From polynucleotide phosphorylase to neurobiology.

In the fall of 1944, I enrolled at the Hebrew University of Jerusalem. The student body numbered about 700 and the choice of faculties was somewhat limited.My hopewas to study medicine, but the plans to open a medical school were still at the drawing board stage. I therefore chose to study chemistry with biochemistry and bacteriology as minor subjects, which I thought I would need later if I went into medicine. As employment opportunities were limited in British Mandatory Palestine, it was hoped that university training would help me get a job in the food technology industry or at the Dead Sea potash industry. When I started as a student, the structure and function of DNA and RNA were not known. Thymonucleic acid (DNA) had been isolated from thymus and pus, and zymonucleic acid (RNA) was found in yeast. The tetranucleotide hypothesis for DNA suggested by Phoebus Aaron Theodor Levene still prevailed, and there were speculations about branched chain as distinct from linear structures for RNA. Nucleic acids were also considered as nothing more than a storehouse of phosphorus for the varying requirements of the cell. However, the role of DNA in bacterial transformation, demonstrated byOswald Theodore Avery, ColinMacLeod, andMaclynMcCarty in 1944, was discussed extensively during our bacteriology courses. Within a few years, I had the good fortune to enter the nucleic acid field where progress had evolved dramatically. In June 1949, upon the completion of my studies at the Hebrew University of Jerusalem, Professor Ernst David Bergmann, the Scientific Director of theWeizmann Institute of Science, invited me to join him as his Ph.D. student. I gladly accepted and moved to Rehovot, which was then a small village with about 7000 inhabitants. Ernst Bergmann was an organic chemist, a former student of the noted German chemist, Wilhelm Schlenk, and co-worker of Professor Chaim Weizmann, the first President of the State of Israel. Bergmann had a dynamic and brilliant personality with an encyclopedic knowledge of chemistry and a broad interest in science (1). For my doctoral dissertation, Bergmann recommended I choose a subject close to Chaim Weizmann’s scientific interests, namely the mechanism of pentose fermentation in bacteria.While I was in the advanced stages ofmy doctoral work, Sol Spiegelman from theDepartment ofMicrobiology of the University of Illinois, Urbana came to Rehovot to consider an offer that had been made to him to join the Weizmann Institute. Spiegelman suggested that for my postdoctoral studies I contact Arthur Kornberg, Head of the Department of Microbiology of theWashington University School ofMedicine in St. Louis,Missouri. Kornberg had justmoved from theNational Institutes ofHealth (NIH) and was recruiting people for his new department. I was greatly impressed by Arthur Kornberg’s early publications on coenzyme and nucleotide synthesis and decided to write and ask if he would accept me as a postdoctoral fellow. Spiegelman offered to talk to Kornberg on my THE JOURNAL OF BIOLOGICAL CHEMISTRY VOL. 280, NO. 47, pp. 38889 –38897, November 25, 2005 © 2005 by The American Society for Biochemistry and Molecular Biology, Inc. Printed in the U.S.A.