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  • Cell & Developmental Biology  (5)
  • Semi-arid shrubs  (2)
  • Wiley-Blackwell  (5)
  • Springer  (2)
  • American Association for the Advancement of Science
  • American Physical Society
Collection
Keywords
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  • Wiley-Blackwell  (5)
  • Springer  (2)
  • American Association for the Advancement of Science
  • American Physical Society
Years
  • 1
    Electronic Resource
    Electronic Resource
    Nonstructural carbohydrate allocation following different frequencies of simulated browsing in three semi-arid shrubs (1995)
    Springer
    Oecologia 102 (1995), S. 238-245 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00333256
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  • 2
    Electronic Resource
    Electronic Resource
    Regrowth and tannin production in woody and succulent karoo shrubs in response to simulated browsing (1993)
    Springer
    Oecologia 96 (1993), S. 562-568 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00320514
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  • 3
    Electronic Resource
    Electronic Resource
    Response regulation in bacterial chemotaxis (1993)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 51 (1993), S. 41-46 
    Details
    ISSN: 0730-2312
    Keywords: CheY ; CheZ ; response regulators ; histidine kinase ; switch complex ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The signal transduction system that mediates bacterial chemotaxis allows cells to moduate their swimming behavior in response to fluctuations in chemical stimuli. Receptors at the cell surface receive information from the surroundings. Signals are then passed from the receptors to cytoplasmic chemotaxis components: CheA, CheW, CheZ, CheR, and CheB. These proteins function to regulate the level of phosphorylation of a response regulator designated CheY that interacts with the flagellar motor switch complex to control swimming behavior. The structure of CheY has been determined. Magnesium ion is essential for activity. The active site contains highly conserved Asp residues that are required for divalent metal ion binding and CheY phosphorylation. Another residue-at the active site, Lys109, is important in the phosphorylation-induced conformational change that facilitates communication with the switch complex and another chemotaxis component, CheZ. CheZ facilitates the dephosphorylation of phospho-CheY. Defects in CheY and CheZ can be suppressed by mutations in the flagellar switch complex. CheZ is thought to modulate the switch bias by varying the level of phospho-CheY. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240510109
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanisms of receptor function and the molecular biology of information processing in bacteria (1987)
    New York, NY : Wiley-Blackwell
    BioEssays 6 (1987), S. 199-203 
    Details
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Bacteria adapt to changes in their environment by altering their metabolism, turning on and off genes, and moving toward favorable conditions. Recent results indicate that a common molecular logic may underlie the decision-making processes by which these simple cells adjust to their surroundings.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bies.950060502
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  • 5
    Electronic Resource
    Electronic Resource
    Identification of estrogen receptor mRNA and the estrogen modulation of parathyroid hormone-stimulated cyclic AMP accumulation in opossum kidney cells (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 150 (1992), S. 517-525 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The opossum kidney (OK) cell was used as a model to test the hypothesis that estrogen directly affects proximal renal tubular epithelial cells. To demonstrate the expression of estrogen receptor in OK cells, we developed an approach using reverse transcription and the polymerase chain reaction. Analysis of the DNA amplified with nested primers revealed the predicted size fragment and restriction enzyme digestion products. To demonstrate the functional effects of estrogen, OK cells at confluence were preincubated in serum-free medium for 7-10 days with or without 17β-estradiol. Bovine PTH(1-34) (bPTH(1-34)) then stimulated a dosedependent intracellular accumulation of cAMP that was maximal after 1 min and then gradually declined. Cyclic AMP in the medium slowly increased over 60 min. Preincubation with 17β-estradiol did not affect cell proliferation as measured by total protein content but caused an inhibition of bPTH(1-34)-stimulated intracellular cAMP accumulation that was maximal at 10-11M 17β-estradiol (71 ± 3% control, p 〈 .001). bPTH(1-34) also increased cAMP release into the medium, an effect maximal using 10-10M 17β-estradiol (118 ± 3% control, p 〈 .001). Preincubation with the inactive isomer 17α-estradiol caused no changes in cAMP accumulation or release. Coincubation with the antiestrogen tamoxifen blocked the effects of 17β-estradiol. Sodium-dependent phosphate transport was: (1) inhibited by 2-h incubations with 10-8 or 10-10 M bPTH(1-34) and not affected by preincubation with 17β-estradiol, and (2) not inhibited by a 20-min incubation with 10-8 M bPTH(1-34) unless cells were preincubated with 10-8 M 17β-estradiol, suggesting that any possible effects of estrogen on phosphate transport are not directly mediated by changes in cAMP. These studies demonstrate the presence of estrogen receptor mRNA in OK cells as well as direct and specific effects of physiologic concentrations of estrogen on cAMP accumulation in these cells. This system may be a good model for further study of estrogen and PTH effects on the kidney.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041500312
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  • 6
    Electronic Resource
    Electronic Resource
    What the Papers Says: A membrane receptor kinase that regulates development in Bacillus subtilis (1990)
    New York, NY : Wiley-Blackwell
    BioEssays 12 (1990), S. 387-388 
    Details
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bies.950120808
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  • 7
    Electronic Resource
    Electronic Resource
    Patterning of the mammalian dentition in development and evolution (1997)
    New York, NY : Wiley-Blackwell
    BioEssays 19 (1997), S. 481-490 
    Details
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mammalian dentition is a segmented organ system with shape differences among its serially homologous elements (individual teeth). It is believed to have evolved from simpler precursors with greater similarities in shape among teeth, and a wealth of descriptive data exist on changes to the dentition that have occurred within mammals. Recent progress has been made in determining the genetic basis of the processes that form an individual tooth, but patterning of the dentition as a whole (i.e. the number, location and shape of the teeth) is less well understood. In contrast to similarly organized systems, such as the vertebral column and limb, Hox genes are not involved in specifying differences among elements. Nevertheless, recent work on a variety of systems is providing clues to the transcription factors and extracellular signalling molecules involved.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bies.950190607
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