- Joe Hin Tjio
Joe Hin Tjio (1916 - 2001), was a
cytogeneticist who is renowned because he was the first person to recognize the normal number of humanchromosome s. This epochal event occurred on December 22, 1955 at the Institute of Genetics of theUniversity of Lund inSweden , where Tjio was a visiting scientist.Tjio (whose name is pronounced CHEE-oh) was born to Chinese parents in
Java , then part of theDutch East Indies . His father was a photographer. Tjio was educated in Dutch colonial schools, trained inagronomy in college, and did research on potato breeding. He was imprisoned for 3 years and tortured by the Japanese in aconcentration camp duringWorld War II .After the war ended, Tjio went to
The Netherlands , whose government provided him with a fellowship for study in Europe. He worked in plant breeding inDenmark ,Spain and Sweden. From 1948 to 1959 he did plant chromosome research inZaragoza in Spain and spent his summers and vacations in Sweden working with ProfessorAlbert Levan in Lund.It was during one of his vacation stays in Lund that Tjio made his discovery of the correct human chromosome. For fully a half century it had been accepted that people have 48 chromosomes. Now Tjio knew "the chromosome number of man" was 46. Tjio's revolutionary finding was published (with Levan as his co-author) in the Scandinavian journal "Hereditas" on January 26, 1956, only a month and four days after the discovery.
In 1958 Tjio went to the
United States and in 1959 he joined the staff of theNational Institutes of Health inBethesda, Maryland . He spent the balance of his long career at theNIH in human chromosome research. He retired in 1992.References
*Tjio JH, Levan A. The chromosome number of man. Hereditas vol. 42: pages 1-6, 1956.
External links
* [http://www.medterms.com/script/main/art.asp?articlekey=19198 Human chromosome count] in MedTerms Medical Dictionary
* [http://www.nih.gov/news/NIH-Record/02_11_97/story01.htm Tjio Ends Distinguished Scientific Career] by Rich McManus in The NIH Record
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