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  • 1980-1984  (4)
  • 1981  (4)
  • Life and Medical Sciences  (4)
  • Acetylcholine esterase
  • Physics
  • 1
    Electronic Resource
    Electronic Resource
    Correlation of cyclic GMP and cyclic AMP immunofluorescence with cytochemical patterns during dormancy release and development from gemmules in Spongilla lacustris L. (Porifera: Spongillidae) (1981)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 167 (1981), S. 53-63 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The spongillid freshwater sponges asexually produce an encapsulated dormant stage, the gemmule. With release from dormancy, internal, yolk-laden, binucleate thesocytes differentiate into histoblasts or archeocytes. The histoblasts emerging first from the gemmule form the initial pinacoderm of the hatching sponge. Immunohistochemistry was employed to examine the distribution of cyclic GMP (cGMP) and cyclic AMP (cAMP) following dormancy release and during gemmule germination and hatching in the freshwater sponge, Spongilla lacustris L. Cyclic nucleotide fluorescence patterns were analyzed in relation to the distribution of cytochemically demonstrable macromolecular constituents and intracellular organelles. Twenty-four hours following temperature-activated release from dormancy, cGMP fluorescence levels are elevated in thesocytes at the gemmule periphery prior to histoblast formation. The cAMP fluorescence in the gemmule also occurs first in those thesocytes differentiating into histoblasts. Cytochemical patterns in germinating gemmules are comparable with those described by Ruthmann ('65) and Tessenow ('69). However, cytochemically demonstrable events of cytodifferentiation follow the earlier appearance of cGMP and cAMP in the histoblast precursors by approximately 12 hours. In addition, cGMP appears to be associated with the membranes of cytoplasmic organelles, possibly lysosomes or lipid inclusions, in the region of vitelline platelets and with symbiotic algae. cAMP is located primarily on the membranes of the vitelline platelets and on membranes of vacuoles involved in forming the spicular skeleton These observations suggest that cGMP and cAMP are involved in the mobilization of nutrient reserves and in ion transport during dormancy release and development from gemmules in freshwater sponges.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051670106
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Commitment and proliferation kinetics of human lymphocytes stimulated in vitro: Effects of α-MM addition and suboptimal dose on concanavalin a response (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 108 (1981), S. 25-34 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have examined the effect of alpha-methylmannoside (α-MM) addition to concanavalin A (con A)-stimulated peripheral human lymphocytes. With a previously established kinetic model, we have, from the time course of proliferation, extracted the responding clone size, rate of entry of this clone into S phase, and the length of the lag period. We have studied the effect of con A dose and time of addition of α-MM to optimally stimulated cells on these kinetic parameters. We show that neither a low dose of con A nor an early addition of --MM to optimally stimulated cells results in a change in the responding clone size. That is, all of the potentially responsive cells appear to become “committed” to enter the cell cycle regardless of the presence of α-MM early in the culture or in the presence of suboptimal stimulation. However, the rate at which these committed cells enter the first S phase is a function of the dose of con A and time of addition of α-MM and varies over a wide range. It is the variation in this parameter that accounts for virtually all of the diminished response previously interpreted as a time-dependent irreversible commitment of mitogen-stimulated cells. The previous work using only fixed time points for measuring thymidine uptake and the concept of commitment must be reevaluated in light of the kinetic evidence presented.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041080105
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Carbon dioxide efflux accompanies release of fertilization acid from sea urchin eggs (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 108 (1981), S. 115-122 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: “Fertilization acid” is released from sea urchin eggs upon fertilization and decreases the pH of the surrounding seawater. In bicarbonate-free artificial seawater flushed with nitrogen gas, the pH shift still occurs but returns to the original value in a few minutes, suggesting that the released acid is volatile. A likely candidate for a volatile acid is carbon dioxide released from the eggs. Therefore, the total CO2 content of seawater was measured pre- and post-fertilization and was found to be correlated stoichiometrically with released proton equivalents, leading to the conclusion that fertilization acid is largely carbon dioxide. Manometric analysis of cell extracts and ashed eggs suggest that the carbon dioxide may be stored in the unfertilized egg as an inorganic carbonate.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041080202
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of intermittent 60-Hz high voltage electric fields on metabolism, activity, and temperature in mice (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 2 (1981), S. 291-303 
    Details
    ISSN: 0197-8462
    Keywords: 60-Hz electric fields ; motor activity ; carbon dioxide production ; oxygen consumption ; core body temperature ; mice ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Transient effects of 100-kV/m extremely low frequency electric fields were studied in the white footed deermouse, Peromyscus leucopus. Gross motor activity, carbon dioxide production, oxygen consumption, and core body temperature were monitored before, during, and after intermittent field exposures (four hour-long exposures, at one-hour intervals). Thirty-four mice were exposed in cages with plastic floors floating above ground potential, and 21 mice were exposed in cages with grounded metal floor plates. The first field exposure produced an immediate, transient increase of activity and gas measures during the inactive phase of the circadian cycle. All measures returned to baseline levels before the second exposure and were not significantly changed throughout the remainder of the exposures. The rapid habituation of field-induced arousal suggests that significant metabolic changes will not be measured in experiments in which the interval between exposure and measurement is greater than two hours.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250020402
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    Paper (German National Licenses)
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