THE UNIVERSITY OF CHICAGO 
DEPARTMENT OF BIOPHYSICS AND THEORETICAL BIOLOGY 
CUMMINGS LIFE SCIENCE CENTER 
920 EAST 5 8 T H STREET 
CHICAGO • ILLINOIS 60637 
December 18, 1978 
Dr. Donald Frederickson 
Director 
National Institutes of Health 
Bethesda, MD 20205 
Dear Dr. Fredrickson: 
I strongly support your proposal that "experiments involving propagation 
of recombinant DNA in EK-1 hosts should be exempted from the Guidelines, 
but be carried out at the PI level of physical containment. ..." 
(Federal Register, Nov. 30, 1979). This proposal is a reasonable one 
considering our extensive knowledge of I[. coli K12, and it does not 
compromise high standards of containment. 
Sincerely 
Richard A. Fisher, Ph.D. 
ap 
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