2 
DNA on the pathogenicity of E.coli because prokaryotic signals 
for transcription and translation differ markedly from eukaryotic 
signals . 
6. Does E.coli K-12 implant in the intestinal tract of laboratory 
animals? 
7. Does E.coli K-12 implant in the human intestine? 
The arguments developed in response to questions 6 and 7 were 
used to justify revision of the guidelines in 1978. 
8. Does E.coli infect laboratory personnel? 
The data cited in response to this question comes from the 
laboratories of Dr. Mark Richmond (Bristol), Dr. E.S. Anderson 
(London), and Dr. Stanley Falkow (Seattle). The data shows that 
neither workers in these laboratories nor their families acquired 
bacterial strains or plasmids employed in the laboratories. 
Again, these results are reassuring, but their use to support 
the dismantling of the NIH guidelines is questionable. The observations 
were made in the laboratories of three leading bacteriologists , 
whose staffs are trained in the handling of pathogenic organisms. 
Thus the most likely interpretation of these results is that micro- 
organisms can be handled safely by trained personnel. If this inter- 
pretation is correct, the results say nothing about the handling 
of microorganisms by untrained personnel under conditions of minimal 
control . 
9. Will E.coli K-12 carrying recombinant DNA survive? 
It should be noted that this question is meaningless as it stands. 
The question appears to mean; "Can E.coli K-12 carrying recombinant 
DNA survive in competition with other bacterial strains in mam- 
malian hosts?" Preliminary results of two experiments are cited, 
presumably in support of the view that E.coli K-12 cannot survive 
under such circumstances , or survives with very low probability . 
The first result is a table, submitted by D. Brown , ~' c detailing the 
results of competition experiments between K-12 strains with and 
without recombinant DNA inserts. The table shows that while the 
strain without the insert always outgrew the same host with recombinant 
DNA, "the growth differential was not large, since it sometimes took 
many generations for the host to take over the population." The 
second result is a table, submitted by P. Burnett" '''detailing survival 
of E.coli K-12 strains carrying recombinant plasmids containing 
insulin gene sequences. The table shows that in conventional rats 
and mice, the strain and the plasmid were lost during a time period 
of 72- 192 hours. In germ-free rodents, the plasmid persisted longer, 
up to 50 days. 
* Item #4 in part 2 of "Background Documents on E.coli K-12/P1 
Recommendation." * **Item #9 in part 2 of the "Background Documents." 
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