Prefixation chromosome banding with heparin.

Attempts to achieve chromosomal banding by removal of histone proteins by acid or fixation procedures have failed up to now. Numerous biochemical investigations have shown that heparin has a strong and specific affinity to histone proteins. We describe a procedure by which treatment with heparin of nonfixed and fixed metaphase chromosomes leads to G banding; in the former case the effect is observed after a few minutes of heparin treatment; in the latter, much higher concentrations of heparin and 18--24 h incubation are needed. The morphologic effects of heparin treatment, the gradual disruption of chromosomal and nuclear chromatin, are associated with progressive reduction of histone detection (until completely negative) by the alkaline fast green test.