10 
uct, it may be propagated at the same containment level as its 
purified natural DNA counterpart. For example, a synthetic DNA 
segment, to be propagated in E_. col i K-12, which corresponds to 
a nonharraful gene of birds, would require P2 physical containment 
plus and an EK1 host-vector, or PI ♦ EK2 . 
"If the synthetic DNA segment is not expressed as a poly- 
nucleotide or polypeptide product, or the products have no natural 
counterparts, the organisms containing the recombinant DNA mole- 
cules are exempt from the Guidelines." 
• The 1976 Guidelines and your proposed revised Guidelines in the 
section on "Fungal or Similar Lower Eukaryotic Host-Vector 
Systems" give little detail, "since the development of these 
host-vectors is presently in the speculative stage." The recent 
development of a Saccharomvces cerevis iae system makes this 
obsolete and suggests that this section be expanded. What is 
the Committee's view on the following proposed language? 
"Fungal or Similar Lower Eukaryotic Host-Vector System s 
"The containment criteria for DNA recombinant experiments 
using these host-vectors most closely resemble those for pro- 
karyotes, rather than those for the preceding eukaryotes, since 
the host cells usually exhibit a capacity for dissemination 
outside the laboratory that is similar to that for bacteria. 
Therefore, the procedures established for certification of HV 
systems other than E. coli K-12 (Section II-D-2) will also 
[511] 
