Freeze-fracture autoradiography of the red blood cell plasma membrane

Morphological changes of the plasma membrane in the white adipose cell associated with lipid mobilization were assessed qualitatively and quantitatively on freeze-fracture replicas of epididymal adipose tissue from fasted and from streptozotocin-diabetic rats. The number of plasma membrane invaginations and intramembranous particles were evaluated per square micrometer of membrane and per entire adipocyte. These two determinations show that the number per square micrometer (local concentration) of both structural features progressively increases with the duration of diabetes and fasting, while that at the same time their number per entire cell (total content) remains unchanged. These data thus show: (a) a reorganization of the adipose cell plasma membrane during lipolysis; and (b) that this reorganization can be detected only by determining the concentration and the total content of the structural features of the membrane involved.

Download Full-text

Lack of morphological changes of the adipose cell plasma membrane during aging: Application of the freeze-fracture technique

AGE ◽

10.1007/bf02432249 ◽

1979 ◽

Vol 2 (3) ◽

pp. 70-72 ◽

Cited By ~ 1

Author(s):

Annick Jacobs ◽

Claude Remacle ◽

Michel Jeanjean

Keyword(s):

Plasma Membrane ◽

Morphological Changes ◽

Freeze Fracture ◽

Cell Plasma Membrane ◽

Adipose Cell ◽

Cell Plasma

Download Full-text

Studies of membrane fusion. IV. Fusion of HeLa cells with Sendai virus

Journal of Cell Science ◽

10.1242/jcs.36.1.73 ◽

1979 ◽

Vol 36 (1) ◽

pp. 73-84

Author(s):

S. Knutton

Keyword(s):

Plasma Membrane ◽

Membrane Fusion ◽

Cell Fusion ◽

Hela Cells ◽

Sendai Virus ◽

Freeze Fracture ◽

Viral Envelope ◽

Cell Plasma Membrane ◽

Virus Particles ◽

Cell Plasma

The Sendai virus-induced fusion of HeLa cells has been studied by freeze-fracture electron microscopy. Freeze-fracture observations confirm previous scanning electron-microscope studies (1977) and show that at 4 degrees C virus particles bind to the cell surface and that cell agglutination results from the crosslinking by virus particles of microvilli on adjacent cells. Incubation at 37 degrees C initiates a change in viral envelope structure and fusion of ‘altered’ virus particles with the cell plasma membrane. Fusion of a virus particle with two crosslinked cells is probably the membrane fusion event which initiates cell-cell fusion; fusion is completed as a result of virally induced cell swelling. Lateral diffusion of viral envelope components following virus-cell fusion and, in some instances, an aggregation of plasma membrane intramembrane particles occurs in swollen cells. These observations show that the mechanisms of viral envelope-cell and probably cell-cell fusion are the same as have been reported for erythrocytes. Although endocytosis of intact virus particles does occur, the specialized cell-mediated mechanism for fusion of the viral envelope with the cell plasma membrane suggests that this, and not viropexis, is the mechanism of Sendai virus infection.

Download Full-text