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  • 1
    Electronic Resource
    Electronic Resource
    Properties of Electrolytic Solutions. XXV. The Conductance of Choline and Related Picrates in Ethylene Chloride at 25° (1947)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 69 (1947), S. 528-530 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja01195a018
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  • 2
    Electronic Resource
    Electronic Resource
    Chlamydia trachomatis type III secretion: evidence for a functional apparatus during early-cycle development (2003)
    Oxford, UK : Blackwell Publishing Ltd.
    Molecular microbiology 48 (2003), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The obligate intracellular bacterium Chlamydia trachomatis occupies a parasitophorous vacuole termed an inclusion. During its intracellular developmental cycle, C. trachomatis maintains this intracellular niche, presumably by expressing a type III secretion system, which deploys a set of host cell-interactive proteins including inclusion membrane-localized proteins termed Incs. Some Incs are expressed and secreted by 2 h (early cycle) after infection, whereas the expression of type III-specific genes is not detectable until 6–12 h (mid-cycle). To resolve this paradox, we investigated the presence of a type III apparatus on elementary bodies (EBs) that might function early in infection. We demonstrate the existence of the type III secretory apparatus by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) and immunoblot analyses of purified EB extracts. Immunoblots using polyclonal antibodies specific for the core apparatus component CdsJ identified this protein in both EB and reticulate body (RB) extracts. Furthermore, CdsJ-specific signals were detected by immunoblot of whole infected-culture extracts and by indirect immunofluorescence of infected monolayers at times before the detection of cdsJ-specific message. Finally, expression of IncC, expressed by 2 h after infection during C. trachomatis infections, in Yersinia pseudotuberculosis resulted in its secretion via the Yersinia type III apparatus. Based on these data, we propose a model in which type III secretion pores are present on EBs and mediate secretion of early Incs and possible additional effectors. Mid-cycle expression of type III genes would then replenish secretion apparatus on vegetative RBs and serve as a source of secretion pores for subsequently formed EBs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03462.x
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  • 3
    Electronic Resource
    Electronic Resource
    Process studies in aPinus radiata-pasture agroforestry system in a subhumid temperature environment. I. Water use and light interception in the third year (1995)
    Springer
    Agroforestry systems 32 (1995), S. 163-183 
    Details
    ISSN: 1572-9680
    Keywords: water balance ; Pinus radiata ; Lolium perene ; Medicago sativa ; Trifolium spp ; rainfall interception ; competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In this study we determined soil moisture storage, evapotranspiration (ET) and light interception in an agroforestry trial consisting of pine trees grown over (1) control (bare ground), (2) ryegrass/clovers (Lolium perene/Trifolium spp.), (3) lucerne (Medicago sativa), and (4) ryegrass only during the third growing season between 1992 and 1993. The results show that: 1. In the period when rainfall was frequent and exceeded the evaporative demand (Epot), ET and depletion of soil moisture were not affected by the ground cover treatments. During summer when rainfall was less frequent, but with moisture readily available in the soil profile, ET was associated with plant canopy, and was significantly higher for the pasture ground covers than for the control. Therefore, the more rapid growth by lucerne caused higher ET in this ground cover than in the ryegrass/clovers ground cover in which the pasture was slow growing. At the end of the study period, total ET was in the following order: lucerne (757 mm) 〉 ryegrass/clovers (729 mm) 〉 Control (618 mm). 2. ET was dominated by pasture transpiration (Ep) during most of the growing season, but by tree transpiration (Et) in winter when large parts of the pasture canopy was shaded. Ep was always at least 16% higher for lucerne than for ryegrass/clovers species as a result of a greater radiation intercepted by the former. 3. Fraction of incoming radiation intercepted by the tree crowns was in the following order: control 〉 ryegrass 〉 ryegrass/clovers 〉 lucerne. At the end of the one-year period, fraction of intercepted radiation was 140% greater for control than for lucerne ground cover. 4. The control produced the largest tree crowns, which were almost twice the tree crowns in the lucerne ground cover which produced the smallest trees. Accordingly, the trees in the control intercepted more radiation and rainfall, with the former being lost to evaporation, than the trees in the pasture. 5. The fractions of radiation intercepted and ET accounted for by the trees and pastures were associated with the proportion of the plot area they occupied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00711571
