Comparative Study of Chromosomal Structure

Abstract

X-ray diffraction and freeze fracture of purified nucleohistones and nuclei of selected cell types establish a foundation for the nucleosome as a fundamental subunit of chromosomal structure. Glycerol-buffer (50% v/v) solutions at 4°C improved preservation of the giant salivary gland chromosome (Drosophila) within nuclei. Two results are achieved as observed with freeze fracture and transmission electron microscopy.
1. Where chromosomal bands and interbands unfold into nucleosomal sub-units and the nucleus is swollen.
2. Where chromosomal bands and interbands composed of nucleosomal subunits are preserved as condensed polytene chromosomes which completely fill the nucleus without detectable distortion.