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These stories describe NIGMS-funded medical research projects. Although only the lead scientists are named, they work together in teams to do this research.

Making Heads or Tails of Regeneration

Fluorescent dyes
show cells in a flatworm that have copied their DNA. Courtesy: Phillip Newmark

At less than an inch in length, a flatworm called a planarian can regrow its entire body from just a section of tissue. In this image from under a microscope, fluorescent dyes show which cells in the worm have copied their DNA and are ready to split in two. Courtesy: Phillip Newmark

A small flatworm called a planarian possesses an extra ordinary ability: It can regenerate its entire body from a tiny slice of tissue. Scientists in Massachusetts have discovered how the worm makes heads or tails of what body part to regrow from a wound site.

The process involves a gene called notum and a genetic pathway called Wnt. Researchers led by Peter Reddien at the Whitehead Institute for Biomedical Research in Cambridge discovered that Wnt stops a wounded planarian from sprouting a head. But with Wnt around, how do heads ever form?

The scientists found that, if a wound is near the top half of the worm, Wnt activates notum. The notum gene appears to keep Wnt in check, dialing down the pathway's activity so a head can form.

In back-end wounds, the researchers noted that notum is less active, allowing tails to grow.

Both notum and Wnt are found in organisms ranging from fruit flies to humans. Could it play a role in repairing—or even regrowing—tissue in these other animals? Only science can tell.
—Allison MacLachlan

Microscopic Mood Rings

The stressed region of this polymersome is evident (in green) before the membrane ruptures. Courtesy: Neha Kamat, University of Pennsylvania

The stressed region of this polymersome is evident (in green) before the membrane ruptures. Courtesy: Neha Kamat, Uuniversity of Pennsylvania

Scientists have designed tiny, glowing capsules that shine in stressful situations—literally. A team led by Daniel Hammer and Ivan Dmochowski at the University of Pennsylvania in Philadelphia engineered polymersomes, membraneencased spheres only a few microns in diameter. The polymersomes act as miniscule mood rings, changing color in response to stresses like heat, membrane-disrupting chemicals and the mech anical stress of being sucked into a glass tube.

Here's how it works: The polymersomes are studded with natural light-emitting pigments called porphyrins that change shape when exposed to environmental stress. For porphyrins, a shape change means a change in the wavelengths of light they emit—their color. The new color reveals when and where the membrane is stressed.

The scientists suggest lots of potential applications. Polymersomes could be injected into the bloodstream to provide clues about nearby stresses, such as arterial blockages. They might carry a med icine into the body and reveal its release over time. They could even be used in bodyscanning technology that would rely on light rather than radiation. —A.M.

Other Spotlights

Drake. Courtsey: Stephanie DziezykDrakes: A Mythological Model Organism
With the aid of Web-based programs that use dragons, high school students are learning about complex genetic concepts and gaining an appreciation for how science is done—all the while having fun.
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A typical animal cell, sliced open to reveal cross-sections of organelles. Courtsey: Judith Stoffer.The Amazing World Inside a Human Cell
Imagine you've shrunk down to 3 millionths of your normal size. At this scale, a medium-sized human cell looks as big as a football field. Let's take a quick trip inside to see how it works.
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Map of the disease-carrying tsetse fly across the country of Kenya. Courtsey: Joseph Messina.Solving the Sleeping Sickness 'Mystery'
Since before the 1300s, people living in Africa have been dying from a disease known as sleeping sickness. Epidemiologists are working toward eradication by predicting where cases will emerge next.
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Simulation developed by Chand John and his colleague Eran Guendelman. Walking the Line
Researchers model leg muscles in motion to study ordinary movement and walking disorders.
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This page last reviewed on February 15, 2012