THE UNIVERSITY OF CHICAGO 
DEPARTMENT OF BIOPHYSICS AND THEORETICAL BIOLOGY 
Dr. Donald Fredrickson 
Director 
National Institutes of Health 
Bethesda, MD 20205 
Dear Dr. Fredrickson: 
This letter is in support of the proposed amendment 
to the recombinant DNA guidelines pertaining to experiments 
using E. coli K22 Host vector systems (Federal Register M*_, N232, 
p. 69218, Nov. 30, 1979). The experience and knowledge obtained 
during the last years fully substantiates these changes. 
CUMMINGS LIFE SCIENCE CENTER 
920 EAST 58TH STREET 
CHICAGO • ILLINOIS 60637 
December 10, 1979 
Sincerely yours 
Lucia B. Rothman-Denes 
Assistant Professor 
LBRD : ap 
1439 ] 
