9701282 Fuerst This award will provide funds for materials and supplies to enhance the dissertation research of Jeannette Krieger, a doctoral student at Ohio State University working under the supervision of Dr. Paul Fuerst. Ms. Krieger's dissertation research involves a study of intraindividual DNA sequence variation (i.e., among individuals) in the nuclear-encoded, 18S ribosomal RNA (rRNA) gene among species of sturgeon from North America. Sturgeons belong to an ancient group of fish whose origins date at least to the Jurassic. Phylogenetic relationships among species of sturgeons are not well known, and may species currently are threatened or endangered. The nuclear genome of sturgeons appears to have undergone repeated cycles of duplication. Tandemly-repeated DNA sequences such as the ribosomal genes, however, are thought to evolve as a unit because of a phenomenon named "concerted evolution" (also called "meiotic drive"). This project is designed to: (i) characterize the degree of intraindividual and interindividual variation in 18S rRNA gene sequences in nine sturgeon species; (ii) determine whether all rRNA gene variants are actively transcribed; and (iii) localize (via in-situ hybridization) all identified rRNA gene variants to specific homologous and non-homologous chromosomes. Characterization of variation in the 18S rRNA gene (at all hierarchical levels) will help determine the utility of these sequences in phylogenetic inference. Data obtained also will be paramount in testing various hypotheses (model) regarding patterns of concerted evolution. Support for training of graduate students in modern technologies is critical to maintain the workforce of scientists capable of addressing questions and issues in glo`al biology.
