HARVARD UNIVERSITY 
The Biological Laboratories 
16 Divinity Avenue 
Cambridge, Massachusetts 02138 
Sept. 24, 1978 
re: Recombinant DNA Guidelines 
Dr. Donald S. Fredrickson 
Director 
National Institutes of Health 
Bethesda, Maryland, 20014 
Dear Dr. Fredrickson: 
Bert Ely sent me a paper to review, "Transfer of Drug Resistance 
Factors to the Dimorphic Bacterium Caulobacter crescentus " . He asked 
that I send you a letter regarding Caulobacter and recombinant DNA, 
based on this paper. 
Ely's use of transposons is an exciting new way of labeling 
genetic material that is transmitted between organisms. I have 
already started similar experiments in Rhizobium . His evidence that 
ColE^ replicates in Caulobacter is also very encouraging. 
I feel that Bert Ely has demonstrated genetic exchange between 
Caulobacter and E. coli . I would therefore urge you to include 
Caulobacter in the list of exempted organsims found in Appendix A 
as described in Section I-E-4 of the Revised Guidelines. 
Sincerely, 
Harry Meade 
[A-335] 
