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i 
The effects on mice following infection with E. coli cells 
carrying the cDNA’s to C-type virus should give concrete 
information on the fear of inadvertent cloning of retrovirus 
genomes in the course of shot-gun experiments with 
mammalian DNAs. At a later stage, cloning or replication- 
defective murine-sarcoma viruses could be studied, and 
attempts could be made to induce carcomas in mice with 
such clones. 
Finally, shot-guns of chromosomal DNA from mice known to 
contain C-type viruses could provide much wanted in- 
formation. Although not cited by Dr. Stetten, the NIH En- 
vironmental Impact Statement can be considered: the 
possible undesirable impact of experiments conducted 
under the guidelines, is concluded to be extremely unlikely, 
and difficult to evaluate in realistically meaningful terms (see 
Holliday’s paper listed in Bibliography section). 
The alteration of the biological properties of useful animals or plants 
by the introduction of recombinant DNA molecules will certainly involve 
a series of specific experimental steps. Each will be designed to 
overcome one or more of the series of barriers in the recipient 
organisms and, of course, the experiments will require appropriate 
physical containment until the recipient organism has been thoroughly 
characterized. We consider the probability of accidentally altering the 
biology of plants and animals' outside the laboratory to be in practice 
negligible. 
Question 7: 
“Clarify aspects of the ecology and natural history of 
microorganisms, plasmids and bacteriophages as they relate to the 
probabilities of disseminating infections via such vectors.” 
Comments: 
There is some overlap with these responses and answers to Question 
3. Thus: 
(i) Dr. Bollard (New Zealand: Document No. 9) cites experiments 
of Professor Bacon (Massay University) which are testing the 
ability of chloramphenicol-resistant conforms isolated from 
sewage to transfer drug resistant plasmids to E. coli K-12. It 
is hoped that these results, as well as data from W. Arber 
(Switzerland; Document No. 5) regarding incorporation of 
insertions or deletions into PI plasmids, will be available in 
the not-too-distant future. 
(ii) Dr. T. lino (Japan; Document No. 19) reports that the 
“distribution of R-plasmids and their transferability in the 
natural environment’’, is being studied and that Professors. 
Mitsuhashi, Gumma University, is the Convenor of the 
relevant research group sponsored by the Japanese Ministry 
of Education, Science and Culture. 
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