HARVARD UNIVERSITY 
The Biological Laboratories 
16 Divinity Avenue 
Cambridge, Massachusetts 02138 
December 20, 1979 
Dr. Donald Fredrickson, Director 
National Institute of Health 
Bethesda, MD 20205 
Dear Dr. Fredrickson: 
The purpose of this letter is to express my approval and support of 
the proposed guidelines for recombinant DNA research as they appeared in 
the federal register, November 30, 1979. 
In particular, I would like to express my approval of section III-O 
(page 69218) which concerns the classification of experiments using E. 
coli K-12 host vector systems. I strongly support the proposal that most 
experiments employing IT_ coli K-12 should not require registration with 
N.I.H. In my opinion, recombinant DNA experiments employing E. coli K-12 
can be safely carried out using PI physical containment and EK1 biological 
containment. I base this statement on: i) five years of personal experience 
performing recombinant DNA experiments, and ii) my assessment of experiments, 
reported in the literature, designed to test the safety of the K-12 system. 
I also support the proposal that experiments involving a deliberate attempt 
to efficiently express eukaryotic genes in E. coli K-12 should require 
prior I.B.C. approval. 
Sincerely yours. 
Frederick M. Ausubel 
Assistant Professor of Biology 
Harvard University 
FMA/rh 
[ 558 ] 
