Genetics is a discipline initially worked out by Gregor Mendel (Austrian monk) using common pea plants in his garden.Since then many great minds used genetics to understand important problems of biology, including the study of evolution and how plants and animals develop. The power of genetics and its importance to mankind was first time recognized by the award of Nobel prize in Physiology or medicine in 1933 to T.H.Morgan . The role of his students, especially A.H.Sturtevant, C.B. Bridges and H.J.Muller was immense in making Drosophila, a powerful model system to understand genetics. The legacy of great geneticists was continued by Edward B. Lewis, an American scientist born on May 20, 1918. Ed Lewis scientific work can be divided into two parts: First his Drosophila research and second his work on ionizing radiation and cancer.

Ed’s goals while studying Drosophila were: “understanding gene, its function, how it mutates and how it evolve”. Ed worked on various aspects of genetics in early part of his career but his work on Bithorax mutants made him most popular. Infact for me the terms “Hox genes” and “Ed Lewis” are synonyms.

Ed’s 1978 article in Nature about bithorax complex is a paradigm for genetic control of development. Information of 30 years of work is mentioned in six pages. It’s one of most difficult papers to read and understand but it’s more than worth giving a try but don’t be upset if you don’t understand as it is really a complex genetic study. Ed was the first person to predict that substances of bithorax complex would function both by activation and repression. Genetic analysis performed by Lewis also helped him to predict that the genes in bithorax complex were evolved by tandem duplication: Now we know that there are three tandemly duplicated protein coding Hox genes Ubx, Abd-A and Abd-B forming the bithorax complex. Ed lewis identified the famous mutants of bithorax region like Cbx and Pbx, which are the basis for his famous four winged fly. But he was wrong on one count in predicting 12 genes in bithorax complex ,which turned out to be only three. Most of the 12 genes which Ed identified turned out to be cis regulatory elements which control the time , place and expression of protein coding genes of bithorax complex.

Its not all his fault as it not possible for anyone to predict molecular complexity solely on genetic studies, one need molecular tools also. A Collaboration with David Hogness led to a giant step in mechanistic understanding of development, which was instrumental is first positional cloning of a gene (The gene was Ubx ) and first functional analysis. Functional cloning of Ubx also played a important role in landmark discovery of Homeo domain by Walter Gehring’s lab in 1984.

Ed Lewis was awarded Nobel Prize in Physiology or Medicine in 1995 which he shared with Eric Wieschaus and Christine Nussllein Volhard. Ed died of Cancer July 21 2004,at the age of 86(he was active in the lab until shortly before his death) bringing an end to outstanding seven decades of research and an era in Drosophila genetics and developmental biology.

Refernece :
Howard D. Lipshitz
From fruit flies to fall out: Ed Lewis and his science.
Journal of genetics, Vol 83, No. 2, August 2004.

LS. Shashidhara
Edward B Lewis (1918–2004)

A gene complex controlling segmentation in Drosophila.
Lewis EB.
Nature. 1978 Dec 7;276(5688):565-70.

Related Posts:

• Top 15 articles on Hox function- Part I
• Homeotic genes / Hox genes
• Top 15 articles on Hox function- Part III
• Origin of Helmets in Treehoppers: A beautiful example of evolution at work
• Top 15 articles on Hox function- Part II

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