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  • 4
    Electronic Resource
    Electronic Resource
    Process studies in aPinus radiata-pasture agroforestry system in a subhumid temperature environment. II. Analysis of dry matter yields in the third year (1995)
    Springer
    Agroforestry systems 32 (1995), S. 185-204 
    Details
    ISSN: 1572-9680
    Keywords: competition ; water use efficiency ; radiation use efficiency ; land equivalent ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In this paper we analyzed the dry matter yields (DM) produced in an agroforestry trial consisting of pine trees grown over (1) Control (bare ground), (2) ryegrass/clovers (Lolium perene/Trifolium spp.), (3) ryegrass only, and (4) lucerne (Medicago sativa) during the third growing season between 1992 and 1993. In addition these pastures were grown alone in separate plots in the open. The results show that: 1. Pasture yields during the one-year period in the agroforestry plots were little affected by the presence of trees although there were seasonal trends: yields were generally unaffected or increased in summer, but reduced in spring as a result of tree shade. Total pasture yield during the one-year period was in the following order: lucerne 〉 ryegrass/clovers 〉 ryegrass. This trend was the exact opposite of that shown by the above-ground tree weight which was reduced in the pasture ground covers by between 16 and 52%. The reduction in tree weights was associated with reduced soil moisture availability arising from competition with the pasture species. Thus the relationship between the yields of trees and pasture species in the agroforestry plots was reciprocal. 2. The combined DM for both the trees and pastures in the agroforestry plots during the one-year period was in the following order: lucerne (20 t ha−1) 〉 ryegrass/clovers (16 t) 〉 ryegrass (11 t) 〉 control (6 t) which was consistent with the total water used and photosynthetically active radiation (PAR) intercepted. The trees accounted for 55, 44, 34 and 24% of water used respectively in control, ryegrass, ryegras/cclovers and lucerne ground covers. The balance was largely accounted for by pasture transpiration, except in the control where soil evaporation was significant. The fraction of intercepted PAR accounted for by the trees followed a similar trend to that of the water used. 3. The crop coefficient for water use efficiency (k) (Pa) was 2.3 for radiata pine, 3.6 for ryegrass/clovers, 2.8 for ryegrass and 4.8 for lucerne. The DM produced per unit of water used (kg mm−1 ha−1) during the one-year period was 24.5 for radiata pine, 41.1 for lucerne, 30.0 for ryegrass/clovers and 23.1 for ryegrass. Radiation use efficiency (g DM MJ−1 m−2) was 1.33 for pine, 1.83 for ryegrass/clovers, 1.49 for ryegrass and 2.34 for lucerne. 4. The land equivalent ratio (LER), i.e. the sum of ratios of DM produced by the plant species in the agroforestry plots to those produced in the sole plots, was 1.95 for ryegrass, 1.71 for ryegrass/clovers and 1.45 for lucerne ground covers. 5. These results indicate the susceptibility of pasture species to shading and interception of rainfall by the tree crowns (aboveground interactions), and the trees to competition for soil moisture (underground interaction).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00711572
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  • 5
    Electronic Resource
    Electronic Resource
    Biological nitrogen fixing capacity and biomass production of different understorey pastures in a Pinus radiata-pasture agroforestry system in New Zealand (1996)
    Springer
    Agroforestry systems 34 (1996), S. 33-49 
    Details
    ISSN: 1572-9680
    Keywords: nitrogen fixation ; 15N ; %Ndfa ; ryegrass+clover pasture ; silvopastoral system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Quantitative field measurements of biological nitrogen fixation (BNF) and biomass production by four different understorey pastures in a Pinus radiata-pasture agroforestry system were determined over a period of one year. The trees were two years old at the beginning of this study and the understorey pastures were being cut and removed for silage. The BNF was determined using the 15N dilution technique. Pastures of ryegrass+clover, cocksfoot+clover, phalaris+clover and lucerne were used. Substantial amounts of BNF were found (71 to 230 kg N ha−1 year−1) with lucerne showing the highest N fixation. However, lucerne derived only 71 to 72% of its N from the atmosphere (%Ndfa) during the spring/summer period compared to 83–97% with clovers, thus the net N demand from the soil was substantially higher with lucerne. This caused increased N stress to the trees. Clover in ryegrass+clover pasture fixed more N than the other grass+clover pastures. Although pasture position in relation to trees did not affect annual pasture total DMY and %Ndfa, pastures north of tree row grew better than those in other positions. Trees significantly affected the BNF of legumes and the botanical composition of pastures with highest BNF and legume production occurring in pastures midway between two rows of trees. These results suggest that it would be advantageous to evaluate different legumes and grasses for tolerance of shade and moisture stress in future studies. As the trees studied were only 1.5 to 3 m in height, their effects on BNF, seasonal pasture biomass production and botanical composition are expected to increase with tree dominance in the ecosystem with time. Amounts of N fixed were related to the productivity (i.e. dry matter and N yield) and seasonal persistence of the legumes. The productivity was high in spring and summer and low in autumn and winter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00129631
