Dr. Julie Alexander, Research Associate

Phone:    541-737-1849; Nash Room 522
Education:  Ph.D. Biology, Montana State University

 My research interests lie in the field of disease ecology.  I am fascinated by parasites that exploit multiple hosts (myxozoans in particular) during their life cycles as a means of ensuring their reproductive success.  I am interested in factors that drive and determine the outcomes of host-parasite interactions, how interactions may change under different environmental contexts, and how ecological and life history variables influence host-parasite dynamics and evolution.


Dr. Stephen Atkinson, Research Associate

Phone:  541-737-1856
Education: Ph.D. Parasitology, University of Queensland, Australia

I research myxozoans - a widespread group of parasitic Cnidaria.  Though they are related to corals and jellyfish, myxozoans are obligate parasites of fish and invertebrates.  My work includes describing new species, exploring the evolutionary relationships between hosts and parasites, and developing methods for detecting myxozoans in environmental samples. Publications


 Dr. Leigh Combrink, Research Associate (Postdoc)

Phone:  541-740-7831
Education:  PhD Ecology, UKZN, South Africa

My current research interests lie in disease ecology and the associations of infections with microbiome dysbiosis. The role of microbiomes in the development, health and survival of wildlife is largely unknown. In ungulates, and bovids in particular, juvenile survival is critical to population performance. My research will determine the patterns of gut and nasal microbiome development in African buffalo calves and how these relate to their growth, development, survival, and disease susceptibility. The results from this study will improve our understanding of the links between microbiome variation and wildlife population health.


Dr. Karen Dierksen, Research Associate

Education:  Postdoctoral Researcher, University of Otago, Dunedin, New Zealand
Ph.D., Microbiology, Oregon State University

My research in the Trempy Lab is focused on developing new strains of lactic acid bacteria of potential interest to the food, dairy and/or pharmaceutical industries.  Our original patent strain, Lactococcus lactis Ropy 352, which produces a unique exopolysaccharide, has been licensed commercially.


Dr. Sascha Hallett, Senior Research Associate

Phone:  541-737-4721
Education: Ph.D. The University of Queensland, Australia

I find parasites fascinating organisms and have always been drawn to the aquatic environment. Thus, I am interested in parasites of marine and freshwater fish. Most of my research has focused on one phylum - the Myxozoa and I've never dissected a fish without encountering at least one of these microscopic, spore-forming, endoparasitic metazoans. Over 2000 are found in fish world-wide and most do not harm their host, but there are several that cause serious diseases (Ceratomyxa shasta, Parvicapsula minibicornis, Myxobolus cerebralis) in the Pacific Northwest of North America. My current research focuses on answering questions about these parasites so that we can make informed management decisions and reduce their impact on native fishes.

Dr. Richard Holt, Senior Research Associate

Phone:  541-737-0743
Education:  Ph.D. Microbiology, Oregon State U.

Forty-two years of experience in the study of fish disease as Senior Fish Pathologist at the Oregon Department of Fish and Wildlife (Retired).  Previous activities include conducting research in the diagnosis and treatment of fish parasites, pathogens in hatchery fish, detection of pathogens in wild stocks of fish and determining causes of fish losses in Oregon.  Principal area of research and publications has been in studies of the yellow pigmented bacterial fish pathogens such as Flavobacterium psychrophilum agent of cold-water disease and F. columnare, agent of columnaris disease.  Currently participating on a project to study the occurrence of the myxosporean parasite, Ceratomyxa shasta, and its impact on wild salmonid stocks in the Klamath River watershed.


Dr. Anne Taylor, Research Associate

Phone:  541-737-4136
Education: M.S. BioResource Research, Soil Science, Oregon State; Ph.D. Environ. Engr., Oregon State

Our lab studies the nitrogen cycle in soil, and specifically the oxidation of ammonia to nitrite. This process is known as nitrification and is carried out by ammonia oxidizing archaea and bacteria (AOA and AOB). Over the past few years my work has focused primarily on developing tools to distinguish the contributions to nitrification by AOA and AOB. Using these tools I am now investigating how different environmental conditions, such as temperature and soil water content, influence the ecology, physiology, and function of the two groups of nitrifiers in soil. This work has particular significance as global climate change becomes more pronounced. Changes in soil temperature and rainfall patterns will affect the contributions of the AOA and AOB to nitrification, and may have profound effects on nitrogen balance in agricultural and forest soils and the production of greenhouse gasses. 




Dr. Luis Bolanos, Postdoc

Phone:  541-737-3502; Nash Room 254
Education:  Ph.D. Biomedical Sciences, National Autonomous University of Mexico

My research interests lie in the understanding of the factors that shape the dynamics and interactions of microbial ecosystems.  I am currently investigating the diversity of marine plankton in the North Atlantic bloom and how it changes at different depths and cycle time points.



