19 
A second new paragraph would be added to Appendix C-III to read as follows: 
"Experiments which use Saccharcryces uvarum host- vector systems, with 
the exception of experiments listed below, are exempt from these NIH 
Guidelines . " 
Drs. Glass and Yocum argued there is no clear distinction between laboratory 
and industrially useful strains of Saccharcrnyces cerevisiae by biochemical 
and morphological criteria. Laboratory strains are derived from wild and 
industrial strains and are therefore genetically closely related to these 
strains . The arguments supporting the exemption of laboratory S^_ cerevisiae 
strains from the NIH Guidelines (e.g. , nonpathogenicity) apply to industrial 
strains and warrant the extension of exempt status to jh_ uvarum . 
Drs. Glass and Yocum proposed that all strains classified as Saccharomyces 
uvarum (including those designated £h_ carlsbergensis vshich have recently 
been reclassified as Saccharcrnyces uvarum ) be given exempt status. 
Dr. Yocum said uvarum is used in the production of lager beer while S. 
cerevisiae is used for producing ale and wine, in distilling and in baking, 
although some distillery strains are classified as uvarum . 
Dr. Yocum distributed data which demonstrated greater variability among 
the cerevisiae strains than between the Sj_ uvarum strains and the S. 
cerevisiae strains. 
Dr. Mortimer said cerevisiae and S^ uvarum are very similar. 
Dr. MacQuillan said it appears that Sj_ uvarum strains are very closely re- 
lated to Sj_ cerevisiae strains and that laboratory strains of cerevisiae 
are very similar to industrial strains. However, the molecular and genetic 
evidence supporting this observation is limited since only portions of the 
genomes of these organisms have been analyzed. 
Dr. Davis said no Saccharomy oe s has ever been shewn to be pathogenic for 
man or animals or to colonize man. He could not imagine the environment 
or human beings being threatened by ary recombinant Saccharcryces unless 
toxin genes were introduced. Dr. Davis suggested the NIH Guidelines" be 
revised to exempt all Saccharomyces species. Dr. Cohen agreed. 
Dr. Gottesman said historically RAC has evaluated several issues in deter- 
mining appropriate containment. Pathogenicity is but one of the issues. 
Another area of concern has been dispersal of recombinant DNA through 
novel routes of transfer. 
Dr. MacQuillan agreed an organism certifiable as S^_ cerevisiae should be 
exempt under Appendix C of the NIH Guidelines. He was not certain, however, 
that all Saccharomyces strains should be exempted as proposed by Dr. Davis. 
Dr. MacQuillan said the issue is the difficulty in identifying and defining 
Saccharomyces strains. 
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