Proteomics & Environmental Phenotype Assessment

Development of Phenotypic Biomarkers of Environmental Impacts
in Wild Marine Fishes of Southern California

Our ongoing studies have revealed endocrine disrupted conditions in wild marine and estuarine
fishes in California’s urban aquatic environments, including in the southern California coast and in
San Francisco Bay.  These altered conditions in fish have been directly related to impacted
environments, such as wastewater treatment plant (WWTP) outfalls, urban river outlets, or sites
contaminated with industrial chemicals.  From these studies, it is evident that distinct endocrine and
physiological systems may be impacted dependent upon the study location, types of environmental
factors (e.g., contaminants) present, and the species’ niche in the environment.  

Most studies on fish endocrinology or toxicology employ single or a limited set of measures, or
"biomarkers", such as alteration in the expression of a protein or concentration of a hormone in
order to identify an environmental effect (e.g., Kelley et al., 2002, 2006).  However, the choice of
which biomarker(s) to use can be difficult at the outset of a study or assessment effort.  In addition,
single bioassay approaches cannot provides much insight on physiological performance impacts or
underlying mechanism(s) of the effect.  Therefore, effects assessment methodologies to date have
been limited in their scope and power to define or understand the integrated impacts of an
environment, such as a contaminated industrial site or WWTP outfall.  It is of course the complex,
integrative biological response of an animal to a given environment that will be most directly
relevant to evaluating potential adverse effects.  While single endpoint biomarkers continue to have
great value in environmental studies and assessment, the absence of a more comprehensive,
“integrative” biomarker approach constrains our ability to establish cause-effect relationships,
predict or classify types of adverse environmental factors and their impacts on wildlife, and thus to
eventually identify mitigation strategies.  

Recent technological advances in the areas of genomics and proteomics have provided
environmental scientists with new tools for identifying and developing biomarkers.  Most
impressively, these technologies allow simultaneous measurement of multiple biomarkers that,
collectively, can reflect the types of chemical (and/or other factors) exposure and the systemic
(integrated) biological effects in animals.  While genomics (microarrays) are proving useful in this
approach, it is also recognized that changes in gene transcription (mRNA) do not routinely correlate
with protein expression or protein activity.  Proteins are the primary effectors for adaptive changes
in cellular and physiological functions (phenotype changes) in response to environmental stimuli.
While individual proteins in proteomic analyses provide specific information on impact [and can be
developed as new biomarkers], the larger protein expression profile (PEP), or “fingerprint”, is the
integrative assessment of overall phenotypic condition.  Thus, a comparison of a control vs.
impacted condition in an animal reveals a set of biomarkers specifically indicative of the altered
state and environmental factors at play.  

Our research is capitalizing on proteomics technologies and is aimed at developing more powerful
diagnostic tools using PEPs.  This multi-biomarker approach is expected to enhance the power of
"effects assessment" and increase understanding of environmental effects in marine organisms.

This work has brought together academic researchers with scientists at the Orange County
Sanitation District (OCSD) who offer key expertise in the environmental and ecological aspects of
impacted study sites off shore of Orange County, CA, and the Southern California Bight generally.  
The research findings and outcome of this work (development of enhanced diagnostic and
screening tools) will be directly disseminated to a wide variety of agencies concerned with
environmental assessment and protection.

On board OCSD's boat, Nerissa, used in ocean environmental monitoring, wild English sole have
been sampled from the OCSD outfall (offshore of Newport Beach), an OCSD reference (“far-field”)
location offshore of Bolsa Chica, and an EPA reference location offshore of Dana Point.  Fish from
each site have been found to exhibit distinct patterns of tissue-accumulated contaminants, with
Dana Point exhibiting the lowest overall contaminant levels.  Results to date indicate substantial,
consistent differences in many hepatic proteins in fish from the different field sites.  Ongoing
research is identifying the large suite of altered proteins and their likely phenotypic meaning.  


This work is funded by the
California Ocean Protection Council
through the
USC Sea Grant Program
that emphasizes "urban ocean" research


http://resources.ca.gov/copc  

www.usc.edu/org/seagrant