Biographical Memoirs Volume 78 (2000) / Chapter Skim
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George Wald
George Wald
Pages 298-317
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— Ace —— 7~> ~)
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initiating conformational changes in the protein that leacl eventually to the excitation of the photoreceptor cells. Walcl's finclings represented!
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in the Universe" to political issues. The Vietnam War horrified him and, beginning in the micI-1960s until shortly before his death, he was deeply involved in anti-war and anti-nuclear activities.
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H Morgan en cl met Selig Hecht, his future mentor.
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the native pigment has a reciclish-purple color, termed visual purple by Kuhne and later called rhodopsin. In light the pigment bleaches to a yellowish-orange product (visual yellow)
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In the micicIle of the summer, however, a fortuitous situation arose that enabler! George to make a quantum leap forward in the unclerstancling of visual pigment biochemistry.
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retinas of certain fish were a darker purple than were frog retinas, and so in the mid1930s he began to study this en cl other questions in the summers at the Marine Biological Laboratory at Woocis Hole. He returned to Woocis Hole virtually every summer, teaching for many years in the famous physiology course en cl becoming eventually a trustee of the laboratory.
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Salmon live in salt water but spawn in fresh water, whereas eels clo the opposite. The result he founcl was that the vitamin A usecl and the visual pigment produced goes with the spawning environment.
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At the conclusion of the war, Wald returned to studying visual pigment molecules. He was joined in this work by two inclivicluals who were to play essential roles in his laboratory until he retired en cl who themselves became clistinguishecl investigators, Ruth Hubbard joined the laboratory as a graduate student en c!
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cis isomer, 9-cis, will form a light-sensitive pigment, but with lower light sensitivity and a different absorption maximum. No other isomer works at all.
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. Membrane voltage of the photoreceptor cell relates to cyclic GMP levels en cl moclulates neurotransmitter release from the cell.
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Metarhodopsin II is the active intermediate leading to excitation of the photoreceptor cell. Eventually, the chromophore of rhodopsin, retinal, separates from the protein opsin and is reduced to vitamin A (retinol)
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At the same time, Paul Brown built a microspectrophotometer in the laboratory that enablecl the measurement of the absorption spectrum of the human fovea en c! then of single cones.
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George presided and we discussed science, politics, or whatever, and all joined in, from undergraduates like myself to professors emeriti such as Alex Forbes. The discussions were entertaining Provocative and invariabIv stimulating.
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From that moment on, politics became his primary interest: He was a forceful spokesperson against the Vietnam War, nuclear arms proliferation, en cl the military-inclustrial complex. In this effort, his wit en c!
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TIMOTHY GOLDSMITH, DONALD GRIFFIN, and particularly Ruth Hubbard and Elijah Wald provided material for this memoir. The piece that Ruth Hubbard and Elijah Wald wrote for the Novartis Foundation Symposium held in Japan in 1998 in honor of George Wald was particularly helpful (R.
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1919. Sensory equilibrium and dark adaptation in Mya arenaria.
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GE ORGE WALD SELECTED BIBLIOGRAPHY 1934-1935 Vitamin A in eye tissues.
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Visual pigments in single rods and cones of the human retina. Science 144:45.
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GE ORGE WALD 1968 317 Les Prix Nobel en 1967. The molecular basis of visual excitation: Nobel Lecture.
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