MINUTES OF MEETING - March 6-7 
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XVI. PROPOSALS REQUIRING ASSIGNMENT OF CONTAINMENT LEVEL 
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A. Request to consider containment appropriate to returning 
Helminthosporium roaydis ENA cloned in yeast to the host of origin 
Dr. Zaitlin introduced the request (tab 833, 843/12) of Dr. Olen Yoder 
of Cornell Chiversity to consider the containment level appropriate 
for the return of Helminthosporium maydis ENA, which had been cloned 
in Saccharomyces cerevisiae , to the host of origin. Dr. Zaitlin 
said that there are a number of races of the fungus Helminthosporium 
maydis , one of which, race T, produces a potent toxinT Certain 
varieties of corn are susceptible to this fungus. Dr. Zaitlin said 
that Efcr. Yoder intends to study the non-toxin producing race 0 which 
is not a pathogen in the U. S. except for the very southern tip of 
Florida. Dr. Zaitlin recommended approval of the project. Dr. Brill 
seconded the motion. 
Dr. Gottesman asked if Helminthosporium maydis might exchange genetic 
information with other organisms. Dr. Zaitlin responded that Helmintho- 
sporium maydis is a difficult organism to grow and genetic exchange 
has not been studied. 
Dr. Gottesman noted that this experiment returns cloned ENA to the 
host of origin. She stated that the RAC at seme point might wish to 
consider the generic issue of return of ENA cloned in yeast host- 
vector systems to the host of origin. Dr. Gottesman said that this 
issue is complicated by the variety of yeast cloning vehicles, and 
their behavior in yeast. She said the yeast vector Dr. Yoder preposes 
to employ recombines into the chromosome. Random pieces of yeast 
chromosome thus may be picked up by the integrated plasmid. However, 
she said she felt the proposed experiment to be acceptable at the P2 
level requested by Dr. Yoder. 
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Dr. Goldstein requested that Dr. Zaitlin summarize information about 
the pathogenicity of this organism. Dr. Zaitlin responded that race 
T of Helminthosporium maydis is a serious corn pathogen in the United 
States^ He said that race 0 is not. He pointed out that Dr. Yoder 
does not prepose any experiments with plants, but wishes to study 
race 0 under laboratory conditions. Dr. Gottesman asked whether race 
0 ever produces a toxin. Dr. Zaitlin said it apparently does not 
produce a toxin. Dr. Goldstein asked hew race 0 induces disease. 
Dr. Tblin responded that race 0 causes a mild disease by direct action 
on the leaves in contrast to race T, the toxin of which causes complete 
collapse of the leaf. 
Dr. Goldstein asked whether the lack of health surveillance at Cornell 
Uhiversity for experiments conducted at the PI or P2 levels of contain- 
ment conforms with NIH policy. Dr. Gartland said the Guidelines mandate 
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