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Killer strains of Saccharomyces cerevisiae secrete a toxin which kills sensitive strains. The toxin and immunity are encoded by a cytoplasmically inherited double-stranded (ds) RNA plasmid 1.8 kbp in length designated M. Nearly all strains of S. cerevisiae contain another dsRNA 4.8 kbp in length designated L. Killer strains always contain L and M. / This study describes the discovery and characterization of four new species of dsRNA in the superkiller strain, T158C. The new species were found to be 1.4, 1.2, 1.1 and 0.9 kbp in length. Growth at elevated temperature resulted in the loss of the four additional species as well as the M dsRNA. Northern hybridization analysis demonstrated that the extra components possess sequence homology to M. / Analysis of polyadenylate enriched (+poly A) single-stranded (ss)RNA preparations from T158C by Northern "dot" hybridization demonstrated the presence of ssRNA that is complementary to dsRNA. Single-stranded RNA homologous to L and M was found to represent about 1.0% and 5.0% of the +poly A RNA, respectively. / A further analysis of the killer system was made by the use of the four oligodeoxyribonucleotide primers oligo dT(,12-18), oligo dA(,12-18), oligo dG(,12-18), and oligo dC(,12-18) as primers for avian myeloblastosis virus reverse transcriptase using denatured dsRNA as templates. Oligo dT and oligo dA were found to prime the synthesis of 1.1 kb, and 1.0 kb reverse transcripts, respectively, using denatured M dsRNA as a template. The oligo dT and oligo dA primed cDNAs of M dsRNA hybridized to the region of the M dsRNA that encodes the killer toxin and to each other. Addition of oligo dT to reverse transcription reactions of denatured L dsRNA produced a 4.3 kb cDNA. / During the course of this investigation oligo dC was observed to be a highly efficient primer for reverse transcription of yeast 18S ribosomal RNA. Oligo dC primed the synthesis of a 1.0 kb reverse transcript of 18S rRNA which hybridized to the large Eco RI fragment of the yeast 18S rRNA gene cluster which contains the 5'-terminus of the mature 18S rRNA. / Source: Dissertation Abstracts International, Volume: 43-07, Section: B, page: 2104. / Thesis (Ph.D.)--The Florida State University, 1982.
ContributorsBRIZZARD, BILLY LEE., Florida State University
Source SetsFlorida State University
Detected LanguageEnglish
Format131 p.
RightsOn campus use only.
RelationDissertation Abstracts International

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