FEBRUARY 15-16 - MINUTES OF MEETING 
7 
(4) Data on the stability and maintenance of the cloned 
segment and vector in nonselect ive media. 
(5) Measurement of the relative ability (in a worst 
case analysis) of fertile parents of the sterile 
HV2 candidate to mate at low cell density canpared 
to optimal conditions. 
(b) An experimental estimate of the frequency of transfer 
of a model cloned segment (in a worst case analysis, 
again with a fertile strain) to a non-mating, indus- 
trial strain, after prolonged cultivation in mixed 
culture. 
Changes of auxotrophic selective markers in host and vector, or 
change in mating type allele, are trivial modifications not requir- 
ing certification, provided the level of sterility is not decreased. 
Certified EK2 E. coli vector DNA or fragments thereof can be used 
in HV2 S. cerevisiae ." 
Dr. Parkinson noted no numerical values appear to be required in 
the preposed data to be supplied. For example, what frequency of 
mating would be unacceptable, and should not this value be in the 
report. It was stated that the combined effect of various contain- 
ing features (the product) is the important consideration. Explicit 
in the Guidelines is the factor of 10“® (See Section II-D-l-b). 
Investigators will have to present data that will at least satisfy 
this value. Dr. Gottesman stated that the proposal will allow 
Da lancing between survival and mating. Dr. Setlcw stated that the 
Worxing Group did not want to put definite numbers into the report. 
Drs. Kutter and Campbell pointed out that the requirements for EK2 
systems were not entirely clear at the beginning and working group 
had to evolve more refined criteria. 
Dr. Kutter moved to accept this section of the report. The motion 
carried by a vote of 19 in favor, 1 opposed. 
C. USE OF UNMODIFIED LABORATORY STRAINS OF N. CRASS A . 
The RAC considered the following proposal for use of unmodified 
laboratory strains of N. crassa : 
"Unmodified laboratory strains of N. crassa can be used 
in experiments that require the HV1 level of containment 
provided that these are carried out at physical contain- 
ment one level higher than required for HV1. However, 
if P3 physical containment is specified for HV1, this 
level is considered adequate for unmodified N. crassa . 
For P2 physical containment, special care must be 
exercised to prevent aerial dispersal of macroconidia. " 
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