Michael E. Geusz
DEPARTMENT OF BIOLOGICAL SCIENCES
Bowling Green State University
Ph.D., Vanderbilt University
My lab studies interactions between the circadian clocks of the nervous system and the body that generate near 24-hour rhythms in behavior. My primary interest is the organization of the circadian timing system of mice as a model for understanding the impact of circadian physiology on human diseases. We examine the regulation of circadian clocks by imaging rhythms in gene expression of whole mice, neural explants, and other tissues maintained in culture. These daily cycles are recorded using bioluminescent transgenic mice containing the firefly luciferase gene controlled by immediate-early gene promoters of mPer1, c-fos, and the major immediate-early gene of the human cytomegalovirus. Through long-term imaging studies, we are characterizing coupled circadian rhythms in midbrain nuclei controlling feeding behavior and others in the pancreas and cornea. These gene expression assays in live cells are combined with pharmacology, microscopy, neural recordings, and behavioral monitoring to identify the signaling mechanisms acting between circadian clocks.
Collaco AM, Rahman S, Dougherty EJ, Williams BB, Geusz ME (2005) Circadian regulation of a viral gene promoter in live transgenic mice expressing firefly luciferase. Molecular Imaging and Biology 7:342-50.
Collaco, A.M. and Geusz, M.E. 2003. Imaging whole body immediate-early gene expression in haired and hairless transgenic mice. BMC Physiology 3: 8-19.
Sigworth, L. A., Liao, L., Chandler, T. R., and Geusz, M.E. 2003. Luciferase expression controlled by a viral gene promoter in a mammalian circadian pacemaker. NeuroReport 14: 443-447.
Geusz, M.E. 2001. Bioluminescence imaging of gene expression in living cells and tissues. In: Methods in Cellular Imaging. Basics of Fluorescence, Fluorophores, Microscopy and Detectors. A. Periasamy, (ed.) Oxford Univ. Press, New York .395-408
Nunemaker, C.S., R.A. DeFazio, M.E. Geusz, E.D. Herzog, G.R. Pitts and S.M. Moenter. 2001. Long-term recordings of networks of immortalized gonadotropin-releasing hormone neurons reveal spontaneous episodic patterns of action potential firing. J Neurophysiol 86: 86-93.
Sigworth, L.A., Chandler, T.R., Liao, L., and Geusz, M.E. 2000. Luciferase imaging reveals distinct patterns of gene regulation in live brain slices. In: Bioluminescence and Chemiluminescence 2000. J. F. Case, P.J. Herring, B.H. Robison, SHD Haddock, LJ Kricka, PE Stanley (eds.) World Scientific, Singapore.185-188
Tosini, G. Doyle, S., Geusz, M.E., and Menaker, M. 2000. Induction of photosensitivity in neonatal rat pineal gland. Proceedings of the National Academy of Sciences (USA) 97: 11540-11544.
Geusz, M.E., Fletcher C., Block, G.D., Straume, M., Copeland, N.G., Jenkins, N.A., Kay, S.A., Day, R.N. 1997. Long-term monitoring of circadian rhythms in c-fos gene expression from suprachiasmatic nucleus cultures. Current Biology 7: 758-766.
Herzog, E.D., Geusz, M.E., Khalsa, S.B., Straume, M., and Block, G.D. 1997. Circadian rhythms in mouse suprachiasmatic nucleus explants on multimicroelectrode plates. Brain Research 757: 285-290.
Geusz, M.E., Foster, R.G., DeGrip, W.J., and Block, G.D. 1997. Opsin-like immunoreactivity in the circadian pacemaker neurons and photoreceptors in the eye of the opisthobranch mollusk Bulla. Cell and Tissue Research 287: 203-210.
Block, G., Geusz, M., Khalsa, S., Michel, S. 1995. A clockwork Bulla: Cellular study of a model circadian system. Seminars in the Neurosciences 7: 37-42.
Geusz, M.E., and Block, G.D. 1994. Intracellular calcium in the entrainment pathway of molluscan circadian pacemakers. Neuroscience and Biobehavioral Reviews 18: 555-561.
Tominaga, K., M.E. Geusz, S. Michel, and S.T. Inouye. 1994. Calcium imaging in organotypic cultures of the rat suprachiasmatic nucleus. NeuroReport 5: 1901-1905.
Geusz, M.E., Michel, S. and Block, G.D. 1994. Intracellular calcium responses of circadian pacemaker neurons measured with fura-2. Brain Research 638: 109-116.
Michel, S., Geusz, M.E., Zaritsky, J.J., and Block, G.D. 1993. Circadian rhythm in membrane conductance expressed in isolated neurons. Science 259: 239-241.
Block, G. D., Khalsa, S. B. S., McMahon, G. D., Michel, S., and Geusz, M. E. 1993. Cellular mechanisms of biological timekeeping. International Review of Cytology 146: 83-144.
Geusz, M.E., and Block, G.D. 1992. The retinal cells generating the circadian small spikes in the Bulla optic nerve. Journal of Biological Rhythms 7: 255-268.
Geusz, M.E., and Page, T.L. 1991. An opsin-based photopigment mediates phase shifts of the Bulla circadian pacemaker. Journal of Comparative Physiology A 168: 565-570.
Geusz, M.E., and Page, T.L. 1990. The circadian rhythm and photosensitivity of small impulses of the Bulla eye. Journal of Comparative Physiology A 166: 795-801.