41 
wise, the experiments should be carried out under P3 conditions if the 
source of the inserted DNA is not itself a pathogen, or known to carry 
such pathogenic agents, or to produce harmful products--and under P4 
conditions if these conditions are not met. 
The development and use of host-vector systems that exhibit a 
high level of biological containment permit a decrease of one step in 
the physical containment specified above (P4 -*■ P3 P2 -* PI ) . 
<c> Fungal or similar lower eukaryotic host-vector systems 
The containment criteria for experiments on recombinant DNAs using 
these host-vectors most closely resemble those for prokaryotes, rather 
than those for the preceding eukaryotes, in that the host cells usually 
exhibit a capacity for dissemination outside the laboratory that is 
similar to that for bacteria. We therefore consider that the contain- 
ment guidelines given for experiments with E_. col i K-12 and other pro- 
karyotic host-vectors (Sections 1 1 IB-1 and -2, respectively) provide 
adequate direction for experiments with these lower eukaryotic host- 
vectors. This is particularly true at this time since the development 
of these host-vectors is presently in the speculative stage. 
IV. Implementation 
A. Role of the principal investigator - The principal investigator 
has the responsibility for estimating the potential biohazards associated 
with the experiments on recombinant DNAs performed in the laboratories under 
ner or h^s direction, for instituting the appropriate safeguards within these 
1 aboratories , for developing procedures for minimizing the effects of 
acc'dents, r or training and ensuring the proficiency of relevant personnel 
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