Ethidium bromide
Ethidium bromide is an intercalating
Intercalation (chemistry)
In chemistry, intercalation is the reversible inclusion of a molecule between two other molecules . Examples include DNA intercalation and graphite intercalation compounds.- DNA intercalation :...

 agent commonly used as a fluorescent tag
Fluorescent tag
In molecular biology and biotechnology, a fluorescent tag is a part of a molecule that researchers have attached chemically to aid in detection of the molecule to which it has been attached. The tag is some kind of fluorescent molecule...

 (nucleic acid
Nucleic acid
Nucleic acids are biological molecules essential for life, and include DNA and RNA . Together with proteins, nucleic acids make up the most important macromolecules; each is found in abundance in all living things, where they function in encoding, transmitting and expressing genetic information...

Staining (biology)
Staining is an auxiliary technique used in microscopy to enhance contrast in the microscopic image. Stains and dyes are frequently used in biology and medicine to highlight structures in biological tissues for viewing, often with the aid of different microscopes...

) in molecular biology
Molecular biology
Molecular biology is the branch of biology that deals with the molecular basis of biological activity. This field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry...

 laboratories for techniques such as agarose gel electrophoresis. It is commonly abbreviated as "EtBr", which is also an abbreviation for bromoethane
Bromoethane, also known as ethyl bromide, is a chemical compound of the haloalkanes group. It is abbreviated by chemists as EtBr. This volatile compound has an ether-like odour.-Preparation:...

. When exposed to ultraviolet light, it will fluoresce
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation of a different wavelength. It is a form of luminescence. In most cases, emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation...

 with an orange colour, intensifying almost 20-fold after binding to DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

. Under the name homidium, it has been commonly used since the 1950s in veterinary medicine to treat trypanosomosis in cattle, a disease caused by trypanosomes.