Graduate Research

Climate change and the weather underground

by Marcia Goodrich

Glaciers are melting and the Sahara is expanding. But what effect will climate change have on the world under our feet?

Carley Kratz, who is working on a doctorate in forest science, aims to find out. With her co-advisors, Andrew Burton and Erik Lilleskov, she is studying how added warmth affects the soil’s tiniest creatures.

“My role is to look at how microorganisms are moving matter around in the soil, especially how they are cycling nutrients like carbon,” said Kratz, who received a fellowship from the US Department of Energy Office of Science to pursue her research. To do that, she is analyzing all the DNA present in the soil using a new technology called pyrosequencing, which helps her identify the types of microorganisms and also gives information on how much carbon dioxide they may be producing.

The study started last fall at the University’s Ford Center in Alberta, and Kratz is seeing some early results. “So far, it does seem like there is some change in metabolic function,” she said. “Everything is respiring faster, working harder. Things are happening more quickly, which is kind of what you’d expect, considering basic chemistry: everything happens faster at higher temps.”

She has seen a corresponding decrease in biomass below ground, which suggests that fungi have shifted into overdrive as they break down organic matter. To measure the action of fungi more precisely, Kratz uses hyphal ingrowth bags. “Some people call them little burritos,” she notes. Filled with sand, they are made of a mesh that blocks roots and worms but allows in hyphae—miniscule fungal threads that can form symbiotic relationships with plant roots and greatly expand a plant’s absorbing system.

“I measure their mass and also their respiration, the amount of carbon dioxide they give off,” she says. “If more carbon dioxide is given off in warmer temps, it could mean that the warmth is accelerating the decay process”—and possibly loading the atmosphere with even more greenhouse gas.

But it’s too early to reach any definitive conclusions, Kratz stresses. She is also working at the Harvard Forest, in Massachusetts, on two long-term studies of soil warming. “In Harvard, the biomass below ground is about the same as in the control plots, whereas here, we’ve seen a decrease,” she said. That suggests that soil microorganisms may eventually return to equilibrium as the soil warms up, but whether that happens in Alberta remains to be seen.

Whatever the outcome, Kratz is very happy she chose Michigan Tech for graduate school. “The labs here are amazing; the amount of space and equipment I have for my research is wonderful,” she says. “It’s been really great.”


A “package deal” for treating PKU

by Dana Yates

Eating a hot dog is a simple pleasure of childhood. But for kids with phenylketonuria (PKU), consuming this high-protein food can lead to seizures and a slowdown of motor skills and cognitive abilities. At Michigan Tech, though, biochemistry PhD candidate Kara Vogel is searching for a new way to manage PKU—one that she hopes will enable children to eat hot dogs without jeopardizing their health.

According to the American College of Medical Genetics, at least one in 25,000 babies born in the US has PKU. One of the most commonly inherited metabolic disorders, PKU is marked by a missing enzyme called phenylalanine hydroxylase (PAH). Without this enzyme, people are unable to process an amino acid called phenylalanine. Consequently, phenylalanine builds up in the body, crossing from the blood into the central nervous system and brain, and causing damage and developmental delays.

“You need some phenylalanine in your diet, but not a lot. It can be a difficult balance for someone with PKU to achieve,” Vogel says. That’s because a wide variety of foods contain phenylalanine, including meat, eggs, dairy products, pasta, bread, chocolate, and certain fruits and vegetables.

Babies with PKU must consume a phenylalanine-free formula, and children and adults should follow a low-phenylalanine diet to avoid health problems. But the restrictive, lifelong regimen isn’t a perfect solution; phenylalanine levels can still remain elevated. Furthermore, while one drug has been approved to treat PKU, the medication only targets a less-common type of the disorder.

Not good enough, says Vogel. So, under the supervision of Michael Gibson, professor and chair of the Department of Biological Sciences, she is studying a novel treatment for PKU: amino acid transport inhibitors. These substances, when bundled with a deficiency of the enzyme PAH, have been shown to inhibit the movement of phenylalanine across the blood-brain barriers of laboratory mice. Now, Vogel is working to resolve an unintended consequence of this “drug packaging”: a depletion of other important brain chemicals, including serotonin (the so-called “happy hormone” that influences mood).

Down the road, Vogel’s research may lead to the development of a pill to manage PKU. Although the drug won’t cure the condition, it could dramatically improve the quality of life of those who have the disorder. And that works for Vogel.

“My goal is to help alleviate suffering,” she says.


Toward painless artificial legs

by Marcia Goodrich

Brandon Pereles has a knack for engineering and a heart for people. So it’s no surprise that he has turned his talents toward those who have lost a leg.

In particular, he wants to help prevent the skin problems associated with using prosthetic legs. Unlike the sole of the foot, the skin on an amputee’s stump is delicate and not designed to handle the stresses of walking. “If the force from the prosthesis isn’t well distributed, you can get abrasions, sores, and cysts,” says Pereles. Sometimes the pain can cause patients to quit walking all together.

Pereles’s work is supported through a National Defense Science and Engineering Grant and additional funding from the US Department of Defense, which has a significant stake in the health of soldiers and veterans who have lost limbs in combat.

To address the problem, Pereles, a PhD candidate in biomedical engineering, is using sensing strips that could be embedded within the base of the sleeve at the top of the artificial leg. The strips would measure the force applied to the stump while the person walks and detect pressure imbalances early, so skin problems could be averted before they begin.

The sensing strips are made from Metglas, a thin, inexpensive alloy that, when excited by a magnetic coil, responds magnetically to varying amounts of force. “That makes it a wireless pressure sensor,” Pereles says.

The entire system could be set up in a typical doctor’s office. To measure forces on the stump, the patient would simply walk around briefly carrying a battery in a fanny pack. The magnetic coil would be held to the stump by a cuff, like a blood-pressure monitor. Results would be transmitted wirelessly to a computer. In addition to generating a color-coded map indicating pressure points, the system could also record the pressure on the stump quantitatively, in pounds per square inch or newtons.

The technology has potential for other uses as well. “We want to focus on biomedical engineering, but this could just as easily be put in concrete, in an airplane, anywhere you want to monitor force wirelessly,” says Pereles.

He started doing research as a sophomore under the direction of Associate Professor Keat G. Ong, who is now his advisor.

“I realized I wanted to get into device development,” Pereles says, so staying on as a graduate student was a natural choice. “I liked Dr. Ong, I liked the projects, and I like Michigan Tech,” he says. “I’ve always liked building stuff and working with my hands, and I also want to help people. So this is a perfect fit.”