C-banding with specific fluorescent DNA-ligands: a new approach to constitutive heterochromatin heterogeneity.

The employment of certain DNA-specific fluorescent stains on unbanded and C-banded chromosomes of two species of grasshoppers shows remarkable differences among C-heterochromatic regions supposed to be similar in their base pair composition, according to their response to the standard fluorescence techniques. The possible interspersion of the opposite DNA base pairs in these regions as well as the role played by proteins in chromosome banding are discussed.