Date of Award


Publication Type

Master Thesis

Degree Name



Chemistry and Biochemistry

First Advisor

Ananvoranich, S.


Chemistry, Biochemistry.




Delta ribozyme is a RNA enzyme derived from the genome of hepatitis delta virus (HDV). It can specifically cleave a RNA substrate and is the only ribozyme that can function naturally in human cells. These properties make the delta ribozyme attractive as a gene modulator. Toxoplasma gondii, a pathogenic parasite to humans and pets, has been used for genetic studies. Genes encoding uracil phosphoribosyltransferase (UPRT) and hypoxanthine-xanthine-guanine phosphoribosyltransferase (HXGPRT), which are the operative enzymes of the pyrimidine and purine salvage pathway, respectively, in T. gondii , were chosen for the study of the down regulation effect of delta ribozymes. Different delta ribozymes were engineered to recognize different locations on the UPRT and HXGPRT mRNA. Cleavage assays of the ribozymes using RNA substrates (ranging from 15 nt to 725 nt) have been carried out. The engineered ribozymes were electroporated into the parasites. UPRT activity was monitored by measuring 3H-uracil incorporation, while HXGPRT activity was monitored by measuring 3H-hypoxanthine incorporation. In addition, a stable cell line of T. gondii expressing the engineered delta ribozymes against UPRT was established. (Abstract shortened by UMI.)Dept. of Chemistry and Biochemistry. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2003 .S54. Source: Masters Abstracts International, Volume: 42-03, page: 0942. Adviser: Sirinart Ananvoranich. Thesis (M.Sc.)--University of Windsor (Canada), 2003.