Dr. Cleo Davie-Martin, Postdoc   Accepted position in Copenhagen

Phone:  541-737-1839; Nash 334      
Education: Postdoc Department of Microbiology, Oregon State U.; Ph.D. Environmental and Analytical Chemistry; University of Otago, Dunedin, New Zealand

My research investigates the microbial cycling of volatile organic compounds (VOCs) in the oceans under both controlled laboratory and field conditions using proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOF/MS).  PTR-TOF/MS allows for real time detection of VOCs at trace levels, through which we can determine the production and consumption rates pf VOCs by marine plankton and explore how these change under various conditions and at different stages of the bloom cycle.


Dr. James Fox, Postdoc

Phone:  541-737-7020; Nash Room 334
Education:  PhD Marine Biology, University of Essex

My research investigates how the physiology and composition of marine plankton communities are linked to variability in carbon export efficiencies.  Through ship-based observations and experimental approaches my work will (i) shed light on how bulk photic layer plankton properties can be linked to optical properties retrievable from remote sensing and (ii) explore the potential of active sensor-based technologies.



Phone:  541-737-9664; Nash Room 514        
Education: Ph.D., Biochemistry and Biophysics, Oregon State University

C. shasta is a freswater parasite that is responsible for "gut rot" in salmonids.  Outbreaks caused by C. shasta have devastating effects in both wild and aquaculture settings.  I am using immunoprecipitation coupled with mass spec to characterize the extracellular proteome of this parasite.  My goal is to have a better understanding of how C. shasta senses its host and interacts with its environment and to ultimately develop therapies to prevent or control C. shasta outbreaks.


Dr. Tyrell DeWeber, Postdoc ACCEPTED POSITION IN GERMANY        

Phone:  541-737-1859; Nash Room 546         
Education: Postdoc Department of Microbiology, Oregon State U.
Ph.D. Wildlife and Fisheries Service, Penn State U.
M.S. Fisheries and Wildlife Service, Virginia Tech; B.S. Biology, Liberty U. 

I am interested in understanding the effects of human activities on river systems and fish populations to help guide management and conservation.  River system alteration and pollution can result in stressful conditions and increased disease, eventually leading to widespread mortality of wild adult and juvenile fish.  I am working with Dr. Michael Kent in the Microbiology Program at Oregon State University investigating causes of prespawn mortality in Spring Run Chinook salmon in the Willamette River Basin.   



Dr. Christopher Gaulke, Postdoc 

Phone:  541-737-8630; Nash Room 546
Education:  Postdoc, Department of Microbiology, Oregon State U.; Ph.D. University of California, Davis

A growing body of evidence has identified the gut microbiome as an important factor involved in the maintenance of gastrointestinal homeostasis.  However, relatively little is known about how routine environmental exposures might influence the structure and function of these microbial communities and how these shifts might alter host physiology.  My research employs high-throughput molecular and computational techniques to evaluate the impact of environmental exposures on microbial abundance, function, and host physiology.  These investigations aim to (1) identify potential microbial biomarkers of environmental exposure, (2) Define microbial functions that are associated with host health, and (3) Generate testable hypotheses about how microbial communities interact with their hosts.



Dr. Brett Mellbye, Postdoc
Phone: 541-737-; ALS 3125
Education:  Ph.D. Molecular and Cellular Biology, OSU

I am interested in multi-species interactions and prokaryotic physiology in environmental systems.  My research focuses on bacterial cell-cell signaling (quorum sensing), nitrification, and microbial communities in soils.  My previous postdoctoral work focused on the role of acyl-homoserine lactone quorum sensing in nitrifying bacteria and constraint-based modeling of nitrogen oxide fluxes during nitrification.  My current research with Ryan Mueller and David Myrold is focused on protein turnover in forest soils as a bottleneck in the nitrogen cycle.




Phone: 541-737-3189; Nash Room 254
Education: B.S., M.S., and Ph.D. in Microbiology, University of Hawaii at Manoa, Marie-Curie Incoming International Postdoctoral Fellow (Uppsala University, Sweden)

My research project focuses on understanding the interaction of SAR11 bacterial clade with dissolved organic matter (DOM) in the ocean. I am particularly interested in analyzing the evolutionary ‘hotspots’ within the genomes of divergent SAR11 strains in the ocean to understand how these genomic regions may play a role in shaping their metabolic capabilities and ultimately on how they break down DOM. I am also interested in evolutionary forces shaping these regions. We plan to carry out deep sequencing of single-cell genomic and metagenomic libraries that will be generated from an upcoming cruise to Bermuda as part of the BIOS-SCOPE research collaboration.



