RNA Genetics 
quickly the cellular molecules that are involved 
in any given process. Virus-like particles contain- 
ing double-stranded RNA genomes replicate in 
the cytoplasm of yeast cells in large numbers. 
Their genetic analysis, however, will depend on 
our ability to make defined mutations in their 
RNA genomes. To this end, we are constructing 
perfect DNA replicas of these RNA genomes. 
It has been necessary to develop the technol- 
ogy of introducing RNA directly into yeast cells. 
Using RNA molecules encoding the luciferase 
protein of fireflies, we have been able to demon- 
strate the direct introduction of RNA into yeast, 
and to determine how best to transfect RNA viral 
genomes into yeast cells. By introducing into 
cells mutant RNA viral genomes, we will be able 
to study any mutation-induced defects in the re- 
sulting infection. And, by studying the effects of 
yeast mutants, we will be able to assess contribu- 
tions of the host cell to the infectious process. 
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