-4- 
Theoretically, the investigator has the following options: 
Option(i) : If bacterium A is transformable and a vector capable of 
replicating in it is available, the investigator could clone DNA from A 
directly into the mutants. Alternatively, the investigator could construct 
a "colony bank" by cloning the DNA from bacterium A using A as the host. 
He would then reintroduce recombinant molecules into each mutant of A, 
either by transformation with DNA extracted from the recombinant clones, or 
by conjugative mobilization using an appropriate conjugative plasmid as a 
mobilizer. Such a plasmid, if not already present naturally, can be intro- 
duced artificially into the cloning host prior to the initial cloning step 
or subsequently, into the individual recombinant colonies, for example, 
by performing tri parental crosses. 
None of the above steps would involve "novel" recombinant molecules; 
therefore, none of the regulations contained in the proposed revisions will 
apply. Thus, (1) organisms A and the vector plasmid will not have to be 
certified as a host-vector system; (2) A could contain conjugative plasmids; 
(3) the construction of strains simultaneously carrying conjugative elements 
and "non-novel" recombinant plasmids would not be prohibited (4) in fact, the 
vector plasmid could be a conjugative one (for example, RP4 or RK2 ! ) . According 
to the revisions, the investigator could also transfer his recombinant plasmids 
to any organism with which organism A can exchange chromosomal DNA by natural 
physiological processes and in which the plasmid vector could normally rep- 
licate, without having to comply with regulations. 
Option (ii): The investigator could construct a "colony bank" using DNA 
from bacterium A and another bacterial host B, with which A may not exchange 
chromosomal DNA by natural physiological processes but which satisfied better 
the technical prerequisites of transformability, vector replication, recombination- 
[ Appendix A — 113] 
