Clues from clams and hydra


Steven Austad, Ph.D., professor of cellular and structural biology, points to clams in an aquarium at the Sam and Ann Barshop Institute for Longevity and Aging Studies. The institute is part of at the UT Health Science Center at San Antonio. “The lighter ones, typically called ‘hard clams,’ are served in restaurants and live 100 years,” he says. “The darker ones, called ‘ocean quahogs,’ live 400 to 500 years. These clams are older than any other living animal.”

Steven Austad, Ph.D.

Steven Austad, Ph.D., holds clam specimens he is studying at the internationally known Sam and Ann Barshop Institute for Longevity and Aging Studies.

It’s a little-known fact that clams have beating hearts. “Its heart beats slower than the human heart but it lives much, much longer,” Dr. Austad says. “In fact, it beats as many times as the human heart over its lifetime.” To determine the age of a clam, its shell is cut open with a diamond saw and its internal rings are counted. From examining the width of these rings, which is much like reading a bar code, marine biologists study ancient ocean conditions.

In another room, Dr. Austad encourages visitors to peer through a microscope at hydra — small polyps typically found on the underside of aquatic vegetation in freshwater pools and streams. These fascinating invertebrates don’t age and have virtually unlimited regenerative potential. He compares hydra to a villain from one of the “Terminator” movies who, whenever shot or otherwise maimed, pools himself back together. Hydra species can be disassembled into “a pile of cells that remarkably can reassemble themselves into a whole hydra again,” Dr. Austad says.

Dr. Austad, interim director of the Barshop Institute, studies the comparative biology of aging.The field asks questions about species because of their exceptionally slow or rapid aging rates. The goal is to understand the unknown and unexplored mechanisms of aging. What causes us to age? What factors, both genetic and environmental, impact the process?

In clams, he is assessing the rate of protein turnover. In hydra, he is inducing the polyps to reproduce, which ends the polyps’ immortal status and sets them on the path of aging. “This tells us which genes are important,” Dr. Austad says. In one of his many scientific articles, he writes of the hydra: “Thus, we have the intriguing phenomenon that aging and its absence can potentially both be observed in the same species.”

Mexican free-tail bats, selected small nonhuman primates, and birds such as budgerigars, canaries and zebra finches are also under study or are candidates for study. Because of new cellular and molecular techniques for investigating novel species, “the new comparative biology of aging is poised to dwarf earlier contributions,” Dr. Austad says.

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