Education

• A.B. Stanford University, 1970
• M.S. University of Oregon, 1972
• Ph.D. University of Oregon, 1975
• Postdoctoral: Stanford University, 1975-1978
  

Research Interests

Cellular Studies of a Biological Clock

My laboratory is interested in the cellular basis of circadian rhythms. Most organisms exhibit twenty-four hour rhythms that are controlled by endogenous pacemakers commonly referred to as "biological clocks". Recent studies reveal that the biological clock system in mammals is complex consisting of a central clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus and other clocks, typically not as robust as that in the SCN, located in other brain regions as well as in non-neural tissues. My laboratory's primary focus is in understanding at what levels of neural organization the adaptive properties of the biological clock system emerge. There is evidence in a number of mammalian systems that individual SCN neurons are capable of generating 24-hour cycles in electrical activity. We are studying the properties of these single-cell oscillators and also studying how the various single-neuron oscillators interact within the SCN to produce a unified behavioral rhythm. We believe that this multi-leveled approach will allow us to deduce the organizing principles of mammalian temporal organization. The laboratory employs a range of techniques from planar electrode and patch clamp recording, to photometric measurements of reporter genes, to flow-through peptide assays. The laboratory is currently supported by grants from NSF, NIH and the Air Force Office of Scientific Research.

Representative Publications

Michel, S. Geusz, M., Zaritsky, J. and Block, G. (1993) Circadian rhythm in membrane conductance expressed in dissociated molluscan neurons. Science 259: 239-241

Block, G.D., Khalsa S., Michel, S. Geusz, M. and McMahon, D. (1993) Cellular basis of biological timekeeping. Int. Rev. Cyt. 146: 83-144

Geusz, M., Foster, R., DeGripp, W. and Block, G. (1997) Opsin-like immunoreactivity in the circadian pacemaker neurons and photoreceptors of the Bulla eye. Cell Tissue Res. 287:203-210.

Page, T., Fletcher, J. and Block, G. (1997) After-effects of Entrainment on the Period of the Pacemaker in the Eye of the Mollusk Bulla gouldiana. J. Biological Rhythm 12:218-225

Khalsa, S. and Block, G. (1997) The role of Na in the Bulla circadian pacemaker. Chron. Intl. 14:1-8

Herzog, E., Geusz, M., Khalsa, S.B.S., Straume, M. and Block, G. (1997) Circadian Rhythms in Mouse Suprachiasmatic Nucleus Explants on Multimicroelectrode Plates. Brain Res. 757:285-290.

Herzog, E., Takahashi, J., Block G. (1998) The role of clock and tissue organization in period determination of suprachiasmatic nucleus neurons. Nature Neuroscience 1: 708-713

Geusz, M.E., Fletcher, C., Kay, S.A., Block, G.D., Straume, M., Copeland, N.G., Jenkins, N.A., Day, R.N. (1997) Long-term monitoring of rhythmic c-fos gene expression from mouse brain explant cultures. Current Biology 8:758-766.

Michel, M., Manivanan, K., Zaritsky, J., Block, G., (1999) A delayed rectifier current is modulated by the circadian pacemaker in Bulla., J. Biol. Rhythms, 14: 141-150

Yamazaki, S., Abe, M., Numano, R., Hida, A., Block, G., Sakaki, Y., Tei, H., Menaker M., (2000) Disruption of circadian organization in jet-lagged transgenic rats. Science, 280: 1599-1603

Herzog, E., Grace, M., Harrer C., Williamson J. and Block, G. (2000) The effects of the Clock mutation on the developmental expression of neuropeptides in the suprachiasmatic nucleus, J. Comp. Neurology, 242: 86-98

Michikazu, A, Herzog, E. and Block, G. (2000) Lithium lengthens the circadian period of individual suprachiasmatic nucleus neurons, NeuroReports, 11:3261-3264