ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Springer  (87)
  • Canadian Science Publishing  (1)
  • Springer Science + Business Media
  • 1995-1999  (25)
  • 1990-1994  (39)
  • 1970-1974  (24)
Collection
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 77 (1990), S. 453-453 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Until now, many extracellular matrix proteins, e.g. osteopontin and osteonectin, have been used to determine a cell’s osteogenic maturation. The disadvantage in evaluation of these proteins is their relative wide-ranging appearance throughout the osteogenic differentiation process. Thus, the aim of this study was to establish an immunohistochemical setup using E11, a marker that binds selectively to cells of the late osteogenic cell lineage. In addition, the histochemical expression of the bone matrix proteins osteonectin, osteopontin and fibronectin was compared to that of E11 using monoclonal antibodies. For light microscopical detection of osteogenic markers in cultured cells we developed a simple paraffin technique using a fibrin glue as embedding medium. This allows the handling of cultured cells such as a tissue sample and includes the use of stored biological specimens for further immunohistochemical experiments. We used newborn rat calvariae for whole tissue preparations and for isolation and cultivation of bone cells. In addition, we included the rat osteosarcoma cell line ROS 17/2.8 in this study. For the first time, we have localised E11 in osteocytes of rat calvaria preparations at the electron microscopical level. E11 was detected at plasma membranes of osteocytes and their processes, but not at those of osteoblasts. Accompanying experiments with cultured newborn rat calvaria cells and ROS 17/2.8 cells revealed E11 reactivity on a subset of cells. The results obtained confirm the suitability of the differentiation marker E11 as a sensitive instrument for the characterisation of bone cell culture systems.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Experiments with Prunus armeniaca were carried out under conditions of constant temperature but varying air humidity. Experiments were also contucted with a constant water vapor difference between the evaporating sites in a leaf and the air, but with varying leaf temperature. These served as a basis for predicting the daily course of total diffusion resistance under the natural climatic conditions of a desert. For the simulation, the rsults of the experiments at constant conditions with only one variable factor are fitted with empirical equations which serve as “calibration curves” to predict the change in diffusion resistance caused by a change in humidity and temperature calculated from the meteorological data of a desert day. The simulation shows that for P. armeniaca humidity and temperature are the dominating factors in controlling the daily course of diffusion resistance. For meteorologically very different days the simulation allows the increase in diffusion resistance in the morning to be predicted with an accuracy of 90%–105% as compared to directly observed measurements. In the afternoon, especially after extreme climatic conditions during the morning, the deviation between predicted and observed values of diffusion resistance may be greater, but not more than -20% to -30%. This possibly indicates the existence of an additional factor of significance which was not included in the simulation. The two peaked curves of net photosynthesis and transpiration characteristic of plants living under arid conditions can be explained in this species by the humidity-and temperature-controlled stomatal response. This stomatal regulation leads to a decreasing total daily transpirational water loss on a dry day as compared to a moist one. The significance of this controlling mechanism for the primary production and the water relations of P. armeniaca is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary During the dry season in the Negev desert (Israel) Artemisia herbaalba in its natural habitat has a very low water content. It shows values of negative hydrostatic pressure in the xylem down to -163 bars and an extreme of osmotic potential in the leaves of -92 bars. The diurnal water stress does not decrease strongly in the night. Under these conditions Artemisia is still photosynthetically active for a few hours of the day during the whole dry period.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A digital registration system used with temperature- and humidity-controlled cuvettes for net photosynthesis and transpiration measurements in the field is described. The associated errors of the measured parameters and calculated data are estimated. The digitalization is based on an analogue registration which is of primary importance in the control of experimental conditions in the cuvettes. The digital system is connected to the analogue registration in series. The error associated with digitalization is 0.1% across 70% of the scale. This error increases to 0.2% between 3 and 30% on the scale due to a minor lack of linearity. The reproducibility of the digitalization is ±0.024%. The error associated with data transfer in the digitalization and the errors of the analogue registration are estimated