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1983 (1)
1Author    J. Kukulies, W. Stockem, K.E W Oh Lfarth-B, Tterm AnRequires cookie*
 Title    Caffeine-Induced Surface Blebbing and Budding in the Acellular Slime Mold Physarum polycephalum  
 Abstract    The mechanism of plasma m em brane proliferation was studied in the acellular slime mold Physarum polycephalum with the aid o f light and electron microscopical techniques. Treatm ent of protoplasmic drops with a Tris-buffered 15 m M caffeine solution causes surface blebbing and budding over periods of 5 -9 0 min. The process o f surface blebbing is coupled to a 5 -10-fold increase of the surface area in conjunction with characteristic changes in cytoplasmic m orphol­ ogy. Successive constriction of blebs exhibiting different sizes and degree o f hyalo-granulo-plasmic separation leads to the form ation of num erous spherical caffeine droplets. D uring the process of surface budding and droplet formation the total surface area o f the original (genuine) protoplasmic drop is not reduced, but continues to grow. Freeze-etch studies show that caffeine concomitantly causes characteristic changes in the fine structure of the plasma membrane. D uring the initial phase of surface blebbing the original density of intram embranous particles (IMP) is reduced from 3676/|am2 to 1669/um2 and the PF; EF ratio (IM P/|im 2 protoplasmic face: exoplasmic face) shifts from 2.4:1 to 2.8:1. W hen surface budding is completed the IMP-density in the plasm a m em brane of single caffeine droplets increases again to 2289/nm 2 and the P F :E F ratio changes to 1.5:1. Simultaneously, the isolated caffeine droplets produce numerous small hyaline m em brane protrusions, which are pinched off and contain no IMP. Control experiments dem onstrate that T ris-buffer w ithout caffeine also shows a weak capacity to induce surface blebbing, to change the IM P-density and the P F : EF ratio (2443/nm2; 1.5:1); but Tris-buffer fails to cause surface budding. On the other hand, different concentrations of sucrose (2 5 -2 0 0 m M) can supress to a certain degree both caffeine-and Tris-buffer-induced surface blebbing, but not caffeine-dependent surface budding. The caffeine-effect is reversible insofar as protoplasm ic drops with blebbing and budding activity recover to normal morphology, fine structure and locom otion when transferred to physiological conditions. The mechanisms of successive changes in plasm a m em brane morphology as well as the mode of a participation of the actomyosin system in cell surface dynamics are discussed. 
  Reference    Z. Naturforsch. 38c, 589—5 (1983); received F ebruary 7 1983 
  Published    1983 
  Keywords    Physarum polycephalum, Surface Blebbing and Budding, Caffeine, Plasmalemm a, Cytoplasmic Äctomyosin 
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 TEI-XML for    default:Reihe_C/38/ZNC-1983-38c-0589.pdf 
 Identifier    ZNC-1983-38c-0589 
 Volume    38