New Haven, Connecticut 06520 
DEPARTMENT OF BIOLOGY 
Kline Biology Tou er 
P.0. Box 2169 
December 21, 1979 
Dr. Donald S. Fredericks on 
Director, National Institutes of Health 
Bethesda, Maryland 20205 
Dear Dr. Frederickson : 
I am pleased that you are considering a reduction in containment require- 
ments for recombinant ENA experiments involving E. coli K12. Experience during 
the past few years in many laboratories in this country and Europe have demon- 
strated beyond reasonable doubt that the original concerns over such experiments 
were considerably exaggerated. With a reduction in the amount of unnecessary 
extra work, experiments using recombinant ENA methodologies can proceed more 
efficiently with benefit to all concerned. 
Joseph G. Gall 
Professor of Biology 
JGG/db 
[ 579 ] 
