19 
The remainder of the proposed sentence, which reads as follows, would be 
eliminated : 
"...but if co-infection or co-cultivation is utilized absence 
of the assisting organism must be demonstrated." 
Dr. Fedoroff proposed that the language of proposed Section III-B-4-c-(2) 
be modified to read in part: 
"...Antibiotic resistance genes may be introduced as selectable 
marker traits if stable integration into the host DNA is known 
to occur, and the antibiotic is one not generally used for treat- 
ment of human, animal, or plant diseases." 
Dr. Vidaver asked if Section III-A-3 of the Guidelines prohibits the deli- 
berate transfer of a drug resistance trait. Dr. Nightingale said Section 
IIInA-3 refers to microorganisms and does not cover plants. 
Dr. Brill said restriction of the use of antibiotic markers will stifle 
plant molecular biology. He said selectable markers, whose products don't 
kill or debilitate the plant or prevent regeneration, are necessary and 
the selectable markers many laboratories use are antibiotic resistance genes. 
Dr. Tblin said the issue of the use of antibiotic markers had been discussed 
at the January 21 meeting of the Working Group on Revision of the Guidelines. 
From the discussion, Dr. Tblin reasoned that if a gene is stably integrated 
into the chromosome, the probability that it might be transferred to other 
organisms is extremely low. Dr. Gottesman said stable integration of some 
of the DNA does not mean other copies could not be transferred to other 
organisms, only that a mechanism for stable integration exists. 
Dr. Vidaver said that a large percentage of microorganisms found in 
nature already harbor multiple antibiotic resistance markers. Some of 
these antibiotics are clinically important. She saw no justification for 
restricting the use of genes coding for antibiotic resistance in plants. 
Dr. Clowes said he did not understand the proposed restriction on the use 
of antibiotic resistance markers in plants. He could understand why one 
would not want such resistance to get into microbial pathogens for which the 
antibiotic is used in treatment. The case in plants, however, was completely 
different. Dr. Fedoroff withdrew her proposed amendment. 
Dr. Gottesman said the proposed Federal Register language does not specify 
containment. Dr. Fedoroff added that there is no data base for these types of 
experiments. She suggested these experiments could generate some risk assess- 
ment data on dispersal of organisms containing recombinant CNA. She proposed 
that the following sentence be added at the end of Section III-B-4-c-( 4 ) : 
"Procedures for assessing the spread of organisms containing 
recombinant DNA must be developed and approved by the IBC 
and the results of the test should be submitted for review 
to the IBC and copies submitted to the Risk Assessment 
Subcommittee of the RAC." 
UP41 