Dr. Keaton Stagaman, Postdoc

Phone: 541-737-9664; Nash Room 514
Education: Ph.D. University of Oregon, Ecology and Evolution

The gut microbiome is a complex and dynamic community with an incredible metabolic potential. The makeup of the microbiome (i.e., its constituent species and their genes) is influenced by multiple processes including selection by the host, interactions between the microbes, and (my focus) exposure to environmental compounds such as toxins and drugs. The metabolic capabilities of the microbiome influence how such environmental compounds are processed within the host: potentially mitigating or exacerbating toxic effects. My goal, using observational studies in humans and experiments in model organisms, is to ascertain how the environment influences the metabolic potential of the microbiome, and in turn, how the microbiome alters the effects of environmental compounds on the development and health of the host.



Dr. Chris Suffridge, Postdoc

Phone: 541-737-3502; Nash 250
Education: Ph.D. Biology, University of Southern California

My research is focused on understanding how trace organic cofactors, such as B-vitamins, influence the structure and function of marine microbial communities.  Currently, I am exploring the connections between the cellular biochemistry and environmental availability of vitamin B1 and its biochemical congeners, and the ways that this coenzyme is able to control planktonic community dynamics. 




Ryan Craig, Faculty Research Assistant

Phone:  541-737-0743

Education:  B.S. Environmental Science, Oregon State U.

As a research assistant at the JL Fryer Aquatic Animal Health Lab, I am responsible for the daily animal husbandry, maintenance of the facility, and assisting researchers with experimental design. In addition, I am involved in the field work for projects monitoring the prevalence of Ceratonova shasta, its invertebrate host, and the effect of the parasite on salmonids in the Klamath River.

Publications:  Bruce A. Menge, Sally D. Hacker, Tess Freidenburg, Jane Lubchenco, Ryan Craig, Gil Rilov, Mae Noble, Erin Richmond (2011). Potential impact of climate-related changes is buffered by differential responses to recruitment and interactions. Ecological Society of America 81(3) 493-509.


Fabian Martinez, Faculty Research Assistant--Now a Graduate Student in Pharmacy

Phone:  541-737-1846
Education:  B.S. Cell and Molecular Biology, U. of Northridge

The work I am doing in the Geller lab involves testing PPMOs (peptide-conjugated phophorodiamidate morpholino oligomer) against multi-drug resistant strains of pathogenic bacteria. Molecular and biotechnology techniques coupled with in-vitro/ in-vivo is being utilized to test these PPMOs. Using antisense tech as a means to neutralize essential genes to kill the bacteria. 

MARC Scholar; Dexamethazone protects neonatal hypoxic eschemic brain injury via L-PGDS-dependent PGD2-DP1-PERK signaling pathway. PLOS One. Loma Linda.



Dr. Lixin Li, Faculty Research Assistant   

Phone:  541-737-1846 
Education: M.S. University of Southern China, School of Medicine
M.D. University of Southern China, School of Medicine

I am working on antisense effects on multi-drug resistance bacteria.  Basically, synthetic nucleotide analogs are utilized to target specific antibiotic resistant genes, and the effects are tested, using molecular and cellular biotechnology and rodent models.


Ruth Milston-Clements, Faculty Research Assistant   

Web Site:
Phone: 541-737-0743      
Education: B.S. Environmental Science, Lancaster University
M.S. Fisheries Science, Oregon State University Department of Fish and Wildlife

Worked for the Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO) at the OSU Department of Integrative Biology and the Crop and Food Research Institute in Nelson, New Zealand; before starting my current position in the J.L. Fryer Aquatic Animal Health Laboratory at OSU.  As Lab Manager, I am responsible for maintaing the research facility and physical plant; coordinating resarchers, and ensuring proper care and health of the aquatic animals.  My research interests are focused on the effect of environmental stressors such as temperature or pollutants on the immune systems of aquatic animals.


Colleen Al-Samarrie, Faculty Research Assistant

Phone:  541-737-1858
M.S. in Microbiology from Oregon State University and a Certificate focused in Aquarium Science from Oregon Coast Community College.

I maintain and manage the Kent Lab zebrafish facilities.  This includes coordinating daily animal care, maintaining life support/water systems, and managing lab safety and animal husbandry compliance.  I also assist with research related to fish disease, which currently includes several disease transmission studies in zebrafish.



 Virginia Watral, Faculty Research Assistant  RETIRED!

Phone: 541-737-1858

I have been involved with the study of the diseases of salmonids and zebrafish for the past 30 years.

Currently the focus of my research has been on the impacts of the diseases of zebrafish on experimental outcomes due to non-protocol induced variation and the development of specific pathogen free fish lines to aide in alleviating this problem.  I am also investigating various drug treatments and disinfectants for their potential to control zebrafish diseases. Most recently I have been working on transmitting and identifying the etiological agent causing intestinal tumors in zebrafish. In the past I have also conducted numerous field studies including studying the lifecycles and possible effects of parasites on endangered Klamath Lake suckers and determining a parasitic causation of skeletal deformities in Willamette River fishes. Most of these studies necessitate the need for a zebrafish disease facility which I maintain and manage.