The tubeworm's amazing life

The deep-sea tubeworm, Lamellibrachia luymesi, is a marvel of adaptation, not only surviving in one of the world's most hostile environments, but thriving with lifespans of up to 250 years.

Researchers in the lab of Penn State University biologist Charles Fisher and colleagues at several other institutions recently have uncovered some of the secrets that allow the worms to live near hydrothermal vents and cold seeps in the ocean bottom, where they endure crushing pressure and sulfide levels that would kill most aquatic life.

It turns out that the tubeworm's hemoglobin, the molecule that carries oxygen to its cells, contains zinc that binds sulfide. This protects the worm from the sulfide, while also serving to deliver it as hydrogen sulfide to bacteria that live in the worm's body. Those bacteria gobble up hydrogen sulfide and produce nutrients that the tubeworm needs to survive.

These findings were reported earlier this month in the online edition of the Proceedings of the National Academy of Science.

But scientists have been puzzled as to how the tubeworms obtain enough sulfide to live such long lives. In a paper published last week in the online journal PLoS Biology, Fisher and his colleagues suggest that sulfate that is produced as waste by the tubeworms is not released into the water, but into the ocean sediment through the worms' root-like extensions. Bacteria and archaea in the sediments, in turn, use the sulfate to produce sulfides.

This model, which must still be confirmed by direct observation, suggests that a colony of tubeworms would survive only 39 years if sulfates were not returned to the sediment.

CMU scientist wins top honor

Edmund M. Clarke, a computer scientist at Carnegie Mellon University, has been elected to the National Academy of Engineering for his work in developing a technique for finding errors in computer hardware and software.

The technique, called model checking, has proven superior to simulation in detecting flaws in computer circuits. Since Clarke and several students began developing model checking in 1981, companies such as IBM, Hewlett Packard, Intel, Siemens and Fujitsu have used it to improve verification of circuit designs.

Clarke, received both his master's and doctoral degrees in computer science at Cornell University. Before joining Carnegie Mellon in 1982, he taught at Duke and Harvard universities. Election to the engineering academy is one of the highest professional distinctions an engineer can achieve.