LIGHT-MICROSCOPIC STUDIES OF 3T3 CELL PLASMA-MEMBRANE ALTERATIONS MEDIATED BY MELITTIN

W.-C. J. Lo, W. G. Henk and F. M. Enright. Light-microscopic studies o f 3T3 cell plasma membrane alterations mediated by melittin. Toxicon 3 5, 15-26, 1997.-Various light microscopic techniques were used to stud y the effect of melittin, a major toxic constituent of honey bee venom , on plasma membranes of 3T3 mouse fibroblasts. Bright-field light mic roscopy and Trypan Blue dye exclusion were used to demonstrate changes in membrane permeability after exposure to melittin. Differential int erference contrast (DIG) microscopy showed that membrane vesiculation induced by melittin was dose dependent. Using both fluorescent lipid a nd glycoprotein markers, we found that membrane vesicles were primaril y composed of lipids. A sequence of events associated with Vesicle for mation was depicted by DIC and fluorescence microscopy. Confocal laser scanning fluorescence microscopy demonstrated a translocation of memb rane glycoproteins from the plasma membrane to the cytosol following m elittin treatment. The significance of membrane vesiculation and trans location of membrane glycoproteins in damaged cells is discussed. Copy right (C) 1996 Elsevier Science Ltd.