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i 
animal host) that determine if a DNA molecule can be 
transferred intact from E. coli host into mammalian 
cells. Broader scopes are proposed in other tests, 
involving shot-gunning of yeast, Dictyostelium, 
Salmonella and Drosophila DNA into E. coli K-12 and 
the study of possible alterations of its pathogenicity in 
mice. 
(vi) Dr. J. Goodman of SAI (Science Applications Inc., Ca.; 
Document No. 15) offers the professional collaboration of his 
organization, specialized in risk assessment efforts related 
to atomic energy facilities. 
(vii) Dr. D.F. Liberman, of MIT Biohazards Assessment Office 
(Document No. 16) describes procedures to test the escape 
of non-lytic and lytic EK-1 and EK-2 bacteriophage systems 
from primary physical containment. They are explicity 
directed at the problem of environment and personal 
monitoring, and designed to provide information concerning 
the effectiveness of containment under laboratory con- 
ditions. 
In summary, the answers which we received and those analyzed in 
this report confirm that both the USA and UK are carrying on studies 
specifically directed at the evaluation of physical and biological con- 
tainment. WHO is aiming at a broader objective, safety in all 
microbiological laboratories, through a reappraisal of all the relevant 
factors. 
Question 3: 
Estimate the frequencies of pro - and eukaryotic genetic exchanges in 
Nature (i.e. how widespread and frequent are foreign DNAs taken up, 
and maintained by pro - and eukaryotic organisms ?). 
Comments: 
Concerning Question 3, pro- and eukaryotic genetic exchanges in 
Nature, we have distinguished the following four parameters: 
a. uptake by pro- or eukaryotic cells of foreign DNA: 
b. integration of foreign DNA into the host cell genome; 
c. peristence or maintenance of foreign DNA in the host cell 
genome; 
d. expression of foreign DNA. 
Concerning point a. there is ample evidence in the literature that DNA 
of almost any origin can be taken up both by bacterial and eukaryotic 
cells. 
As for point b., integration of foreign DNA is clearly demonstrated in 
several instances; 1) integration of a piece of plasmid DNA from 
Agrobacterium tumefaciens into plant genomes causes tumor for- 
mation in plants (data of Schell and Van Montagu and other cited in our 
bibliography and by Dr. W. Fiers of Belgium; (Document No. 10). 2) In- 
tegration of eukaryotic DNA into a prokaryotic genome (S.N. Cohen 
cited in our bibliography). In other cases, integration is demonstrated 
indirectly by the expression of the foreign DNA (see below under d). 
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