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2001

Dalton picture
Treetop Secret
by Todd Schwartz
Memo to Central Casting: character type for Reed plant physiologist in question could be somewhat less swashbuckling Indiana Jones, minus the hat, whip, and evil nemesis. And with better funding. Surround him with eager college students and set scene hundreds of feet up a tree or deep in the wilds of Mexico. Plot line: important science, mixed with sense of adventure. Working title: David Dalton and the Temple of Oxygen Toxicity.

You may have to wait for the movie—faculty research isn’t high on the Hollywood hot list—but you can always read the script. It takes the form of numerous publications in the areas of biological nitrogen fixation and oxygen toxicity in plants from beach grass to sequoias.

Like every member of the Reed biology faculty, associate professor Dalton is heavily invested in teaching and face time with students, and so sacrifices some of the time (and grad student help) he might find to do research at the typical graduate school. And like all Reed professors, he doesn’t mind a bit.

Dalton in lab“I’m at Reed because I really enjoy working with bright, engaged students,” Dalton explains. “Reed is a unique undergraduate institution—our students expect a lot from themselves. We provide the atmosphere for meaningful research and they come eager to do it. And I think doing faculty research at Reed has a number of professional advantages—without graduate institution-style pressure, I can explore certain projects briefly, some can be pretty wild ideas, and if they don’t work out it won’t be a career-ending situation.”

A lot of things have been working out lately for Dalton and his students. One group has been studying stress physiology in tall trees. Trees have stress, you ask? What—bad day down at the photosynthesis plant? Well, in a manner of speaking, yes. It turns out that big trees, those busy oxygen-makers, suffer free-radical damage to their cells just like the rest of us aging creatures.

Imagine the environment at the top of an old-growth forest canopy: baking all day in the summer sun; dried by the wind; 70, 80, even 90 meters above what little water may be in the ground. Stress in the upper reaches of conifer country takes the form of drought and intense light. In summer there is very little water at the tops of tall trees (and in case you wonder how they get what there is all the way up to the top, they pull it: evaporation from the leaf surfaces creates negative pressure inside the tree, as low as minus 25 atmospheres at the very top).

More information on the many research interests of the Reed biology faculty is available online at www.reed.edu/academic/ departments/biology.

The stress causes oxidative damage. Trees have several defenses, and Dalton and his students are among the first to study those defenses at the top of the canopy. Dalton and his students have gone up there by climbing—as high as 110 meters in the redwood forest—but these days they have ample (and less death-defying) access to the U.S. Forest Service’s Wind River Canopy Crane Research Facility near Carson, Washington. So far they have discovered new information about the biochemistry used by the trees to make antioxidants for protection. Vitamins C and E, along with a host of other free-radical-scavenging enzymes manufactured by the trees, help them fight the damage caused by the very oxygen they’re happily churning out.

As noted, Dalton is always on the lookout for ways to let his students mix science with adventure, and his most recent work is no exception. He and a group of students are just back from a trip far back into the mountains of southern Mexico, where they were in search of an ancient kind of corn that might make its own nitrogen fertilizer out of thin air. Self-fertilizing corn—that sound you just heard was a roomful of Monsanto executives dropping their jaws.

What Dalton found was an Indian village where they have been growing maize for centuries, without any fertilizer, on the same patch of tired soil. When the Reed group was there, the plants were already 15 feet tall and exceptionally healthy. Dalton theorizes that there may be a type of bacteria growing on the plants that allows them to convert nitrogen from the air into usable fertilizer. You heard it here first. End of Article

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2001