Teaching a course on nucleic acid structure is a hazardous undertaking,
especially if one has no continuous teaching obligations. I still have
done it on several occasions in various French universities, when
colleagues, suffering from admin- istrative overwork and excessive
teaching obligations, had asked me to do so. This was generally done
with a pile of notes and a dozen slides, and I always regretted that no
small, concise, specialized book on nucleic acid structure for students
at the senior or beginning graduate level ex- isted. Every year, the
lecture notes became more and more voluminous, with some key reprints
intermingled. Everything changed when, in the spring of 1973, I re-
ceived an invitation to teach such a course, under the
UNESCO-OAS-Molecular Biology Program at the Universi- dad de Chile in
Santiago during October 1973. I had ac- cepted rather enthusiastically,
but soon discovered that it would be necessary to produce a photocopied
syllabus for the students. This was the fi rst premanuscript of this
book. For nonscientific reasons, the course was first canceled and then
postponed until December 1973. Nearly a year later, the course, in
slightly amended form, was presented at the Lemonossow-State University
in Moscow.