ENVIRONMENTAL DEFENSE FUND 
257 Park Avenue South 
New York, NY 10010 
(212)505-2100 
January 21, 1987 
1616 P Street. NW 
Washington. DC 20036 
(202) 387-3500 
1405 Arapahoe Avenue 
Boulder. CO 80302 
(303)440-4901 
2606 Dwight Way 
Berkeley, CA 94704 
(415)548-8906 
1 108 East Main Street 
Richmond. VA 23219 
(804)780-1297 
Director 
Office of Recombinant DNA Activities 
Building 31, Room 3B10 
National Institutes of Health 
Bethesda, MD 20892 
Dear Members of the RAC: 
Please consider the following comments concerning 
the proposed changes to the NIH Guidelines for Research 
Involving Recombinant DNA Molecules (Federal Register 
51:45650-3). As section I is a reasonable procedural 
change, and section II is difficult to assess before 
Appendices M, N, and 0 are written, these comments 
focus on sections III and IV of the proposed revisions. 
SECTION III : Working Group Proposition 
The Working Group on Definitions presents a 
proposition- -recombinant DNA experiments that do not 
involve the introduction of foreign DNA should not 
continue to be subject to regulation as "recombinant 
DNA"- -and two options for implementing it. However, RAC 
should consider the merits of this proposition before 
considering its implementation. 
The rationale for this proposition is based on 
laboratory observations of the labile nature of 
prokaryote genomes. Because DNA deletions and 
rearrangements are common in laboratory populations , it 
is assumed that such changes regularly occur in all 
species in nature. Therefore, the argument goes, 
releases of comparably altered organisms should not be 
subject to special scrutiny. 
It is necessary to ask, however, whether these 
laboratory observations accurately portray the genetics 
of natural populations of prokaryotes. Although 
laboratory observations led to the notion a few years 
ago that there might be complete gene exchange among 
many types of bacteria (see discussion in Selar.der, 
1985) , recent studies of the population genetics of 
bacteria reveal that many populations have high levels 
of linkage disequilibrium; these populations are 
collections of independent clones (e.g. Caugent et al . , 
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