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  • 6
    Electronic Resource
    Electronic Resource
    The role of agroforestry in industrialized nations: the southern hemisphere perspective with special emphasis on Australia and New Zealand (1995)
    Springer
    Agroforestry systems 31 (1995), S. 143-156 
    Details
    ISSN: 1572-9680
    Keywords: silvopastoral ; shelterbelts ; woodlots ; amenity plantings ; erosion control ; conservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Agroforestry in Australia and New Zealand is dominated by silvopastoralism. Farmers may employ combinations of shelterbelts, shade trees, widely spaced trees over pasture, or more densely planted woodlots. In addition to wood production and shelter, erosion control, amenity and landscape planting, and conservation of natural forest are often important. Many farm forestry people show considerable innovation. In temperate wetter areas of Australia, eucalyptus and, to a lesser extent,Pinus radiata (radiata pine) dominate agroforestry tree plantings for wood, shade, shelter, and salinisation and erosion prevention. The One Billion Tree Program, initiated by the Australian Federal Government, provides limited funding for tree planting. Joint farmer ventures with the State or local industry are also common. Most State governments also provide advice, and planting is tax deductible. Local landcare groups, formed to encourage sustainable agriculture, often promote tree planting, particularly where soil degradation is a problem. Melbourne University and other Techncial Institutes offer training in agroforestry. In New Zealand, a third of the farms require trees for soil conservation. This, together with the growing recognition of the financial benefits of planting trees, has resulted in small landowners doing most of the current planting of 80,000 to 100,000 ha yr−1. Most farmers plant radiata pine, but eucalyptus and other hardwoods, including willows and poplars, are also widely used. There are almost no government incentives for tree planting in New Zealand. The Farm Forestry Association is the major extension organization. Lincoln University has an important teaching and research commitment, and the New Zealand Forest Research Institute Limited has developed very useful management models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00711722
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  • 7
    Electronic Resource
    Electronic Resource
    Fertilizer movement in a a slash pine ecosystem (1975)
    Springer
    Plant and soil 43 (1975), S. 467-478 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The distribution of N from labeled ammonium sulphate fertilizer was studied 19 months after application to an 11-year-old slash pine stand. The fertilizer was broadcast around single trees at rates equivalent to 0, 56, and 224 kg N/ha. Only 50 per cent of the fertilizer N was recovered in the ecosystem. Some 10.5 per cent of the fertilizer N was recovered in the study trees and 15.0 per cent in surrounding trees. Most of the remaining 24 per cent was accounted for in the litter layer and in soil sampled to a 2 m depth. Nitrogen uptake was directly related to application rate. Labeled N primarily moved to regions of highest metabolic activity within the tree. Approximately 41 per cent of the total labeled N found in the trees was present in the foliage, while only 15 per cent was in the root system. The distribution of N within the crown at the end of the second growing season confirmed that the available fertilizer N was largely depleted, because uptake of labeled N was minimal during the second growing season. Furthermore, labeled N tended to become increasingly diluted by internal cycling as it moved from the roots into the crown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01928508
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  • 8
    Electronic Resource
    Electronic Resource
    Fertilizer movement in a slash pine ecosystem (1975)
    Springer
