Biotechnology

Biotechnology

The goal of this Delaware Sea Grant strategic priority is to catalyze the exploration, development, and use of marine biotechnologies to improve and protect the coastal ocean and human health and develop novel industrial processes and products based on the specific adaptations found in marine organisms.

The following Biotechnology projects have been funded by Delaware Sea Grant for the 2003–2005 period:

Molecular Genetic Tools for Monitoring Stock Enhancement Efforts: Application to Chesapeake Bay Oysters
Using Biotechnology to Develop a Sustainable Source of Attractant from the Horseshoe Crab, Limulus Polyphemus

For additional information, please also see our latest annual report.

Molecular Genetic Tools for Monitoring Stock Enhancement Efforts: Application to Chesapeake Bay Oysters
Project: A/I-1. Principal Investigator: Patrick Gaffney
University of Delaware College of Marine and Earth Studies, Lewes Campus
Project Period: Feb. 1, 2005 – Jan. 31, 2007


Dr. Patrick Gaffney is developing a new genetic technique to help scientists and resource managers rapidly determine whether disease-resistant oysters in the bay have been derived from wild stocks or from hatcheries. The technique will help scientists assess the effectiveness of oyster restoration efforts. Gaffney is pictured here with doctoral candidate Robin Varney.

For more than a century, enhancement projects have attempted to restore or supplement depleted natural stocks of finfish and shellfish. In the last decade, a concerted effort has been underway to restore the decimated oyster population of Chesapeake Bay, which has been ravaged by a century of overharvesting, habitat degradation and disease.

According to Patrick Gaffney, professor of marine biology–biochemistry and director of the Marine Biology–Biochemistry Program, millions of dollars are being spent on habitat restoration and restocking the Chesapeake Bay with hatchery-produced oyster seed. However, despite the considerable expense involved, it is rare for these programs to be rigorously evaluated.

In a previous project supported by Sea Grant, Gaffney and his research team demonstrated that large numbers of oyster babies (or spat), which originated in the Gulf Coast and were planted in a tributary of the Chesapeake Bay, could be quickly and reliably identified by genetic techniques. The technique, called high-throughput SNP (single nucleotide polymorphism), was successful because these oysters had a unique gene that reflected their Gulf coast origin, which could be used to differentiate them from native oysters.

"Most current and proposed oyster restoration programs for the Chesapeake Bay, however, use hatchery lines derived from Atlantic Coast oysters," says Gaffney. "Effective genetic tagging of these hatchery stocks required a more sophisticated approach."

In this Sea Grant Project, Gaffney and his research team will expand on their previous Sea Grant work and develop more advanced genetic techniques that can be used to reliably identify outplanted oyster stocks derived from the Eastern oyster, Crassostrea virginica. In addition, the techniques will provide a way to rapidly and efficiently analyze large numbers of wild-caught individuals so that it can be used to assess novel larval- and spat-based stock enhancement efforts.

The development of these techniques can be used to evaluate marine-stock enhancement programs, which typically cost considerable taxpayer money yet are rarely evaluated objectively for their ability to enhance natural populations. At the regional level, the information will be useful for determining whether spawner enhancement programs in the Chesapeake Bay are likely to help restore the bay's oyster populations. At the national level, the protocols developed in this project can be applied to other shellfish and finfish restoration programs.

These techniques also could be readily adapted to screen natural populations of organisms found in sediments or ballast water for the presence of a particular species. This would be very useful in cases where the target species is difficult to identify or where it is extremely rare, such as in the early stages of a biological invasion.

Finally, the techniques could be used to study the dynamics of oyster reproduction and recruitment, by allowing researchers to map the geographical and temporal distribution of genetically tagged animals, both as larvae in the water column and subsequently as settled spat. The ability to directly and effectively monitor the distribution of larvae originating from a point source would be invaluable for the study of larval dispersal, which has occupied the attention of oyster biologists for decades.

This research will evaluate oysters planted in the Little Choptank River in 2002 and 2003 by Dr. Don Merritt at the University of Maryland Horn Point Lab and the Oyster Recovery Partnership.

Using Biotechnology to Develop a Sustainable Source of Attractant from the Horseshoe Crab, Limulus Polyphemus
Project: R/F-9. Principal Investigators: Pamela Green and Yu-Sung Wu
University of Delaware College of Marine and Earth Studies and the Delaware Biotechnology Institute
Project Period: Feb. 1, 2005 – Jan. 31, 2007


Dr. Pam Green, Crawford H. Greenewalt Professor at the University of Delaware, is part of a research team whose goal is to isolate and synthesize the "fish attractant" in horseshoe crabs for use in an artificial bait.

Of the four species of horseshoe crabs that exist in the world, three are found in the western Pacific, from Japan to Vietnam, and one species, Limulus polyphemus, is found along the western Atlantic coast from Maine to the Yucatán Peninsula, with the center of the population in Delaware Bay.

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.