Higher-order structure of chromatin from resting cells. II: High-resolution computer analysis of native chromatin fibres and freeze-etching of nuclei from rat liver cells

• Published in: Journal of cell science Vol. 62; no. 1; pp. 103 - 115
• Main Authors: NICOLINI, C, CAVAZZA, B, TREFILETTI, V, PIOLI, F, BELTRAME, F, BRAMBILLA, G, MARALDI, N, PATRONE, E
• Format: Journal Article
• Language: English
• Published: Cambridge Company of Biologists 01-07-1983
• Subjects: Animals; Biological and medical sciences; Cell Nucleus - ultrastructure; Chromatin - ultrastructure; Chromatin. Chromosome; Freeze Etching; Fundamental and applied biological sciences. Psychology; Image Enhancement; Liver - ultrastructure; Microscopy, Electron; Minicomputers; Molecular and cellular biology; Molecular genetics; Osmolar Concentration; Rats; Molecular arrangement; High performance; Chromatin; Rat; Image processing; Interphase; Liver; Cell nucleus; Rodentia; Electron microscopy; Vertebrata; Image analysis; Mammalia; Computerized processing; Freeze etching; G zero Phase
• ISSN: 0021-9533; 1477-9137
• DOI: 10.1242/jcs.62.1.103

Non-destructive electron microscopy of native chromatin from rat liver nuclei reveals that the 30 nm fibre is formed of four 11 nm nucleofilaments, arranged in a coiled-coil (or rope-like) conformation. At low ionic strength, native fibres show an alternating pattern of compact and unwound regions. Freeze-etching experiments carried out on the same nuclei are compatible with the existence of periodic attachments of the fibres to the nuclear envelope near the pores in a regular, drapery-like fashion. For the first time, computer image analysis has been applied to electron micrographs of giant chromatin fibres and a few essential geometrical parameters characterizing the conformation of the higher-order structures have been determined. No significant difference has been found between calf thymus and rat liver chromatin.