Theophilus Shickel Painter (August 22, 1889 – October 5, 1969) was an American

zoologist Zoology ( , ) is the scientific study of animals. Its studies include the structure, embryology, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems. Zoology is one ...

best known for his work on the structure and function of chromosomes, especially the sex-determination genes X and Y in humans. He was the first to discover that human sex was determined by an X/Y heteromorphic chromosomal pair mechanism. He also carried out work in identifying

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 in fruit flies (''

Drosophila ''Drosophila'' (), from Ancient Greek δρόσος (''drósos''), meaning "dew", and φίλος (''phílos''), meaning "loving", is a genus of fly, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or p ...

''). His work exploited the giant polytene chromosomes in the salivary glands of ''Drosophila'' and other

Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advance ...

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e. Painter was elected to the United States

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 1938 and the

American Philosophical Society The American Philosophical Society (APS) is an American scholarly organization and learned society founded in 1743 in Philadelphia that promotes knowledge in the humanities and natural sciences through research, professional meetings, publicat ...

in 1939.

Academic administration

Painter joined the faculty at the

University of Texas The University of Texas at Austin (UT Austin, UT, or Texas) is a public research university in Austin, Texas, United States. Founded in 1883, it is the flagship institution of the University of Texas System. With 53,082 students as of fall 2 ...

in 1916 and, except for military duty during World War I, stayed there his whole career. He was, in succession, associate professor, professor and distinguished professor of zoology. He served as acting president (1944–1946) and president (1946–1952) of the University of Texas and retired from active teaching in 1966.

Racial segregation

Painter was president of the University of Texas when Texas resident Heman Marion Sweatt applied for and was denied admission due to his race. Painter spoke out against integration, and voiced his disapproval of Sweatt's admittance. '' Sweatt v. Painter'', 339 U.S.629 (1950), which proved an integral stepping stone in the landmark case '' Brown v. Board of Education of Topeka, Kansas'' that held that "separate is inherently unequal" and led to the integration of America's public schools.

Gender research

Painter is also known for his early study of human chromosomes. In a paper published in 1923, he first gave the number 24 for the count of human meiotic

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. He had tried to count the tangled mass of chromosomes he could see under a microscope in

spermatocyte Spermatocytes are a type of male gametocyte in animals. They derive from immature germ cells called spermatogonia. They are found in the testis, in a structure known as the seminiferous tubules. There are two types of spermatocytes, primary and s ...

s in slices of

testicle A testicle or testis ( testes) is the gonad in all male bilaterians, including humans, and is Homology (biology), homologous to the ovary in females. Its primary functions are the production of sperm and the secretion of Androgen, androgens, p ...

and arrived at the figure of 24. Others later repeated his experiment in other ways and agreed upon the number of 24. Popular thinking held that if there were 24 chromosomes in spermatocytes, there must be an equal number contributed by the female and the human chromosome number must be 48, which was undisputed for more than 30 years. Then in 1955, Joe Hin Tjio and Albert Levan, using more advanced techniques, looked at the chromosomes in human somatic cells and found 46 chromosomes and the human chromosome number was finally revised. In 1934 Painter was awarded the Daniel Giraud Elliot Medal from the

References

External links

* * {{DEFAULTSORT:Painter, Theophilius Painter, Theophilus Shickel Members of the United States National Academy of Sciences Painter, Theophilus Shickel Painter, Theophilus Shickel Painter, Theophilus Shickel Painter, Theophilus Shickel American science teachers 20th-century American academics Members of the American Philosophical Society

Academic administration

Racial segregation

Gender research

See also

References

External links