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NOTICES 
netic functions, the current revisions 
intend to remove as a focus of atten- 
tion the type of project that does no 
more than mimic nature and to permit 
serious attention to new developments 
that would further the expression of 
new genetic functions. 
All the accumulated evidence on ex- 
periments permitted under the guide- 
lines indicates that the proposed revi- 
sions would have no significant envi- 
ronmental impact. 
The categorization of experiments is 
based on several premises, as ex- 
plained in the 1977 environmental 
impact statement. Shotgun experi- 
ments with DNA from primate sources 
require containment because they in- 
volve genes that might function in 
humans with untoward effects. Con- 
tainment levels, however, have been 
lowered here because the concern 
about a hazard from pathogenic viral 
DNA's residing in primate tissue has 
been largely laid to rest in the viral re- 
ports. Alternatives in the use of physi- 
cal and biological containment are 
provided in a number of cases on the 
premise that the greater the contain- 
ment afforded by the host-vector 
system, the lower the physical con- 
tainment needed. Requirements con- 
tinue to be more stringent when the 
source of foreign DNA is known to be 
pathogenic or toxigenic, or might be 
infected with a pathogen, or is known 
to make harmful products. 
For shotgun experiments when the 
source of DNA is prokaryotic organ- 
ism. the guidelines specify contain- 
ment levels according to whether the 
organism is known to recombine genet- 
ic information with E. coli in nature. 
Many of the experiments involving ex- 
changers are now exempt under Ex- 
emptions I-E 4 in the PRG NIH. The 
lowering of containment recommenda- 
tions for those experiments in which 
the source is a prokaryote that does 
not naturally exchange genetic materi- 
al with E. coli reflects the safety in 
the use of E. coli K-12. Scientific in- 
formation over the past 2 years shows 
that recombinant DNA experiments 
are most unlikely to create new genet- 
ic combinations never tested by nature 
and that the possibility of transform- 
ing E. col i K 12 into an epidemic path- 
ogen is virtually nil. 
In the case of a clone that has been 
rigorously characterized and is free 
from harmful genes, the safety is such 
as to permit provision for actions by 
the local biohazard committee rather 
than NIH. Purification greatly reduces 
the potential for growth of a hazard- 
ous organism, and the containment re- 
quirements should be correspondingly 
lower. 
The changes in the eukaryotic host- 
vector systems reflect in large part the 
recommendations concerning work 
with viruses and plants. As noted in 
the original EIS. recombinant DNA 
experiments here involve the use of 
systems in which the host cells have 
little or no chance of escaping from 
the laboratory as an E. coli ceil might. 
New scientific information indicates 
that a variety of organisms, such as 
the lower eukaryotes fungi and yeast, 
may be useful hosts for experiments 
with recombinant DNA's; and useful 
vectors are now becoming available for 
these systems. Hence, this section of 
the guidelines has been expanded to 
detail safe use of these systems. In ad- 
dition. because of the ability to use 
synthetic DNA in recombinant DNA 
experiments, a new section has been 
added to the PRG-NIH to specify safe 
containment levels for this research. 
NIH has been mindful of the con- 
cerns of those who requested that the 
EIS on the original guidelines contain 
further information on individual ex- 
periments. We have tried to meet that 
need by the analysis provided in this 
section and in Appendix B. 
At the public hearing on the PRG- 
RAC in December 1977. some critical 
comments were directed at NIH's EIS 
on the original guidelines. Most of the 
comments centered on NIH policies 
vis-a-vis permissible experiments. An 
analysis of those comments appears as 
Appendix C. 
Because of the critical Importance of 
E. coli K-12 in recombinant DNA re- 
search. an assessment of the use of 
this organism in recombinant DNA ex- 
periments follows. 
Background on the use of E ccli K 12 
in recombinant DMA experiments 
Escherichia co'.i designates a range 
ot bacteria] strains. Each is adapted to 
live in a certain habitat. Its habitats 
are found primarily in the vertebrate 
gut, ar.d it cannot long survive else- 
where— for example, in sewag e.<2) 
Some strains are pathogenic, causing 
disease in the gastrointestinal tract of 
man or other animals. (3,4) One strain 
of E. coli, called K-12.” has been used 
in laboratory experiments for over 50 
years. (2) It is not known to have ever 
caused disease.! 3) 
K-12 became the favorite organism 
for genetic research because it repro- 
duces rapidly and thrives under con- 
trolled laboratory conditions. No living 
creature is known more thoroughly. 
Its single chromosome can be easily 
manipulated by genetic means, permit- 
ting its gene structure to be mapped. 
This work has greatly advanced under- 
standing of how genes express and reg- 
ulate inherited characteristics. 
The chromosome of K-12 is a circu- 
lar molecule of DNA with about 4 mil- 
lion subunits. These compose 3.000 or 
4.000 genes, of which about 650 have 
been identified and assigned locations. 
(5) An arc of the genetic map of E. coli 
K-12 is shown below .(5) 
The NIH guidelines limit the vast 
majority of recombinant DNA experi- 
ments to the use of E. coli K-12 as 
host for the foreign genes. This is be- 
cause the unaltered organism is non- 
pat hogenic and well known in its natu- 
ral properties— both factors lending 
confidence that it can be handled 
safely. 
Figure 4 
FEDERAL REGISTER. VOl. 43. NO. 146— FRI0AY, JULY 28. 1978 
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