Calvin Blackman Bridges was an American scientist, known for his contributions to the field of genetics

Genetics

Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....

. Along with Alfred Sturtevant

Alfred Sturtevant

Alfred Henry Sturtevant was an American geneticist. Sturtevant constructed the first genetic map of a chromosome in 1913. Throughout his career he worked on the organism Drosophila melanogaster with Thomas Hunt Morgan...

 and H.J. Muller, Bridges was part of the famous fly room of Thomas Hunt Morgan

Thomas Hunt Morgan

Thomas Hunt Morgan was an American evolutionary biologist, geneticist and embryologist and science author who won the Nobel Prize in Physiology or Medicine in 1933 for discoveries relating the role the chromosome plays in heredity.Morgan received his PhD from Johns Hopkins University in zoology...

 at Columbia University

Columbia University

Columbia University in the City of New York is a private, Ivy League university in Manhattan, New York City. Columbia is the oldest institution of higher learning in the state of New York, the fifth oldest in the United States, and one of the country's nine Colonial Colleges founded before the...

.

Bridges wrote a masterful Ph.D. thesis on "Non-disjunction as proof of the chromosome

Chromosome

A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...

 theory of heredity." It appeared as the first paper in the first issue of the journal Genetics in 1916.

His work with sex linked traits in the fruit fly Drosophila melanogaster

Drosophila melanogaster

Drosophila melanogaster is a species of Diptera, or the order of flies, in the family Drosophilidae. The species is known generally as the common fruit fly or vinegar fly. Starting from Charles W...

suggested that chromosome

Chromosome

A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...

s contained gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

s. Later Nettie Maria Stevens was able to prove this hypothesis by examining the chromosomes of the fruit flies. Bridges wrote a couple of papers presenting the proof. He thanked her as "Miss Stevens" without stating what her contribution was nor referring to her PhD.

Bridges' best-known contribution among Drosophila researchers is his observation and documentation of the polytene chromosome

Polytene chromosome

To increase cell volume, some specialized cells undergo repeated rounds of DNA replication without cell division , forming a giant polytene chromosome...

s found in larval salivary gland cells. The banding patterns of these chromosomes are still used as genetic landmarks even by contemporary researchers.

Further reading

• Allen, Garfield E. Thomas Hunt Morgan: the man and his science. Princeton University Press 1978
• E.A. Carlson, Mendel's Legacy: The Origin of Classical Genetics, (Cold Spring Harbor Laboratory Press, 2004). ISBN 0-87969-675-3
• E.A. Carlson, The Gene: A Critical History, (Iowa State Press, 1989). ISBN 0-8138-1406-5
• Kohler, Robert E. Lords of the fly: Drosophila genetics and the experimental life. University of Chicago Press 1994.
• A. H. Sturtevant, A History of Genetics, (Cold Spring Harbor Laboratory Press,2001). ISBN 0-87969-607-9