67 
Slide 3 
Strains xl776 and xl876: 
1. Cannot survive passage through intestinal tracts of rats 
when 10'® cells suspended in milk are introduced by 
using a stomach tube 
2. Die, degrade their DNA, and lyse in growth media lacking 
diaminopimel ic acid and thymidine 
3- Die at variable rates following drying or when suspended 
in water or in physiological saline 
A. Cannot transmit genetic information by transduction or 
conjugation at detectable frequencies under any of the 
above-described non-permi ss i ve conditions 
rates following drying or when suspended in water or in physiological saline 
and four, cannot transmit genetic information to other robust laboratory 
E. coli K12 strains by transduction or conjugation at detectable frequencies 
under any of the above-described non-permissive conditions. 
I should clearly indicate that I am not claiming that these strains are 
EK2 hosts, since all our data on testing the strain must still be subjected 
to the scrutiny and evaluation during peer review by scientists selected 
by NIH. 
Lights, please. 
I have recently been writing a review on the potential benefits and 
biohazards associated with the use of microorganisms for recombinant DNA 
molecule research. In the remaining few minutes, I will abstract from this 
review and briefly consider some estimates for the probabilities of escape, 
survival, and manifestation of adverse consequences of recombinant DNA 
molecules contained in various bacterial host-vector systems. 
Next slide (4), please. 
[ 208 ] 
