39 
The fourth group of experiments which are not to be initiated at pres- 
ent are as follows: certain of the possible beneficial applications of DNA 
recombinant research involve the creation of organisms with the ability 
to carry out useful environmental functions. Release of such organisms 
into the environment may, at some point, be required to test their efficacy 
and certainly to make use of them. The guidelines advise that widespread 
release of any organism containing recombined DNA not be undertaken at 
present unless a series of controlled tests leave no reasonable doubt as 
to their safety. 
Fifth, the resistance of various clinically important microorganisms 
to drugs, such as antibiotics is known to result from particular genes 
encoded in DNA. Recombinant experiments could therefore result in the in- 
troduction of resistance into species that do not naturally acquire such 
resistance. The guidelines advise that such experiments be deferred if 
they could compromise the use of a drug for the control of disease agents 
in medicine or in agriculture. 
Finally, the guidelines advise that experiments with recombinant mole- 
cules be limited in scale to volumes less than 10 liters if harmful genes 
are present. This recommendation reflects the greater probability of escape 
of organisms when large volumes are manipulated. 
The guidelines state that the advisory committee may make exceptions 
to this rule for particular experiments deemed to be of direct societal 
benefit. 
May I have the lights, please? 
The proposed guidelines then proceed with the classification of cur- 
rently permissible experiments. Recognizing the relation between the host- 
vector system required by the experiment, and the design of suitable bio- 
logical containment, experiments using the same host-vector system are 
grouped together in the document. At present the system of choice for many 
experiments is the common laboratory bacterium E_j_ coli — in particular, 
strain K12 — and independent genetic elements known to reside in this strain. 
There are two factors contributing to this conclusion. The first is 
that the strain has been studied extensively and can be readily manipulated 
for recombinant DNA experiments. Second, this same extensive experience and 
ease of manipulation permits modification of coli strain K12 and the vec- 
tors for the purpose of establishing biological containment. The strain, 
as well as various possible vectors can, to some degree, be made to behave 
to order by the use of classical genetics techniques, not by recombinant 
DNA methodology. 
It should be pointed out that the guidelines also discuss arguments 
against the use of E^_ coli K12, in particular the intimate association of 
[180] 
