A simple procedure for obtaining autoradiographs of G-banded chromosomes.

Chromosomal preparations from cells flash-labeled with 3H-dT were Giemsa-banded following trypsin digestion, allowed to air-dry, and then were coated with a layer of 1% Formvar. The slides were subsequently coated with radiographic emulsion (NTB2) and processed for autoradiography. The resulting chromosomes had distinct G-banding and radiographic labeling patterns. Chemographic grain formation in the emulsion, normally caused by Giemsa stain, was prevented by the film of Formvar, allowing a very low background grain level.