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5 December 2013 11:26 am ,
Vol. 342 ,
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
- 5 December 2013 11:26 am , Vol. 342 , #6163
- About Us
Like Clockwork No Longer
29 August 2001 7:00 pm
As a body ages, daily rhythms such as sleep patterns become less regular. Now, a study in mice has shown that these changes take place within the individual brain cells that make up the biological clock. Experts say the study, published in the September issue of Neuroscience, offers a unique perspective on a process usually studied in tissues. "We're not often able to measure aging at the single cell level," says neuroscientist Martha Gillette of the University of Illinois, Urbana-Champaign.
Older mice, like older people, often have sleep problems. When kept in the dark 24 hours a day, juveniles doze at regular intervals, but middle-aged mice exhibit irregular sleep. To see whether this disruption arises with individual neurons or results from their interaction, University of Virginia neuroscientist Gene Block and colleagues examined cells from the brain region in charge of daily timing, called the suprachiasmatic nucleus (SCN). They recorded the electrical activity of mouse SCN neurons cultured in such low concentrations that they were unlikely to communicate with one another.
Eight neurons from middle-aged mice beat irregularly for days in the dish, they found, while 12 cells from young adults keep strict rhythm. The research suggests that overall decline in SCN behavior is driven in large part by the deterioration of individual neurons, says neuroscientist Martha Harrington of Smith College in Northampton, Massachusetts.
Paradoxically, the researchers observed that aging appears to disrupt the rhythm of single cells more severely than it does the animals' overall behavior, as measured by their sleep patterns. That raises an interesting biological question, Block says: "How do you get reliability [despite] unreliable parts?"