My research has long focused on the eukaryotic cilia and flagella. The basic '9+2' axonemal structure is 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 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.
The laboratory is now focusing on protozoan parasites of invertebrates in the phylum Apicomplexa called Gregarines. Well known members of the phylum include the causative agents of malaria and other diseases of medical and veterinary importance. Gregarines only possess flagella for a very short part of its life cycle in male gametes. We studies 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 fluorescent light and electron microscopy.
Mathematics provides an important and useful tool for biological research. 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. In collaboration with Bob Dillon, an applied mathematican at WSU, we are developing a three-dimensional model of axonemal motion.
Many apicomplexa possess a non-photosynthetic plastid called the apicoplast. A former graduate student, Marc Toso, investigated extranuclear DNA in Gregarina niphandrodes. He showed that Gregarina niphandrodes, unlike other apicomplexa do not possess an plastid nor plastid genome. He also did some beautiful electron microscopic analysis of various stages of the life cycle of this organism.
An undergraduate student, Yesenia Rodriguez, studied the impact of gregarines on the population and longevity of the host beetle, Tenebrio molitor, and showed that despite the high level of experimental infection of the host, there was no significant impact on the host population dynamics.
Currently, I am investigating the possibility that gregarines, particularly eugregarines which do not seem to negatively impact the host, may provide competition to other parasites which may negatively impact the host.