Dr. William Gartland 
May 11, 1979 
Page Four 
of some but not all individual mice and rats fed various EK1 hosts. All these 
results imply that although EK1 hosts may be less able to colonize the intestinal 
tract than natural E_. col i isolates, there are substantial differences dependent 
upon the Individual challenged and the means by which the bacteria are grown 
prior to challenge. Third, S. Levy has observed excretion of xl?76 containing 
pBR322 (x2236) for 4 days following feeding to humans. Since xl776 lacking a 
plasmid vector did not survive under the same experimental conditions and since 
we and others can find no differences in the x2236 isolates fed and recovered from 
the humans compared to x!776 (other than resistance to ampicillin and tetracy- 
cline), one can only infer that the pBR322 cloning vector confers a protective 
influence on survival of xl776 in the human but not in the rodent intestinal 
tract. Fourth, B. Sagik has observed that xl776 survives for several days but 
does not multiply, DP50 survives and does multiply to some extent and Charon 4A 
survives very well during sewage treatment. Fifth, as stated above, derepressed 
conjugative plasmids are more prevalent than previously realized. While only 
the last point would cause me to increase slightly our previously estimated prob- 
abilities for conjugational transmission of nonconjugative plasmid vectors per 
surviving EK1 and EK2 host cell per day, the first four points would indicate 
that the cumnulative likelihoods for transmission of recombinant DNA from EK1 and 
EK2 host-vector systems are considerably higher than previously believed. Thus, 
I surmise that if the participants at the Falmouth Conference had been aware of 
these data, more consideration would have been given to possible consequences of 
transmission of recombinant DNA to indigenous microorganisms of various natural 
environments. Similarly, the virologists attending the Ascot Conference might 
have also given due consideration to this issue rather than disregard it in pro- 
posing revised containment categories for cloning of eukaryotic viral information 
in E_. col i K-12 host-vector systems. 
Item 12 - Proposed cloning in spore-forming derivatives of Bacillus subtil is 
and Streptomyces coelicolor . I disagree with this proposed change in (or 
allowance under) the Guidelines. I do not believe it is prudent to permit 
spore-formers as hosts for cloning DNA from organisms that do not normally 
exchange DNA with the host. Indeed, had I read the January 15, 1979 Federal 
Register, I would have argued against allowance of any host-vector system for 
cloning foreign DNA unless it had a non-reverting mutation abolishing capacity 
to produce spores, conidia, etc. It seems to me that knowledge is altogether too 
fragmentary to validly conclude that the inadvertent, infrequent release of 
spores, conidia, etc. containing foreign DNA with the potential of survival for 
millenia would be totally harmless. 
I have restricted my comments to only those items on which I have strong feelings 
and at least some knowledge to evaluate the proposed changes. Nevertheless, I 
have the distinct feeling that many of the other proposed changes may be as ill 
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