NSF Award
9602135
9602135 Yao The genetic properties of rRNA will be investigated using Tetrahymena thermophila as a model organism. Work from this laboratory has demonstrated that one of the variable regions of the ribosome, D8, has an essential conserved role in cell growth. Furthermore, that work has shown that some variable regions can accommodate short insertions without affecting ribosome function and antisense ribosomes" have been made and used to suppress specific regions in the mRNA. That study will be continued by determining the optimal length of the antisense RNA, the best target regions in the mRNA and the most appropriate sites within the rRNA variable regions for such insertions. The interaction between the targeted mRNA and the ribosomes will be studied. The antisense ribosome technology will be used to develop a new strategy for cloning Tetrahymena genes by their null phenotypes. Additionally, the study will create rRNAs that contain active ribozymes as inserts. The well characterized "hammer-head" ribozyme will be inserted into a characterized variable region of the rRNA. The ability of this ribozyme to cleave targeted mRNA in vivo will be determined by analyzing the phenotype and molecular composition of transformed cells. %%% The ribosomal RNAs of eukaryotes are composed of well conserved sequences that are interspersed with highly divergent regions. Despite extensive study, only some conserved sequences and none of the variable sequences have been linked to specific ribosome functions. This study will give insight into the genetic properties of the rRNA, especially the variable regions and explore a novel role of the ribosome using Tetrahymena thermophila as a model organism. This ciliated protozoan has only one copy of the rRNA genes in its germline genome. Transformation methods for replacing the rDNA with reconstructed copies have been developed making Tetrahymena the only organism in which both classical and molecular genetical analysis of rDNA can be conducted.
