Dr. Donald Fredrickson 
October 27, 1978 
Page Two 
for cloning of primate, mammalian and avian DNA in E^. col i K- 12 host-vector 
systems. The second argument, concerned with the ease with which the EK2 
system can be used, is more valid and I think pertains mostly to the use of 
xl776, which Is a rather fastidious microorganism. Certainly, approved EK2 
lambda vector-host systems are no more difficult to use than, and even have 
some advantages over, currently utilized EK1 lambda-host systems. In terms 
of the problems that some investigators have had in working with xl?76, 
persons In our own laboratory, even those who were not involved with the con- 
struction of x 1776, have had n0 difficulty and we have continually developed 
procedures for improving the ease with which this strain can be used. For 
example, we have developed a new transformation method which yields 10 7 trans- 
formants per microgram of plasmid DNA and have developed methods for amplification 
of ColEl-derlved vectors in \\11S with yields nearly equal to those obtained with 
various EK1 hosts. These new methods have been published or in the case of the 
xl 776 transformation method have been disseminated to those attending the bio- 
hazard courses held in September and October as well as to individuals requesting 
xl776. I personally believe that some of the difficulty that some investigators 
have had has been due to failure to read the material sent to them with \\llb 
and/or to scientific ineptitude. I should indicate that failure to follow care- 
fully the directions we have distributed with xl 776 or to pay close attention to 
the properties of the host-vector system leads to difficulty in using the xl 776 
plasmid systems for recombinant DNA research and thus has led to complaints on 
the part of recombinant DNA researchers. On the other hand, a substitution of 
P3 containment so that one can use EK1 systems is not accompanied by any penalty 
for scientific ineptitude if the P3 containment facilities and procedures are not 
functioning and/or are not adhered to since the experiments will still work even 
if the containment is inoperative at the P3 level. As you are well aware, the 
people now engaged in recombinant DNA research come from a diversity of backgrounds 
and the same people who have difficulty in using the xl 77 6 plasmid vector systems 
are also the same individuals who have never been adequately trained in medical 
microbiological techniques and are most likely to not use P3 containment facilities 
and procedures in the manner prescribed in the Guidelines. I thus respectfully 
request that you give careful consideration to these points and hope that you 
finally decide to leave the requirement of P2 + EK2 containment for the cloning 
of primate, manmalian and avian DNA in E_. col i K- 12 host-vectors. 
RCIII/pp 
[A-447] 
