recombinant DNA will eliminate regulation of experiments with 
prokaryote DNA cloned into E. c oli K-12 where the organisms normally 
exchange genetic information with E. coli K-12. 
Dr. Helinski then summarized the results from a series of 
published and unpublished experiments that the RAC believed justi- 
fied its decision to lower containment levels. A recent conference 
held on risk assessment indicated that E. coli K-12 could neither be 
converted to a pathogen nor could it colonize the normal human gut. 
The variant strain ^1776 could not even be established in germ 
free mice. Other data indicated that plasmid transfer in the 
intestines was infrequent and required the use of conjugative 
plasmids, and the narrow host range of phage vectors markedly 
limited their transmissabil ity. Dr. Helinski went on to present 
evidence that exchange of genes can occur in nature in normally 
nonexchanging species. Finally he described experiments in which 
plants have been shown to take up bacterial DNA and alternatively 
in which eukaryotic DNA has been taken up by bacterial cells and 
incorporated in the host genome. 
Dr. Helinski then responded to questions from the DAC. He 
noted that decisions on exceotions to prohibited experiments would 
be made by the Director, NIH on the recommendation of the RAC. 
He also pointed out that experiments were underway to assay for 
the possibility of plasmid escape through the sewage system or 
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