Dr. Ron Tjalkens

<< Back to Faculty

Center for Environmental Medicine
1681 Campus Delivery
Colorado State University
Fort Collins, CO 80523
Phone: (970) 491-8635
Email: CEM@colostate.edu

Degrees

Ph.D., Toxicology, University of Colorado Health Sciences Center
B.S., Chemistry/Biochemistry, University of California at San Diego

Dr. Tjalkens is a Faculty Affiliate in the Center for Environmental Medicine and an Associate Professor in the Department of Environmental and Radiological Health. He also is a faculty member with the Program in Molecular, Cellular and Integrative Neurosciences.

Research Interests

A central focus of research in Dr. Tjalkens laboratory is the role of astrocytes in modulating neuronal function, both in normal physiology and in neurodegenerative disorders. The laboratory team uses a variety of real-time fluorescence imaging techniques to probe the role that mitochondrial dysfunction (such as that observed in Parkinson’s disease) plays in altering normal calcium signaling in astrocytes and in contributing to aberrant neuro-glial interactions. In pursuit of these questions, a number of neurotoxicants are employed to disrupt normal mitochondrial function in cells and transgenic animals, including the dietary metal, manganese (Mn 2+) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a synthetic heroin derivative that has produced irreversible Parkinsonism in humans. Another area of research interest involves the role of inflammatory activation of glial cells in neurodegeneration.

Recent Publications

  • Tjalkens RB, Liu X, Mohl B, Wright T, Carbone DL, Moreno JA, and Safe S. The PPAR-γ agonist 1,1-bis(3'-indolyl)-1-(p-trifluoromethylphenyl) methane suppresses manganese-induced production of nitric oxide in astrocytes and inhibits apoptosis in co-cultured PC12 cells. J. Neurosci. Res. (in press, Oct 07)
  • Tjalkens RB, Zoran M, Mohl B, and Mouneimne R. Manganese suppresses ATP-dependent intercellular calcium waves in astrocyte networks through alteration of mitochondrial and endoplasmic reticulum calcium dynamics, Brain Res. 1113, 210-219, 2006.
  • Liu X., Sullivan K.A., Madl J.E., Legare M., and Tjalkens R.B. Manganese-induced neurotoxicity: the role of astroglial-derived nitric oxide in striatal interneuron degeneration, Toxicol. Sci. 91(2):521-531, 2006.
  • Peters JL, Earnest BJ, Tjalkens RB, Cassone VM, Zoran MJ. Modulation of intercellular calcium signaling by melatonin in avian and mammalian astrocytes is brain region-specific. J. Comp. Neurol. 493(3):370-380, 2005.
  • Liu X, Buffington JA, and Tjalkens RB. Astroglial-mediated neuronal apoptosis following exposure to manganese and cytokines requires NF-kB-dependent production of nitric oxide Mol Brain Res 141(1): 39-47, 2005.
  • Ng Y, Barhoumi R, Tjalkens RB, Fan YY, Kolar S, Wang N, Lupton JR, and Chapkin RS. The role of docosahexaenoic acid in mediating mitochondrial membrane lipid osidation and apoptosis in colocytes. Carcinogenesis(June 23; E-pub ahead of print) 2005
  • Mounemne R., Faske J., Liu X., and Tjalkens R.B., Manganese potentiates lipopolysaccharide-induced expression of NOS2 in C6 glioma cells through mitochondrial-dependent activation of nuclear factor kappa B. Mol. Brain Res. (122): 167-179, 2004
  • Tjalkens, R.B., Phelka, A.D., Beck, M.J., and Philbert, M.A. Regional variation in activation threshold for 1,3 dinitrobenzene-induced mitochondrial permeability transition (MPT) in brainstem and cortical astrocytes. Neurotoxicol 24(3):391-401, 2003
  • McQueen , C.A. , Chau, B., Erickson, R.P., Tjalkens, R.B., and Philbert, M.A. The effects of genetic variation in N-acetyltransferases on 4-aminobiphenyl genotoxicity in mouse liver. Chemico-Biological Interact. 146(1):51-60 ., 2003
  • Miller T.J., Phelka A.D., Tjalkens R.B., Dethloff L.A., and Philbert M.A., CI-1010 Induced Opening of the Mitochondrial Permeability Transition Pore Precedes Oxidative Stress and Apoptosis in SY5Y Neuroblastoma Cells, Brain Research 963:43-56, 2003.
  • McQueen , C.A. , Mitchell, K.M., Dang, L.N., Chau, B., Tjalkens, R.B., and Philbert, M.A. Prenatal expression of N- acetyltransferases in C57Bl/6 mice. Chemico. Biol. Interact 145: 77-87, 2003.
  • Brasuel, M., Kopelman, R., Miller, T.J., Tjalkens, R., and Philbert, M.A. Fluorescent Nanosensors for Intracellular Chemical Analysis: Decyl Methacrylate Liquid Polymer Matrix and Ion Exchange Based Potassium PEBBLE Sensors With Real Time Application to Viable Rat C6 Glioma Cells. Anal. Chem. 73(10): 2221-2228, 2001.
  • Taneja, N., Tjalkens, R., Philbert, M.A., and Rehemtulla, A. Mitochondria as the Primary Target for Ionizing Radiation-Induced Apoptosis.Oncogene, 20: 167-177, 2001.
  • Tjalkens, R.B. , Ewing, M., and Philbert, M.A. Differential cellular regulation of the mitochondrial permeability transition in an in vitro model of 1,3-dinitrobenzene-induced encephalopathy. Brain. Res., 874(2): 165-177, 20