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  • Vaccinium  (2)
  • Actin  (1)
  • Springer  (3)
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  • Springer  (3)
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 259 (1990), S. 443-454 
    ISSN: 1432-0878
    Schlagwort(e): Ciliogenesis ; Actin ; Microfilaments ; Cytochalasin D ; Coturnix coturnix japonica (Aves)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The effects of cytochalasin D (CD) were studied by scanning (SEM) and transmission (TEM) electron-microscopic examination at different stages of ciliary differentiation in epithelial cells of quail oviduct. Immature quails were prestimulated by estradiol benzoate injections to induce ciliogenesis in the undifferentiated oviduct. After 24 h of CD culture, SEM study revealed inhibition of ciliogenesis and dilation of the apex of non-ciliated cells. TEM study showed that 2 h of CD treatment produced dilation of lateral intercellular spaces, after 6 h of treatment, this resulted in intracellular macrovacuolation. Vacuoles were surrounded by aggregates of dense felt-like material. CD also induced the disappearance of microvilli, and rounding of the apical surface of undifferentiated cells and those blocked in ciliogenesis. Centriologenesis was not inhibited by CD; basal bodies assembled in generative complexes in the supranuclear region after 24 h of treatment. However, the migration of mature basal bodies towards the apical surface was impaired. Instead, they anchored onto the membrane of intracellular vacuoles; growth of cilia was induced in the vacuole lumen. Cilium elongation was disturbed, giving abnormally short cilia with a dilated tip; microtubules failed to organize correctly.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1573-5052
    Schlagwort(e): Evergreen ; Herbivory ; Regrowth ; Vaccinium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The evergreen dwarf shrub lingonberry (Vaccinium vitis-idaea L.) was subjected to microtine herbivory simulations to investigate its recovery in a boreal forest. Beside the control (A), the study included three levels of herbivory: clipping of half the annual branches from 50% of ramets (B), removal of 50% of ramets (C), and removal of 100% of ramets (D). Density, growth, and fecundity of the ramets were monitored during the study. New ramets emerged rapidly from dormant basal buds at the base of the removed ramets in groups C and D. After three growth seasons, 60–117% and 42–112% of density and biomass, respectively, had been regained in the groups damaged relative to the control, the difference being insignificant between the treated groups apparently because of the small sample size. Survival, fecundity and net growth of ramets were not affected by the treatment. Mean dry weight of annual branches in new ramets was lower in the damaged groups than the control. The recovery of the lingonberry was unexpectedly good. The results suggest that, since natural herbivory seldom is as heavy as in this work, the time between population density peaks of microtine rodents is usually long enough for the lingonberry to recover in boreal ecosystems.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 1573-5052
    Schlagwort(e): Allocation ; Biomass production ; Clone ; Compensation ; Herbivory ; Vaccinium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The effects of herbivory were simulated on stands of bilberry (Vaccinium myrtillus L.) in a boreal Empetrum-Myrtillus type forest. Five harvesting intensities were used (0% (A), 25% (B), 50% (C), 100% (D) of the bilberry ramets or all the ramets of all species (E)). Density and biomass of the stands, and growth of the ramets were monitored for five growth seasons, from 1986 to 1990. After damage new ramets emerged rapidly from dormant buds at the base of removed ramets. Between 70 and 97% of the density relative to the control level was regained by the final harvest. However, only between 11 and 64% of the biomass relative to the control level was recovered. Clipping reduced the branch growth, both in the new ramets and in the new parts of the old, unclipped ramets. Severe treatments (D and E) decreased the growth more than did light harvesting (B and C). Survival and fecundity of the ramets were not affected. The result therefore suggested that the bilberry is not able to recover totally from severe herbivory damage between the years of peak rodent population that shows a 3–4 year cycle. Nevertheless, extreme grazing pressure is rare in boreal ecosystems as alternative food is available for herbivores, and predators also limit the herbivore population. Hence the bilberry exhibits moderate tolerance of the usual level of herbivory damage.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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