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  • LIFE SCIENCES (GENERAL)  (3)
  • Induced pinocytosis  (2)
  • Life Sciences (General)  (1)
  • Nuclear reactions
  • 1975-1979  (6)
Collection
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Pinocytosis and locomotion in amoebae (1979)
    Springer
    Protoplasma 100 (1979), S. 33-43 
    Details
    ISSN: 1615-6102
    Keywords: Amoeba proteus ; Ca++-binding sites ; Cytochemical demonstration ; Induced pinocytosis ; Plasma membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Different methods were used to demonstrate the existence of Ca++-binding sites (Ca++-bs) at the plasma membrane ofAmoeba proteus. In pinocytoting animals the number (indicated by the average distanced in nm) and size (average longitudinal axiss in nm) of Ca++-bs at the cytoplasmic surface of the cell membrane were significantly increased (d=162±15;n=41 ands=93±5;n=47) in comparison to controls (d=208 ±21;n=37 ands=59±8;n=45). The ratio of P: Ca obtained by X-ray microanalysis was in the range of 1.5. The differences observed in the two experimental groups of amoebae are explained by conformational changes in the molecular structure and an increased Ca++-permeability of the plasma membrane during induced pinocytosis. Microplasmodia of the acellular slime moldPhysarum polycephalum investigated for comparison were found to have no Ca++-bs at the interior cell surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01276299
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Pinocytosis and locomotion of amoebae: XII. Dynamics and motive force generation during induced pinocytosis in A. proteus (1979)
    Springer
    Cell & tissue research 197 (1979), S. 263-279 
    Details
    ISSN: 1432-0878
    Keywords: Induced pinocytosis ; Dynamics ; Motive force generation ; Light and electron microscopy ; Amoeba proteus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The mechanism of induced pinocytosis was investigated in Amoeba proteus by light and electron microscopy. The application of nine different inducing substances revealed that pinocytotic channel formation, elongation, vesiculation, shortening and disappearance are the result of the successive or simultaneous action of both traction and pressure forces, which are produced by the contractile activity of a plasma membrane-associated layer of filaments ranging from a few hundred nm to several μ in thickness. The initial phase of channel formation is caused by traction forces according to the membrane flow concept, whereas channel elongation and vesiculation mainly result from pressure forces in conjunction with the extrusion of small hyaline pseudopodia. Shortening and disappearance of the pinocytotic channels are brought about by local contractions of the cortical filament layer in the basal region of the hyaline pseudopodia. Experiments using latex beads as marker particles together with inducing substances show that a rapid membrane turnover during pinocytosis can be excluded, and that the plasma membrane slides as an entire structure over the underlying cytoplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233919
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  • 3
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    Factors affecting the palmitoyl-coenzyme A desaturase of Saccharomyces cerevisiae (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The activity and stability of the palmitoyl-coenzyme A (CoA) desaturase complex of Saccharomyces cerevisiae was influenced by several factors. Cells, grown nonaerobically and then incubated with glucose, either in air or under N2, showed a marked increase in desaturase activity. Cycloheximide, added during such incubations, prevented the increase in activity, suggesting de novo synthesis. The stability of the desaturase from cells grown nonaerobically was affected by subsequent treatment of the cells; enzyme from freshly harvested cells, or from cells that were then shaken under nitrogen, readily lost activity upon washing or during density gradient analysis, whereas aerated cells, in the presence or absence of glucose, yielded stable enzyme preparations. The loss of activity in nonaerobic preparations could be reversed by adding soluble supernatant from these homogenates and could be prevented by growing the cells in the presence of palmitoleic acid and ergosterol, but not with several other lipids tested.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Journal of Bacteriology; 124; Nov. 197
    Format: text
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  • 4
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    Oxygen as a factor in eukaryote evolution - Some effects of low levels of oxygen on Saccharomyces cerevisiae (1979)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: A comparative study of the effects of varying levels of oxygen on some of the metabolic functions of the primitive eukaryote, Saccharomyces cerevisiae, has shown that these cells are responsive to very low levels of oxygen: the level of palmitoyl-Co A desaturase was greatly enhanced by only 0.03 vol % oxygen. Similarly, an acetyl-CoA synthetase associated predominantly with anaerobic growth was stimulated by as little as 0.1% oxygen, while an isoenzyme correlated with aerobic growth was maximally active at much higher oxygen levels (greater than 1%). Closely following this latter pattern were three mitochondrial enzymes that attained maximal activity only under atmospheric levels of oxygen.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Origins of Life; 9; Sept
    Format: text
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  • 5
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    Effects of aeration on formation and localization of the acetyl coenzyme A synthetases of Saccharomyces cerevisiae (1979)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Previous studies on the yeast Saccharomyces cerevisiae have shown that two different forms of the enzyme acetyl coenzyme A synthetase (ACS) are present, depending on the conditions under which the cells are grown. The paper evaluates the usefulness of a method designed to assay both synthetases simultaneously in yeast homogenates. The data presented confirm the possibility of simultaneous detection and estimation of the amount of both ACSs of S. cerevisiae in crude homogenates of this strain, making possible the study of physiological factors involved in the formation of these isoenzymes. One important factor for specifying which of the two enzymes is found in these yeast cells is the presence or absence of oxygen in their environment. Aeration not only affects the ratio of the two ACSs but also appears to affect the cellular distribution of these enzymes. Most of the data presented suggest the possibility that the nonaerobic ACS may serve as a precursor to the aerobic form.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Journal of Bacteriology; 137; Jan. 197
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  • 6
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    The Effects of Space Flight on Some Liver Enzymes Concerned with Carbohydrate and Lipid Metabolism in Rats (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: The activities of about 30 enzymes concerned with carbohydrate and lipid metabolism and the levels of glycogen and of individual fatty acids were measured in livers of rats ex- posed to prolonged space flight (18.5 days) aboard COSMOS 986 Biosatellite. When flight stationary, (FS) and flight centrifuged (FC) rats were compared at recovery (R(sub 0)), decrceases in the activities of glycogen phosphorylase, alpha glycerphosphate, acyl transferase, diglyceride acyl transferase, acconitase and Epsilon-phosphogluconate dehydrogenase were noted in the weightless group (FS). The significance of these findings was strengthened since all activities, showing alterations at R(sub 0), returned to normal 25 days post-flight. Differences were also seen in levels of two liver constituents. When glycogen and total fatty acids of the two groups of flight animals were determined, differences that could be attributed to reduced gravity were observed, the FS group at R(sub 0) contained, on the average, more than twice the amount of glycogen than did controls ad a remarkable shift in the ratio of palmitate to palmitoleate were noted. These metabolic alterations appear to be unique to the weightless condition. Our data justify the conclusion that centrifugation during space flight is equivalent to terrestrial gravity.
    Keywords: Life Sciences (General)
    Type: Physiologist; 21; 4
    Format: text
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