Chilton - p. 4 
Drs. Kado , Panopoulos, Shepherd and Bruening in a letter to 
the Director of NISI. These plant pathologists recommend no 
containment higher than P2EK2 for the cloning of DNA from 
plant pathogenic bacteria. This places such cloning experi- 
ments at the same level of containment as those involving 
plant viral genomes. I would strongly urge that the level of 
containment for cloning DNA from plant pathogenic bacteria 
be set at P2EK2. The only experiment of this type currently 
being performed to my knowledge is the cloning of Agrobacterium 
Ti plasmid DNA, an experiment which was explicitly designated 
P2EK2 in the previous Guidelines. It would be particularly 
ironic for these cloning studies to be the only experiment 
whose containment level is elevated in the revised Guidelines t 
studies of the natural genetic engineering potential of these 
Ti plasmids are cited as part of the justification for general 
decrease in containment of recombinant DNA experiments. 
2. Handling of Recombinant DNA . The Guidelines dictate 
that novel recombinant DNA be handled with "good microbiological 
techniques equivalent to those in a PI laboratory." The im- 
plication is that novel recombinant DNA which comes from a P4 
level cloning experiment can be disinfected (for example, 
mixed with a phenolic agent, a step commonly used in the isolation 
of biologically active transforming DNAl ) and poured down the 
sink. Transformation of several species of bacteria can occur 
[Appendix A — 153] 
