FEBRUARY 15-16 - MINUTES OF MEETING 
6 
routes of _E. coli , i.e., it is not found in sewage or the intestinal 
tract. If the organism does escape from the laboratory, it is 
unlikely to establish itself or to transfer DNA. Dr. Krimsky asked 
whether anyone has attempted to make S. cerevisiae or N. crassa 
into a pathogen. Dr. Day stated that no deliberate attempts had 
been made. Dr. Noviek pointed out that attempts were made to 
convert E. coli K-12 to a pathogen because certain strains of E. 
coli are pathogens, whereas S5. cerevisiae and N. crassa are not 
pathogens. 
Dr. Gottesman made a motion to accept this section of the report. 
The motion carried by a vote of 19 to 0 with 1 abstention. 
B. S. CEREVISIAE AS AN HV2 SYSTEM. 
The RAC considered the following criteria for the use of £5. 
cerevisiae as an HV2 system: 
"S. cerevisiae as an HV2 system. Biological containment 
of yeast is a product of several factors: (a) probability 
of encounter of the host-vector with a wild type yeast 
outside the laboratory; (b) the abundance of wild type 
strains able to mate with a laboratory strain; (c) the 
frequency of mating under the dilute conditions simulat- 
ing natural environments; (d) the reduction in mating 
frequency conferred by the sterility mutations; (e) the 
stability of the cloned segment and its vector; (f) the 
survival and growth ability of the host relative to wild 
types. " 
The following data are to be supplied in support of a candidate 
S. cerevisiae for HV2 certification: 
(1) Genotype of the strain, description of the vectors 
and selective markers to be used, the nature and 
stability of the mutations(s) contributing to ster- 
ility and the mode of construction of the strain. 
(2) The frequency of mating (in a worst case analysis 
under optimal conditions) with a fertile strain of 
opposite mating type. 
(3) Relative growth rates of the candidate strain and 
suitable industrial wild types, separately and in 
mixed culture. (The specification of industrial 
strains reflects the rarity of S. cerevisiae in 
nature under non-domesticated conditions.) 
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