Calvin Blackman Bridges (January 11, 1889 – December 27, 1938) was an American scientist known for his contributions to the field of

genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinians, Augustinian ...

. Along with

Alfred Sturtevant Alfred Henry Sturtevant (November 21, 1891 – April 5, 1970) was an American geneticist. Sturtevant constructed the first genetic map of a chromosome in 1911. Throughout his career he worked on the organism ''Drosophila melanogaster'' with ...

and H.J. Muller, Bridges was part of

Thomas Hunt Morgan Thomas Hunt Morgan (September 25, 1866 – December 4, 1945) was an Americans, American evolutionary biologist, geneticist, Embryology, embryologist, and science author who won the Nobel Prize in Physiology or Medicine in 1933 for discoveries e ...

's famous "Fly Room" at

Columbia University Columbia University in the City of New York, commonly referred to as Columbia University, is a Private university, private Ivy League research university in New York City. Established in 1754 as King's College on the grounds of Trinity Churc ...

Early life

Calvin Blackman Bridges was born in Schuyler Falls,

New York New York most commonly refers to: * New York (state), a state in the northeastern United States * New York City, the most populous city in the United States, located in the state of New York New York may also refer to: Places United Kingdom * ...

in 1889 to the parents of Leonard Bridges and Charlotte Blackman. Tragically, Calvin's mother died when he was two years old, and his father died a year later, leaving the young Calvin an orphan. Bridges was subsequently taken in and raised by his grandmother. It took Bridges several years to complete high school, graduating when he was 20 years old. Despite this setback, he moved on to be an outstanding student at

New York City New York, often called New York City (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...

, which he attended both undergraduate and postgraduate school. While taking a

zoology Zoology ( , ) is the scientific study of animals. Its studies include the anatomy, structure, embryology, Biological classification, classification, Ethology, habits, and distribution of all animals, both living and extinction, extinct, and ...

class at Columbia, Bridges met

. This started a relationship which would eventually lead to many important scientific discoveries regarding genetics and

evolution Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

Work and research

The "Fly Room" experiments began in 1910 and continued for seventeen years, with Thomas Hunt Morgan being the project's lead experimental developer."Bridges, Calvin Blackman." Complete Dictionary of Scientific Biography. Vol. 2. Detroit: Charles Scribner's Sons, 2008. 455-457. Gale Virtual Reference Library. Web. 28 Jan. 2015. Among many others working alongside Bridges and Morgan in the laboratory were

and

Hermann Joseph Muller Hermann Joseph Muller (December 21, 1890 – April 5, 1967) was an American geneticist who was awarded the 1946 Nobel Prize in Physiology or Medicine, "for the discovery that mutations can be induced by X-rays". Muller warned of long-term dang ...

. The "Fly Room" experiments were the first to use the common fruit fly ''

Drosophila melanogaster ''Drosophila melanogaster'' is a species of fly (an insect of the Order (biology), order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly", "pomace fly" ...

'' for research in genetics, because they are cheap, easily accessible, and reproduce quickly.Muhlrad, Paul J. "Fruit Fly: Drosophila." Genetics. Ed. Richard Robinson. Vol. 2. New York: Macmillan Reference USA, 2003. 42-45. Gale Virtual Reference Library. Web. 28 Jan. 2015. The experiments resulted in many important early discoveries in the field, resolved previously unclear issues such as the organization of genetic information within

chromosome A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most import ...

s, chromosomal arrangement, and linkage in

sex chromosome Sex chromosomes (also referred to as allosomes, heterotypical chromosome, gonosomes, heterochromosomes, or idiochromosomes) are chromosomes that carry the genes that determine the sex of an individual. The human sex chromosomes are a typical pair ...

s, and contributed to the emergence of modern treatments of genetics and

evolutionary biology Evolutionary biology is the subfield of biology that studies the evolutionary processes such as natural selection, common descent, and speciation that produced the diversity of life on Earth. In the 1930s, the discipline of evolutionary biolo ...

from their classical foundations, all in an era before

molecular biology Molecular biology is a branch of biology that seeks to understand the molecule, molecular basis of biological activity in and between Cell (biology), cells, including biomolecule, biomolecular synthesis, modification, mechanisms, and interactio ...

had yet revealed the structure or nature of

DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...

