Hospital lab tech, student strive to add life to bay scallops
BY PETER B. BRACE INDEPENDENT WRITER
Dr. Steve Estabrooks and Nantucket High School sophomore, Leah Blount, have joined forces to help prolong the life of the bay scallop and in doing so, the research duo could more than double the two-year life span of the scallop and stabilize the fishery.

"Scallops have been around for 240 million years and humans have been around five to seven million years," said Estabrooks. "The fact that we have the same [DNA] sequence as scallops is generally something important, considering it's been conserved through evolution."

Estabrooks started his studies after serving in the Air Force. His career light bulb moment came during his first invertebrate zoology class.

"I took this one course in invertebrate zoology and the professor just happened to mention [bay scallops]. She said, 'Just off our coast on Cape Cod they have scallops that live less than two years and nobody knows why.' And, that was the spark for me," said Estabrooks.

For 16-year-old Blount, her moment came while working with Estabrooks, a medical technologist at Nantucket Cottage Hospital, who volunteers in the science department at Nantucket High School, when she discovered the genetic sequence of telomeres - protective molecules on the ends of chromosomes - in the mahogany clam, Artica islandica, for her winning entry in the Nantucket High School science fair.

"I didn't expect to enjoy it as much as I did," said Blount, who will continue her research with Estabrooks over the summer. "It's very intriguing and I want to go into a science or medical career so it's a good experience for me."

Lucky for Nantucket that Estabrooks landed here and that he inspired Blount, since their research on the longevity of mollusks could produce bay scallops, Argopecten irradians irradians, that live five years or more reenergizing scallop populations in island harbors and helping to stabilize the fishery.

Estabrooks and Blount, with the financial aid of the Shellfish & Harbor Advisory Board (SHAB) and others, is studying molecular structures at the ends of bay scallop chromosomes that determine how long scallops and almost all living things live.

At the May 20 SHAB meeting, the board voted unanimously to give Estabrooks $2,000 to help him continue his research and $1,500 to Blount for her research.

These critical DNA molecules, telomeres, form a protective shell around the ends of chromosomes sort of like the plastic tips at the ends of shoelaces. The more telomeres, the thicker the protection and the longer a particular life form lives.

The trouble is, explained Estabrooks, as cells divide, the telomeres wear away with each new cell replication. When enough of the telomeres are lost due to cell division, the cells go into crisis and die.

And because most living things on the planet, including scallops, have a set number of telomeres - humans have enough for 60 to 70 cell divisions - death is inevitable. Estabrooks is trying to learn how to extend the lifespan of bay scallops, which he believes is two years or less, by cracking the telomeres code. This includes the possible cross breeding of our bay scallops with their closest relatives found along the coasts of Chile and Peru.

Currently, Estabrooks is putting together a research group consisting of himself and Blount working in Nantucket's marine lab in the boathouse at Brant Point, researchers at universities in Chile and at the National Oceanographic & Atmospheric Administration Lab (NOAA) in Milford, Conn., with the latter providing a sterile, safe place to breed Nantucket bay scallops with the South American bay scallops.

"The first part of it was the identification of the telomeres in bay scallops," said Estabrooks. "We had to work out the sequences of the repeating sequences in the scallop and it turns out it is the same sequence found in humans: TTAGGG. Those all stand for the nucleic acids; they make up the genetic code."

The nucleic acids, adenine (A), guanine (G), cytosine (C), and thymine (T), in different repeating sequences in chains form DNA in chromosomes.

Telomeres are generated by an enzyme in genes called telomerase, but for most living things including human and scallops, it is turned off and consequently, turning this biomechanism on and off has been the subject of much research in the last 10 to 15 years by cancer researchers, said Estabrooks.

Because cancer cells have the ability to turn this enzyme on, they can create as much telomerase as they need to make telomeres to protect themselves and grow.

Through this crossbreeding experiment, Estabrooks, Blount and the research group are hoping to produce a scallop whose chromosomes are protected with enough telomeres to allow it to survive longer than two years.

Blount's research on the mahogany clam, which is known to live 200 to 300 years, is targeted at discovering whether this clam's genes have the ability like cancer cells, to turn the enzyme telomerase on to create more telomeres and prolong its life.

Recently, a mahogany clam found off the coast of Iceland was determined to be more than 400 years old.

"There are some animals that have this enzyme telomerase in all of their tissues such as sponges and the common lobster," said Estabrooks. "They'll live until some disease gets them or until somebody grabs them. "What we're going to be doing, we're going to be determining if there is this enzyme in all of the tissue of this clam. That might determine its longevity. The alternative is that this clam has lots of telomeres and a very slow metabolism."

Blount's volunteer hours with Estabrooks during her science fair research evolved into a summer-long project that is likely to continue into her junior years as she begins her college selection process.

"I really enjoy the preciseness of it and orderliness of the experiments and I enjoy being in control of variables and I also enjoy that don't know what's going to happen," she said. "I love the environment of the lab and enjoy learning new things. I want to go into cancer research,

so this all kind of ties together." I