Dr. Donald S. Fredrickson 
Page Three 
C . Biological Containment Criteria Using E. Coli K-12 Host-Vectors 
3. I believe this version of the guidelines should state that the 
Committee has, until further notice, the responsibility to certify for use 
any and all EK2 or EK3 vector-host systems. May I urge, however, 
that the guidelines acknowledge that with the experience and knowledge 
gained from the proliferation of EK2 and eventually EK3 vector-host 
systems, such certification can be assumed by more widely based scien- 
tific review groups, i. e. , study sections. 
D. Classification of Experiments Using the E. Coli K-12 Containment 
Systems 
1. Embryonic material must be handled aseptically to qualify for 
lower containment. 
2. I suspect that your proposal to increase the containment re- 
quirements for cloning DNA of cold-blooded vertebrates generated consi- 
derable flack at the Committee meeting. You state that there is not 
available evidence or arguments that support the previously recommended 
levels but I wonder what arguments there are for increasing them? I 
believe that with sterile embryonic or germ line DNA from such organisms, 
the P2 4- EKl requirement is reasonable (one should not underestimate the 
containment capability of EKl). There is the mistaken impression that 
anything in an EKl system is sure to become widely dissemated but the 
Committee report goes to some lengths to point out that that is not true. 
3. The whole business about insect pathogens and the possibility 
of contaminating the insect is beyond my competence so I won't comment 
(I do include a copy of a letter I recently received that is interesting in 
this context). But I do think the guidelines should take care not to include 
all lower eukaryotes with insects. Common yeast, Dictyostelium, tetra- 
hymera etc. are certainly not in the same category as organisms which 
might themselves be or harbor potential pathogens. If all experiments 
with lower eukaryotes were required to use EK2, that would immediately 
eliminate the very important and appropriate procedures developed by 
John Carbon for cloning pro- and lower eukaryote DNAs in E. coli plasmids. 
5. I believe the concern you express here should pertain to pro- 
karyote DNAs from organisms that are pathogenic or make a toxic product ; 
otherwise, I fail to see why EK2 should be required in place of EKl. 
Your suggestion to require EK2 for experiments involving DNA from pro- 
karyotes that do not exchange their DNA with E. coli concerns me. How- 
ever, your suggestion does include the possibility that the higher contain- 
ment requirement can be reduced if the recombinant genes are not 
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