HARVARD UNIVERSITY 
The Biological Laboratories 
16 Divinity Avenue 
Cambridge, Massachusetts 02138 
December 14, 1979 
Dr. Donald Fredrickson 
Director of the N.I.H. 
Bethesda, Maryland 20205 
Dear Dr. Fredrickson: 
I strongly urge that the proposed new recombinant DNA guidelines, 
as specified in the Federal Register of November 30, 1979, be 
approved. I was one of those who originally had concerns about 
the safety of these experiments, but I am now firmly convinced 
that the dangers have been vastly overrated and that the current 
set of regulations is unnecessary and highly detrimental to the 
development of science. 
I am concerned about one sentence in the proposed guidelines, 
namely, the one beginning "An exception, however, which does 
require prior review...". There is no evidence to suggest 
that E. ooli K12 synthesizing a eukaryotic protein would be 
harmful, and I think that our recent experience shows that 
specifying special precautions against purely hypothetical and 
very unlikely hazards is a dubious policy at best. I therefore 
urge that this sentence be eliminated. Failing that amendment, 
I must ask for a clarification of the intent of the sentence in 
question. As I read the relevant paragraph, these "expression" 
experiments are understood to be appropriately carried out at 
the Pl-EKl level of containment. I am afraid that an alternate, 
presumably unintended, reading would be that each IBC is urged 
to set its own standards on these experiments. This policy, I 
am sure you would agree, would be disastrous. 
Sincerely, 
MARK PTASHNE 
Professor of Biochemistry 
and Molecular Biology 
MP : c jm 
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