for temperature and humidity measurements (error of air and leaf temperature is ±0.1° C; error of the dew point temperature is ±1.1° C dew point). The effect of these errors on the calculation of relative humidity and the water vapour difference between the leaf and the air is determined using the progressive error law. At 30° C and 50% relative humidity, the error in relative humidity is ±7.4%, the error for the water vapour difference is ±6.6%. The dependence of these errors on temperature and humidity is shown. The instrument error of the net photosynthesis measurement is calculated to be ±4.2%. Transpiration measurements have an average inaccuracy of ±8.3%. The total diffusion resistance which is calculated from values of transpiration and the water vapour difference has an average error of ±10.9%. The sizeable influence of errors in humidity and temperature measurements on the calculated diffusion resistance is demonstrated. The additional influence of biological errors associated with field measurements is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1432-1939
    Keywords: Boreal forest ; Nitrogen, phosphorus, and cation nutrition ; Stable isotopes ; Picea glauca Calamagrostis Vaccinium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Natural abundances of nitrogen isotopes, δ15N, indicate that, in the same habitat, Alaskan Picea glauca and P. mariana use a different soil nitrogen compartment from the evergreen shrub Vaccinium vitis-idaea or the deciduous grass Calamagrostis canadensis. The very low δ15N values (-7.7 ‰) suggest that (1) Picea mainly uses inorganic nitrogen (probably mainly ammonium) or organic N in fresh litter, (2) Vaccinium (-4.3 ‰) with its ericoid mycorrhizae uses more stable organic matter, and (3) Calamagrostis (+0.9 ‰) exploits deeper soil horizons with higher δ15N values of soil N. We conclude that species limited by the same nutrient may coexist by drawing on different pools of soil N in a nutrient-deficient environment. The differences among life-forms decrease with increasing N availability. The different levels of δ15N are associated with different nitrogen concentrations in leaves, Picea having a lower N concentration (0.62 mmol g−1) than Vaccinium (0.98 mmol g−1) or Calamagrostis (1.33 mmol g−1). An extended vector analysis by Timmer and Armstrong (1987) suggests that N is the most limiting element for Picea in this habitat, causing needle yellowing at N concentrations below 0.5 mmol g−1 or N contents below 2 mmol needle−1. Increasing N supply had an exponential effect on twig and needle growth. Phosphorus, potassium and magnesium are at marginal supply, but no interaction between ammonium supply and needle Mg concentration could be detected. Calcium is in adequate supply on both calcareous and acidic soils. The results are compared with European conditions of excessive N supply from anthropogenic N depositions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1432-1939
    Keywords: Key words Water transport ; Grass roots ; Hydraulic lift ; Deserts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Downward transport of water in roots, in the following termed “inverse hydraulic lift,” has previously been shown with heat flux techniques. But water flow into deeper soil layers was demonstrated in this study for the first time when investigating several perennial grass species of the Kalahari Desert under field conditions. Deuterium labelling was used to show that water acquired by roots from moist sand in the upper profile was transported through the root system to roots deeper in the profile and released into the dry sand at these depths. Inverse hydraulic lift may serve as an important mechanism to facilitate root growth through the dry soil layers underlaying the upper profile where precipitation penetrates. This may allow roots to reach deep sources of moisture in water-limited ecosystems such as the Kalahari Desert.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Temperature dependence of net photosynthesis under conditions of light saturation and maximum air humidity was measured throughout the season in the Central Negev Desert (Israel). Experimental plants were the wild growing Hammada scoparia and Prunus armeniaca cultivated in the runoff farm of Avdat. The optimum temperature for net photosynthesis and the upper temperature compensation point of CO2 exchange showed a characteristic seasonal variation with low values in spring and fall and high values in mid-summer. This shift was exhibited by plants growing under conditions of normal soil-water stress as well as by irrigated plants. There was no general correlation between the changes in temperature dependence of net photosynthesis of the plants, their maximum photosynthetic capacity under the experimental conditions, their daily photosynthesis maximum under natural conditions, and their rate of dark respiration. The seasonal shift of the photosynthetic response to temperature cannot be explained by changes in the temperature sensitivity of the stomata. It may be caused by seasonal changes of biochemical and/or biophysical properties. A number of observations made on other wild plants also showed, in all cases, seasonal shifts of the upper temperature compensation point, with an amplitude of 6.0°C–13.7°C.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1432-1939
