70 
In the second example, the robust E^_ coli is used, with a nonconjuga- 
tive pSClOl plasmid vector. All probabilities remain the same as for the 
first example, except the probability for transmission of recombinant DNA, 
which is now reduced to 10”!^ that is one with another 10 zeroes on this 
number, per surviving escaped bacterium per day. 
In these first two examples, the potential problem is therefore asso- 
ciated with a reasonably high potential of the escaped bacteria to survive 
in nature. 
In the last example an EK2 E. coli host is used, and since this strain 
should not be able to survive in nature, the perpetuation of the recombinant 
DNA in nature becomes equal to the probability of survival times the proba- 
bility of transmissability , an exceedingly unlikely event. 
Lights, please. 
It is therefore my current opinion that the use of genetically disarmed 
host-vectors in conjunction with appropriate physical containment facilities 
and practices should reduce the probabilities of danger, if indeed they 
exist at all, to an astronomically small value. Nevertheless, this is not a 
reason to reduce our guard, since much information is lacking, and informa- 
tion is needed to permit a more accurate assessment of these potential bio- 
hazards associated with recombinant DNA molecule research. 
Thank you. 
DR. FREDRICKSON: Thank you very much. Dr. Curtiss, especially the 
additional small abstract on those interesting strains which are numbered 
with some extraordinary historical perspective. 
Drs. Singer, Berg, Hogness and Curtiss will be, I think, with us this 
afternoon. However, if there are any questions to any of these individuals, 
particularly that any member of the committee would like to bring up, we can 
afford to spend five or ten minutes in that exercise at this time. 
Mr. Hutt? 
MR. HUTT: Don, I am not sure whether they are the persons to address 
the question to, but one question that occurs to me is that we have not con- 
sidered how easy these experiments are — that is, what type of equipment is 
necessary simply to do the type of scientific experimentation, how readily 
available the raw materials or whatever you call them are, and therefore 
whether these could be done, for example, by a high school biology teacher 
or by a college level, or only a graduate level, et cetera. 
DR. FREDRICKSON: That is a fair question. Dr. Berg? 
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