th The 16 Jerusalem Symposium debated on one of the most im­ portant subjects of modern molecular biology: the nucleic acids. It continued the tradition of gathering the most distinguished experts in the field. Placed under the auspices of the Isra~l Acade~y of Sciences and Humanities and the Hebrew University of Jerusalem it was sponsored by the Institut de Biologie Physico-Chimique (Fondation Edmond de Rothschild) of Paris and the Na~ional Foundation for Cancer Research of Bethesda, U. S. A. We wish to express our deep thanks to the Baron Edmond de Rothschild for his continuous generosity which guarantees the perenniality of these meetings and to the authorities of the National Foundation for Cancer Research, in particular Mrs Tamara Salisbury and Dr. Franklin Salisbury for having joined hands with us in this venture. We wish also to express our gra~itude to the adminis­ trative staff of the Isra~l Academy and in particular to Mrs Avigail Hyam for the efficiency and excellency of the local arrangements. Bernard Pullman , Joshua Jortner B. Pullman and J. Jortner (eds. ) , , Vucleic Acids the Vectors of Life, /-/5. © 1983 by D. Reidel PuhlisliinK Company. BASE SEQUENCE. I-!E. LJY ":'TRIJCTIIR!: I\NI' INTRIN