My research has long focused on the eukaryotic cilia and flagella. These structures are amazingly similar over a wide range of organisms from protozoa such as paramecium, green algae such as Chlamydomonas, and spermatozoa of many animals. They are also found in a variety of tissues in the human body.
My laboratory has investigated the mechanism of regulation of axonemal motion by using mutants and nucleotide analogs 1 2. We have discovered that manipulation of nucleotide concentrations allow paralyzed flagella mutants of Chlamydomonas to move. See the Videos! 3 4. We have also uncovered evidence for the role of nucleotides as a regulator of movement in addition to their well known role as the energy source. 5, 6.
My former graduate student, Scott Boitano, investigated the mechanism of activation of spermatozoa. He discovered that the fundamental underlying mechanism of activation of salmonid spermatozoa is membrane hyperpolarization.
Mathematics provides an important and useful tool to analyze axonemal motion. In collaboration with mathematicians, I have estimated the rate of vanadate dissociation, and discovered an unusual type of cooperativity 7 8 unique to axonemal motion. Currently with Bob Dillon, an applied mathematician at WSU, we hope to take advantage of the reduced axonemal structure found in gregarines (see below) to develop a three-dimensional model of axonemal motion.
The laboratory is now studying protozoan parasites of invertebrates in the phylum Apicomplexa called Gregarines. Members of this phylum possess reduced axonemal structures such as '6+0' or even '3+0' structures.
Gregarines only possess flagella for a very short part of its life cycle in male gametes. We have begun studies on this stage of the life cycle in collaboration with David Sibley of Washington University in St. Louis by EST (expressed sequence tag) analysis and with Ryoko Kuriyama and Joseph Schrevel by light and electron microscopy.
Another former graduate student, Marc Toso, investigated extranuclear DNA in Gregarina niphandrodes. He showed that Gregarina niphandrodes, unlike many apicomplexa do not possess an plastid nor plastid genome.