title: Configurational changes in chromatids from helical to banded structures.
abstract: Induction of configurational changes in the helical chromatids of air dried chromosomes was used to explore the mechanism of G-banding. From the water-Giemsa stained metaphase spreads of Chinese hamster cells, chromosomes having clearly helical chromatids were selected and photographed. Then the chromosomes were decolorized, treated with trypsin, and restained with saline-Giemsa (1X SSC). Such procedures were repeatedly carried out upon the same chromosomes. Subsequent examination of the chromosomes showed that configurational changes from a helical structure to a banded structure had occurred. Some chromosomes revealed a variety of transitional changes between these two configurations. During the repeated G-banding treatments, the distances between bands along the same chromatids changed each time. The results obtained seem to indicate that the G-banding results from locally induced compaction of chromosomal materials along the chromatids.
mesh_terms: D000818:Animals; D001399:Azure Stains; D002842:Chromatids / Q000648:ultrastructure*; D002875:Chromosomes / Q000032:analysis; D006224:Cricetinae; D010640:Phenothiazines
chemical_list: D001399:Azure Stains; D010640:Phenothiazines