Clemson marine biologist seeks genetic pearls in oyster DNA

Published: September 19, 2012

CLEMSON — The drab shell of an oyster is complex and the animal that lives inside can adapt to stressful living conditions, according to a team of marine biologists, including a Clemson University researcher, that identified and catalogued the genes of the Pacific oyster. Their research is published in the journal Nature this week.

The Pacific oyster is the first mollusk to have its genome decoded, sequenced and analyzed. What the researchers discovered is an animal with a robust ability to deal with its changing environment and a remarkable protective shell. The research will have an impact on the eastern oyster, as well, which is the focus of study at Clemson University.

The research shows that the oyster’s genes enable it to adapt and cope with environmental stresses, such as temperature and saltwater changes, air exposure and heavy metal pollution; and that shell formation is a far more complex process than previously thought.

Clemson marine biologist Andrew Mount of the College of Agriculture, Forestry and Life Sciences focused on the genes related to the oyster shell for the team led by Goufan Zhang of the Institute of Oceanology at the Chinese Academy of Sciences.

“I am honored to have participated in the project, which took more than three years to complete,” said Mount, a research associate professor. “The genome sequencing and the research to understand how genes work represent a first and highly significant step in marine genomics. It identified the genetic mechanisms that give oysters the ability to respond to environmental stress and produce their protective shell.”

The Pacific oyster (Crassostrea gigas), also known as Japanese oyster or Miyagi oyster, is native to Japan and the most widely farmed and sold oyster in the world. China grows more than 80 percent of the commercial oyster crop. The Pacific oyster was brought to the Pacific Coast of the United States in the 1920s. 

A close relation is the eastern oyster (Crassostrea virginica) — also called Atlantic oyster or Virginia oyster — that lives in tidal waters along the Eastern Seaboard and Gulf of Mexico. 

“We are in an exciting time in understanding how sea shells are made,” Mount said. He founded and leads the Okeanos Research Laboratory at Clemson, where studies about how shells form, grow and are nourished have led to new technologies. 

Using sophisticated imaging instruments showing shell structure in fine detail, Mount and his post-doctoral and graduate students have revealed how the calcium-carbonate shell is made. They have applied their discoveries to designing innovative coatings to repel marine life that attaches to boat hulls and fouls their bottoms, increasing fuel, delivery and maintenance costs.

The research reported in Nature provides genomic evidence that oyster shell formation begins with cells in the blood, confirming what Mount’s lab presented in its 2004 publication in Science.

“The animal’s blood cells generate and deliver crystals that begin mineralization,” said Mount. 

Mount’s work on shell formation has led him to see the mollusk’s cell as a way of gauging the threat of ocean acidification.

“The oceanographic geochemistry community has become alarmed over the past several years over increasing levels of ocean acidification,” caused when the sea absorbs carbon dioxide from the atmosphere, he said.

“As the pH level drops, there is concern that marine calcifying organisms such as oysters and corals could be negatively impacted. Now that we have a better understanding of how these organisms actually calcify at an intracellular level, science is better equipped to investigate the threat that ocean acidification poses to the future of the world’s food security.”

Oysters offer the potential biotechnological pearls. The ability of oyster cells to produce one of the toughest bioceramic materials known, coupled with the knowledge of the genes involved, presents a portal for innovation in materials science.

“Biologically produced, cellular materials have a hierarchy of order that is unmatched by mankind,” said Mount. “The production of useful and novel materials by harnessing the genome of mineralizing cells opens a bold new frontier for technological development.”

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