (I 0). Reducing external sodium does not affect (δV m ), but increases I 0. Reducing external calcium also does not affect (δV m ), but decreases I 0. These effects are adequately described by the model if it is also assumed (a) that changing the external sodium does not significantly alter the transmembrane sodium gradient, and (b) that sodium and calcium ions compete for the sensitivity control mechanism. Differential-depth recording between the fixed electrode at the surface and another electrode that could be moved into the retina revealed that the two component appearance of the transretinal ERG arose from the superposition of two vitreal-negative waveforms. An initial “fast” component was mainly recorded in the photoreceptive distal segments while a “slow” component was prominent in the more proximal regions of the retina. Perfusion with high K+ salines resulted in a decrease in the amplitudes of both fast and slow components of the response whereas reducing external Na+ reduced the amplitude of the fast component at all light intensities but reduced the amplitude of the slow component only at low intensities. The amplitudes of both the fast and slow components increased on reducing external calcium, but the rate of rise and fall of the fast component was independent of external calcium. The rate of rise of the slow component was also independent of the external Ca2+ level but a minimum in the recovery time (t F ) was shifted to a lower intensity value at lower calcium concentrations. The shift of the minimum was to a higher intensity value with lowered sodium perfusing solutions. On the basis of the differential sensitivity of the two components to ion changes, as well as stimulus intensity and intraretinal distribution of the components, it is suggested that they reflect two distinct processes in the light-evoked potential of the photoreceptor cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00537612
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  • 12
    Electronic Resource
    Electronic Resource
    Ultrastructural effect of penicillin and cycloheximide onChlamydia trachomatis strain HAR-13 (1982)
    Springer
    Medical microbiology and immunology 171 (1982), S. 151-159 
    Details
    ISSN: 1432-1831
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of cycloheximide and penicillin on the ultrastructural morphology ofC. trachomatis strain HAR-13 was examined by electron microscopy. HAR-13 infected McCoy cells were either treated with cycloheximide (1Μg/ml) or cycloheximide (1Μg/ml) plus penicillin G (100 U/ml). The studies revealed that cycloheximide alone induced no morphological alterations into the ultrastructure of HAR-13. Both HAR-13 developmental forms, the elementary body and reticulate body, were present inside the treated McCoy cells. The elementary bodies contained the central dense nucleoid and were about 0.3Μm in diameter, while the reticulate bodies were of typical gram negative bacterial morphology and were from 0.5–1.0Μm in diameter. Cycloheximide in combined treatment with penicillin produced giant, swollen reticulate bodies that were 2–4Μm in diameter and in some cases vacuolated. Elementary bodies were noticeably absent. These results indicate that cycloheximide does not alter the morphology of HAR-13. This system is a useful model for studying the ultrastructural morphology ofC. trachomatis strain HAR-13.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02123623
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  • 13
    Electronic Resource
    Electronic Resource
    Complement dependent in vitro neutralization of Chlamydia trachomatis by a subspecies-specific monoclonal antibody (1987)
    Springer
    Medical microbiology and immunology 176 (1987), S. 225-228 
    Details
    ISSN: 1432-1831
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Three murine monoclonal antibodies which combined specifically with Chlamydia trachomatis strain HAR-13 (Serotype A) were characterized. All antibodies cross-reacted with subspecies-specific epitopes in previously undescribed patterns. One of the antibodies showed a complement-dependent partial neutralization of strain HAR-13 in vitro, whereas the remaining two antibodies did not neutralize under any experimental conditions tested. The significance of subspecies-specific antibodies in neutralizing chlamydial infectivity in vivo remains to be determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196690
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  • 14
    Electronic Resource
    Electronic Resource
    Growth and nutrient uptake of sorghum cultivated with vesicular-arbuscular mycorrhiza isolates at varying pH (1994)
    Springer
    Mycorrhiza 4 (1994), S. 185-191 
    Details
    ISSN: 1432-1890
    Keywords: Key words: Dry matter yields – Sand culture – Shoot concentrations of P, K, Ca, Mg, S, Mn, Fe, Cu, and Zn –Sorghum bicolor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. This study was conducted to determine the effects of different pH regimes on root colonization with four vesicular-arbuscular mycorrhiza (VAM) isolates, and VAM effects on host plant growth and nutrient uptake. Sorghum [Sorghum bicolor (L.) Moench] was grown at pH 4.0, 5.0, 6.0 and 7.0 (±0.1) in hydroponic sand culture with the VAM isolates Glomus etunicatum UT316 (isolate E), G. intraradices UT143 (isolate I), G. intraradices UT126 (isolate B), and an unknown Glomus isolate with no INVAM number (isolate A). Colonization of roots with the different VAM isolates varied differentially with pH. As pH increased, root colonization increased with isolates B and E, remained unchanged