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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 3 (1987), S. 107-111 
    ISSN: 1432-0789
    Keywords: Oniscus asellus ; Leaf litter ; Acer negundo ; A. saccharum ; Fagus grandifolia ; Picea rubens ; Tsuga canadensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Feeding by the isopod, Oniscus asellus, produced changes in the sulfur constituents of leaf litter substrates (Acer negundo, A. saccharum, Fagus grandifolia, Picea rubens, and Tsuga canadensis). Isopod consumption of leaf litter generally accelerated the mineralization of carbon-bonded S and increased the formation of ester sulfate in all substrates. After the isopod egestion of A. negundo leaves, fecal decomposition over 6 weeks increased total S concentration from 68 to 120 μmol S/g due to the catabolism of organic carbon. During the same period sulfate decreased from 34 to 20 μmol S/g and carbon-bonded S increased from 34 to 100 μmol S/g. Thus the total S pool in aged feces became enriched with organic S (83% of total S). Macroinvertebrate consumption accelerated the transformation of S constituents and the carbon-bonded S concentration approached that of the Oa organic horizon of a northern hardwood forest.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 7 (1989), S. 239-246 
    ISSN: 1432-0789
    Keywords: Nutrient cycling ; Oniscus asellus ; Hardwood forest soil ; Leaching ; Macrofauna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Oniscus asellus produced changes in the nutrients leached from Oie and Oa horizons of a hardwood forest soil. Soil with isopods lost more K+ (54%) from the Oie horizon and more Ca2+ (25%), Mg2+ (40%), and water-extractable S (23%) from the Oa horizon than soil without isopods. In contrast, soils with isopods lost less Ca2+ (39076) from the Oie horizon and less dissolved C-bonded S (33%) from the Oa horizon than soil without isopods. In addition, the Oia and Oa horizons exhibited different nutrient dynamics. When isopods were present, the Oa horizon leachates accumulated more Na+ K+, Ca2+, Mg2+, NO3 − , water-soluble SO4 2−, and dissolved C-bonded S, and the Oie horizon retained more of these nutrients. The type of leaching solution also had a major effect on nutrients. Leaching with a simulated soil solution resulted in smaller nutrient losses for K+ and Mg2+ in both horizons and for Na+, Ca2+, and NO3 − in the Oa horizon than leaching with distilled water.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 68 (1987), S. 411-416 
    ISSN: 1432-1106
    Keywords: Trigeminal organization ; Cornea ; HRP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Experiments were carried out in cats to learn the location of sensory axons from the cornea in the trigeminal nerve root just prior to its entry into the brainstem. HRP injected into the cornea labelled these axons and indicated they were not restricted to the ophthalmic division of the nerve root as had been indicated from previous studies. These findings, if representative of other branches of this nerve, offer a partial explanation for the variable preservation of function following transection of an entire division of the trigeminal nerve root in cases of trigeminal neuralgia.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-5079
    Keywords: fluorescence induction ; photosynthesis ; photosystem II ; Triticum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fluorescence of the chlorophyll associated with photosystem II was studied in seedling and flag leaves of Triticum species. Seedling leaves of the diploid species T. urartu had higher values of t (the normalised area over the fluorescence induction curve of DCMU treated leaves) than those of the other species studied which included hexaploid T. aestivum. However this difference was not evident when leaves were grown in a low light intensity (40 µmol quanta of photosynthetically active radiation m−2 s−1). The smaller total number of chlorophyll molecules per photosystem II reaction centre (chl/RCII) in T. urartu (177) as compared with the other species (mean 234) was deduced from the observed differences in t. As a consequence of its lower chl/RCII, despite slightly lower chlorophyll content (mg m−2), T. urartu had a greater density of reaction centres than the other species (2880 cf 2230 nmol m−2 of leaf). Consistent with the lower chl/RCII of T. urartu, it had a higher chlorophyll a/b ratio than the other genotypes. Seedling leaves of T. urartu had higher light saturated rates of photosynthesis than those of the other species, when grown at high light, a difference associated with reaction centre density. In flag leaves, when the complications due to variable development and senescence patterns were eliminated, t of the diploid species including T. urartu was lower than that of T. aestivum. The lower apparent chl/RCII of T. urartu arose partly because the molar extinction coefficient of the chlorophyll in the leaves of T. urartu was greater than in T. aestivum. However, the density of PS II reaction centres was slightly lower for the diploid species studied because their chlorophyll contents were lower than the hexaploids. The validity of the method for estimating chl/RCII from fluorescence transients is discussed. The possibility is considered that the difference in apparent chl/RCII of flag and seedling leaves of R. urartu as compared to the other five genotypes is a consequence of its different adaptive response to the spectral quality of the light.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-5079
    Keywords: Chlorophyll a fluorescence ; photoacoustic spectroscopy ; photosystem I ; photosystem II ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Usisng intact leaves, the extent of the decrease in chlorophyll a fluorescenece caused by the addition of continuous 710 nm light superimposed on modulated (20 Hz) 550 nm light was used to determine the distribution of this absorbed light between photosystems I (α) and II (β). The Fo and Fm levels, which defined the total variable fluorescenece, were taken as equal to those obtained with excess 710 nm light and with saturating blue-green light, respectively. An analogous procedure was used with a photoacoustic detector, saturating white light defining a base line for oxygen yield, the levels with an without 710 nm light being used to define β and α respectively. The two methods gave similar values for the distribution of light between the two photosystems for the experimental conditions used, β averaging 0.55 for a range of Triticum genotypes and Brachypodium sylvaticum grown in high or low light.
    Type of Medium: Electronic Resource
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