2 
"III-O. Classification of Exper intents Using the E. coli K-12 
Host-Vector Systems. Most recombinant DNA experiments 
currently being done employ E. coli K-12 host-vector 
systems. These are the systems for which we have the 
most experience and knowledge. 
Seme experiments using E. coli K-12 host-vector systems 
are prohibited (see Section I-D). 
Some experiments using E. coli K-12 host-vector systems 
are exempt from the Guidelines (see Section I-E). 
Other experiments using E. coli K-12 shall use Pi physical 
containment and, except as specified in the last paragraph 
of this section, an EKl host-vector system [i.e. (a) the 
host shall not contain conjugation proficient plasmids or 
generalized transducing phages, and (b) lambda or lambdoid 
bacteriophages or non-conjugative plasmids shall be used 
as vectors] . For these experiments no Memorandum of 
Understanding and Agreement (MUA) as described in 
Section IV-EKL-c need be submitted, nor is any registra- 
tion with NIH necessary. However, for these experiments, 
prior to their initiation, investigators must submit to 
their Institutional Biosafety Committee (IBC) a registra- 
tion document that contains a description of (a) the 
source(s) of DNA, (b) the nature of the inserted ENA 
sequences, and (c) the hosts and vectors to be used. 
This registration document must be dated and signed by 
the investigator and filed only with the local IBC. The 
IBC shall review all such proposals but such review is 
not required prior to initiation of experiments. An 
exception, however, which does require prior review and 
approval by the IBC is any experiment in which there is 
a deliberate attempt to have the E^_ coli K-12 efficiently 
express any gene coding for a eukaryotic protein. 
Experiments involving the insertion into E^_ coli K-12 of 
ENA from prokaryotes that exchange genetic information 
with E^ coli by known physiological processes will be 
exempted from these Guidelines if they appear on the 
'list of exchangers' set forth in Appendix A (see 
Section I-E-4 ) . 
For those not on the Appendix A list but which exchange 
genetic information [35] with E^_ coli , experiments may be 
performed with any E^ coli K-12 vector (e.g. conjugative 
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