    Plant and soil 43 (1975), S. 451-465 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The movement of N in an 11-year-old slash pine forest ecosystem was followed over two growing seasons by using N15-labeled ammonium sulphate, applied in the spring at 0, 56, and 224 kg N/ha. The initial uptake of P32, applied as concentrated superphosphate at 90 kg P/ha, and of labeled N from the highest application rate was followed in two trees for 71 days. Dry weather following fertilizer application delayed uptake and both isotopes were first observed in the foliage 7 days after application. While uptake of P32 was at a steady rate between the third and tenth week, the uptake of N15 declined, due to reduced availability in the soil, after seven weeks. Concentrations of both isotopes were greater in the lower foliage than in the upper crown. The N15 levels were higher in currently developing foliage than in older foliage, while the reverse was true for P32. The maximum concentration of labeled-N occurred in the foliage at about 12 weeks. At this time the current foliage had derived 8.5 per cent of its N from the fertilizer in the low-N treatment and 27.5 per cent at the high-N treatment. However, N15 uptake into the developing foliage continued, at a reduced rate, until mid winter. In the second growing season, the foliage formed in the previous growing season decreased in total and labeled-N content due to translocation to newly developing tissue. The N15 leached rapidly through the litter with only 9 per cent of the applied N, in the high-N treatment, occurring in the litter at the end of 6 weeks. In the first 12 weeks the amount of N15 in the litter and topsoil decreased rapidly (to 21 per cent in the high-N plots) but changed little thereafter. This decrease was related to uptake and probably to leaching.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01928507
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  • 9
    Electronic Resource
    Electronic Resource
    Fertilizer movement in a a slash pine ecosystem (1975)
    Springer
    Plant and soil 43 (1975), S. 467-478 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The distribution of N from labeled ammonium sulphate fertilizer was studied 19 months after application to an 11-year-old slash pine stand. The fertilizer was broadcast around single trees at rates equivalent to 0, 56, and 224 kg N/ha. Only 50 per cent of the fertilizer N was recovered in the ecosystem. Some 10.5 per cent of the fertilizer N was recovered in the study trees and 15.0 per cent in surrounding trees. Most of the remaining 24 per cent was accounted for in the litter layer and in soil sampled to a 2 m depth. Nitrogen uptake was directly related to application rate. Labeled N primarily moved to regions of highest metabolic activity within the tree. Approximately 41 per cent of the total labeled N found in the trees was present in the foliage, while only 15 per cent was in the root system. The distribution of N within the crown at the end of the second growing season confirmed that the available fertilizer N was largely depleted, because uptake of labeled N was minimal during the second growing season. Furthermore, labeled N tended to become increasingly diluted by internal cycling as it moved from the roots into the crown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01928508
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  • 10
    Electronic Resource
    Electronic Resource
    Fertilizer movement in a slash pine ecosystem (1975)
    Springer
    Plant and soil 43 (1975), S. 451-465 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The movement of N in an 11-year-old slash pine forest ecosystem was followed over two growing seasons by using N15-labeled ammonium sulphate, applied in the spring at 0, 56, and 224 kg N/ha. The initial uptake of P32, applied as concentrated superphosphate at 90 kg P/ha, and of labeled N from the highest application rate was followed in two trees for 71 days. Dry weather following fertilizer application delayed uptake and both isotopes were first observed in the foliage 7 days after application. While uptake of P32 was at a steady rate between the third and tenth week, the uptake of N15 declined, due to reduced availability in the soil, after seven weeks. Concentrations of both isotopes were greater in the lower foliage than in the upper crown. The N15 levels were higher in currently developing foliage than in older foliage, while the reverse was true for P32. The maximum concentration of labeled-N occurred in the foliage at about 12 weeks. At this time the current foliage had derived 8.5 per cent of its N from the fertilizer in the low-N treatment and 27.5 per cent at the high-N treatment. However, N15 uptake into the developing foliage continued, at a reduced rate, until mid winter. In the second growing season, the foliage formed in the previous growing season decreased in total and labeled-N content due to translocation to newly developing tissue. The N15 leached rapidly through the litter with only 9 per cent of the applied N, in the high-N treatment, occurring in the litter at the end of 6 weeks. In the first 12 weeks the amount of N15 in the litter and topsoil decreased rapidly (to 21 per cent in the high-N plots) but changed little thereafter. This decrease was related to uptake and probably to leaching.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01928507
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