IN THIS ISSUE .
May 16, 2007
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Cool Image: Planting Roots
At the root tips of the mustard plant Arabidopsis thaliana (red), two proteins work together to control the uptake of water and nutrients. When the cell division-promoting protein called Short-root moves from the center of the tip outward, it triggers the production of another protein (green) that confines Short-root to the nutrient-filtering endodermis. The mechanism sheds light on how genes and proteins interact in a model organism and also could inform the engineering of plants. Courtesy of Hongchang Cui, a postdoctoral fellow working with Duke University biologist Philip Benfey.
Benfey lab home page
Article abstract (from the April 20, 2007, issue of Science)
Molecular Clock Ticks to the Seasons
Circadian rhythms, which control a range of biological processes, keep time to molecular "clocks" that cycle about every 24 hours. A group led by behavioral geneticist Michael Rosbash of Brandeis University previously showed that "morning" and "evening" nerve cells keep circadian time in fruit flies. Following up, the group has now learned that these nerve cells are part of a dynamic network that responds to seasonal cues. During the summer, the light-activated evening cells are in charge. In the winter, the morning cells take over to adapt to shorter days. The results point to prospects for better understanding insomnia as well as jet lag, depression, and other conditions linked to faulty body clocks.
This work was also supported by NIH's National Institute of Neurological Disorders and Stroke.
Rosbash lab home page
Article abstract (from the April 6, 2007, issue of Cell)
New Molecule May Improve Cancer Treatment
The side effects of chemotherapy, such as hair loss and weakened immunity, occur because the anticancer drugs also kill healthy cells. A research team led by biophysicist Donald Engelman at Yale University has found a molecule named pHLIP that selectively targets tumor cells in mice. The molecule is attracted to the tumor cells' acidity. The scientists previously showed that the molecule can bore through the outer membrane of cells and, like a microscopic syringe, squirt chemicals inside. With these traits, pHLIP could improve cancer treatments and be used to monitor the course of the disease.
NIH's National Center for Research Resources also supported this work.
Engelman home page
Article abstract (from the May 1, 2007, online edition of PNAS)
Faulty DNA Repair Linked to Huntington's Onset
Artistic rendering of a damaged DNA from a mouse nerve cell. Courtesy of McMurray.
Huntington's disease, a fatal neurodegenerative disorder, affects roughly 30,000 Americans. While the disease gene is inherited at birth, symptoms usually don't appear until middle age. The onset may be triggered by faulty DNA repair, which occurs increasingly with age, according to a new study led by Mayo Clinic pharmacologist Cynthia McMurray. Working in mice, McMurray's team found that missteps in repairing a type of damage to DNA called oxidative lesions worsen the genetic defect that causes Huntington's disease. The findings suggest that minimizing the DNA damage or blocking the repair pathway could delay the onset of Huntington's disease.
This work was also supported by NIH's National Institute of Neurological Disorders and Stroke and National Institute of Environmental Health Sciences.
McMurray home page
Article abstract (from the April 22, 2007, online edition of Nature)
Dandruff Fighter Might Treat Seizures
The active ingredient in many dandruff shampoos may do more than relieve itchy, flaking scalps—it could potentially treat seizures. Neuroscientist Min Li of Johns Hopkins School of Medicine and his team tested thousands of molecules for their ability to help open potassium channels, which allows excited nerve cells in the brain to calm down. In seizure disorders such as epilepsy, nerve cells fire excessively. The dandruff-fighting chemical zinc pyrithione appeared to help defective potassium channels, including a form that causes seizures in infants, work better.
Li lab home page (no longer available)
Article abstract (from the May 2007 issue of Nature Chemical Biology)