with isolate I, and was low at pH 4.0 and high at pH 5.0, 6.0, and 7.0 with isolate A. Isolates E and I were more effective than isolates A and B in promoting plant growth irrespective of pH. Root colonization with VAM appeared to be independent of dry matter yields or dry matter yield responsiveness (dry matter produced by VAM compared to nonmycorrhizal plants). Dry matter yield responsiveness values were higher in plants whose roots were colonized with isolates E and I than with isolates A and B. Shoot P concentrations were lower in plants colonized with isolates E and I than with isolates A and B or nonmycorrhizal plants. This was probably due to the dilution effect of the higher dry matter yields. Neither the VAM isolate nor pH had an effect on shoot Ca, Mg, Zn, Cu, and Mn concentrations, while the VAM isolate affected not only P but also S, K, and Fe concentrations. The pH×VAM interaction was significant for shoot K, Mg, and Cu concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005720050019
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  • 15
    Electronic Resource
    Electronic Resource
    Growth and nutrient uptake of sorghum cultivated with vesicular-arbuscular mycorrhiza isolates at varying pH (1994)
    Springer
    Mycorrhiza 4 (1994), S. 185-191 
    Details
    ISSN: 1432-1890
    Keywords: Dry matter yields ; Sand culture ; Shoot concentrations of P, K, Ca, Mg, S, Mn, Fe, Cu, and Zn ; Sorghum bicolor ; Sorghum bicolor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study was conducted to determine the effects of different pH regimes on root colonization with four vesicular-arbuscular mycorrhiza (VAM) isolates, and VAM effects on host plant growth and nutrient uptake. Sorghum [Sorghum bicolor (L.) Moench] was grown at pH 4.0, 5.0, 6.0 and 7.0 (±0.1) in hydroponic sand culture with the VAM isolates Glomus etunicatum UT316 (isolate E), G. intraradices UT143 (isolate I), G. intraradices UT126 (isolate B), and an unknown Glomus isolate with no INVAM number (isolate A). Colonization of roots with the different VAM isolates varied differentially with pH. As pH increased, root colonization increased with isolates B and E, remained unchanged with isolate I, and was low at pH 4.0 and high at pH 5.0, 6.0, and 7.0 with isolate A. Isolates E and I were more effective than isolates A and B in promoting plant growth irrespective of pH. Root colonization with VAM appeared to be independent of dry matter yields or dry matter yield responsiveness (dry matter produced by VAM compared to nonmycorrhizal plants). Dry matter yield responsiveness values were higher in plants whose roots were colonized with isolates E and I than with isolates A and B. Shoot P concentrations were lower in plants colonized with isolates E and I than with isolates A and B or nonmycorrhizal plants. This was probably due to the dilution effect of the higher dry matter yields. Neither the VAM isolate nor pH had an effect on shoot Ca, Mg, Zn, Cu, and Mn concentrations, while the VAM isolate affected not only P but also S, K, and Fe concentrations. The pH x VAM interaction was significant for shoot K, Mg, and Cu concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00206778
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  • 16
    Electronic Resource
    Electronic Resource
    Voltage-Sensitive Dye Mapping of Activation and Conduction in Adult Mouse Hearts (2000)
    Springer
    Annals of biomedical engineering 28 (2000), S. 958-967 
    Details
    ISSN: 1573-9686
    Keywords: Mouse heart ; Electrocardiogram ; Voltage–sensitive dye ; Anisotropic conduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract A custom-made apparatus based on a charge-coupled-device camera has been used to monitor changes in fluorescence from Langendorff-perfused adult mouse hearts stained with a voltage-sensitive dye, di-4-ANEPPS. With this approach it is possible to monitor activation of the ventricles at high temporal (375 μs/frame) and spatial resolution 72 × 78pixels,100 ×100 μm/pixel. In sinus rhythm, activation occurred with a complicated breakthrough pattern on both ventricles, and a total activation time of 3.51 ± 0.16ms (32 °C). A stimulus applied near the apex of the left ventricle resulted in a single activation wave front with a total activation time of 8.18 ± 0.25 ms. Pacing from a site near the middle of the left ventricular epicardial surface revealed anisotropic conduction, indicating that conduction occurs preferentially in the direction of the predominant fiber orientation. The total activation time in this configuration was 5.44 ± 0.24 ms. The difference in total activation time between sinus rhythm and epicardial stimulation suggests an important role for transmural conduction (the Purkinje system) in the mouse heart. These findings provide much of the necessary background needed for studying conduction abnormalities in genetically altered mice and suggest that the comparison of sinus rhythm and epicardial pacing can be used to reveal transmural conduction abnormalities. © 2000 Biomedical Engineering Society. PAC00: 8719Nn, 8719Hh, 8716Uv, 8764Ni
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1114/1.1308501
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  • 17
    Electronic Resource
    Electronic Resource
    Effects of soil temperature on root and shoot growth traits and iron deficiency chlorosis in sorghum genotypes grown on a low iron calcareous soil (1991)
    Springer
    Plant and soil 130 (1991), S. 97-103 
    Details
    ISSN: 1573-5036
