Worms Able to Control Lifespan At High Temperatures

April 19th, 2009

A common research worm called Caenorhabditis elegans (c. elegans for short) was found to not only regulate its response to hotter environments, but also to control the pace of its aging as a result of that heat, according to new research at the University of California, San Francisco.

Before this discovery cold-blooded animals were thought to have aged significantly faster in higher temperature environments than they did in colder environments. At temperatures of 25 degrees Celsius and above, worms move, eat and digest food faster, mature faster and age faster than their counterparts at a more normal 20 degrees.

UCSF Professor Cynthia Kenyon, PhD, who was senior researcher on the paper, said that the accelerated aging process at higher temperatures occurred passively, in much the same way that a chemical reaction speeds up at higher temperatures. Until now the common assumption was that these worms could not keep themselves alive as long in these temperatures.

“We’ve shown it’s not so simple,” said Kenyon, a professor in the UCSF Department of Biochemistry and Biophysics and director of the Larry L. Hillblom Center for the Biology of Aging at UCSF. She is renowned for her ongoing research on C. elegans (Caenorhabditis elegans) and aging.

“It’s true that worms don’t regulate their body temperature, but they do regulate their response to high temperature, slowing down processes that would otherwise go much faster. In fact, they even use steroid hormones to do this, just as we do to regulate our temperature,” she said, noting that this might have been a very early evolutionary link between cold- and warm-blooded animals.

C. elegans has been known to have thermosensory or heat-sensing neurons, which allow the worms to move towards temperatures they associate with food. If the “chemical reaction” theory were accurate, worms at a constant hotter temperature would age at the same fast rate, whether their thermosensory neurons perceived the heat or not.

The researchers found that when they either killed the heat-sensing neurons or deactivated the worm’s genes that produce steroids, the worms had an even greater response to the heat, and as a result aged and died much faster than their counterparts with active neurons. The authors conclude that these heat-sensing neurons actually help the worm regulate its response to increasing heat like credit report services help you stay on top of your credit score.

“These findings probably won’t result in a new cure for cancer or Alzheimer’s,” she said. “But they may force us to rewrite the section on cold-blooded animals in high school biology textbooks.”