Ethidium Bromide intercalates within structure of the nucleic acids in such a manner that they fluoresce under the UV light. Ethidium bromide staining is generally used to visualize RNA or DNA in the agarose gels placed on the UV light boxes. Proper precautions are needed, because the ethidium bromide is extremely mutagenic and the UV light damaging to eyes. Ethidium bromide is also involved in cesium chloride gradients during the process of ultracentrifugation, to separate the supercoiled circular DNA from linear and the relaxed circular DNA.