Case-Hooper Assistant Professor of Zoology

Phone: (405)325-6760
Lab: (405)325-6760
Fax: (405)325-6202

RM/Lab:RH411A/410

Micheal Markham

Current Research Interests and Subject Areas Available for Graduate Research

My laboratory studies how ion channels, hormones, and behavior interact in a vertebrate communication system.  We pursue this goal in a unique and powerful model organism, weakly electric fish.  These fish image their world and communicate by generating electric fields in the surrounding water and detecting minute distortions of their electric fields.  The electric fields are generated by the discharge of a specialized electric organ, and each electric organ discharge (EOD) is produced by the simultaneous action potentials of specialized cells within the electric organ, known as electrocytes.

Electric fish are specialists in both the modulation and precise regulation of action potential waveform, making them ideal model organisms for exploring the biochemical and biophysical control of excitable membrane physiology where real-time changes in ion channel activity have direct and immediate effects on behavior.   Sex steroids organize sexual dimorphism and shape plasticity in the electrocyte action potentials, and peptide hormones regulate rapid changes in the ionic currents that shape the electrocyte action potential, producing rapid modulations of EOD waveform in in response to circadian cues and immediate social conditions. Our work focuses on investigating the cellular and ionic mechanisms of EOD generation and plasticity, the regulation of electrocyte ion currents by steroid and peptide hormones, as well as the behavioral consequences of EOD waveform modulations.

To learn more about this research, visit Dr. Markham's research web page. and Dr. Markham's personal web page.


 


Ph.D., University of New Mexico

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Representative publications:

  • Markham, M. R., Stoddard, P. K., 2013. Cellular mechanisms of developmental and sex differences in the rapid hormonal modulation of a social communication signal. Hormones and Behavior, 63, 586-597.

  • Markham, M.R. (in press). Electrocyte physiology: 50 years later. Journal of Experimental Biology.

  • Markham, M. R., Kaczmarek, L. K., Zakon, H. H., 2013. A sodium-activated potassium channel supports high-frequency firing and reduces energetic costs during rapid modulations of action potential amplitude. The Journal of Neurophysiology, 109, 1713-1723.

  • Markham, M.R., McAnelly, M.L., Stoddard, P.K., Zakon, H.H. (2009).  Circadian and social cues regulate ion channel trafficking.  PLoS Biology, 7, e1000203. Free Access Online

  • Allee S.J., Markham, M.R., Stoddard P.K. (2009)  Androgens enhance plasticity of an electric communication signal in female knifefish, Brachyhypopomus pinnicaudatus. Hormones and Behavior, 56, 264-273.

  • Markham, M.R., Allee, S.J., Goldina, A., Stoddard, P.K. (2009). Melanocortins regulate the electric waveforms of gymnotiform electric fish. Hormones and Behavior, 55, 306-313.

  • Stoddard, P.K. & Markham, M.R. (2008) Signal cloaking by electric fish.  Bioscience, 58, 415-424.

  • Allee S.J., Markham, M.R., Salazar  V.L., Stoddard P.K. (2008)  Opposing actions of 5HT1A and 5HT2-like serotonin receptors on modulations of the electric signal waveform in the electric fish Brachyhypopomus pinnicaudatus. Hormones and Behavior, 53, 481-488.

  • Markham, M. R. & Stoddard P. K. (2005). Adrenocorticotropic hormone enhances the masculinity of an electric communication signal by modulating the waveform and timing of action potentials within individual cells. Journal of Neuroscience, 25, 8746-8754.

  • Stoddard, P. K., Markham, M. R., & Salazar, V. L. (2003). Serotonin modulates the electric waveform of the gymnotiform electric fish, Brachyhypopomus pinnicaudatus. Journal of Experimental Biology, 206, 1353-1362

 

 

 

 

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