    Keywords: Key words Carnivorous plants ; Pitcher plants ; Insect nitrogen ; Nitrogen partitioning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study investigated the nitrogen (N) acquisition from soil and insect capture during the growth of three species of pitcher plants, Nepenthes mirabilis, Cephalotus follicularis and Darlingtonia californica. 15N/14N natural abundance ratios (δ15N) of plants and pitchers of different age, non-carnivorous reference plants, and insect prey were used to estimate proportional contributions of insects to the N content of leaves and whole plants. Young Nepenthes leaves (phyllodes) carrying closed pitchers comprised major sinks for N and developed mainly from insect N captured elsewhere on the plant. Their δ15N values of up to 7.2‰ were higher than the average δ15N value of captured insects (mean δ15N value = 5.3‰). In leaves carrying old pitchers that are acting as a N source, the δ15N decreased to 3.0‰ indicating either an increasing contribution of soil N to those plant parts which in fact captured the insects or N gain from N2 fixation by microorganisms which may exist in old pitchers. The δ15N value of N in water collected from old pitchers was 1.2‰ and contained free amino acids. The fraction of insect N in young and old pitchers and their associated leaves decreased from 1.0 to 0.3 mg g−1. This fraction decreased further with the size of the investigated tiller. Nepenthes contained on average 61.5 ± 7.6% (mean ± SD, range 50–71%) insect N based on the N content of a whole tiller. In the absence of suitable non-carnivorous reference plants for Cephalotus, δ15N values were assessed across a developmental sequence from young plants lacking pitchers to large adults with up to 38 pitchers. The data indicated dependence on soil N until 4 pitchers had opened. Beyond that stage, plant size increased with the number of catching pitchers but the fraction of soil N remained high. Large Cephalotus plants were estimated to derive 26 ± 5.9% (mean ± SD of the three largest plants; range: 19–30%) of the N from insects. In Cephalotus we observed an increased δ15N value in sink versus source pitchers of about 1.2‰ on average. Source and sink pitchers of Darlingtonia had a similar δ15N value, but plant N in this species showed δ15N signals closer to that of insect N than in either Cephalotus or Nepenthes. Insect N contributed 76.4 ± 8.4% (range 57–90%) to total pitcher N content. The data suggest complex patterns of partitioning of insect and soil-derived N between source and sink regions in pitcher plants and possibly higher dependence on insect N than recorded elsewhere for Drosera species.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1432-1939
    Keywords: Terrestrial biomes ; Cumulative root fraction ; Root biomass ; Rooting density ; Soil depth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Understanding and predicting ecosystem functioning (e.g., carbon and water fluxes) and the role of soils in carbon storage requires an accurate assessment of plant rooting distributions. Here, in a comprehensive literature synthesis, we analyze rooting patterns for terrestrial biomes and compare distributions for various plant functional groups. We compiled a database of 250 root studies, subdividing suitable results into 11 biomes, and fitted the depth coefficient β to the data for each biome (Gale and Grigal 1987). β is a simple numerical index of rooting distribution based on the asymptotic equation Y=1-βd, where d = depth and Y = the proportion of roots from the surface to depth d. High values of β correspond to a greater proportion of roots with depth. Tundra, boreal forest, and temperate grasslands showed the shallowest rooting profiles (β=0.913, 0.943, and 0.943, respectively), with 80–90% of roots in the top 30 cm of soil; deserts and temperate coniferous forests showed the deepest profiles (β=0.975 and 0.976, respectively) and had only 50% of their roots in the upper 30 cm. Standing root biomass varied by over an order of magnitude across biomes, from approximately 0.2 to 5 kg m-2. Tropical evergreen forests had the highest root biomass (5 kg m-2), but other forest biomes and sclerophyllous shrublands were of similar magnitude. Root biomass for croplands, deserts, tundra and grasslands was below 1.5 kg m-2. Root/shoot (R/S) ratios were highest for tundra, grasslands, and cold deserts (ranging from 4 to 7); forest ecosystems and croplands had the lowest R/S ratios (approximately 0.1 to 0.5). Comparing data across biomes for plant functional groups, grasses had 44% of their roots in the top 10 cm of soil. (β=0.952), while shrubs had only 21% in the same depth increment (β=0.978). The rooting distribution of all temperate and tropical trees was β=0.970 with 26% of roots in the top 10 cm and 60% in the top 30 cm. Overall, the globally averaged root distribution for all ecosystems was β=0.966 (r 2=0.89) with approximately 30%, 50%, and 75% of roots in the top 10 cm, 20 cm, and 40 cm, respectively. We discuss the merits and possible shortcomings of our analysis in the context of root biomass and root functioning.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...