George Wald (November 18, 1906–April 12, 1997) was an American scientist who is best known for his work with pigments in the retina. He won a share of the 1967 Nobel Prize in Physiology or Medicine with Haldan Keffer Hartline and Ragnar Granit. November 18 is the 322nd day of the year (323rd in leap years), with 43 remaining. ... 1906 was a common year starting on Monday (see link for calendar). ... April 12 is the 102nd day of the year in the Gregorian calendar (103rd in leap years). ... 1997 is a common year starting on Wednesday of the Gregorian calendar. ... This article is about the profession. ... Human eye cross-sectional view. ... 1967 was a common year starting on Sunday of the Gregorian calendar. ... List of Nobel Prize laureates in Physiology or Medicine from 1901 to the present day. ... Haldan Keffer Hartline (December 22, 1903 - March 17, 1983) was an American physiologist who was a cowinner (with George Wald and Ragnar Granit) of the 1967 Nobel Prize in Physiology or Medicine for his work in analyzing the neurophysiological mechanisms of vision. ... Ragnar Arthur Granit (October 30, 1900, Helsinki, Finland - March 12, 1991, Stockholm, Sweden) was a Finnish scientist who won the Nobel Prize in Physiology or Medicine in 1967, along with Haldan Keffer Hartline and George Wald. ...

Research

Wald plotted the absorbance of rod pigment (black curve), then later the absorbance of cone pigments (red, green, and blue curves)

As a postdoctoral researcher, Wald discovered that vitamin A was a component of the retina. His further experiments showed that when the pigment rhodopsin was exposed to light, it yielded the protein opsin and a compound containing vitamin A. This suggested that vitamin A was essential in retinal function. Spectral absorption curves of the short (S), medium (M) and long (L) wavelength pigments in human cone and rod (R) cells. ... Spectral absorption curves of the short (S), medium (M) and long (L) wavelength pigments in human cone and rod (R) cells. ... Retinol, the dietary form of vitamin A, is a fat-soluble, antioxidant vitamin important in vision and bone growth. ... A rhodopsin molecule (yellow) in the cell membrane (blue). ...

In the 1950s, Wald and his colleagues used chemical methods to extract pigments from the retina. Then, using a spectrophotometer, they were able to measure the light absorbance of the pigments. Since the absorbance of light by retina pigments corresponds to the wavelengths that best activate photoreceptor cells, this experiment showed the wavelengths that the eye could best detect. However, since rod cells make up most of the retina, what Wald and his colleagues were specifically measuring was the absorbance of rhodopsin, the main photopigment in rods. Later, with a technique called microspectrophotometry, he was able to measure the absorbance directly from cells, rather than from a extract of the pigments. This allowed Wald to determine the absorbance of pigments in the cone cells (Goldstein, 2001). In physics, spectrophotometry is the quantitative study of spectra. ... Prism splitting light Light is electromagnetic radiation with a wavelength that is visible to the eye (visible light) or, in a technical or scientific setting, electromagnetic radiation of any wavelength. ... The wavelength is the distance between repeating units of a wave pattern. ... Photoreceptor cells are contained in the retina and are responsible for transducing, or converting, light into signals that can be ultimately transmitted to the brain via the optic nerve. ... Normalised absoption spectra of human rod (R) and cone (S,M,L) cells. ... Normalised absorption spectra of human cone (S,M,L) and rod (R) cells Cone cells, or cones, are cells in the retina which only function in relatively bright light. ...

