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Tiniest creatures may reveal health of oceans

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Her subject, the diatom Thalassiosira pseudonana, is one of the simpler diatoms to study. Its physical traits are well-known, and it's "cosmopolitan," she says, allowing researchers to apply their results broadly.

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One surprise: Although, like a plant, it loves nitrogen, particularly in the form of ammonia, it handles that ammonia as an animal does, through a urea cycle. In animals, the cycle rids them of ammonia as a toxin. In diatoms, it appears to be a biological contradiction. "It's like: What?!? How is that possible?" Armbrust asks. It's one of several mysteries about the organism researchers hope to solve.

For Rocap, two types of cyanobacteria took center stage - with names certain to quickly fall from the list of monikers parents consider for their newborns: Prochlorococcus MED4 and Prochlorococcus MIT9313. Each is found in the open ocean, but each is found at a different depth. They are giving new meaning to the phrase "genetic diversity."

They pick up genes "from organisms they're not even related to - not their parents, not even their species. It's as though humans could exchange genes with a fungus," Rocap says. "We know this is possible [in cyanobacteria], but the more genomes we sequence, the more we see this is active and extremely influential in the evolution and ecology of these organisms."

These observations are necessarily broad. More-detailed links between genes, an organism's functions, and the environment will require much more detective work. Yet these and similar efforts are raising the prospect that taking the genetic pulse of the ocean is not far off. Already, scientists and engineers are thinking of ways to equip moored buoys or robotic underwater vehicles with special computer chips with genetic tools. Data could leave the vehicle, ricochet off a communications satellite, and land in a database available to scientists worldwide.

Out of both genome projects are coming "new views of the diversity of life in the ocean," Armbrust says. "We're just beginning to prop open the door to see this incredible diversity. We're in a time of exploration during a time of environmental change." Exploration "makes it exciting," she says, and environmental change "is what motivates us."

Oceans' tiniest beings

• Although they lack the roots, leaves, and other structures typical of plants, algae capture more of the sun's energy and produce more oxygen (a byproduct of photosynthesis) than all other plants combined.

• Algae vary greatly in size: from microscopic phytoplankton (1,000 could fit on the head of a pin) to seaweed that stretches 300 feet from the ocean bottom to the water's surface.

• By some estimates, a form of algae known as diatoms pull as much carbon dioxide from the atmosphere as all the rain forests combined.

• Another form of algae, called carrageen, is used in brownie mix, cottage cheese, infant formula, toothpaste, relishes, and pet food.

Sources: Bioproject, NASA

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