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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. |
GENERAL RESEARCH INTERESTS 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. ACTIVE PROJECTS 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. CONTINUING PROJECTS 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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Stephen Ebbs
URL: http://www.ebbslab.siu.edu/index_files/research_Ebbs.htm
Last updated: 19-Nov-13 / sde