Curt Stern (August 30, 1902 - October 23, 1981) was a German-American geneticist. He made several important genetic discoveries, demonstrating chromosomal crossover in Drosophila weeks after Barbara McClintock and Harriet Creighton had done so in 1931. He demonstrated that there were multiple genes on the Drosophila Y chromosome and described the mechanism of dosage compensation. During World War II he led research for the American government on low dose radiation safety, his group concluding that there is no "safe" threshold below which radiation is not harmful. After the War his research focussed on human genetics; he wrote the very successful textbook Principles of Human Genetics, and studied what is now known as gene regulation. August 30 is the 242nd day of the year in the Gregorian Calendar (243rd in leap years), with 123 days remaining. ... 1902 was a common year starting on Wednesday (see link for calendar). ... October 23 is the 296th day of the year (297th in leap years) in the Gregorian Calendar, with 69 days remaining. ... 1981 is a common year starting on Thursday of the Gregorian calendar. ... Chromosomal crossover is the process by which two chromosomes, paired up during Prophase I of meiosis, exchange some distal portion of their DNA. Crossover occurs when two chromosomes, normally two homologous instances of the same chromosome, break and then reconnect but to the different end piece. ... Species Many; see text. ... Barbara McClintock For the illustrator named Barbra McClintock see, Barbara McClintock (illustrator). ... 1931 is a common year starting on Thursday. ... The human Y chromosome is one of two sex chromosomes, it contains the genes that cause testis development, thus determining maleness. ... Dosage compensation is a genetic regulatory mechanism which operates to equalize the phenotypic expression of characteristics determined by genes on the X chromosome so that they are equally expressed in the human XY male and the XX female. ... World War II was a truly global conflict with many facets: immense human suffering, fierce indoctrinations, and the use of new, extremely devastating weapons such as the atom bomb World War II, also known as the Second World War, was a mid-20th-century conflict that engulfed much of the... Gene regulation is the general term for cellular control of protein synthesis at the DNA-RNA transcription step. ...

Reference

• Burian, Richard M. 2000. Stern, Curt. American National Biography Online