116 
Drs. Helinski, Rowe, and I think Dr. Zaitlin, replacing Dr. Day in the plant 
area, to take up the revisions that pertain to the experimental Guidelines. 
Dr. Helinski, are you ready to begin? 
DR. HELINSKI: Well, to give you an idea of what is ahead, I am going 
to take something like 15 to 20 minutes to make some comments on Section 
III, the experimental section of the Guidelines. I will be followed by 
Drs. Rowe and Zaitlin. Some of the things I am going to say have already 
been said, and I am sorry if some of this sounds a little bit repetitious, 
but I would like to try to give you more or less a complete picture which 
has served as a major basis for the revisions we've proposed in the experi- 
mental section of the Guidelines. 
This section deals both with prohibited recombinant DNA experiments, 
and also with containment levels for permissible experiments. The present 
Guidelines list five classes of recombinant DNA experiments and practices 
that at the present time are prohibited. I emphasize that there are no 
revisions in this list of experiments that have been proposed, and that is 
because the Committee feels that, while certain of the recombinant DNA 
experiments on this list may indeed not pose any biohazard, nevertheless 
in our view it remains prudent, given our present state of knowledge, to 
continue to defer from conducting these experiments at the present time. 
However, as part of this section, it is proposed as a revision that spe- 
cific experiments in each of the five classes may be exempted from this 
prohibition on the basis of compelling scientific and/or social reasons, and 
any such exemption must have the express approval of the Director of NIH. 
Now, I would like to comment on the revisions and the containment 
levels for the so-called permissible experiments. While recombinant DNA 
experiments potentially can be carried out with a great variety of host- 
vector systems — I say potentially — most of these experiments, I think you 
are aware, at the present time utilize the bacterium Escherichia coli K-12 
as the host cell. Thus, while the revised Guidelines provide in some detail 
a consideration of other host-vector systems as discussed earlier this after- 
noon by Dr. Gottesman, the Guidelines, including the proposed revisions, 
continue to be concerned mainly with the well-studied E. coli K-12 strains 
as a prokaryotic host for recombinant DNA. 
In proposing the revisions and containment levels for recombinant 
DNA experiments using this E. coli K-12 host-vector system or systems, it 
should be emphasized at the outset that our Committee, the RAC group, is 
attempting as best as we can to fulfill what we view is our responsibility 
to periodically review and modify the Guidelines to reflect improvements 
in our knowledge of the potential biohazards from this research, and the 
available safeguards. This responsibility of the Committee, I emphasize, 
is a major principle in the design of the present NIH Guidelines for Recom- 
binant DNA Research — that is, the Guidelines that were issued in July of 
last year. 
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