Study the effects of metallic ions on the combination of DNA and histones with molecular combing technique

The effects of monovalent (Na, K) and divalent (Mg, Ca, Mn) ions on the interaction between DNA and histone are studied using the molecular combing technique. λ-DNA molecules and DNA-histone complexes incubated with metal cations (Na, K, Mg, Ca, Mn) are stretched on hydrophobic surfaces, and directly observed by fluorescence microscopy. The results indicate that when these cations are added into the DNA solution, the fluorescence intensities of the stained DNA are reduced differently. The monovalent cations (Na, K) inhibit binding of histone to DNA. The divalent cations (Mg, Ca, Mn) enhance significantly the binding of histone to DNA and the binding of the DNA-histone complex to the hydrophobic surface. Mn also induces condensation and aggregation of the DNA-histone complex.