• Post-doctoral Fellow 1968-1971
  Molecular Biology Laboratory
  University of Wisconsin-Madison

• Ph.D. (Zoology) 1968
  University of Iowa

• B.S. cum laude (Zoology) 1962
  Howard University

• Course Certificate in Invertebrate Zoology, 1961
  Marine Biological Laboratory; Woods Hole, Massachusetts

Current Research

Internalization of particulates and fluids through phagocytosis and endocytosis is of fundamental importance to diverse cell types. Studies of several model systems have demonstrated that endocytic/phagocytic pathways involve specific membrane receptors, actin-dependent redistribution of the plasma membrane, membrane fusion to engulf fluids and/or particulates, maturation of nascent endocytic vacuoles, and signaling pathways that regulate the entire process. Endocytic and phagocytic vacuoles move throughout the cell, and vacuolar content is either degraded or chemically modified to support a variety of biochemical reactions within the cell.

There is a continuing need for studies that refine our knowledge of this fundamental process. My laboratory discovered MYO1, a divergent unconventional myosin that affects phagocytosis in the ciliate Tetrahymena. Myosins are complex enzymatic motors that catalyze an energy-yielding reaction that generates unidirectional, chemo-mechanical force along actin filaments. In a genomic knockout of MYO1, phagosomes formed at a slower rate than in wild-type cells.

Regulation of phagosome formation in Tetrahymena could involve a feedback loop that coordinates phagosome formation with phagosome maturation. Failure of directed phagosome motility could delay recycling of phagosomes at the cytoproct and consequently, inhibit phagosome formation. In order to test this idea and to demonstrate interaction of Myo1p with the actin cytoskeleton and the machinery for phagocytosis, actin distribution and phagosome motility are being investigated in a Tetrahymena strain that expresses GFP-actin and in a MYO1-knockout strain. These studies are aimed at determining the precise role of Myo1p in the phagocytosis process.

A few highlights from publications in major journals (since 2000):

• Williams, S. A. and Gavin, R. H. 2005. Myosin genes in Tetrahymena thermophila. Cell Motil. Cytoskel. 61:237-243.

• Hosein, R. E., Williams, S. A., and Gavin, R. H. 2004. Directed motility of phagosomes in Tetrahymena thermophila requires a dynamic actin cytoskeleton and Myo1p, a divergent unconventional myosin. Cell Mottl. Cytoskel. 61:49-60

• Garces, J. A., Williams, S. A., and Gavin, R. H. 2003. Chromosome Walking by Inverse PCR. In: Weissensteiner, T. (ed.), PCR Technology: Current Innovations, 2nd Edition. CRC Press, London.

• Hosein, R. E., Williams, S. A., Haye, K. A., and Gavin, R. H. 2003. Expression of GFP-actin leads to failure of both nuclear elongation and cytokinesis in Tetrahymena thermophila J. Eukot. Microbiol. 50: 394-399.

• Gavin, R. H. 2001. Myosins in Protists. In: Jeon, K. W. (ed.), International Review of Cytology. Academic Press, NY. 206:97-134.

• Garces, J. A., and Gavin, R. H. 2000. Using an inverse PCR strategy to clone large, contiguous genomic DNA fragments. In: Gavin, R. H. (ed.), Methods in Molecular Biology: Cytoskeleton Methods and Protocols. Humana Press, New Jersey. 161:3-8.

• Gavin, R. H., Hoey, J. G., and Garces, J. A. 2000. Immunogold electron microscopy of Tetrahymena. In: Asai, D. J. and Forney, J. D. (eds.), Methods in Cell Biology: Tetrahymena thermophila. Academic Press, New York. 62:333-343.

• Williams, S. A., Hosein, R. E., Garces, J. A., and Gavin, R. H. 2000. MYO1, a novel, unconventional myosin gene affects endocytosis and macronuclear elongation in Tetrahymena thermophila. J. Eukot. Microbiol. 47:561-568.

Book:

Gavin, R. H. (ed.), 2000. Methods in Molecular Biology: Cytoskeleton Methods and Protocols. Humana Press, New Jersey. Vol. 161 (288pp) ISBN: 0-89603-771-1.