EMBO EUROPEAN MOLECULAR BIOLOGY ORGANIZATION 
Dr. D. S. Fredrickson 
Dept, of Health, Education, and 
Welfare 
Public Health Service 
NIH 
Bethesda, Md. 20014 
USA 
EMBO European MolaCuiar 0<o'ogy Organization 
Posrfach K 722 40 6900 Ha.<j*barQ 1 
Postfach 1022.40 
6900 Heidelberg 1 
West Germany 
Tel. Heidelberg (062 21) 38 30 31 
14 September 1978 
Dear Don, 
Thank you for your kind letter of September 5th. EMBO is grateful 
to have been given the opportunity of assisting in the development of 
the revised guidelines , and we hope that they can be formally adopted 
without significant change. They will greatly reduce the impediments to 
research without sacrificing levels of containment adequate to protect 
the environment from conjectural hazards. The decision to adopt the 
revised guidelines will, of course, have considerable repercussions in 
Europe, especially in those countries which either use the NIH guide- 
lines or have national guidelines closely modelled on the latter. 
There is one general point I would like to make which relates not 
so much to the revised guidelines themselves but to decisions that will 
have to be taken once they come into force. It seems to me that three 
general sorts of evidence have led to the conclusion that it is reason- 
able to relax the guidelines : first, there is the general argument that 
organisms carrying foreign DNA are likely to be at a selective disadvantage 
to their wild type counterparts ; secondly, there is the point that the 
split gene organisation in eukaryotes reduces the probability of an 
eukaryotic gene being expressed in a prokaryote unless elaborate measures 
are taken to induce expression ; thirdly, and perhaps most importantly , 
so long as E.coli K12 systems are being used there seems to be no 
significant risk of harm to anyone or anything. However, this confidence 
in the safety of E.coli K12 systems should not blind us to the fact that 
we are very ignorant of the ecologies and biologies of other species which 
might be used as host/vector systems. We must be very careful when, 
bolstered by this confidence in E.coli K12 systems, we try to extrapolate 
to B. subtilis, yeast, etc. etc. 
[A-147] 