    Keywords: chlorosis severity ; dry matter yields ; growth chamber ; leaf area ; root length ; shoot/root ratio ; Sorghum bicolor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Iron deficiency chlorosis (FeDC) is a common disorder for sorghum [Sorghum bicolor (L.) Moench] grown on alkaline calcareous soils. Four sorghum genotypes were grown in growth chambers on a low Fe (1.3 μg/g DTPA-extractable), alkaline (pH 8.0), calcareous (3.87% CaCO3 equivalent) Aridic Haplustoll to determine effects of different soil temperatures (12, 17, 22 and 27°C at a constant 27°C air temperature) on various root and shoot growth traits and development of FeDC. As soil temperature increased, leaf chlorosis became more severe, and shoot and root dry weights, root lengths, and leaf areas increased markedly. Shoot/root ratios, shoot weight/root length, leaf area/shoot weight and leaf area/root weight and root length also increased while root length/root weight decreased as soil temperature increased. Severe FeDC developed in all genotypes even though genotypes had previously shown different degrees of resistance to FeDC. Genotypes differed in most growth traits, especially dry matter yields, root lengths, and leaf areas, but most traits did not appear to be related to genotype resistance to FeDC. The most FeDC resistant genotype had the slowest growth rate and this may be a mechanism for its greater resistance to FeDC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00011862
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  • 18
    Electronic Resource
    Electronic Resource
    Calcium sulfate or coal combustion by-product spread on the soil surface to reduce evaporation, mitigate subsoil acidity and improve plant growth (1996)
    Springer
    Plant and soil 182 (1996), S. 209-219 
    Details
    ISSN: 1573-5036
    Keywords: aluminium toxicity ; evaporation retardation ; fly ash, gypsum ; soil acidity ; Sorghum bicolor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Removal of sulfur dioxide from flue gas produced by coal-burning power plants has increased the availability of by-products that may be useful as soil amendments for agriculture. We studied the effects of surface layers (caps) of fluidized bed combustion residue-fly ash mixture (FBCR-FA) or calcium sulfate on reduction of evaporative water losses and improvements in subsurface acid soil chemical characteristics. Caps 3.8 cm thick of porous FBCR-FA, hydrated commercial calcium sulfate (CCS), or soil (check) were placed on columns of coarse-loamy, mixed, mesic Umbric Dystrochrept soil of pH 4.2. After the addition of 40 cm of water during a 16-week period, mean daily water loss from the column with the FBCR-FA cap was 0.51 mm compared to 0.98 mm in the check. Mean increase in soil exchangeable Ca in the 5- to 40-cm depth for the CCS treatment was 0.83 cmolc kg−1 and mean pH (H2O) increase was 0.21 units. Mean KCl-extractable Al decreased from 6.08 to 5.52 cmolc kg−1. Roots of sudangrass (Sorghum bicolor (L.) Moench) planted in the columns after removal of the caps reached 2 cm depth in the control, 18 cm in the FBCR-FA and 38 cm in the CCS treated columns after 47 days of growth. The gypsum cap was effective in improving deep rooting in acid soils and the FBCR-FA cap reduced evaporative water losses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029052
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  • 19
    Electronic Resource
    Electronic Resource
    Internal root control of iron uptake and utilization in maize genotypes (1974)
    Springer
    Plant and soil 40 (1974), S. 669-677 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Studies were conducted to determine whether Fe uptake and transport in maize (Zea mays L.) is controlled inside or outside the root. Two maize genotypes exhibiting wide differences in Fe uptake and utilization were used. They were the Fe-efficient genotype WF9 and the Fe-inefficient genotype ys1/ys1. Iron-stressed WF9 produced higher amounts of H-ions and ‘reductant’ in nutrient solutions and reduced more Fe at the root surface than ys1/ys1. These properties were measured outside the root and they were associated with increased Fe uptake by WF9. When WF9 and ys1/ys1 were grown together in the same container, these properties did not benefit Fe uptake and utilization in ys1/ys1. Thus, we conclude, Fe-efficiency in WF9 and ys1/ys1 is controlled inside the root. re]19731029
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010522
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  • 20
    Electronic Resource
    Electronic Resource
    Effect of aluminum on growth and mineral elements of al-tolerant and Al-intolerant corn (1977)
    Springer
    Plant and soil 47 (1977), S. 653-662 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Growth and P, K, Ca, Mg, Mn, Zn, Fe, and Cu concentrations and contents were determined in Al-tolerant and Al-intolerant corn (Zea mays L.) inbreds when grown at various levels of Al. B57 was more tolerant to Al than was Oh40B. Relatively low Al levels (up to 5 mg/l) enhanced B57 growth but inhibited Oh40B growth. With few exceptions, Oh40B root and leaf concentrations of the elements decreased with added Al. The decreases in element concentrations were not as large for B57 as they were for Oh40B. The Mg concentrations and contents decreased more than the other elements in all inbreds with added Al. Root Mg decreased more than leaf Mg. Total uptake of some elements were higher at low Al than with no Al. Inasmuch as Mg has a pronounced effect on root growth, low Mg may be an important response in plants sensitive to Al.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00011034
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