NORTHWESTERN UNIVERSITY 
BVANSTON, ILLINOIS 60201 
DEPARTMENT OF BIOCHEMISTRY 
AND MOLECULAR BIOLOGY 
18 August 1978 
Donald S. Fredrickson, Director 
National Institutes of Health 
Bldg. 1, Room 124 
Bethesda, Maryland 20014 
Dear Dr. Fredrickson: 
I read the proposed revisions of the guidelines governing NIH-sponsored recombinant 
DNA research with great interest. First, let me say that I strongly endorse the 
general relaxation of the current guidelines. I agree with the report (p. 33047, 
Federal Register, Vol. 43, No. 146) that in view of the recent findings in both 
viruses and eucaryotic structural genes (i.e., that intervening sequences interrupt 
coding portions of genes) , the possibility of genes of higher organisms being 
expressed in procaryotic hosts is greatly reduced. It appears that nature has 
already provided a more stringent requirement for expression than we had perceived, 
and also probably provides better safety features than those presently uhed 
in our EK2 host/vector constructs. (I feel compelled to point out that this change 
in our perception was obviously the result of structural studies on recombinant 
DNA's by Leder and Chambon, and the use of recombinant DNA probes by Flavell) . 
Thus, I think that the decision to revise the guidelines to allow research under 
more relaxed physical and/or biological containment conditions is both judicious and 
timely. 
Sir ’ ‘ 
James Douglas Engel, Ph.D 
Assistant Professor 
JDE/kaf 
[A-28] 
