clone. The definition of a clone is, in fact, a population, all of which 
are derived from a single parent. 
51 
In the experiment on this slide the clone contains only recombinant B. 
Cloned populations are judged to be inherently less potentially hazardous 
for reasons similar to those outlined for the case when purified DNA frag- 
ment is used for the joining. Consequently, the containment required once 
the cloning procedure has been carried out is less than the containment 
required for the original shotgun experiment. 
The cloning of a desired fragment will, of course, as pointed out by 
Dr. Berg before, be one of the normal aims of many recombinant experiments. 
As shown in the next slide, (13) the guidelines state that the cloned 
recombinant DNA must be characterized in indicated manners, be free from 
harmful genes, and also that approval must be obtained from the agency sup- 
porting the work before the containment can be lowered to the categories 
which are shown here. There are two categories, one for DNA which origi- 
nally came from species which exchange information in nature with _E. coli 
and another category for those that don't. 
Slide 13 
Guidelines for Experiments with E. coli 
"Host-Vector" Systems III 
Cloned Recombinant DNA 
a) rigorously characterized 
b) absence of harmful genes 
c) approval from granting agency 
Then: 
"Exchangers" 
"Non-exchangers" 
PI 
EK1 
P2 
EK1 
[192] 
