SCANNING FORCE MICROSCOPY REVEALS ELLIPSOID SHAPE OF CHICKEN ERYTHROCYTE NUCLEOSOMES

Scanning force microscopy was used to investigate the conformation of hypotonic spread chicken erythrocyte nucleosomes. Nucleosomal chains w ere prepared in low-salt conditions and fixed before centrifugation on to glass coverslips and air drying, The images of single nucleosomes w ere isolated by image processing, and the height and geometry of the r esulting three-dimensional structures were investigated. An average nu cleosome height of 4.2 +/- 1.1 nm was determined, A virtual cross sect ion at half-maximum height of the nucleosome structure was used for a characterization of the nucleosome geometry, The shape of this cross s ection was best described by an ellipse with an aspect ratio (major/mi nor axis) of similar to 1.30.