Biography

Wald was born in New York City to Isaac Wald and Ernestine Rosenmann, Jewish immigrant parents. He received his Bachelor of Science degree from New York University in 1927 and his PhD in zoology from Columbia University in 1932. After graduating, he received a travel grant from the US National Research Council. Wald used this grant to work in Germany with Otto Heinrich Warburg where he identified vitamin A in the retina. Wald then went on to work in Zurich, Switzerland with the discoverer of vitamin A, Paul Karrer. Wald then worked briefly with Otto Fritz Meyerhof in Heidelberg, Germany, but left Europe for the University of Chicago in 1933 when Adolf Hitler came to power and life in Europe became more dangerous for Jews. In 1934, Wald went to Harvard University where he became an instructor, then a professor. He was elected to the National Academy of Sciences in 1950 and in 1967 was awarded the Nobel Prize for Physiology or Medicine for his discoveries in vision. New York City, officially named the City of New York, is the most populous city in the United States, the most densely populated major city in North America, and is at the center of international finance, politics, entertainment, and culture. ... The word Jew ( Hebrew: יהודי) is used in a wide number of ways, but generally refers to a follower of the Jewish faith, a child of a Jewish mother, or someone of Jewish descent with a connection to Jewish culture or ethnicity and often a combination of these attributes. ... New York University (NYU) is a major research university in New York City. ... Zoology (Greek zoon = animal and logos = word) is the biological discipline which involves the study of animals. ... Columbia University is a private university in the Morningside Heights neighborhood of Manhattan, New York City. ... Location within Switzerland   Zürich[?] (German pronunciation IPA: ; usually spelled Zurich in English) is the largest city in Switzerland (population: 366,145 in 2004; population of urban area: 1,091,732) and capital of the canton of Zürich. ... Paul Karrer (April 21, 1889-June 18, 1971) was a Swiss biochemist best known for his work on vitamins. ... Otto Fritz Meyerhof (April 12, 1884 - October 6, 1951), German-U.S. physician and biochemist. ... Map of Germany showing Heidelberg Heidelberg (halfway between Stuttgart and Frankfurt) is a city in Baden-Württemberg, Germany. ... The University of Chicago is a private co-educational university located in Chicago, Illinois. ... Adolf Hitler ( ♫) (April 20, 1889 – April 30, 1945) was Chancellor of Germany from 1933 and Führer und Reichskanzler (Leader and Chancellor) of Germany from 1934 to his death. ... Harvard University is a private university in Cambridge, Massachusetts, USA, and a member of the Ivy League. ... President Harding and the National Academy of Sciences at the White House, Washington, DC, April 1921 The National Academy of Sciences (NAS) is a corporation in the United States whose members serve pro bono as advisers to the nation on science, engineering, and medicine. ... Sir Edward Appletons medal Photographs of Nobel Prize Medals. ...

Wald spoke out on many political and social issues and his fame as a Nobel laureate brought national and international attention to his views. He was a vocal opponent of the Vietnam War and the nuclear arms race. The Vietnam War or Second Indochina War was a conflict between the Democratic Republic of Vietnam (DRVN, or North Vietnam), allied with the National Liberation Front (NLF, or Viet Cong) against the Republic of Vietnam (RVN, or South Vietnam), and their allies—notably the United States military in support of... The nuclear arms race was a competition for supremacy in nuclear weapons between the United States and Soviet Union during the Cold War. ...

In 1980, Wald served as part of Ramsey Clark's delegation to Iran during the Iran hostage crisis. 1980 is a leap year starting on Tuesday. ... Attorney General Clark & President Lyndon B. Johnson. ... The Iran hostage crisis was a 444-day period during which the new government of Iran after the Iranian Revolution held hostage 66 diplomats and citizens of the United States. ...

With a small number of other Nobel laureates, he was invited in 1986 to fly to Moscow to advise Mikhail Gorbachev on a number of environmental questions. While there, he questioned Gorbachev about the arrest, detention and exile to Gorki of Yelena Bonner and her husband, fellow Nobel laureate Andrei Sakharov, (Peace, 1975). Wald reported that Gorbachev said he knew nothing about it. Bonner and Sakharov were released shortly thereafter, in December, 1986. Mikhail Sergeyevich Gorbachyov (Gorbachev)   listen[?] (Russian: ; pronunciation: ) (born March 2, 1931), was leader of the Soviet Union from 1985 until 1991. ... The name Gorki or Gorky (Горький) can refer to any of the following things: Leninskie Gorki (Горки) - a village near Moscow where Lenin died in 1924 Nizhny Novgorod (from 1932-1990 called Gorki) Maxim Gorky Arshile Gorky Gorky Park (Novel) - a novel by Martin Cruz Smith Gorki,a Belgian band... Yelena Bonner (born February 15, 1923) is a human rights activist in the former Soviet Union and wife of late Andrei Sakharov. ... Andrei Sakharov, 1943 Andrei Dmitrievich Sakharov (Андре́й Дми́триевич Са́харов, May 21, 1921 – December 14, 1989), was an eminent Soviet-Russian nuclear physicist, dissident and human rights activist. ...

Wald died in Cambridge, Massachusetts. City Hall - Cambridge MA Cambridge is a city in the Greater Boston area of Massachusetts, United States. ...

References

Goldstein, B. 2001. Sensation and Perception, 6th ed. London: Wadsworth.

External links

• Nobel Prize Biography
• A remembrance by fellow biologist John Dowling
• A remembrance by his son Elijah

Two of George Wald's speeches can be read on-line:

• A Generation in Search of a Future
• The Origin of Death