Inquiring Minds

The Great Strawberry Hunt

On a cold Saturday morning in mid-winter, Tom Davis stands waist-high among tables of strawberry plants--about 500 of them. Inside the UNH greenhouse the air is moist. It is quiet except for the hum of the fans. The lanky professor of plant biology plucks a leaf and rolls it between his fingers. Back in the lab, it will be crushed in a mortar and pestle, mixed with liquid nitrogen to stabilize the DNA, and then put through a molecular sifting process called a polymerase chain reaction. His goal is to generate DNA fingerprints that will reveal the plant's defining characteristics, and potentially, its ancestry.

The strawberry, it turns out, has a long and complicated family history. "The cultivated strawberry is interesting from a genomic perspective," says Davis, "because it's a polyploid hybrid species." Unlike peas, for example, or humans, for that matter, which are diploids (with two sets of chromosomes), a strawberry is an octoploid (with eight sets of chromosomes).

How some strawberries evolved from diploids to octoploids is part of the story Davis is trying to unravel. Ultimately, this research effort could help to "build a better berry," shedding light on the genes that control economically important traits such as disease resistance and fruit quality. "Breeders are very interested in wild relatives as genetic resources, because it's still possible to make crosses between cultivated species and some of their wild relatives," he says. The work could create a bridging method by which genes from wild diploid strawberries can be transferred into cultivated octoploid strawberries.

The strawberry's recent history, unlike its mysterious past, is well understood. It begins like a classic love story, with a chance meeting in Europe. Two species of wild strawberries, one from North America, one from South America, cross the Atlantic escorted by 17th-century plant collectors. The two species wind up in the same garden, mate, and produce progeny that exhibit the best characteristics of both parents--good size, rich color and sweet taste. Voila! So begins the story of the plump summer treat we enjoy today. But what happened before these two wild octoploids met and mated remains a mystery.

"We have to scour the world for different species of strawberries," says Davis, "analyzing them to see which wild ones match most closely the DNA fingerprints of cultivated genomes." Davis's sleuthing has led him to Asia, home to about a dozen species of wild diploid strawberries. This summer he's off to Japan, where he will make his way to different sites, trowel in hand, collecting specimens for study and breeding.

Another suspect will arrive in the mail this spring, sent by a Russian colleague who hiked across grueling bear-infested terrain on a remote island north of Japan to bring back a rare wild strawberry.

One of these days, Davis may have his own bear stories to tell. His next destination in the Great Strawberry Hunt, he hopes, will be northwestern Alaska. "No one's looked up there, as far as we know," he says, pointing out that the search will require a small seaplane to go lake-hopping in the vast, roadless region.

Meanwhile, Davis continues his patient work in the greenhouse, tweezers in hand, pollinating individual blossoms, tagging them and waiting and watching for the next clue to help solve his strawberry mystery.

Visualize Ice

On research scientist Martin Jakobsson's computer screen, a river of light cuts across a dark continental plane.Vivid reds, yellows and oranges reveal the dips and elevations of the ocean floor. These graphic representations might have started as a sideline to his studies of sub-oceanic geography, but they are quickly becoming a way for scientists involved in interdisciplinary projects to find common ground.

Jakobsson, whose specialty is paleoceanography--the study of past configurations of the oceans--has found lately that his skill in manipulating graphics and thinking visually are nearly as important as the complex calculations he makes to determine the geographic arrangement of land beneath the sea.

"I'm always thinking about the idea of visualizing models," Jakobsson says. "The purpose it serves for me as a paleoscientist, and as a person who has to think about process, is that if we can merge data sets into a three-dimensional environment, everybody can talk about the results in a much more understandable way."

Jakobsson's graphic and computational skills recently came into play for an article he co-authored in the journal Nature. The article described a theory to explain the growth of a massive ice sheet covering the Barents and Kara seas, as well as much of Russia, nearly 90,000 years ago.

The theory claims that as the ice sheet began to dam north-flowing rivers in Siberia, backing up the water into huge lakes, it grew at an accelerated rate and loosed a cooler regional climate. It had a spiraling effect, in which reduced ice melt during the summer allowed the ice sheet to advance more rapidly during the winter. The condition persisted until the Earth's rotation around the sun brought on a warmer period that reversed the ice sheet's progress.

Using the findings of an international team of geologists, who searched for clues as to where lakes rested, Jakobsson created reconstructions of what those lakes looked like and adapted them with Fledermaus, a "fly-through" graphics visualization program developed by researchers now at the UNH Center for Coastal and Ocean Mapping/Joint Hydrographic Center, where he works.

The article's finding is important for two reasons: it helps correct earlier assumptions that having lakes near an ice sheet would actually prevent its expansion, and it helps broaden our overall understanding of environmental history.

"For me, you can justify all this research about the past as the only way to try to figure out what's going to happen in the future," says Jakobsson.

Bad Air in a Bag

Coastal New Hampshire has a big problem with smog in the summertime. So why is the National Science Foundation paying Rob Griffin to make more of the stuff? Griffin, an assistant professor of earth sciences, won a prestigious five-year NSF Career Award --granted to young scientists early in their academic careers--to build a chamber that makes smog.

In scientific terms, he and his students are trying to "simulate atmospheric secondary organic-aerosol formation." In the lab, that translates into a rack of fluorescent lights and a big plastic bag filled with gas, to which they add a dash of chlorine.

Aerosols--airborne collections of particles--are a component of smog, along with ozone and other chemicals. The National Science Foundation doesn't want more smog, but it would like to understand how, in coastal areas, chlorine atoms from sea salt contribute to the formation of aerosols. With help from doctoral candidate Xuyi Cai, research staff members and several undergraduates, Griffin built the smog chamber to study that question.

Aerosols and ozone can form when volatile organic compounds (VOCs)--coming from cars' exhausts, for example--react with a photo-oxidant like a chlorine atom. Some studies have shown that this kind of reaction can lead to increases of up to 10 parts per billion of ozone in coastal areas, but little is known about the dynamics of the process, especially when it comes to aerosol formation. Griffin's smog chamber is designed to shed some light on the matter.

The chamber is an airtight, chemical-free vacuum enclosed by theater-grade black curtains to block unwanted light.

A compound like toluene, which is emitted by cars, is injected and the initial conditions in the chamber are measured with a gas chromatograph. Then chlorine is pumped in, a fluorescent-light "sun" is flipped on, and the whole mixture gets cooked. The result is the creation of aerosols, which are measured to determine their number, size and type.

This summer will be a particularly apt time for Griffin to study the ozone and aerosol problems. Beginning in mid-July, hundreds of scientists from around the world will converge on Seacoast New Hampshire to conduct the largest air quality study ever done. Researchers will use the latest scientific equipment aboard 12 aircraft, a 274-foot research vessel, balloons and satellites, and UNH's ground-based monitoring network, AIRMAP, will sniff the air for some 180 chemicals. By the time his colleagues arrive and begin to probe the air, Griffin hopes he will have some answers to the smog problem.

"The field study will look at how pollutants come into the region, react, get baked and mixed, and then get carried out over the Atlantic," says Griffin. Key to that whole process, and central to this summer's field study, he says, is the interaction between marine chemistry and polluted air that comes into New England from the industrial Midwest and is created locally by Eastern Seaboard cities. "Ideally," Griffin says, "we'll be able to observe the same kind of chemistry in the marine coastal area this summer that we see in the chamber."


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