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  • thermogenesis  (3)
  • Semi-arid shrubs  (2)
  • Springer  (5)
  • American Meteorological Society (AMS)
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  • Springer  (5)
  • American Meteorological Society (AMS)
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  • 1
    ISSN: 1432-1939
    Keywords: Browsing responses ; Semi-arid shrubs ; Nonstructural carbohydrate accumulation ; Regrowth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nonstructural carbohydrate allocation patterns in response to different frequencies of simulated browsing (leaf and twig removal) were studied in the following semi-arid shrubs: Osteospermum sinuatum, a dwarf deciduous shrub, Pteronia pallens, a dwarf evergreen shrub, and Ruschia spinosa, a dwarf leaf-succulent shrub. Simulated browsing at all frequencies resulted in the elevation, or had no effect, on total nonstructural carbohydrate (TNC) concentrations of O. sinuatum plant parts, and resulted in the decrease in TNC concentrations of R. spinosa plant parts. The responses of P. pallens were intermediate with elevations as well as declines in TNC concentrations of plant parts measured in response to various clipping frequencies. At the low frequency of simulated browsing (every 26 weeks) elevations in plant TNC content were measured in the two non-succulent shrubs O. sinuatum and P. pallens. It was concluded that the overcompensation with respect to TNC accumulation observed in the two non-succulent species represents one of the ways in which excess photosynthate is utilized by browsed shrubs with a limited regiowth potential. Simulated browsing was the least detrimental with respect to biomass production to the non-succulent O. sinuatum and P. pallens, and most injurious to the leaf-succulent shrub, R. spinosa. The observed TNC allocation patterns could not adequately explain the variation among species in the production of new growth and it was concluded that some factor(s) other than the carbon resource was limiting regrowth.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1939
    Keywords: Induced defence ; Clipping ; Semi-arid shrubs ; Herbivore-deterrents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Allocation of carbon to chemical defences has often been suggested to be a direct response to browsing or grazing by herbivores. This study quantitatively compares total polyphenol and tannin production in response to simulated browsing of three karoo shrubs in order to test this induced defence hypothesis. The three species studied responded to browsing either by rapid regrowth or by increasing polyphenol production in the remaining tissues. The patterns did not follow any phylogenetic relationships but were weakly associated with the palatability of each species. The highly palatable deciduous species Osteospermum sinuatum, which is capable of rapid regrowth, showed no or very low levels of constitutive and browsing-induced total polyphenols, condensed tannins and protein-precipitating tannins. The evergreen sclerophyllous species Pteronia pallens showed a limited regrowth capacity and had intermediate levels of polyphenols, while the evergreen succulent species Ruschia spinosa showed almost no regrowth over the study period. R. spinosa contained the highest constitutive and browsing-induced levels of polyphenols, condensed tannins and protein-precipitating tannins. In two of the species more than one anti-herbivore defence feature co-occur. P. pallens foliage contains both hepatotoxins and polyphenols while R. spinosa has both structural (spines) and chemical defences. Responses of karoo shrubs to simulated browsing are interpreted as the result of passive alterations in plant chemistry rather than as an active defence response to herbivores.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 44 (1988), S. 40-42 
    ISSN: 1420-9071
    Keywords: TRH ; TRH analogues ; thermogenesis ; brown adipose tissue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Acute or chronic injection of RX 77368 (a TRH analogue; 1 mg/kg s.c.) stimulated oxygen consumption (VO2) and brown adipose tissue activity in the rat, and decreased weight gain Other TRH analogues (CG 3509, RGH 2202) and TRH itself also stimulated VO2. These thermogenic actions are probably mediated centrally by stimulation of sympathetic outflow to brown fat.
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  • 4
    ISSN: 1573-4935
    Keywords: tumour necrosing factor ; brown fat ; thermogenesis ; GDP-binding ; food intake ; body weight ; rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A single intravenous injection of recombinant human tumour necrosis factor (TNF) resulted in significant, but transient (24–48 hr) reductions in food intake and body weight, and increases in rectal temperature, resting oxygen consumption (VO2) and brown adipose tissue (BAT) thermogenic activity (mitochondrial GDP-binding). The increased VO2 was inhibited by β-adrenergic blockade (propranolol), and activation of BAT was prevented by denervation of the tissue. In adult (4-month old) animals, TNF induced greater reductions in food intake and body weight, caused general malaise and some fatalities, but did not significantly alter VO2 or BAT activity. However, the reduction in VO2 following β-adrenergic blockade was greater in TNF-treated rats and BAT activity was enhanced when compared to pair-fed controls. Injection of adult rats with gamma-interferon induced small changes in body weight and temperature which were slightly potentiated when injected with a low dose of TNF. The results indicate that TNF stimulates sympathetic outflow to BAT. This effect may be partly responsible for the increases in body temperature and metabolic rate associated with TNF treatment and with cancer cachexia.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Bioscience reports 6 (1986), S. 3-18 
    ISSN: 1573-4935
    Keywords: brown adipose tissue ; thermogenesis ; cold ; diet ; neural control ; hormonal control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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