November 3, 2011

2-4:00 PM: Toxins and Contaminants Research Seminar: A Stakeholder Forum E38-300

Toxins and Contaminants marks the third of our science seminar series, wherein principal investigators funded by the Sea Grant program present the outcomes and accomplishments of their research. This series of forums is envisioned as an opportunity to dialogue with constituents and stakeholders, promote networking, and receive input on outreach programs to deliver economic, societal and/or environmental benefits from our funded research.

Click here for the program. Each speaker presents their scientific findings, then answers questions from the audience. Please join us at 2:00 pm in the E38-300 conference room to listen, learn and participate in this stakeholder forum.

Speakers:
Robert Chen, University of Massachusetts at Boston
Sensor Networks for Studying Episodic Contaminant Releases to Coastal Waters

The Consortium for Ocean Sensing In Nearshore Environments (COSINE) is putting together the components of a smart sensor network to monitoring episodic events such as “first flush” contaminant events by using recent advances in sensor development, telemetry, coastal modeling, and cyberinfrastructure. COSINE is applying stationary and mobile sensor platforms to observe complex interactions in coastal systems including “hotspots and hot moments”, to visualize complex and non-continuous data streams, and to support environmental decision-making processes.


John Stegeman, Woods Hole Oceanographic Institution
Cytochrome P450 Genes in Bivalve Mollusks

Cytochrome P450 (CYP) enzymes catalyze oxygen fixation, in which ½ molecular O2 alters the structure of substrates including xenobiotic pollutants, steroids hormones, and morphogens. Expression of some CYP genes can be induced by xenobiotics, enhancing the rate of metabolism of the chemical, acting in defense as well as being an indicator of exposure to those chemicals. This presentation will consider our studies on the cytochrome P450 genes in bivalve mollusks. Genome and various sequencing studies are revealing the diversity of CYP genes in mollusks, a protostome group with a history of ambiguous results regarding xenobiotic metabolism and its regulation. Cloning studies have identified some CYP that are similar to hydrocarbon inducible CYP genes in vertebrates and other deuterostomes. Experimental exposure of mussels to inducers of vertebrate CYP1 genes produced mixed results. However, a novel P450 gene identified in oysters appears to be inducible by phenanthrene. Molecular modeling studies coupled with induction studies in other bivalves are underway. The studies are expected to expand the understanding of molecular response to chemicals in protostomes, and provide new markers for exposure in bivalves.


Janina Benoit, Wheaton College
The Effect of Bioirrigation on Sediment-Water Exchange of Methylmercury in Boston Harbor

Coastal marine sediments are important sites of methylmercury (MeHg) production, and dissolved efflux provides an important source of MeHg to near-shore, and possibly off-shore, food webs. We measured the flux of MeHg across the sediment-water interface at four sites in Boston Harbor that span a range of infaunal population densities and bioirrigation intensities. At each site we carried out total MeHg flux measurements using core incubations and collected near-surface pore waters to establish MeHg gradients for diffusive flux calculations. The flux cores were also imaged by CT scanning to determine the distribution of infaunal burrows, and they were sieved for infaunal enumeration. Total MeHg fluxes, measured using core incubations, ranged from -8 to 190 pmol/m2d, and total MeHg fluxes were strongly correlated with burrow densities at the sites. Estimated diffusive fluxes were much lower than total fluxes at three of the sites, ranging from 2-18 pmol/m2d. These results indicate that MeHg flux may be significantly enhanced over molecular diffusion in bioturbated sediments and suggest that remediation efforts in impacted estuaries may increase MeHg flux to the water column as sediments are re-colonized.


Juliette Smith, postdoctoral investigator in Don Anderson's lab, Woods Hole Oceanographic Institution
Development of Real-time Instrumentation for the Robotic Detection of Paralytic Shellfish Poisoning (PSP) Toxins in Massachusetts Coastal Waters

The coastal waters of New England are subject to recurrent outbreaks of Paralytic Shellfish Poisonings (PSP) caused by the toxic dinoflagellate Alexandrium fundyense. Economic impacts are significant – i.e., the losses from a single red tide in 2005 cost the Massachusetts Shellfish Industry $50M. To aid in the elucidation of bloom dynamics of harmful algal bloom (HAB) species, including the toxic dinoflagellate A. fundyense, a novel instrument known as the Environmental Sample Processor (ESP) was developed to quantitate real-time in situ cell abundances. Here we propose a study that will develop instrumentation to be incorporated into the Environmental Sample Processor (ESP) to provide real-time, in situ data on the PSP toxicity of A. fundyense within the Nauset Marsh System (NMS), a critical part of the Cape Cod National Seashore that experiences annual closures of its recreational and commercial shellfishing due to PSP toxicity. Resources will also be allocated to determining the relationship between ESP data (i.e., A. fundyense cell abundance and toxin content) and shellfish toxicity on weekly and daily time scales. Under objective 1, to develop the ESP to robotically detect real-time, in situ concentrations of PSP toxins in phytoplankton, we have successfully identified appropriate PSP toxin-protein conjugates that will be adapted for the ELISA (enzyme-linked immunosorbent assay) and preliminary results suggest 50% aqueous methanol will be a suitable extraction solvent for PSP toxins within the ESP architecture. Next steps are to print these toxin-protein conjugates onto test arrays, develop the ELISA protocol, and test the extraction protocol for phytoplankton using the bench-top ESP puck holder.

RSVP appreciated, to Gayle Sherman, gsherman@mit.edu

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