47 
Experiments involving such mixtures of DNA fragments are assumed to 
be of relatively high potential hazard because of the greater likelihood 
of dangerous and unknown genes being introduced into the recipient cell. 
On the other hand, a particular fragment may be purified from the mix- 
ture and used for joining to the vector DNA. Purified fragments containing 
mainly genes whose properties are known and are not harmful offer less po- 
tential hazard than a shotgun experiment. In some instances the foreign DNA 
will itself be derived from extra-chromosomal genetic elements. Such extra- 
chromosomal elements include the DNA of animal viruses, of plant viruses, of 
eukaryote organelles such as mitochondriaer chloroplasts and, finally, pro- 
karyotic plasmids or bacteriophage of the same type used as the vectors. 
Each of these cases is treated separately in the guidelines. 
The word prokaryote refers to some simple one-celled organisms which do 
not contain a well-defined nucleus. The word eukaryote refers to all other 
living species, and these all contain their genetic information within a 
clearly-defined nucleus. Furthermore, the prokaryote sources here are 
treated separately depending on whether the source of foreign DNA is an or- 
ganism that does or does not exchange genetic information with _E. coli in 
nature. 
The next few slides will summarize quickly the recommended containment 
for the various categories summarized here. 
May I have the next slide, please (9)? 
Slide 9 
Guidelines for Experiments with E. coli 
"Host-Vector" Systems. I 
'Foreign' DNA = Mixed Fragments = "Shotgun" 
Containment 
Foreign DNA Source 
Physical 
Biological 
Eukaryoles: Primates 
P3 
EK3 
P4 
° r EK2 
Embryonic 
P3 
EK2 
Other Mammals 
P3 
EK2 
Birds 
P3 
EK2 
Cold Blooded Vertebrates 
P2 
EK2 
embryonic 
P2 
EK1 
Lower Eukaryotes 
P2 
EK1 
if pathogenic 
P3 
EK2 
Higher Plants 
P2 
EK2 
if pathogenic 
P3 
EK2 
[188] 