. The group also contributed to the understanding of the impact of

mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, ...

s on evolution in general. The success of the "Fly Room" experiments eventually made ''D. melanogaster'' a widely popular

model organism A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. Mo ...

for biological research of all types. Bridges in particular was responsible for many improvements regarding the techniques and the equipment used in the experiments. He suggested the use binocular microscopes instead of hand lenses that had been using before, which improved data quality and convenience. Bridges also developed temperature controls for the experiments which proved to be more useful and yielded better results than the previous temperature controls. Bridges published many works, one of his most famous being "Sex in Relation to Chromosomes and Genes". He also contributed many items to the ''Journal of Experimental Zoology'' and ''Science''. His work with sex-linked traits suggested that chromosomes contained

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

s; Nettie Maria Stevens was later able to support 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 Ph.D. Bridges' PhD thesis on " Non-disjunction as proof of the chromosome theory of heredity" appeared as the first paper in the first issue of the journal ''Genetics'' in 1916. In this paper, he also established that the

Y chromosome The Y chromosome is one of two sex chromosomes in therian mammals and other organisms. Along with the X chromosome, it is part of the XY sex-determination system, in which the Y is the sex-determining chromosome because the presence of the ...

does not determine gender in ''Drosophila''. Bridges' best-known contribution among ''Drosophila'' researchers is his observation and documentation of the polytene chromosomes found in larval

salivary gland The salivary glands in many vertebrates including mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands ( parotid, submandibular, and sublingual), as well as hundreds of min ...

cells. The banding patterns of these chromosomes are still used as genetic landmarks even by contemporary researchers. Bridges was elected to the

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, NGO, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the ...

in 1936 for his work with ''Drosophila''. After his death, Bridges' student Katherine Brehme Warren completed work on ''The Mutants of Drosophila melanogaster'' (1944), a classic book which was for two decades an indispensable resource for geneticists, with information from the "Red Book" later being transferred to the FlyBase database. Morgan and Sturtevant destroyed almost all of Bridges' notebooks after his death, except the four which were not in their possession.

Personal life

Bridges married Gertrude Ives, with whom he had four children. He was known to be both brilliant and very kind and considerate, though he was equally well-known for his womanizing and his struggles to keep up with family obligations. He was an atheist.H J Muller, 'Dr. Calvin B. Bridges', ''Nature'' 143, 191–192 (4 February 1939). In 1938, Bridges died from what is believed to have been a case of

syphilis Syphilis () is a sexually transmitted infection caused by the bacterium ''Treponema pallidum'' subspecies ''pallidum''. The signs and symptoms depend on the stage it presents: primary, secondary, latent syphilis, latent or tertiary. The prim ...

References

Sources

1. "Bridges, Calvin Blackman." ''Complete Dictionary of Scientific Biography''. Vol. 2. Detroit: Charles Scribner's Sons, 2008. 455-457. Gale Virtual Reference Library. Web. 26 January 2015. 2. Muhlrad, Paul J. "Fruit Fly: Drosophila." ''Genetics''. Ed. Richard Robinson. Vol. 2. New York: Macmillan Reference USA, 2003. 42-45. Gale Virtual Reference Library. Web. 26 January 2015. 3. "Bridges, Calvin Blackman." ''Britannica Biographies'' (2012): 1. Middle Search Plus. Web. 26 January 2015. 4. Gambis , Alexis, director. The Fly Room . Imaginal Disc, 2014.

External links

National Academy of Sciences Biographical Memoir
* * {{DEFAULTSORT:Bridges, Calvin 1889 births 1938 deaths American atheists American geneticists Columbia University alumni History of genetics People from Schuyler Falls, New York Scientists from New York (state)