Jung-Hsiang Tai

    Ph.D. Michigan State Univ.


Molecular Parasitology

    Major research activities in this laboratory focus on studying the regulation of gene transcription in two important human protozoan pathogens Giardia lamblia and Trichomonas vaginalis, both of which are also recognized to be among the earliest evolved eukaryotic cells. In the past few years, we established DNA transfection systems (1, 4, 8) and characterized DNA regulatory elements of selected genes (3, 7, 8) in each of these organisms. We found that G. lamblia uses multiple copies of a simple T-tract element as core promoter as well as distal activator in a manner quite distinct from other eukaryotes or prokaryotes (3, 7). In T. vaginalis, distinct sets of promoter elements and their associated nuclear proteins, which regulate basal and iron-inducible transcription of the ap65-1 gene, were identified and characterized (8). Southwestern screening of a cDNA expression library resulted in cloning of four MYB-like transcription factors and a single stranded DNA-binding protein p38. Biochemical properties and functions of these proteins are under investigation. Molecular cloning of the iron-inducible nuclear proteins, which may be responsible for iron-induced gene expression in T. vaginalis, is being conducted. Our future directions will focus on basal transcription machinery in G. lamblia and iron-induced transcriptional regulation in T. vaginalis. These studies will broaden our knowledge on transcriptional regulation operating in lower eukaryotes.


  1. Sun, C.H., Chou, C.F. and Tai, J.H. (1998). Stable DNA transfection in the pathogenic protozoan Giardia lamblia. Mol. Biochem. Parasitol. 92: 123-132.
  2. Liu, H.W., Chu, Y.D. and Tai, J.H. (1998). Characterization of Trichomonas vaginalis virus proteins in the pathogenic protozoan T. vaginalis. Arch. Virol. 143: 963-970.
  3. Sun, C.H. and Tai, J.H. (1999). Identification and characterization of a ran gene promoter in the protozoan pathogen Giardia lamblia. J. Biol. Chem. 274: 19699-19706.
  4. Sun, C.H. and Tai, J.H. (2000). Development of a tetracycline-controlled gene expression system in the parasitic protozoan Giardia lamblia. Mol. Biochem. Parasitol. 105: 51-60.
  5. Bessarab, I. N., Liu, H. S., Ip, C. F. and Tai, J.H. (2000). The complete cDNA sequence of a type II Trichomonas vaginalis Virus. Virology 267: 350-359.
  6. Ong, J. J. and Tai, J.H. (2000). Identification of virus-specific vesicles in Giardiavirus-infected Giardia lamblia. J. Microbiol. Immunol. Infect.33: 9-13.
  7. Ong, S.J., Huang, L.C., Liu, H.W., Chang, S.C., Bessarab, I., Yang, Y.C. and Tai, J.H. (2002). Characterization of a bi-directional promoter for divergent transcription of a PHD-zinc finger protein gene and a ran gene in the protozoan pathogen Giardia lamblia. Mol. Microb. 43(3): 665-676.
  8. Tsai, C.D., Liu, H.W. and Tai, J.H.(2002). Characterization of an iron-responsive promoter in the protozoan pathogen Trichomonas vaginalis. J. Biol. Chem. 277: 5153-5162.
  9. Ong, S. J., Huang, S. C., Liu, H. W. , and Tai , J. H. (2004). Involvement of multiple DNA elements in iron-inducible transcription of the ap65-1 gene in the protozoan parasite Trichomonas vaginalis. Mol. Microbiol. 52(6):1721-1730.