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| Marine
Biotechnology
The ocean houses the greatest diversity of living resources on the planet. This vast sea of life — from microscopic bacteria to towering tubeworms — is considered to be a largely unopened treasure chest that, with further exploration, will yield new products and processes of benefit to humankind as well as the environment. This Delaware Sea Grant research priority focuses on marine biotechnology — the use of marine organisms or their components to provide goods or services. New cancer-fighting drugs derived from marine algae, microbes that gobble up oil spills, super-glues based on the natural adhesive the mussel generates, new diagnostic tests to ensure a safe seafood supply — these are just a few of the contributions that can be credited to this growing field. The following Marine Biotechnology projects were funded by Delaware Sea Grant for the 2003–2005 period:
For additional information, please also see our latest annual report. Molecular Probes to Assess
Distributions, Nutrient Influences, and Anthropogenic Transport of Brown-Tide
Blooms in Delaware
In the first phase of this Sea Grant research project, UD marine scientists David Hutchins and Carig Cary developed a molecular probe that can rapidly detect brown tide. The probe is so sensitive it can detect concentrations of the microscopic plant as low as 10 cells per milliliter, dramatically advancing the capability to predict waters at risk for a brown-tide bloom before problems occur. In the second phase of the project, Hutchins' students used the new probe on a scientific reconnaissance mission to determine the distribution and range of brown tide from Delaware south along the East Coast. They found that brown tide is present in variable numbers throughout Delaware's Inland Bays (Rehoboth, Indian River, and Little Assawoman bays) and is distributed as far south as northern Florida. Currently, the research team is exploring how brown tide is making its way to new waters. Their preliminary research has shown that the plant has the ability to survive periods of darkness, increasing the likelihood that the microscopic plant may be hitching a ride to new waters in the ballast tanks of ships and recreational boats. The scientists also are examining how various levels of nutrient inputs affect brown-tide growth in Delaware.
When the research is complete, the results should be useful not only in Delaware, but throughout the brown-tide organism’s range, including states such as New York, New Jersey, Maryland, and Texas, where new detection and monitoring capabilities for the organism are critically needed. "This project will enable rapid and precise monitoring of brown
tide using state-of-the-art molecular methods," Hutchins says.
"The application of this new technology will, in turn, allow us
to inform managers and regulatory agencies of critical details about
the organism's distributions, population cycles, nutrient requirements,
and potential for human-assisted dispersal. Our ultimate aim to is to
provide a framework for management strategies to prevent and mitigate
brown-tide blooms in Delaware and elsewhere, with special attention
to possible regulatory and public education steps that could be taken
to minimize further dispersal of this species by recreational and commercial
boat traffic," he notes.
R/B-42 Quantitative
Impacts of Organic Pollutants on Microbial Community Structure in Estuarine
Ecosystems
While they are the tiniest organisms on Earth, microbes play many mighty roles. In aquatic systems, microscopic plants and animals form the base of the food chain. They impact important geological, biological, and chemical cycles, which among other things, control the amount of oxygen in the water. Some microbes also can detoxify certain pollutants. Marine biologist David Kirchman, who also is associate dean of the UD College of Marine and Earth Studies, and colleague Craig Cary, director of UD's Center for Marine Environmental Genomics, are in the last phase of a major Sea Grant project to determine how a class of toxic pollutants called polyaromatic hydrocarbons, or PAHs, impact microscopic life in the Delaware River and Bay. PAHs originate in tar, wood preservatives, oil, and other fossil fuels. In bays and estuaries, they can cause tumors in fish and accumulate to lethal levels in bottom-dwelling organisms such as oysters. In the first phase of the research, the team used DNA fingerprinting techniques to identify microbes in Delaware River water and compare their genetic composition. They also isolated PAH-degrading bacteria, which was a major scientific accomplishment. "Although many bacteria can degrade PAHs in the lab, our work was the first to show the impact of PAHs on uncultured marine bacteria in a real environment outside of the lab," Kirchman notes. The scientists have shown that some bacteria are enhanced by the addition of PAHs while other bacteria are inhibited by the compounds. The team now is working to develop a molecular technique to quantify these different bacteria and determine how PAHs affect the composition of bacterial communities in the Delaware River and Bay and other estuaries. "Information about the effect of toxic contaminants on bacterial community structure will advance efforts to evaluate whether or not natural processes — so-called 'intrinsic bioremediation' — can adequately reduce pollution in impacted estuaries or whether more active mediation is necessary," Kirchman says. One of the team's collaborators is the U.S.
