Research Interests

My research interests are in three areas: (1) comparative immunology and ecotoxicology,  (2) evolutionary physiology, and (3) conservation genetics of endemic and invasive species.  Tools we use range from molecular and cellular to whole animal, spanning molecular and quantitative genetics, genomics, and phylogenetic techniques.  Our research team includes three Chaminade University undergraduates; we have opportunities for the academic year and for summer research (open to other University students).

1.     Comparative Immunology & Ecotoxicology.  With support from NIH - National Center for Research Resources through an INBRE grant to UH-Manoa, we are investigating how the air-borne oxidant pollutant ozone (O₃^-) influence and promote inflammatory processes in the vertebrate lung.  Ozone is a prevalent component of photochemical smog, and many wilderness areas receive substantial amounts of pollution from urban sources (many of the national parks in the US also have significant local source generators, too).  Ozone damages plants, costing agriculture millions of dollars in lost product, and also affects trees and other plants in natural settings.  The effects of O₃^- on terrestrial  wild animals is generally not known.  In work initiated at the University of Hawaii at Hilo, Dr. Bill Mautz and I investigated the effects of O₃- on an amphibian, the marine toad (Bufo marinus).  Ozone affects many behavioral and physiological processes in the toad, but notably, we found significant impairment in innate immune capacity; this suggests a possible role for ozone in the disappearance of some terrestrial amphibians.  Our research was the first to document a possible role for O₃- in reducing immune function in a wild vertebrate and was highlighted in Feb 5, 2005 issue of Science News. 

Despite significant improvement in air quality in many areas of the United States, O₃- continues to be a significant risk factor in pulmonary and cardiovascular disease in humans (see EPA).  We use both in vivo and in vitro approaches.  We are studying gene expression in the lung and heart via microarray and RT-PCR in ApoE (-/-) knockout mice to gain a better understanding of how O₃- exposure contributes to pulmonary and cardiac disease.  This project is in collaboration with Dr. Ralph Shohet's team at the University of Hawai`i-Manoa's JABSOM.  Ozone causes the dysregulation of more than 30 genes, many involved with the inflammatory process (results to be presented at 2008 meeting of Society of Toxicology).  Our in vitro studies focus on mechanisms involved with inflammatory processes in lung epithelial cells (mouse, rat, human, and gecko). Among the processes we look at are whether cells distinguish between O₃- and other oxidants (e.g., hydrogen peroxide) by comparing gene expression (the transcriptome) and cytokine production (the proteome).  The central experiments use O₃^- to stimulate the cells and monitoring responses, including cell viability (Alamar Blue & MTT-assays, LDH), evidence for membrane peroxidation (ELISA), generation of reactive oxygen species (ROS) and the antioxidant system (catalase, iNOS, SOD), and  including up-regulation of heat shock protein 70 (hsp70) and cytokines  (TNFa, IL-1, 4, -6, -8) (via ELISA, 1D & 2D SDS-PAGE electrophoresis, and immunoblotting).  My long-term goals are to investigate the evolution of signaling pathways involved with inflammation of epithelial cells of the respiratory pathway and ultimately the evolution of signaling between innate and adaptive immune systems.  

2.     Evolutionary physiology.  We are investigating the limits of thermal tolerance in Hawaiian picture wing Drosophila.  The evolution of Hawaiian Drosophila represents a large radiation across the Hawaiian Island chain, currently known to consist of over 500 species. The large number of species found is thought to be a result of the isolation of populations on different islands and movement of populations into nearby but dramatically different climate zones within islands.  Behavioral studies and extensive population genetic analyses have been conducted with the Hawaiian Drosophila, but to date, little is known about their metabolic or physiological adaptations.  One unique characteristic of the majority of the picture wing Drosophila is that they are found only at higher elevations.  For example, Drosophila silvestris is found across the Big Island of Hawaii, but only at elevations between 1000 and 1500 meters.  Although temperatures considered characteristic of Hawaii are typically within a narrow range between 20 and 30 ºC, at these higher elevations, the air temperatures are about 10 ºC lower.  Temperature has profound effects on insect physiology and strongly influences geographical distribution of species, at continental (latitude) and regional (elevation) levels.  Species differ in the range of body temperatures they can survive and thrive (thermotolerance), and temperature has been proposed as an important mechanism in the diversification of Hawaiian Drosophila.  However, this conjecture has never been tested from a perspective of quantifying thermotolerance phenotypes or applying molecular genetic approaches.  We are currently investigating induction of heat shock proteins in adults of two species, Drosophila silvestris and D. heteroneura.  Our preliminary results to date indicate that: (1) significant elevation of hsp70 occurs after 1 hour at 24 ºC in adults of these Hawaiian flies, a temperature routinely used to propagate more typical Drosophila species, and (2) mating success is adversely affected after adults are kept at 24 ºC  for one week.   Dr. Don Price, Associate Professor of Biology at University of Hawaii – Hilo , is a major collaborator with this project.

I maintain an active interest in the evolution of locomotor performance and activity metabolism of vertebrates and use of quantitative genetics approaches for dissecting genetic basis of complex phenotypes.  My graduate studies at University of Wisconsin under Drs. Ted Garland (now Professor of Biology at University of California - Riverside) and Jack Hayes (postdoctoral fellow, now Professor of Biology at University of Nevada - Reno), focused on genetic and environmental bases of individual variation in locomotor performance (sprint running speed, swimming and running endurance) and whole-animal metabolism (basal [BMR], standard [SMR], field [FMR], maximal [VO₂max]) in small vertebrates (rodents, lizards, snakes, amphibians).  Since most activities that animals engage in involve locomotion (foraging, mate acquisition, defense), locomotor performance can be the object of natural selection (escape from predation), and the functional basis of locomotion is relatively well known. Therefore, these traits are important components of Darwinian fitness.  Examples of the kinds of issues I have studied include: genetic bases of individual and population differences in locomotor performance, whole-animal metabolic rates, and their functional correlates; functional limits to altitude acclimation; empirical and theoretical aspects of trade-offs and constraints; evolution of endothermy.

3.       Conservation and Evolutionary Genetics Projects.  We are conducting three projects on genetic variation among groups of island species.  

A.             The first project seeks to test for latitudinal variation (clines) on O`ahu for the alcohol dehydrogenase gene for the invasive fruit fly species Drosophila melanogaster.  We are using a bi-phasa PCR technique to isolate alleles from samples of flies collected from three elevational transects along the southern, central, and northern portions of the island.  This project is intended to establish baseline information about the current geographic variation of populationos of D. melanogaster on O`ahu as we develop isofemale lines for additional genetic inquiries.

B.             A second project is using genetic markers (RAPDS, mtDNA) to investigate population phylogeography of introduced, and now invasive, red algae Gracilaria salicornia.  This species was first introduced to Waikiki and Kane’ohe Bay on Oahu in the early 1970’s as part of a failed effort to establish an aquafarming (for agar).  Since then, the red algae has become established at several locations and may threaten coral health.  The algae forms thick mats and can cover coral reefs.  One technique for removal involves picking plants away from the reef by hand – this is very time consuming, of course, and may also inadvertantly contribute to the spread of the of the invasion because the algae can propagate asexually by fragmentation.  Ron Iwamoto at Chaminade University is a major collaborator with this project.

C.             A third project is looking at a proposed hybrid species between two species of native sandalwoods.  This project also involves heavy reliance on genetic markers.