REU: Ribosomal RNA Sequences in Marine Yeasts: A Model for Identification and Quantification of Marine Eukaryotes

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The ability to distinguish species of marine microorganisms (bacteria protozoans, fungi and microalgae) is a major problem in understanding the processes of primary production and organic recycling. Developments in molecular biology are providing an array of tools to genetically characterize and quantify marine microbes. The first step in applying these techniques to problems in biological oceanography is to develop species- specific genetic markers. There has been extensive study on the 5S, small (SSU) and large (LSU) subunits of ribosomal RNA (rRNA). Studies of conserved regions of rRNA, which evolve slowly, have been instrumental in developing phylogenetic lines of evolution. In addition to conserved regions, there are variable regions in LSU that evolve rapidly. Initial investigations, in Dr. Fell's laboratory and elsewhere, suggest that nucleotide sequences in the variable regions are sufficiently conserved to distinguish organisms at the level of species and genus. This research will amplify preliminary studies of the variable regions of LSU rRNA using marine yeasts as a model for other marine eukaryotes. The yeasts are uniquely appropriate as they can be grown in culture and their nucleotide sequences can be compared with known mating genetic markers. Nucleotide sequencing will use the established techniques of Sanger and Lane. Recognition of nucleotide sequences that are species specific, in combination with techniques such as the polymerase chain reaction and the use of molecular probes and hybridizations, provide powerful tools for the amplification of nucleic acids and the identification and quantification of marine microorganisms from single cell material.