Naval Research Laboratory, which is working to address pollution
of the Delaware River near the former Naval shipyard at Philadelphia
and at other estuarine sites. Proteome Markers in the
Physiological Health of the Hard Clam, Mercenaria mercenaria
Whether steamed and served with butter or swimming in chowder, the hard clam (Mercenaria mercenaria) has lots of fans among seafood lovers. In Delaware, the hard clam supports both commercial and recreational fisheries in the Inland Bays. Regionally, the commercial shellfishery is valued at over $65 million and is expected to grow. UD marine biologist Adam Marsh is leading a Sea Grant research project to develop a new technique for monitoring hard clam health. He and marine biologist Kevin Fielman and Marine Advisory Service specialist John Ewart are examining hard clams at the DNA level to identify "biomarkers" — key stress-response proteins that can be used as a rapid test for QPX disease or other environmental stressors.
QPX is a parasite that can cause high mortalities in hard clam populations. Aggressive monitoring programs for the clam parasite have been established in a number of states, including Virginia, Maryland, and New Jersey; however, none currently exists in Delaware. "This project would establish the first baseline data for disease and environmental stressors in Delaware's hard clam populations," Marsh notes. "With the decimation of oyster populations along the Atlantic seaboard and continuing declines in blue crab landings, hard clams rapidly are becoming a more important fishery resource in the Mid-Atlantic states," he adds. "Consequently, an advanced monitoring program in Delaware's Inland Bays could help aid future management of this public resource."
Using Biotechnology to Develop
a Sustainable Source of Attractant from the Horseshoe Crab,
Limulus Polyphemus
The horseshoe crab provides a host of ecological and human benefits. Hungry shorebirds on their spring migration from Central and South America to nesting grounds in the Arctic stop along Delaware Bay to feast and fuel up on the horseshoe crab's eggs. The crab's blood contains a compound called Limulus amoebocyte lysate (LAL) that is used by the biomedical industry to test intravenous drugs and prosthetics such as heart valves for bacteria. Crabs are bled and then returned to the sea, with a reported mortality rate of 10%. Additionally, the horseshoe crab is used as a bait in the eel and conch fisheries, which currently are valued at about $2 million in the Mid-Atlantic region. A common practice has been to collect the female crabs when they come ashore to spawn and then quarter them for bait for eel and conch pots. Concern about recent declines in the Delaware Bay's horseshoe crab population has spurred Sea Grant research aimed at developing a viable, cost-effective artificial bait for the eel and conch fisheries that mimics the chemical attractant in the horseshoe crab. With previous funding from the Delaware Sea Grant College Program, UD marine biologist Nancy Targett and her research team isolated the active compound in female horseshoe crabs that makes them so attractive to eels and conch. The scientists originally thought the compound was in the tissue of female crabs, but they found that the attractant is concentrated in the eggs. The compound is of low molecular weight and very heat-stable and freeze-tolerant. The researchers then worked to incorporate the active compound into a stable bait matrix for field trials and partnered with two bait manufacturers to formulate and produce a variety of bait products for testing. The scientists then began to explore hemolymph — a component of the horseshoe crab's blood — as a more sustainable source of the attractant than horseshoe crab eggs. The biomedical industry routinely bleeds horseshoe crabs for LAL, a blood compound that detects bacteria (endotoxins), and then returns the live animals back to the sea. Since hemolymph is a by-product of this process, it would be available in large quantities year-round. "However, with the likely success of the cloning of the horseshoe crab endotoxin sensing factor in the near future, it is evident that the LAL industry may be on its way to eliminating the need to bleed horseshoe crabs," Targett says. "Therefore, horseshoe crab hemolymph is no longer a likely long-term sustainable source of the horseshoe crab attractant." While the attractant cannot be easily synthesized via traditional methods due to its size and complexity, Targett says that new tools in marine biotechnology may provide a solution. Currently, Targett and her team are working with molecular biologist Pam Green, Crawford H. Greenewalt Chair and professor of plant and soil sciences and marine studies, and Yu Sung Wu, director of the protein production facility at the Delaware Biotechnology Institute, to develop a source for the attractant that is fully independent of the horseshoe crab. "To insure a sustainable source of the attractant, one that is
independent of horseshoe crabs, we are working toward the production
of a protein that would replace the naturally derived protein in the
artificial bait," Targett says.
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