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Accepting applications for 2013?


No post-doctoral positions are available in the Ebbs lab at this time.  Any open positions in the future will be posted here and advertised.


Applications from both MS and PhD students are being accepted, with the number of students accepted dependent upon the availability of grant funds or other types of assistantships or fellowships from SIUC or other sources. 


Masters students in studying under Dr. Ebbs can apply to do so through either the Plant Biology graduate program or the Plant, Soil, and Agricultural systems graduate program.  


Doctoral students interested in studying under Dr. Ebbs can apply to do so through either the Plant Biology graduate program  or the Environmental and Resource Policy doctoral program. 


The broad focus of my laboratory’s research involves questions at the interface between pollutants, plants, and the soil-water environment.  Having been trained in ecotoxicology, I am interested first and foremost in the pollutants and their fate.  By working with plants, I have the opportunity to focus on a variety of questions of importance to both environmental and human health.  From an empirical perspective, the central questions addressed with my work include:


·        What are the phytotoxic effects of the pollutants?

·        How do plants detoxify or tolerate the pollutants?

·        Does the accumulation of the pollutant in plants pose a risk to animal consumers of those plants?


In examining these questions, my work has involved different combinations of pollutants and plants.  The pollutants of continuing interest include Cd, Zn, cyanide, and metal cyanides while past work has examined Au, Cu, Pb, As, Se, radionuclides (137Cs, 90Sr), and uranium.  More recently, collaborative work is examining engineered nanoparticles and automotive friction materials.  This empirical includes fundamental studies of plant uptake and transport of contaminants, physiological effects of pollutants on plants, interactions of pollutants with mineral nutrients, phytotoxicity, hyperaccumulation, tolerance, and detoxification. My work also focuses on the biogeochemistry of pollutants and their trophic transfer to wildlife and humans.


I also have a long standing interest in phytotechnologies such as phytoremediation, phytomining, and green roofs.  While some field work in these areas has been performed with collaborators, work on phytotechnologies in my laboratory principally involves basic research that contributes to the development of those techniques. 





Engineered nanoparticles and plants (Collaborator: Xingmao Ma, SIU)

Dr. Ma and I are studying several different engineered nanoparticles (ENPs), including TiO2 would and silver NPs, with several different questions in mind.  We are interested in the toxicity of these ENPs to plants, the accumulation of the ENP in plant tissues, and the implications of that accumulation for food safety and human health.  Our work has included a range of plants, with a current emphasis of various agricultural crops.  Included in these efforts are studies of the biogeochemical processes that influence ENP stability and solubility in the soil.  We have currently received a grant from USDA-NIFA to examine the accumulation of metallic nanoparticles in belowground vegetables and tubers and to estimate the dietary impact that consumption of those vegetables may have for human health. 


The Early Development of Sandhill Fen:  Plant Establishment, Community Stabilization, and Ecosystem Development (Collaborator: Dale Vitt, SIU)  This proposed research, funded my Syncrude-Canada, addresses questions centered on plant establishment and development of critical ecosystem functions at Sandhill Fen – Syncrude Canada’s premier fen reclamation project.  The research proposed here follows on to research done at Syncrude’s u-shaped cell over the past three years.  From that research we have learned about which species we might select for establishment on Sandhill Fen, we learned that invasive species may be a real concern, and we learned that several species tolerate the salinity predicted for Sandhill Fen pore waters.  The current project will examine the physiological performance of those species in restoration plots, nitrogen cycling in those systems, and will characterize a series of young and long-established benchmark sites to provide baseline data for future restoration efforts.


The Pollution Potential of Mercury in Legacy Biosolids and Possibilities for its Minimization by Phytoremediation (Collaborator: Spas Kolev, University of Melbourne).  The proposed project will develop novel passive air samplers and analytical methods and analyzers for the determination and speciation of Hg in aqueous, biosolids and plant material samples. This research will also lead to the construction of an automated flow analysis system for dynamic fractionation of Hg and its compounds in biosolids samples. These detectors will be utilized to monitor Hg cycling during the application of phytoremediation to Hg-contaminated municipal biosolids.  The phytoremediation approaches will be based on the identification of native plant species capable of extracting or/and immobilizing Hg thus allowing the reuse of the biosolids studied. Therefore, the successful completion of this project will lead to a significant improvement of the capabilities of the corporate partner, Melbourne Water Corporation, to substantially reduce the Hg pollution potential in the biosolids stockpiles at their water treatment plant and the reuse of those biosolids in land applications.





Physiological roles of the b-cyanoalanine pathway in plants

Plants are exposed to cyanide from both endogenous and exogenous sources.  To prevent this poison from inhibiting metabolism, the b-cyanoalanine pathway uses cyanide to synthesize either asparagine or aspartate and ammonium.  Work from my laboratory and others have suggested that this pathway has physiological roles in plants beyond simple cyanide detoxification.  We’ve found evidence of a role in basic nitrogen metabolism and in the response to some abiotic stresses.  Ongoing work using Arabidopsis thaliana and mutants for genes associated with this pathway are being used to explore these questions. 


Characterization of transporters from the metal hyperaccumulator Noccaea caerulescens (Collaborator: Leon Kochian, USDA)

Noccaea caerulescens (=Thlaspi caerulescens) is a small plant known for its capacity to accumulate very high concentrations of Zn and Cd in its leaves without experiencing phytotoxicity.  Dr. Kochian’s lab has spent years studying this physiological and genetic basis of these traits in this species.  My lab’s contribution to this ongoing research involves functional comparisons of ion transport by homologous membrane proteins from different ecotypes of this hyperaccumulator and the model plant Arabidopsis thaliana.  We have found several amino acid polymorphisms in the sequences of these homologous proteins and have also found that the ion specificity of the homologues differs.  Planned research in my laboratory will attempt to link specific polymorphisms to specific alterations in ion specificity of the transporters, thereby gaining important information on structure-function relationships for these proteins. 


Transport of Cd and Zn to plant seeds (Collaborator: Renuka Sankaran, Lehman College)

Researchers have long been trying to increase the micronutrient density of the grains and seeds of food crops while simultaneously preventing the accumulation of heavy metal analogs.  This research has focused largely on the redistribution of these elements from leaves via the phloem during seed set.  Our preliminary studies, in agreement with other recent work, has indicated that when these elements are presented to plant roots during seed set, a considerable fraction accumulates in the seeds but not the leaves, suggesting a developmentally-dependent pathway.  We are working to understand the pathway these elements traverse from roots to seeds and the key steps that not only regulate this process but differentiate between Zn and Cd.  Our long term goal is to link these studies with efforts that would biofortify staple food crops.  For now, we are using Arabidopsis thaliana and other model plants in which to conduct our initial studies along with parallel work in other cereals. 


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SIUC / Plant Biology / Faculty/ Stephen Ebbs
URL: http://www.ebbslab.siu.edu/index_files/research_Ebbs.htm

Last updated: 19-Nov-13 / sde